Design & optimization of modular tank systems for vehicle wash facilities

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1 Design & optimization of modular tank systems for vehicle wash facilities Dimensionering & optimering av modulära tanksystem för fordonstvättar Pontus Marco Faculty of Health, Science and Technology Degree Project for Master of Science in Engineering, Mechanical Engineering 30 hp Supervisor: Anders Gåård Examiner: Jens Bergström

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3 Abstract Keywords: Water reclamation system, Water treatment, Washing system, Modular, Tank system, Fluid flow, Microsoft Excel, Visual Basic for Applications Clean and safe water is important for the well being of all organisms on earth. Therefore, it is important to reduce harmful emissions from industrial processes that use water in different ways. In vehicle washing processes, water is used in high-pressure processes, as a medium for detergents, and for rinsing of vehicles. The wastewater produced by these functions passes through a water reclamation system. A water reclamation system has two main functions, to produce reusable water to be used in future washing cycles, and to separate contaminants and purify the wastewater so it can be released back into the commercial grid. The reclamation system achieves this by using a combination of different water handling processes, these include: sludge tanks, an oil-water separator, a water reclamation unit, buffer tanks, and a water purification unit. The two components that stand for the more advanced cleaning processes are the water reclamation unit and the water purification unit. In this thesis, in collaboration with the company Westmatic, the water reclamation unit consists of cyclone separators that use centrifugal forces to separate heavy particles and ozone treatment to break up organic substances and combat bad odors. The Purification unit of choice is an electrocoagulation unit that, by a direct current, creates flocculants of impurities that rises to the surface and can be mechanically removed in a water volume inside the unit. This purification process is completely chemical-free thus making the process more environmentally friendly than other purification processes used in other circumstances. This master thesis aimed to develop a dynamic design tool for a modular solution of the different parts in the water reclamation system. This design tool uses specific user input to produce construction information for each instance. As an additional sub-aim, this design tool was linked with a computer-aided design program to produce parametric 3D models with underlying blueprints. This to produce a light solution, that has a short manufacturing time and that are highly customer adjusted. The first course of action was to mathematically define the complete water reclamation system and its components. These sections were described in a flowchart that shows how the different parts interact and operate. From the wash station, wastewater runs trough a course- and fine-sludge tank. From the fine sludge tank, the wastewater is directed in two different directions. Firstly, the water is pumped to the water reclamation unit and to one or multiple buffer tanks to finally be used in the wash station as reclaimed water. Secondly, the water travels to an oil separator, pump chamber, and water purification unit. In the purification unit, 99% of the inlet mass is directed out of the system as purified water. The remaining 1% is directed to a depot that acts like the end stage of the whole system. After all equations were defined and the design was related to the user-defined input flow the design tool was structured. The program of choice to house the design tool is Microsoft Excel. In this Excel document, a user interface with navigation was constructed and the intended user is directed through a series of input pages where input data is defined. This data is used in a normally hidden page where constructional dimensions are calculated. The constructional dimensions are displayed to the user on the second last page. At this stage the Excel document can be connected to a CAD program and 3D models with blueprints can be opened that depend on the output from the Excel file. Additionally, a pipe calculator is provided on the last page of the Excel document where pipe dimensions for different cases can be found. With this solution, glass fiber tanks are molded according to the resulting blueprints that are customer specific. In this way the solution is more adaptive and easier to handle. Additionally, the provided design tool enables an easier and more well-defined methodology when deriving the different needed volume and accompanied constructional dimensions for an arbitrary water reclamation system. I

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5 Sammanfattning Rent och säkert vatten är viktigt för alla organismer. Därför är det viktigt att minska skadliga utsläpp från industriella processer som använder sig av vatten på olika sätt. I fordonstvätthallar används vatten i högtrycksfunktioner, som ett medium för tvättmedel och för sköljning av fordon. Avfallsvatten som produceras av dessa funktioner passerar genom ett vattenåtervinningssystem. Vattenåtervinningssystemet har två huvudfunktioner, att framställa återvunnet vatten som kan användas i framtida tvättcykler, och att rena avfallsvattnet så att det kan släppas ut till avlopp. Återvinningssystemet uppnår detta genom att använda en kombination av olika vattenhanteringsprocesser, dessa inkluderar: slambehållare, en olja-vattenavskiljare, en vattenåtervinningsenhet, buffertankar och en vattenreningsenhet. De två komponenterna som står för de mer avancerade rengöringsprocesserna är vattenåtervinningsenheten och vattenreningsenheten. I denna avhandling, i samarbete med företaget Westmatic, består vattenåtervinningsenheten av cyklonseparatorer som använder centrifugalkrafter för att separera tunga partiklar och en ozonbehandling för att bryta upp organiska ämnen och bekämpa dålig lukt. Reningsenheten som används är en elektrokoagulationsenhet som med likström skapar flocks utav föroreningarna som sedan stiger upp till ytan och kan tas bort mekaniskt inuti enheten. Denna reningsprocess är helt kemikaliefri vilket gör processen mer miljövänlig än andra reningsprocesser som används under andra omständigheter. Syftet med denna avhandling är att utveckla ett dynamiskt designverktyg för modulära lösningar av de olika delarna i ett vattenåtervinningssystem. Detta designverktyg använder sig av användarinmatning för att producera specifika konstruktionsunderlag. Som ett ytterligare delmål, skall detta designverktyg kopplas till ett CAD program för att producera parameterstyrda 3D-modeller med tillhörande ritningar. Detta för att producera en lätt lösning, som har kortare tillverkningstid än tidigare lösningar och som har en hög anpassningsbarhet. Det första steget var att matematiskt definiera hela vattenåtervinningssystemet och dess komponenter. Detta beskrivs i ett flödesschema som visar hur de olika delarna samverkar och fungerar. Från tvättstationen går avloppsvatten genom en grovslams- och finslamsbehållare. Från finslamsbehållaren riktas avloppsvattnet i två olika riktningar. I den första riktningen pumpas vattnet till vattenåtervinningsenheten, sen till en eller flera buffertankar för att slutligen återanvändas i tvättstationen. I den andra riktningen flödar vattnet till en oljeseparator, pumpkammare och vattenreningsenhet. I reningsenheten skickas 99% av inloppsmassan ut från systemet som renat vatten. De återstående 1% skickas till en deponikammare som fungerar som slutsteg för hela systemet. När alla ekvationer är definierade och relaterade till det användardefinierade ingångsflödet kan de användas i programmet. Programmet som användes för att bygga designverktyget är Microsoft Excel. I detta Excel-dokument konstruerades ett användargränssnitt med ett navigeringsfält som leder den avsedda användaren genom en serie av inmatningssidor där inmatning av data sker. Denna data används i ett dolt blad där konstruktionsmått beräknas. Konstruktionsmåtten visas sedan för användaren på den näst sista sidan. I detta skede kan Excel-dokumentet anslutas till ett CAD-program och 3D-modeller med ritningar kan öppnas som då beror på datan från Excel-filen. Utöver detta finns en rörkalkylator på sista sidan i Excel-dokumentet där rördimensioner för olika fall kan tas fram. Med denna lösning formas glasfiberbehållare enligt de resulterande ritningar som är väl kundanpassade. På detta sätt är lösningen mer anpassningsbar än tidigare och dessutom lättare att hantera. Utöver detta, möjliggör konstruktionsverktyget en enklare och mer väldefinierad metodik när olika volymen och tillhörande konstruktionsdimensioner för olika delar i ett godtyckligt vattenåtervinningssystem ska tas fram. II

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7 Nomenclature V Volume [m 3 ] Q Volume flow [l{min] v setteling, v rising Settling/rising velocity of particles/droplets [m{s] ρ Density of a material [kg{m 3 ] µ Fluid viscosity [mp as] g Gravity factor [m{s 2 ] r p, r d Particle/droplet radius [m] h w Water level/height [m] s 1, s 2 Separating factors Unitless N S Nominal size (defined in SS-EN 858) [l{s] f x Hindrance (category) factor Unitless f d Density factor Unitless f f FAME factor Unitless t cyc Wash cycle time for different wash zones [min] t rest Minimum resting time between wash cycles [min] n cyc Number of washing cycles per hour Unitless n buffer Number of x-liter buffer tanks [l] D cyl Cylinder diameter [m] v Flow velocity [m/s] Re Reynolds number Unitless p Pressure [Pa] d pipe Pipe diameter [m] l pipe Nominal pipe length [m] h Height [m] α fall Decline percentage [%] λ Friction coefficient Unitless k Pipe roughness [m] d h Hydraulic diameter [m] S Fluid affected circumference [m] A Cross-section area [m] θ Angle [rad] l Nominal lengths [m] R Cylinder radius [m] t Wall thickness [m] s f Safety factor Unitless n 1st, n 2nd Number of cylindrical segments for the glass fiber tanks Unitless l 1st real, l 2nd real Total/real lengths of the first and second tank [m] III

8 Contents Abstract Sammanfattning Nomenclature I II III 1 Introduction Background Water treatment systems for washing solutions Wash systems Water reclamation systems Purpose and aim Sub-Aim Delimitations System description Parameters and input Modeling of different sections Sludge trench with grating Sludge tanks Oil separator Water reclamation Buffer tank Pump chamber Water purification Depot Connecting pipes Constructional design Glass fiber tanks First tank and buffer tank Second tank Excel program/design tool General design tool layout Input page(s) Data summary & configurations Equations Output summary Pipe calculator Help page CAD extension D models Result and program example 50 6 Discussion Old vs New solution Buffer tanks and WWR unit Excel and CAD Outcome and aims Future Work Conclusion 59 8 Acknowledgments 60 References 61 Appendices 63 IV

9 1 Introduction When different vehicles are cleaned; metals, oils, and other organic or inorganic substances get released. These contaminants are released, either into the ground for outdoor/open washing, or enters the water system in a washing facility. For obvious reasons the latter is preferred so that the waste can be treated properly. The contaminants originate from different sources, they can come from the chemicals in the washing system, dirt, and debris from the road surface, the vehicle itself, or its tires. Pollutant from the paving often contains, among other things, particles from tires, metals, asphalt, oils, salt, sand, fuel, etc, and depends on the season and other geographical factors. From the vehicle manly heavy-metal contaminants get released like cadmium from some types of varnish and zinc from tire particles. The pollution emission is in general greater under the winter portion of the year compared to the summer part of the year due to tougher cleaning conditions [1]. To reduce harmful emissions different water treatment and water recycling systems are implemented in washing facilities to reduce the usage of fresh water. The amount of harmful substances and pollutants in the facility wastewater can differ greatly from company to company. The variation in emissions depends heavily on the complexity of the water treatment portion of the facility. The reuse of water is both environmentally and financially beneficial. This is important to be able to stay competitive in the open market. Westmatic is a company that develops, manufactures, sells, and maintains automatic washing systems for heavy vehicles and purifies water for the industry. These washing facilities include several different sections such as water treatment systems, brushes, and various washbasins. The design of these sections depends heavily on the customer and to get the best effect with as little water waste as possible, the system should be as modular and customizable as possible [1, 2]. 1.1 Background Clean and safe water plays a vital role in the well being of humans, plants, and animals alike. Water is needed to break down and transport substances to different parts of the body. If the water gets contaminated by toxins or other pollution, it must be treated and cleaned before it can safely be consumed [3]. As industries have grown over the past, water has been more and more contaminated. As a result, the recognition of the need for clean water and water scarcity has come more into focus. Alongside this realization more developed water treatment techniques have been researched that uses chemicals, finer materials, or electricity. One result of developments in the implementation of the Clean Water Act in 1972 in the US, otherwise known as Federal Water Pollution Control Act Amendments of This legislation was taken into effect to increase the control and regulate the discharge of untreated wastewater from municipalities, industries, and businesses into different bodies of water (like rivers, lakes, etc) [4, 5]. Even though actions already have been taken to improve the usage of water, the importance of the continuation to improve our water management is still very much relevant. Global water scarcity analyses conclude that up to two-thirds of the world s population will be affected by water scarcity in the near future. Assuming that the world s population keeps growing, the available clean water per capital will decrease and the importance of water management will increase [6, 7]. In industrial applications, water is used in cooling systems, transportation, and washing systems as a solvent and sometimes also as a component of the final product. Cooling systems for thermal and atomic power generation is the major water user. In these applications, a great amount of water is used in cooling assemblies, which, often is kept as closed systems to limit polluted water emissions [8]. 1

10 Vehicle cleaning facilities, however, are one example where, in its simplest form with manual wash stations, an inlet of clean water is used and leaves the process polluted or degraded in some form. Heavy vehicles like buses, trucks, and train locomotives, however, are usually washed in automatic washing facilities where the water can be treated before exiting the system. In Sweden, there are approximately 300 automatic washing stations for buses and trucks. The water usage for these applications differs depending on the type of vehicle and facility and according to Naturvårdsverket [1] the usage can be up to liters per wash cycle for these large vehicles. The numbers can be reduced greatly to liters per wash cycle for facilities with a high water-recycle rate (about 80%). Since vehicle washing is a high water-consuming process that generates wastewater, restrictive legislation pushes the car wash industry to invest in more and better process-integrated solutions, mainly in Europe, Australia, and in the US. The idea is to make the processes more eco-friendly through the use of reclaimed (reused/recycled) water [9]. The requirement to reuse the water is that wastewater needs to undergo separation of grit, oils, and greases. Additional purification processes can then be implemented to allow the reclaimed water to be used in more washing steps (like pre-soaking, wash, and rinse steps) [10]. Decentralized (on-site) water reclamation enables multiple ways to process wastewater and use the water in future cleaning cycles, thus, reducing the usage of fresh water. The use of reclaimed water will decrease the water use significantly since it can be used in all stages of the cleaning cycle except for the final rinsing and/or when applying certain detergents. There are multiple technologies that can be used in a cleaning process in combination with vehicle washing facilities and some examples are given below [9]. Cleaning processes: Flocculation-column-flotation (FCF) FCF is a compact flocculation-flotation unit that is used for solid/liquid separation when treating wastewater from vehicle washes [11]. By implementing an FCF unit to a system, water reclamation as high as 70% can be achieved. The process used in FCF units is called hydraulic flocculation and three main features affect this process. The first one is the generation of bubbles from centrifugal pumps on the bottom of the water volume. The second is the size of the flocs and generated bubbles in the system. The third is the size of the separating column where the separation takes palace. To improve the efficiency of the flocculation process for high-velocity gradients, a plug flow device (a steady-state channel) is implemented. The plug flow device aids the floc/bubble contact to generate the so-called aerated flocs. Additionally, the use of centrifugal pumps as the means to generate microbubbles in the system is a more cost-efficient and safer method than conventional saturation vessels [10]. The interaction mechanisms between microbubbles and particles (flocs) in the FCF process are: Adhesion through hydrophobic forces. Microbubbles nucleation phenomena at solid surfaces. Microbubbles entrapment or physical trapping inside the flocs. Aggregates entrainment. The rising rate of the aggregates is dependent on the number of bubbles attached to and entrapped inside the flocs. The flocs rise to the top of the column and create a top layer that consists of a mixture of foam and aerated flocs with cleaner water substances on the bottom. This sectioning enables the removal of oil/grease, metallic ions, solids removal, and deinking of wastewater [10]. Figure 1 shows an example of an FCF unit. 2

11 Figure 1: FCF unit: 1. Centrifugal multiphase pump, 2. diaphragm pump for reagent dosing, 3. diaphragm pump for ph regulator 4. flocculation unit, 5. column flotation, 6. column flotation water level control, 7. purified water tank, 8. sand filtration, 9. sodium hypochlorite dosing pump, 10. Sludge dewatering. [10] Electrocoagulation Electrocoagulation is a treatment process that generates coagulants of impurities in the wastewater by using direct current between an anode and a cathode. The anodes are often made of aluminum and the coagulant or floc binds impurities in the same way as processes that uses chemical cleaning. The main advantage of using electrocoagulation instead of chemical coagulation processes is that electrocoagulation doesn t require the addition of chemicals. Additionally, the electrolytic process that takes place in the electrocoagulation treatment is generally more efficient [1, 12]. This water cleaning process is used by many companies including Westmatic and as mentioned this method uses current between a cathode and an anode. The cathode is made of stainless steel and the anode is made of an aluminum alloy. The type of aluminum alloy will affect the efficiency of the cleaning process. In the electrolytic process water is reduced to either hydrogen gas (H 2 ) and/or oxygen gas (O 2 ). The micro-bubbles (approx. 20 µm in diameter) rise slowly towards the surface and collides with emulsified or dispersed contaminants like oil or heavy metals. This produces flocculants on the top surface of the tank that can be removed mechanically. In this way, about 80% of the impurities may be removed. To separate the remaining 20%, special aluminum alloys need to be used and the choice of alloy depends on the contaminants to be removed among other things [13]. Figure 2a describes a sketch of an electrocoagulation cell and figure 2b shows the electrocoagulation unit used by Westmatic. (a) Principal sketch of an electrocoagulation cell. [12] (b) Electrocoagulation unit used by Westmatic. [14] Figure 2: Electrocoagulation cell and unit. 3

12 Ultrafiltration membranes Ultrafiltration membranes have been proven to reduce the presence of certain harmful substances in the cleaned water but this technology should be combined with other methods to get proper refinement of the wastewater [15]. Ultrafiltration modules filter the direct flow of passing wastewater and collects impurities. These modules need to be cleaned to prevent build-up that can be done by switching the flow direction of the water to a clean cross-flow and flush away debris with water and air. This is usually done in intervals and the process takes several seconds. Normally, ultra- or microfiltrations membranes are placed behind sedimentation and sand filtration modules [16]. Sand filtration Slow sand filtration (SSF) is one of the oldest forms of water treatment dating back to the 19th century. SSF lost its popularity to rapid sand filtration (RSF) which produces greater water quality in a more compact format. SSF solutions are still used today due to its benefits of lower energy requirements, low chemical use, and simplicity. SSF systems provide a single-stage treatment of wastewater that uses gravity to filter water through different sand/gravel beds. The process can take up to 12 hours depending on the system [17]. Both slow sand filtration and rapid sand filtration uses mechanisms like mechanical straining, physical absorption, and reduction. Rapid sand filtration solution can produce faster cleaning solutions than SSF with the help of chemicals or pressure but is limited in filtering volume and underperforms slightly in comparison with SSF solutions [17, 18]. Figure 3 shows an example of a RSF unit. Figure 3: Example of pressurized RSF. [18] One other method to reduce the use of fresh tap water that isn t about processing wastewater is the implementation of rainwater collections systems. Rainwater collection systems have the potential to save water up to about 70% but the efficiency differs much depending on geographic location, roof surface, and tank capabilities [19]. Most often there are multiple sections with different processes that work together to create a vehicle wash reclamation systems. The most important compartments are oil-water separator systems, sludge removal system and some sort of water purification system like multimedia/sand filters or different flocculation system as mentioned earlier [10, 20]. The washing systems discussed so far can be used to clean a wide range of vehicles that are exposed to different types and amounts of dirt. The type of vehicle and dirt dictates what wash process is needed and hence, the configuration of the wash facility and water reclamation system. For a company that manufactures complete washing solutions and that has a lot of different customers with different needs, it is important to efficiently design a wide variety of water reclamation systems. If a design tool is developed that considers each specific customer needs as variables, these companies could use that tool to efficiently design a modular system for each customer. 4

13 1.2 Water treatment systems for washing solutions Wash systems The two categories of washing systems that use water treatment systems are automatic and manual systems. Manual systems are more commonly used for smaller private cars and aren t relevant for this study. Automatic systems however are used for all kinds of vehicles ranging from train locomotives to heavy-duty mining vehicles to privately own cars. There is no correct or perfect kind of water treatment system. The system configuration differs depending on the circumstances around the facilities; mainly what vehicles are being washed, what environments these vehicles are exposed to, and how often the washing takes place. These systems are almost always accompanied by some other facility like gas stations, maintenance shops, or storage units but there are also stand-alone systems available for the public. In these washing systems different programs are used to wash the vehicles in different ways, figure 4 describes some of the often used programs [1]. Figure 4: Example of washing programs, translated from [1]. The user can choose between the programs to receive the proper wash program for their specific need. Depending on the wash program and what options are available in the wash system, different volumes of liquid and type of chemicals will enter the water cleaning system of the facility. In the prewash, if the vehicle doesn t need heavy cleaning, foam shampoo can be sufficient, otherwise different degreasers can be used. The actual cleaning takes place in the main wash where vehicles can be mechanically washed with brushes and high-pressure streams in combination with detergents. Following the main wash is rinsing and drying steps where potential draining agents and waxes can be applied [1]. The time it takes to complete a washing cycle differs a lot depending on facility configurations and washing program. This will affect the amount of water needed in the system for both the vehicle washing and water cleaning portion of the facility. For a private car, a wash cycle is about 6 to 8 minutes while for standard European trucks and train locomotives, the washing time can differ between 7-14 meters/minutes to 30-60m/min respectively [1, 21] Water reclamation systems As mentioned in chapter 1.1 there are different ways to handle the wastewater from the washing system in a car wash facility. Figure 5-7 describes an overview of the different sections in a reclamation system [1]. Here we can find parts like sludge tanks, recycling(purification) modules, and different separators. In a chemical reclamation system like the one in figure 5, different sludge tanks and oil separators are used to filter the wastewater before final treatment with chemicals. The chemicals typically used in this type of system are flocculants like Polyaluminium chloride and ph controlling chemicals like lye. The system is sometimes complemented with a sand filtration unit to remove residual particles in the water [1]. 5

14 Figure 5: Example of a chemical reclamation system, translated from [1]. A variation of the reclamation system in figure 5 is a closed system seen in fig. 6. Here other challenges are presented regarding the reuse of chemicals and water alike. The big advantage of a closed system is that it minimizes the water used in wash cycles through water reuse. Small compensations with tap water are however, needed to compensate for evaporation and other water losses [1]. Figure 6: Example of a closed reclamation system, translated from [1]. Figure 7 shows a water reclamation system that was implemented in Brazil were a three-stage oil separator, sand filtration, and FCF were used to purify and reuse the wash water. This washing facility also had various sampling points to test the water at different stages in the cleaning process [10]. 6

15 Figure 7: Example of a car water reclamation system. [10] As discussed, different facilities use different water reclamation systems for many reasons. This thesis will focus on the water reclamation system by Westmatic in Arvika, Sweden. The overview of the system is described in figure 8. It is the construction of this system that will be considered while developing a design tool for a water reclamation system [22]. Figure 8: Water reclamation system used by Westmatic. [22 24] 7

16 1.3 Purpose and aim This thesis will focus on the development of a design tool with a focus on the water treatment section of a vehicle washing system. The tool will take critical parameters in consideration that, through a suitable software, results in construction specifications for future products. The future product consists of glass fiber tanks rather the previously used concrete tanks. The specifications will be dependent on customer demand and should be accompanied with simple 2D sketches. This project aims to facilitate the development of future customer-optimized tank systems with the help of a design tool with the purpose of making the development of new water reclamation systems faster and easier Sub-Aim If time is sufficient, the design tool (or resulting output file from the design tool) will be ported to a CAD program (preferably Inventor) and parametric 3D models with underlying blueprints will be outlined. 1.4 Delimitations To limit the project to a reasonable and feasible level the following delimitation were defined. Sizing of the vehicle cleaning portion of the system was excluded. Sizing and determinations regarding electrical flocking processes in the system were excluded. While sizing buffer tanks, the options to consider were one or multiple 1600 liter tanks. 2D drawing to illustrate solutions is sufficient. Only major components like pipes and tanks were taken into consideration while sizing the system. Other information was provided by Westmatic. The environment exposure and geological location of the final product was not taken into consideration. How the vehicle type affects the system was not taken into consideration. Possible phase transitions of the fluids in the system were not taken into consideration. Mass flow simulations to verify results was not conducted. 8

17 2 System description This chapter concludes detailed descriptions for each section in a water reclamation system as well as the definition of user-defined parameters and inputs. The water treatment system to be designed consisted of two containers with different sections. The sections are described in more detail in chapter 2.2 and they need to be defined mathematically. Other components in the systems like buffer tanks and water treatment sections will be external in relation to the tanks. The external sections were however still part of the system. The parameters that affected the design and function of the sections needed to be defined and a mathematical relation between each section was formulated to define the system. The collaborating party to this thesis work, Westmatic, had defined constructional constraints to fit their needs that were as follows: The solution should be contained within two cylindrical glass fiber reinforced polyester tanks with different partitions. The first tank included the coarse sludge tank, the fine sludge tank, and the oil separator. The second tank included the pump chamber and depot. The wastewater originated from a sludge trench and proceeded in sections described in figure 8. One class 1 oil separator was used. The tanks should be installed underground and connected to relevant systems above ground with suitable piping. The glass fiber tanks had a fixed outer diameter of 2000 mm. If possible, the underground tanks should be constructed from 2780 mm long cylindrical segments. The water level inside the tanks was kept at 1750 mm. The tanks had a wall thickness of 10 mm. Separating walls within the tanks had a wall thickness of 10 mm. The spherical ends of the cylinders extended 400 mm. The buffer tanks consisted of one or multiple 1600 liter tanks in series. The decline for connecting pipes without accompanied pumps was defined as 1%. 2.1 Parameters and input The design of the system was heavily dependent on the user input. The input was inserted into the first pages of the program and together with configurations (like constant parameters from predefined standards or constant dimensions) on the following page, all other dimensions regarding the water reclamation system should be defined. Some inputs did not affect this version of the design tool and were added for future development. These inputs were trench type (dry or wet) with accompanied dimension if a wet trench is used and type of vehicle to be washed (truck, bus, train locomotive, etc). The inputs that do affect the dimensions of the final product are parameters regarding the vehicle washing portion of the facility and the necessary water flow associated with the configuration. The washing portion was divided into three zones, Freestanding equipment between entry and machine, Onboard equipment and Freestanding equipment between machine and exit. The different functions 9

18 and choices in these zones can be found in appendix A in more detail. Two other important input that is provided by the user to design the buffer tank(s) and the pump chamber was the number of wash cycles per hour and the shortest time between said wash cycles. 2.2 Modeling of different sections As seen in figure 8 the different sections that were included in the water treatment system was a sludge trench with grating, a coarse sludge tank, a fine sludge tank, a water reclamation unit, one or multiple buffer tanks, a oil separator, a pump chamber, a water purification unit and a depot. The sludge trench was a physical part floor in the washing station and the water reclamation unit, buffer tanks, and water purification unit were external machines with fixed designs. The following sections describe some general information regarding each section and how they affect the system mathematically. An overview of the different flows and tanks in the system and how they are relating to each other can be seen in figure 9. Figure 9: Overview of included system and relevant flows Sludge trench with grating General information The sludge trench is the first part of the facility that collects dirt and grime. There are two different types of sludge trenches; dry and wet. The wet type is always full of water and the overflow flows through a strainer and then to the sludge tanks. The dry type can t keep a water volume, instead, the wash water flows directly through the strainer to the sludge tanks. Here, the most coarse types of dirt and debris get collected like stone/gravel, tree branches, and ice chunks. When the trench is full it s typically emptied with an excavator. In figure 10 the coarse strainer can be seen at the end of the sludge trench as well as a dredging tube. 10

19 Figure 10: Cross-section of a typical wet sludge trench with dredge tubing, translated from [25]. Equations The only parameter that relates to this section is inlet flow that depends on the inlet flow of reclaimed water and tap water into the wash section. This flow varies depending on what washing zone is operational and its relation is defined as equation 1. Since this parameter originated from user-defined input the trench flow was defined as the input flow. The maximum input flow (equation 2) is simply the maximum sum of the tap water flow and reclaimed water flow. Q inputi Q trenchi Q tapi ` Q reci, i 1, 2, 3 (1) Q inputmax pq tapi ` Q reci q max (2) The inlet flow of reclaimed water (Q reci ) and tap water (Q tapi ) is simply the sum of the respective flows from the function library that the user has entered into the system and the i:th, value represents each zone Sludge tanks General information Sludge tanks are used to separate heavy solids from the wastewater. Most often multiple sludge tanks are used in series to separate more particles. In this particular case, two sludge tanks were used, one for coarse particles and one for finer particles. Heavy particles sink to the bottom of the tanks and cleaner water spills over to the next tank. In this gravimetric process solids are collected on the bottom of the tanks and cleaner water is allowed to pass on in the system. To prevent turbulence the inlet pipe in the coarse sludge tank is mounted behind a screen or under the water surface. The fine sludge tank works and is constructed in the same way as the course sludge tank with the exception of an additional outlet to the water reclamation unit. The water level is constant in both tanks while the washing process takes place, this means that for the course tank, the inlet flow equals the exit volume flow. In the same way, in the fine sludge tank the inlet flow equals the sum of the two outlet flows (one for the oil separator and one for the water reclamation unit). 11

20 Equations As mentioned, to keep the same water level in the coarse tank, the inlet flow must be the same as the outlet flow, see equation 3. The flow is the same as the input flow from the trench. The water level in the fine sludge tank, however, can vary when the washing process is inactive since there is an additional outlet to the water reclamation unit (Q W R ), see equation 4. The flow entering the fine sludge tank equals the output flow from the course sludge tank i.e. the input flow. Q coarsein Q coarseout Q input (3) Q finein Q oil ` Q W R Q input (4) The tank volume will depend on how long time it takes for the impurities to separate from the fluid flow. This can be described with the help of Stokes law according to equation 5 which is dependent on multiple factors like fluid viscosity, particle density, and particle size among other things [26]. The tank volume will then affect the construction dimensions which are described in chapter 3. v settling 2 9 where, v settling = settling velocity for a particle ρ p, ρ f = particle and fluid density µ = fluid viscosity g = gravity factor r p = particle radii ρp ρ f µ g rp 2 (5) This equation in combination of settling distance and volume flow can then provide the volume of the tank. The design of the settling tank(s) will follow the settling tank section of the Swedish SS-EN 858 standard for oil separators where the previously mentioned equations and cases are already taken into account. This standard is further described in chapter The combined volume of the fine and coarse sludge tanks will be according to equation 6. The minimum volume for this value is 5000 liters according to the SS-EN 858 standard for automatic car washes [27]. V sludge N S 300 f d (6) Where V sludge is in liter when N S is the nominal size of the oil separator in [l/s] and f d is the density factor. The N S factor in this case, will be defined according to equation 14 with Q s as the flow through the sludge tanks i.e. Q coarse Q input. Knowing this, when equation 14 is combined with 6, the expanded equation 7, which, is dependent on Q input is found. V sludge 300 f x f f Q input (7) 12

21 To properly scale the volume to the system, a separating factor s 1 that can range from 0 to 1 was implemented. Suggestively, this factor should be 3/4 according to norms used in local glass fiber tank manufacturers that collaborate with Westmatic. The final sludge tank volume will then be described as equation 8. V sludge s f x f f Q input (8) To differentiate between the volume for the course and fine sludge tank an additional factor, s 2 that ranges from 0 to 1 is multiplied with V sludge to compute the volume for the course portion of the whole sludge tank. s 2 is suggestively a factor of 2/3 so that the volume for the course sludge tank again follows norms used by local manufacturers. The volume for respective sludge compartment is described according to equation 9 and 10. V coarse s 2 V sludge (9) V fine 1 s 2 V sludge (10) Both s 1 and s 2 is provided as a configuration factor in the program/design tool Oil separator General information After the fine sludge tank, the remaining wastewater needs to be separated from polluting oils. This is done in the oil-water separator where lighter oils accumulate in droplets and rises to the surface. The clean water is then extracted from under the water surface to avoid the oil layer on top of the surface. The design, use, and installation of oil separators in Sweden must compile with the Swedish standard SS-EN 858 for oil-water separators. Oil droplets can be present in water as free oil (with a diameter of >150 µm), dispersed oil ( µm), emulsified oil (5-20 µm), and/or soluble oil (<5 µm). Oil that is in free and dispersed forms has droplets big enough to efficiently be removed by oil separators. Emulsified and/or soluble oil in the wastewater is most often caused by detergents used in the cleaning portion of the facility prior to the reclamation process of the wastewater and this type of oil cannot be removed with oil separators. Instead, other methods like extraction, absorption, or ultrafiltration are used [10, 28]. Figure 11 shows a principal sketch of a small vertical underground oil separator of class II that only uses gravimetric measures to separate oil from water. 13

22 Figure 11: Principal sketch of a class II oil separator. [27] For oil separators to work properly the fluid in the tank should flow as close to laminar flow as possible and the oil droplets should be big enough to rise to the surface during their time in the tank [27]. This principle on it owns only works practically with droplets that are bigger than 150 µm. With smaller droplets, the gravimetric separation takes too long to be practical. To separate smaller oil droplets in a reasonable time coalescing material is used. Coalescing material can be a filtering cloth (12a) or filtering lamella (12b) and their function is to bring small droplets together to make them bigger so they can rise faster. The use of these filters makes it hard to estimate the volume of the oil separator with the help of rising velocity (see equation 11) and residence times. Instead, the design should follow the SS-EN 858 standard. (a) Filtering cloth. (b) Filtering lamella. Figure 12: Coalescing material. [27] 14

23 SS-EN 858 The SS-EN 858 standard is divided into two parts; SS-EN and SS-EN The first part relates to definitions, nominal sizes, classifications, and testing among other things seen in figure 13. The second part relates to design, installation, and maintenance. As mentioned, there are two classes of oil separators, class I (see 14a) and class II (see 14b). A class I separator has a maximum permissible content of residual oil of 5 mg{l while a class II separator is allowed to have an oil content of 100 mg{l when tested. Oil separators with different classifications can be used in the same system or by themself. In this case, one class I separator was used. The standard also states that a class I separator uses coalescing separators, while a class II only uses gravimetric processes. Along with this information, details about manufacturing methods/materials, connection types, and test methods are provided. In this report the design aspects of the dimensions are in focus. Figure 13: Content of the Swedish standard SS-EN 858. (a) Class I (b) Class II Figure 14: Oil-water separators. [29] Equations Stokes law for liquid droplets in fluids where the positive direction is upwards, equation 11 [26]: vrising 2 ρf ρo g rd2 9 µ 15 (11)

24 where, v rising = rising velocity for a droplet ρ o, ρ f = oil and fluid density µ = fluid viscosity g = gravity factor r d = droplet radii Like the sludge tanks, the water level in the oil separator is kept constant so that the outlet flow equals the inlet flow. The flow is equal to the flow from the fine sludge tank (equation 12). By rewriting equation 4 the relation between the volume flow through the oil separator and the input is simply described in equation 13. Q oilin Q oilout (12) Q oil Q input Q W R (13) According to SS-EN 858-2, the design of an oil separator is dependent on its nominal size (N S ) according to equation 14 [27, 29]. where, N S = Nominal size [l/s] Q r = Total rainwater flow [l/s] f x = Hindrance (Category) factor Q s = Total wastewater flow [l/s] f d = Density factor f f = FAME factor N S pq r ` f x Q s q f d f f (14) For this vehicle washing system Q r is negligible because of the physical placement and use. Q s is the flow through the section to be designed. For the oil separator, this means that the total wastewater flow equals the flow in the oil separator from equation 13. The value of the hindrance factor depends on what environment the tank is connected to according to table 1. Table 1: Hindrance factor f x. Discharge type Hindrance factor f x Wastewater from industrial processes, vehicle washing, 2 cleansing of oil-covered parts, or other sources. Rainwater (run-off) that is contaminated with oil from Not relevant, Q s =0 (only impervious areas, e.g. car parks, roads, factory yards rainwater) areas. Spillage from surrounding area 1 The density factor depends on what class of oil separator is used and what density the oil in the system has. This is described in table 2. 16

25 Table 2: Density factor f d for light liquids. Density g{cm 3 ď0,85 0,85-0,90 0,90-0,95 Separator class Density factor f d Class I Class II 1 1,5 2 Class I & II The FAME factor depends on the percentage of biodiesel in the system as well as the separation class according to table 3. Table 3: FAME factor f f. Part biodiesel % ď5% 5-10% ě10% Separator class FAME factor f f Class I Class II 1 1,5 2 Class I & II The volume of the oil separator tank can be described in the same way as the volume for the sludge tank according to equation 6 but with Q s as the flow through the oil tank according to equation 13. The formula for the volume is found when equation 6, 13 and 14 are combined into equation 15 which is defined in liters when the volume flows are inputted as l/min. The minimum value for this volume is the same minimum volume that is defined for the sludge tank. V oil 300 f x f f pq input Q W R q (15) In the same way as for the sludge tanks, an additional term is added to this equation that depends on the s 1 factor mentioned earlier. The final volume will then be described by equation 16 below. V oil p1 s 1 q 300 f x f f pq input Q W R q (16) Water reclamation General information The water reclamation unit is used to remove the remaining particles and dirt from the water coming from the sludge tanks. This water can then be reused in the next washing cycle to reduce the use of fresh tap water. The reclamation unit used by Westmatic (fig. 15) uses a cyclone separator (hydrocyclone) and an ozone generator to clean wastewater into reclaimed water. Two different units are used by Westmatic and these are both the WWR-110 and WWR-220 units. These operate at a pressure of 3-4 bars. They differ in size and flow and the 110 unit has a small internal buffer tank with a volume of 520 liters. 17

26 Figure 15: Water reclamation unit WWR 220 used by Westmatic. [30] Cyclone separator The hydrocyclone typically used in vehicle facilities can remove solid particles with a size as small as 10 µm [1, 23]. The general function of a cyclone separator is to use centrifugal forces and pressure to separate particles from liquid, this can be seen in figure 16. When these centrifugal forces are created, high-density particles are pushed towards the walls of the cone. The high-density particles wander alongside the walls to the outlet at the bottom. The efficiency of separation in a hydrocyclone is based on the design angles, diameters, and flow through the cyclone [31]. This system can recycle up to 85% of the inlet wastewater to be reused in future washing processes, thus, reducing the use of fresh tap water as mentioned earlier. The separated particles are directed back to the sludge trench, or into the ground separation tank. The reclamation unit and fitted hydrocyclone can be seen in figure 15. When higher flows of water are needed, multiple cyclones can be parallel connected to get a balanced flow and particle separation [30]. 18

27 Figure 16: Principal function of a hydrocyclone. [31] Ozone treatment Ozone treatment is a process where heavy oxidation occurs in water due to the addition of oxygen. This process is needed to reduce bad odors in reclaimed water. This process is, therefore, often used in combination with buffer tanks where water can be still for long periods of time. Since ozone is a powerful oxidizing agent it has the ability to break down certain organic substances. The ozone will also reduce the presence of microorganisms that can contribute to bad odors in still waters. Two other methods that combat bad odors is the use of UV-treatments or aeration of the system [1]. Equations Since the water reclamation system is predefined as a WWR-110 or WWR-220 unit the only interesting parameters for this thesis is the flow for each unit. The flow will be the flow that fills the buffer tanks and that can continue even when the washing system is inactive. The available choices are defined in table 4. Table 4: Volume flow for each WWR unit. WWR type Flow [l/min] WWR WWR To be able to determine what unit to use, the Q W R flow is related to the buffer tank and Q reci flows. To satisfy equation 20 as well as possible, if the condition in equation 17 is met, WWR-110 should be chosen and otherwise WWR-220 is chosen. Practically, to fully accomplish that the buffer isn t overfilling, the operational time of the water reclamation unit will be regulated over time with switches. 3ÿ pq reci t cyci q ă Q W Rmax i 1 3ÿ t cyci (17) i 1 19

28 where, QW Rmax is the largest flow for the two water reclamation units. Qreci and tcyci are the reclaimed water flow and cycle time for each wash zone respectively Buffer tank General information The function of the buffer tanks in the system is simply to provide the washing system with reclaimed water. The buffer tanks are predefined as one or multiple 1600 liter tanks with fixed dimensions according to chapter 2. The buffer tank as shown in figure 17 has connected pumps to pump the reclaimed water to the car wash. Figure 17: Buffer tank and pumps used by Westmatic. [22] Equations The water volume of the buffer tank is defined by the differences between the outlet flow of the tank(s) and the inlet flow from the reclamation system. The flow of reclaimed water used in the washing system is user-defined and will vary depending on what zone is operational. The minimum water volume for one wash cycle will be the sum of the net outflow from the tanks times the wash cycle time for each section according to equation 18. Between each wash cycle, the reclamation unit can keep running to fill up the buffer tank(s) again. The volume that the reclamation unit provides during the resting time between cycles is defined by equation 19. Vbuf f ercyc 3 ÿ ` pqreci QW R q tcyci (18) i 1 Vbuf f errest QW R trest (19) where, ncyc = number of wash cycles per hour. trest = minimum time between wash cycles. The total water volume needed in the buffer tank(s) is described in two different cases and depends on the volume that is being emptied per cycle (Vbuf f ercyc ), the volume that is being 20

29 filled between each cycle and the number of cycles. In Case one described in equation 20, the refilling volume is less than the volume being drained for each cycle and, hence, the water level inside the tank(s) will gradually fall. In the second case, where the refilling volume (V bufferrest ) is bigger or equal to the draining volume (V buffercyc ), the buffer tank(s) will be reset and ready for use after each cycle and the total water volume needed can than be described as equation 21 below. To keep the buffer tank(s) from overfilling in the case where the refilling volume is bigger than the draining volume, the reclamation system is shut down with switches when the tank(s) is full. Case 1: V buffer V buffercyc n cyc V bufferrest pn cyc 1q (20) Case 2: V buffer V buffercyc (21) Additionally, for equation 20 to be valid the volume that enters the buffer tank should not be greater than the volume that is exiting the buffer tank under a wash cycle. As mentioned, this is helped by the choice of water reclamation units in equation 17 and by regulating the operation time of the reclamation unit. Depending on what water reclamation unit is used, the choice of number of x liter tank(s) differs. This can be described in three cases. Generally, in Case one, the volume will simply be decided according to equation 22 (x is defined according to chapter 2). However, if the reclamation unit in the system is the WWR-110 unit (with an internal buffer tank volume of 520 liters), and the necessary water volume is greater 520 liters, equation 22 is adjusted into equation 23 for Case 2. Finally for Case 3, if the WWR-110 unit is used but the necessary water volume is less or equal to 520 liters, there is no need for an external buffer tank i.e. equation 24. where n buffer is rounded up to the closest integer. Case 1: n buffer V buffer x (22) Case 2: n buffer V buffer 520 x (23) Case 3: n buffer 0 (24) Pump chamber General information The pump chamber is a simple section with similar functions as the buffer tank. Here water can be accumulated or emptied when the washing section is operational. At this point, the wastewater has passed through both the sludge tanks and the oil separator so the water present in the pump chamber is cleaned to a certain extent. The water needs, however, further purification before it can leave the system completely. The pump chamber provides water to the water purification unit that purifies the water as a final treatment step before releasing water back to the commercial grid. The pump chamber has one inlet and one outlet. The inlet flow is the same as the flow leaving the oil separator (equation 13) and the outlet flow depends on the water purification unit (Q pur ). Equations Since the pump chamber acts much like a buffer tank, the equations will be similar. The big difference is that during the resting period between washing cycles the chamber is being drained rather than filled. This means that the pump chamber is allowed to be both filled or drained during the washing cycle. 21

30 The net water volume that drains (or fills) the chamber per cycle (called the net cycle volume) is described in equation 25, while, the water volume that can be drained during the resting period is described in equation 26. V pumpcyc 3ÿ `Qpur pq inputi Q W R q t cyci i 1 (25) V pumprest Q pur t rest (26) where positive values for V pumpcyc represent the chamber being drained while a negative value represents the chamber being filled. The total water volume for the pump chamber differs in three different cases depending on the conditions of the flow through the input to the pump chamber (V pumpcyc ). For the first case, if the net cycle volume is positive, the water level in the chamber will be reduced for each cycle and the chamber doesn t need to be drained further between cycles. In this case, the purification unit is controlled to avoid the chamber running dry and the needed water volume is described by equation 27. For the second case, provided instead that the net cycle volume is negative (i.e. the chamber is filling up for each cycle), and if the absolute value for the rest volume (V pumprest ) is bigger or equal to the absolute value for the net cycle volume, the chamber is drained sufficiently between cycles and the needed water volume is instead described by equation 28. For the last case, again provided that the net cycle volume is negative but the rest volume is less than the absolute value of the net cycle volume, the water volume needs to be big enough for the system to properly function throughout all wash cycles and the water volume is described by equation 29. where V pumpmin Case 1: V pump V pumpmin (27) Case 2: V pump V pumpcyc (28) Case 3: V pump V pumpcyc n cyc V pumprest pn cyc 1q (29) is provided as a configuration volume in the design tool. Additionally, to make equations 28 and 29 more practical, if either volume is lower than the minimum volume in equation 27, this volume should be chosen instead Water purification General information The purification method of choice for Westmatic s facilities is electroflocculation. This process uses electric currents to create flocculants from the impurities in the water, which, later can be removed. Further details of the electroflocculation unit and its operational principle is found in chapter 1.1. Equations This purification unit has a defined operational pressure range of 1-4 bars and an operational constant flow of 750 l/m designated as Q pur. The purification unit has one inlet and two outlets. The inlet of dirty water from the pump chamber is controlled by the operational flow of the unit. The outlet flows are either to the commercial sewage (about 99% of the inlet mass) or to the depot (about 1% of the inlet mass) [24]. The outlet to commercial sewage is cleaned water while the outlet to the depot is the sludge from the purification process. 22

31 2.2.8 Depot General information The depot is the final section in the water reclamation system. This section is a simple sludge tank where the impurities from the purification unit end up. When the sludge reaches a certain level, the tank is emptied. Equations In addition to the inlet from the purification unit, the depot is equipped with a pump that pumps back the little water still left in the sludge back to the oil separator. This pump is however used sparingly with very low flows so the volume flow from the depot (Q depot ) is approximated as zero for this thesis work. For this reason, the volume of the tank will simply be provided by the user to satisfy their needs. A recommended volume of 6000 liters is defined by recommendations from the tank manufacturers Connecting pipes General information Between the washing station and the fist glass fiber tank, as well as between multiple sections, there are connecting pipes that allow wastewater to pass from section to section. The pipes can be connected to different pumps like centrifugal pumps or submersible drainage pumps. The dimensions of the pipe will be defined by the pump specifications. If instead there isn t an adjacent pump, the pipe dimensions depend on the flow, fall height, and length of the pipe according to the equations below. Equations The equation describing the diameter of a pipe for a certain flow depends on if the flow is laminar or turbulent. A flow is assumed to be fully laminar if the Reynolds number is below If the Reynolds number is above 4000 it is assumed to be turbulent, for values between 2100 and 4000 the flow is a mixture of laminar and turbulent flow (transitional flow). For the mixed case, the flow is assumed to be turbulent to approximate calculations on the safe side. The Reynolds number depends on the volume flow in equation 30 as well as the diameter of the pipe and is defined in equation 31 [32, 33]. v Q pipe A pipe 4 Q pipe π d 2 pipe (30) Re ρ v d pipe µ 4 ρ Q pipe π µ d pipe (31) where, A pipe = cross-section area of the pipe. v = flow velocity. µ & ρ = viscosity and density of the fluid inside the pipe. Q pipe = Volume flow through the pipe. The volume flow trough the pipe depends on where the pipe is fitted, for example, for the pipe fitted between the washing station and the first glass fiber tank, the flow will be defined as the input flow. Depending on if the flow is laminar or turbulent, different equations are used to derive the pipe diameter. However, as seen in equation 31, the Reynolds number that indicates laminar or turbulent flow also depends on the pipe diameter. One approach is to first assume laminar flow, calculate the approximated diameter, and then evaluate if the assumption is valid or not. If the laminar flow assumption isn t valid, turbulent flow is assumed and the pipe diameter is derived from equations for turbulent pipe flow. 23

32 Assuming laminar f low If the flow is assumed to be laminar, the Hagen-Poiseuille equation can be used to describe the volume flow through a smooth-walled circular pipe depending on the diameter of the pipe. The Hagen-Poiseuille equation is described in equation 32 and can be expressed so that the diameter of the pipe depends on the volume flow [32]. Q pipe π p d4 pipe ô 128 µ l pipe 128 lpipe µ Q pipe d pipe π p where, l pipe = nominal length of the pipe. p = pressure difference between the inlet and outlet. 1{4 (32) For straight pipes, the pressure difference to overcome ( p) is a result of the height difference between inlet and outlet described in equation 33 where the height difference can be described with the decline percentage of the pipe (see equation 34). p ρ g h (33) h l pipe sin`tan 1 pα fall q (34) where, h = height difference between inlet and outlet. α fall = decline percentage in decimal. If the equations are combined, an equation describing the pipe diameter is obtained as in equation 35. Here the volume flow is provided by the user and the decline percentage is defined as a configuration factor in the program. 128 µ d pipe π ρ g sin`tan 1 pα fall q Q pipe 1{4 (35) The result of this equation can be inserted in equation 31 and if the flow indeed is laminar, the resulting diameter should be used. If the Reynolds value is larger than 2100 which is highly likely in this application, this result is invalid and turbulent flow must be taken into account to derive a correct pipe diameter. 24

33 Assuming turbulent f low When assuming turbulent flow the Hagen-Poiseuille equation can t be used. Instead, the pipe diameter can be derived from the equation describing the pressure needed to overcome the driving pressure described in equation 33. The equation can be formulated so that the pipe diameter is in focus, which, is shown in equation 36 [32, 33]. p λ lpipe ` ÿ ρ v 2 K L d pipe 2 (36) where, λ = friction coefficient. K L = one-time resistance. The ř K L factor is the sum of resistance from sections like 90 bends, valves, or T-fittings. For this thesis work, the pipe in question is assumed to be straight without additional components. This means that ř K L 0 and the pipe diameter can be described as in equation 37. p λ l pipe ρ v 2 2 d pipe ô d pipe λ l pipe ρ v 2 2 p (37) When equation 37 is combined with equation 30, 33, and 34, the pipe diameter can be described according to equation 38. d pipe λ l pipe ρ 16 Q 2 pipe 2 ρ g l pipe sinparctanpα fall qq π 2 d 4 pipe ô d pipe 4 λ Q 2 pipe g π 2 sinparctanpα fall qq 1{5 (38) The friction coefficient λ is found in Moody s diagram with the appropriate pipe roughness and Reynolds number. Alternatively, when the diagram is unavailable as it would be in a modular program, Moody has derived equation 39 to approximate the right λ value [32]. λ 0, ` k ` 106 1{3 d pipe Re (39) where, k = pipe roughness (see table 5). 25

34 In equation 39, the flow is assumed to be flowing through a circular pipe that is fully filled with the fluid. If the pipe instead would be partially filled or have another cross-section, d would be replaced by the hydraulic diameter described in equation 40. d h 4 A pipe S (40) where, S = fluid affected circumference [33]. The problem with equation 39 is to know λ and then in turn the pipe diameter. The diameter needs already to be known (both directly in equation 39 and in equation 31). To solve this problem, an arbitrary guess/test diameter is used in equation 31 and 39 to calculate the pipe diameter in equation 38. The calculated pipe diameter is then used as a new test value and a new pipe diameter is calculated and so on. In this way the real pipe diameter is incrementally found as the test value approaches the final value. The deviation between the current test value and the most recent calculated value can be used to limit the number of increments. A parameter that describes the deviation in percent is provided in the design tool so that calculations take place until the deviation is less than a certain value. The values of k in equation 39 depend on what material the pipes are made of and relevant information for some materials can be found in table 5. Table 5: Pipe roughness for some materials [33]. Material k (mm) Glass, Plastic 0 Concrete 0,9-9 Wood stave 0,5 Rubber, smoothed 0,01 Copper/brass 0,0015 Cast iron 0,26 Galvanized iron 0,15 Wrought iron 0,046 Stainless steel 0,002 Commercial steel 0,045 26

35 3 Constructional design This chapter concludes detailed descriptions of the constructional outline for the glass fiber tanks and each section of the water treatment system. 3.1 Glass fiber tanks As mentioned, the system will consist of two cylindrical containers with different sections. The fixed dimensions of these tanks are described in chapter 2. The glass fiber tanks are modular and each cylindrical segment is defined as l sec. The diameter of the cylinders is set to D cyl and at each end there is a spherical cap that extends l cap. Between each segment there is an overlapping joint that keeps different segments together. The axial length of the joint is defined as l joint. The wall thickness of the cylindrical segment, spherical cap, and the joint section is defined as t wall, t cap, and t joint respectively. The dimensions are described in figure 18. Figure 18: Principal sketch of a modular glass fiber tank, two segments long. Since the dimensions are fixed, together with a fixed water level height (see fig. 19), the water volume for the spherical cap and the cross-section of the cylindrical segment can be found. With the dimensions defined in figure 19 where portions filled with water are designated with striped areas, the cross-section of the cylindrical segment that is filled with water (A w ) can be found. This is done by first finding the circular section area in equation 41, see figure 19 (i). Then the triangular area in equation 42 (fig. 19 (ii)) is removed from the section area to find the segment area for the air-filled part of the total cross-section as seen in equation 43 (fig. 19 (iii)). Finally, to find the water-filled cross-section area (fig. 19 (iv)) the segment area is subtracted from the total area according to equation

36 Figure 19: Principal sketch of a modular glass fiber tank segments and different cross-sections. A sec R2 θ (41) 2 A t b a R 2 b 2 (42) A seg A sec A t (43) A w A cyl A seg (44) A cyl is simply the total cross-section area of the cylindrical segment according to equation 45 and the angle θ is defined in equation 46. A cyl π R 2 (45) b θ 2 cos 1 (46) R The dimension b referenced to in figure 18 is related to the configuration parameter h w trough the relation b h w R. The water volume for one cylindrical segment is defined in equation 47. V segw A w l seg (47) For the end caps of the fiberglass tanks, the total volume is defined as the volume of a spherical segment according to equation 48. To find the water-filled volume of the end caps, the air-filled volume described by the integer in equation 49 is subtracted from the total volume. This is described in equation

37 V cap π l cap p3 R 2 ` lcapq 2 6 (48) pr 2 x 2 b a q arccos`? b pr2 x 2 q b 2 dx R2 x 2 (49) ż? R 2 b2 V h w R V capw V cap V (50) 3.2 First tank and buffer tank With the glass fiber tanks defined in the previous chapter, the dimensions of the differed compartments within the tanks can be found. Each compartment in the first tank is separated with internal walls that let water overflow from one compartment to the next. Additionally, since the water volume V course, V fine and V oil is defined in liters, an extra constant 10 3 is included in the following equations to convert the units to cubic meters. Dimensions of the course sludge tank: The needed water volume for the course sludge compartment is defined in equation 9 and this volume needs to be related to the needed cylindrical section length. This to later obtain the construction dimensions for the whole tank. Since the course sludge compartment is the first section in the glass fiber tank, some of the needed water volume will reside inside the end cap (V capw ). Equation 51 formulates the relation between the different volumes and relates these to the needed cylindrical length (l coarse ) for the course sludge compartment. V coarse 10 3 A w l coarse ` V capw ô l coarse V coarse 10 3 V capw A w (51) Dimensions of the fine sludge tank: Much like the course sludge tank, the needed length for the fine sludge compartment is defined in equation 52. Since the fine sludge compartment is between the course sludge compartment and the compartment for the oil separator, there is no adjacent spherical cap and the whole section is cylindrical. l fine V fine 10 3 A w (52) Dimensions of the oil separator: Since the oil separator is the last compartment of the first tank and has an adjacent end cap, the length needed is found in the same way as for the course sludge tank in equation 51. The needed cylindrical length for the oil separator compartment is found in equation 53. l oil V oil 10 3 V capw A w (53) Finally, to make equation more practical, a safety factor s f is added to the needed water volumes so that the final equations for each compartment of the first tank is as follows: 29

38 l coarse s f V coarse 10 3 V capw A w (54) l fine s f V fine 10 3 A w (55) l oil s f V oil 10 3 V capw A w (56) The safety factor is provided as a configuration parameter in the design tool/program. Total dimensions for the first tank: The total needed length of the cylindrical section of the first tank will simply be defined as the sum of the three previously mentioned lengths in equation 57. This length can then be related in equation 58 to the number of needed cylindrical segments where one segment is l seg long. l 1st l coarse ` l fine ` l oil (57) n 1st l 1st l seg (58) Where n 1st can t be less than 1 and is rounded up to the closest integer. The final real length and total (or dry) volume of the first tank is defined in equation 59 and 60. l 1st real n 1st l seg ` 2 l cap (59) V 1st real n 1st l seg A cyl ` 2 V cap (60) Dimensions of the buffer tank(s): Since the dimensions of the buffer tanks are fixed to a specific volume, the only factors that govern the total volume across all tanks are described in chapter The number of buffer tanks that are connected in series is also described in chapter by equations Second tank Like the first glass fiber tank, the second glass fiber tank consists of different sections that are separated. In this case, the second tank consists of two compartments, the pump chamber, and the depot. These are completely separated and there is no direct flow between the two. Like before, an extra factor 10 3 is added to the needed water volume for the pump chamber (V pump ) to convert the units to SI units. Dimensions of the pump chamber: The needed water volume for the pump chamber is described by equation depending on what Case (1-3) that is relevant. This compartment like the course sludge tank has a spherical cap where some of the needed volume will fill up. The needed cylindrical length is formulated in the same way as for the course sludge tank with the same added safety factor (s f ) in equation 61. l pump s f V pump 10 3 V capw A w (61) 30

39 Dimensions of the depot: The depot chamber is the second and final compartment in the second tank and this compartment is the only one that isn t typically filled with water. Instead the whole empty/dry volume of the glass fiber tank can be used in theory. Practically, when the sludge level reaches a certain height, an alarm goes off and the tank is emptied. As previously mentioned, there is an inlet and outlet for this compartment but the outlet that directs the little remaining water present in the sludge, back to the oil separator is assumed to be negligible. This means that the only factor that affects the needed volume of this compartment is how often it has to be emptied. That s why the preferred minimum volume is provided by the user when using the design tool. The recommended volume from the tank manufacturer is 6000 liter and information is provided to aid the user. One other factor to help the tank being more practical is the restriction of a minimum length of the cylindrical section. This minimum length is provided as a configuration parameter and the length of the cylindrical part cannot be lower than this value. This is done to enshore that the well/shaft leading from the tank to the surface can be fitted over the depot chamber and enables the tank to be emptied by a vacuum truck. Otherwise, the dimension of the depot chamber is found in equation 62 in the same way as for the pump chamber with the exception that the whole cross-section area of the tank can be used. l depot s f V dep 10 3 V cap A cyl, where l depot ě l depotmin (62) Total dimensions for the second tank: The total needed length of the cylindrical section of the second tank is derived in the same way as for the first tank and is described by equation 63. This length can then be related by equation 64 to the number of needed cylindrical segments where one segment is l seg long. l 2nd l pump ` l dep (63) n 2nd l 2nd l seg (64) Where n 2nd, just like n 1st, can t be less than 1 and is rounded up to the closest integer. The final real length and total (or dry) volume of the second tank is defined in equation 65 and 66. l 2nd real n 2nd l seg ` 2 l cap (65) V 2nd real n 2nd l seg A cyl ` 2 V cap (66) 31

40 4 Excel program/design tool In this chapter the complete description of the design tool and the use of Microsoft Excel is provided. Additionally, the implementation of a CAD program with Excel is described. 4.1 General design tool layout With all equations properly defined in the previous chapter, these can be formulated in an Excel environment in the calculating part of the design tool. The program of choice for the design tool is Microsoft Excel for the simple reason that Excel is a well known and wildly used program in most industries. Provided with Excel is the event-driven programming language Office Visual Basic for Applications (VBA) that are used to create certain macros and functions [34]. These macros and functions will provide the program with necessary scripts that will make the program more understandable and easier to use. The specific lines of codes/macros used in this project can be found in their respective chapter in chapter or in a summary in appendix B. The design tool is divided into four major sections: the input page(s), the data summary and configuration page, the equation page, and the result/output page (see fig. 20). In addition to these four sections is an optional pipe calculator that can be accessed on the last page of the program and a help page that can be accessed at any time by pressing the Help button in the navigation field. Practically, the front page/first input page will start on sheet two since sheet one is reserved for data used in future CAD programs, this is described more in chapter 4.8. Figure 20: General Excel outline. To make the user experience more streamlined, when the Excel document is opened, sheet two will automatically be the active sheet and the user can start using the design tool as intended. This is done with the Auto_Open macro that uses the code ThisWorkbook.Sheets( Dashboard ).Activate. This macro runs when the document is opened and sets the active sheet to sheet two. The code can be found in the Module_Start module in appendix B. The intended user for the design tool is the design engineers at Westmatic as well as their customers. The intended user will not have access to the CAD datasheet, data summary, or equation pages to keep the user experiences streamline. These pages will only be accessed when Westmatic employees want to configure or reprogram the design tool. With this setup, a navigation system other than the standard tab-navigation in Excel is provided and used by the intended user. This also means that the input pages, output summary, pipe calculator as well as the help page should be somewhat more aesthetic than what is needed for the data summary, equation pages or the CAD data page. As seen in figure 22 and most other figures relating to the design tool a blue navigation bar to the left of the screen can be found. This navigation bar will help the user to navigate through the different pages quickly and easy. The navigation bar will also indicate in what stage the user is in the program, which, helps the user by having a better overview of the design tool. In the first part of the program, while 32

41 navigating through the input pages, the only pages available are the ones relevant for user input. This is done to avoid confusion and make the tool more efficient. Only after the user has gone through the input page and clicks on the Finish button seen in figure 26, is the final two available pages Output and pipe calculator apparent in the navigation bar. The navigation bar works simply with hyperlinks connected to different text boxes that cover each cell that refers to different sheets within the Excel file. In this way, the text boxes work like an integrated button without the need for VBA code. Other than the hyperlinks that lead to the different input sheets, a help button is provided that directs the user via a hyperlink to the help page described in chapter 4.7. In addition to the navigation bar, at the end of each sheet one or multiple function buttons can be found, which, if pressed, takes the user either forward or backward in the sheet order. These buttons are inserted via the developer tab found in Excel and when one button is pushed it calls a macro which changes the active sheet. A macro is a script that gets activated when called upon. This can be done with a button being pressed, a change in cell value, or a number of other different ways. In this particular case, the function buttons call upon a macro with one line of code: ThisWorkbook.Sheets( Sheet name ).Activate where Sheet name is changed to the name of the sheet that is to be shown. One macro is needed for each page that the user can be directed to but multiple buttons can call the same macro so there is no need to create a unique macro for each function button. The summary of scripts for the different function buttons can be found in appendix B in the module/window named Module_NextPage. A module is a place in the VBA environment where one or multiple macros reside. If instead code is relevant to a specific sheet or the workbook itself, code or macros can be defined in the sheets or workbook by opening the sheets or workbook in VBA via the project explorer seen in the left-hand side in figure 21. The different modules can also be found in the project explorer as seen in fig. 21. Figure 21: The VBA environment in Microsoft Excel. To prevent the user to change anything else that the intended cells/functions for input, each sheet as well as the workbook structure is protected with a password. When a sheet is protected only certain aspects are available to the user, like selection privileges or formation options of 33

42 the sheet structure. The cells that are intended to receive a value from the user are formatted as unlocked cells before the sheet gets protected. Generally, the only privileges the user has while navigating the program is the selection of unlocked cells and the ability to format columns and/or rows (this is needed to hide functions of rows and columns to work). Pages that don t have cells that need a user value are locked completely and the user can only use function buttons, hyperlinks, and option buttons. The password is known to the Westmatic employees and is used to unprotect sheets or the workbook structure to access the data and equation tab or to make changes to the Excel program itself. In addition to this security, the Excel file itself is encrypted with a password so that only the right people can open the program. 4.2 Input page(s) The first page or pages that the user first encounters are the input pages. Here, as the name implies, the user inputs the data needed for their specific product/problem. As mentioned earlier in chapter 2.1, many of the choices are related to the function library in appendix A. There are four input pages in this design tool and the first page relates to more general information about the reclamation and washing system that the user will supply. The later three pages are dedicated to the information regarding the function library. Input page 1 The first input page called Dashboard is seen in figure 22 and this page handles three different categories of general information which is Washing frequency, Facility & Vehicle type and Depot. Figure 22: The first input page of the design tool. The first category is relevant for the design regarding the size of buffer tanks and pump chamber and here the user is asked to input the number of wash cycles per hour and the minimum time between washes. This is done by selecting either of the dashed boxes and writing the desired value. The value can also be changed via the adjacent spin button which when pressed increases 34

43 or decreases the current value by one increment within the limits. Data validation settings are in effect, which, limits the value in the two cells to whole numbers between 1-10 and decimal values between 0-60 respectively. If any other value, numbers or otherwise, is inserted, an error message with the title Invalid entry with the text Input a value between 1 and 10 for example is shown and stops the user to continue with an invalid entry. The second category regarding facility and vehicle types doesn t affect the program in any way. Instead these options are functional placeholders for further implementation and development of the design tool outside of this master thesis. Here through the use of the data validation function, predefined options are defined in a drop-down menu that the user can choose from. For example, in the dashed box associated with the type of trench (this refers to the sludge trench mentioned in chapter 2.2.1) the user is met with the choice of wet or dry trench type. If the wet trench type is selected, an additional row of dashed boxes appears where the user can input the dimensions of the wet trench. This program response is seen in figure 23. Figure 23: Excel response regarding the selection of trench type This is done by creating a macro directly in sheet 2 which is called upon via a change of cell value, in this case, the value in the striped box associated with trench type. In this macro the argument for the code line Application.ActiveSheet.Rows( row number ).Hidden is either False or True which in turn hides or shows the rows relevant for the dimensions of the wet trench type. The value of the line of code is determined by an IF function that monitors the value in the striped box associated with trench type and then acts accordingly. The complete code can be found in appendix B in the window called Sheet 1. The third and final category only has one striped box for input regarding the minimum volume of the depot chamber which will affect the design of said chamber. The input box working the same way as the boxes in the first category on this page without any additional functions. As seen in figure 22 the striped cell is marked with a red triangle in the upper right corner. This is because there is a note associated with this cell, when the mouse cursor hovers over this cell, a note with the text: Recommended volume: 6000 liters is shown. Input page 2-4 The second input page is the first input page out of three that relates to different functions in the washing facility and their respective volume flows defined in the function library in appendix A. All three of these pages (2-4) works more or less in the same way and handles the same kind of information from different wash zone respectively. The different pages can be seen in figure The name of each sheet that is used in different functions are: Entry - Machine, Onboard Machine, Machine - Exit referring to the different wash zones in the function library. 35

44 Figure 24: The second input page of the design tool. Figure 25: The third input page of the design tool. 36

45 Figure 26: The fourth and final input page of the design tool. Here information is provided by the user with the help of option buttons. For each function in each zone the user can choose from two different water sources, fresh water or reclaimed water, as well as the desired flow. These settings will affect the design of the whole water reclamation system. To get the option buttons to work properly, the group of buttons for each function is kept inside a group box found under the developer tap in Excel. The function of the group box is simply to group and separate different groups of buttons so that only one choice in each group is possible. To convert the choice of selected option buttons from the user to cell values later used in the equation tab, each group of option buttons are linked to one specific hidden cell in the sheet. The value of these cells (one for each group of buttons in each sheet) will display a number corresponding to the activated option button. For example, the option button group inside the group box for the pre-rinse function in the second page where only three choices are present, the value of the linked cell can only either be 1, 2, or 3 depending on the active option button. Here 1 represents the NaN option, 2 the 310 l/min of fresh water option, and 3 the 310 l/min of reclaimed water. The other functions on each page works in the same way, with either more or fewer options and therefore more or less different values on their respective linked cell. One addition of functions over these three pages is the settings relating to the chassis wash and wheel wash on sheet 2. Here if the choice of volume flow for the chassis wash is greater than 300 l/min (i.e. the choices 310 l/min and 400 l/min for either fresh or reclaimed water) is chosen, an additional option for the wheel wash is available where the volume flow is shared between the two functions. The program response is shown with an example of input in figure

46 Figure 27: Excel response regarding the selection of volume flow in the chassis wash function. This is done with two functions/rows of code: ActiveSheet.Shapes.( Option button ).Visible and Application.ActiveSheet.Rows( row number ).Hidden, where Option button is replaced with the name of the option button for the shared with chassis wash choice and row number is replaced with the row to be hidden. These two rows of code is both used in two different macros where the argument for each row is either False and True respectively (for the macro that hides the additional option) or True and False respectively (for the macro that shows the additional option). These two macros are then called upon when the different option buttons relating to the chassis wash is clicked. The button NaN and the two 150 l/min buttons are assigned the hide macro and the four buttons for the 310 l/min and 400 l/min options are assigned the show macro. These macros can be viewed in appendix B in the module/window Module_Shared_button. 4.3 Data summary & configurations When the user has gone through the input pages and is satisfied, the next page the user sees is the output summary. However, in between the last input page and the output summary there are the two additional pages, the datasheet, and the equation sheet. In the datasheet a summary of all useful user data is summarized (to the left-hand side) as well as a section dedicated to configuration parameters (to the right-hand side). The page and different sections can be seen in figure

47 Figure 28: The data summary and configuration page in Excel. In the data summary section labeled: INPUT DATA, a summary of each wash zone from the previous input pages are compiled as well as different relevant sums of volume flows that will be used in the equation sheet. In addition to these, the maximum instantaneous flow is calculated for each type of water (maximum of the total fresh water, the maximum of the total reclaimed water, and the maximum of the total overall flow). Note that these three values do not need to originate from the same wash zone. Lastly the rest of the relevant user input is presented under miscellaneous, wash cycles per hour, the minimum time between wash cycles (called rest time), and the minimum volume for the depot chamber in the last glass fiber tank. In the configuration section labeled: CONFIG. PARAMETERS, all constants, and factors relevant to calculate different aspects of the water reclamation system is compiled. Here things like the constant dimensions of the tanks can be found under tank design alongside with the units for each dimension. Under miscellaneous the water level, cycle time for each washing zone, and the value of the safety factor used. A note for the dimensions affecting the water volume of the spherical caps is provided to remind the user that this volume won t change with the change of dimensions, more on this in chapter 4.4. Beyond this, additional configuration factors for each relevant section of the system. Under SS-EN 858 for the different factors that are defined according to the standard, notes with information from tables 1-3 are provided to aid the user when choosing the value for each factor. To further help the user understand the structure and designations used, two simple sketching visualizing the different dimensions are provided. 39

48 4.4 Equations The second page that the user normally doesn t access is the equations sheet where the vast majority of the equations take place. Here values are used from the datasheet along with different equations, functions, and conditions to produce resulting dimensions in different forms. First, volumes and cross-section areas needed for the tank design are defined followed by a box for each section in the water reclamation system as well as the constructional design of the two glass fiber tanks (the boxes with blue headers). Along with these boxes, an aiding picture is provided to visualize some of the signs, those used to derive certain volume and cross-section areas regarding the tank design. All this can be seen in figure 29. Figure 29: The equation page in the design tool. All the equations used in this page are defined and described in chapter 2.2 and 3. The equations are divided into different boxes relating to different sections in the system or general dimensions. Each box is structured in a way to help users to understand what each row does. The first column defines what sign of the coming equation is using, the second column gives a short description or name of what the sign represents. The third and fourth column contains the equations, the third column describes the equation being used in column four in text to clarify how the equation looks like. The fourth column defines the same equation or conditions to produce a value. It is this column in each box that is the brain of the tool and the complexity of these cells varies from a simple area equation of a triangle to a string of if/else conditions using multiple nested IF functions in combination with AND- and NOT-functions. The fifth and final column defines the unit used. In the equations and conditions in these cells, values are collected from the data and 40

49 equation tab automatically to make all equations run without the need for uses intervention. A simple equation example can be seen in figure 30 where it is clear where values have been collected from the data and equation sheet with the notation Data! and Equations! followed by the cell name. Here only basic mathematical operation tools like multiplication and addition are used. Figure 30: First example of an equation on the equations sheet in the design tool. All other equation that is defined by only one equation follows the same or similar structure. There are however some cases where one equation isn t enough. Here other functions must be used to properly cover all possible cases in the same Excel cell. One example of one of these more complex formulations can be seen in figure 31. Figure 31: Second example of an equation on the equations sheet in the design tool. In these cases where an IF function needs to be used to cover all cases, the third column is complimented with information describing the different conditions and which outcome correlates with what equation. To get a better understanding of all the different outcomes handled in this thesis work, figure 32 shows an overview of flow charts for all conditions for all equations. To reduce the amount of cell argument, several different functions predefined in Excel is used. In fig. 31, both IF-, AND-, NOT- and ABS-functions is used, the IF function consists of three parts: a logic test, an if-true argument, and an if-false argument. The IF function simply returns the true or false argument depending on if the logic test is true or false, the true or false argument can be a numerical value or additional functions like an additional IF function for example. The AND function takes one or multiple logic tests and returns a true value only if all logic tests are true, just like IF functions, logic test is most often an equation. The NOT function is a simple function that returns a false value if the logic test is true or returns a true value if the logic test is false. The ABS function is another simple function that returns the absolute value of an arbitrary number. As can be seen in fig. 31 all four of these are used within each other multiple times to achieve the correct formulation and reduce the overall text length, this is not uncommon throughout the design tool. 41

50 Figure 32: Logic trees for conditional equations. 4.5 Output summary When the user is finished with the input process and has gone through the input pages, all equations have been calculated according to the equations found in the equations sheet together with the data and configurations from the datasheet. The result of the equations relevant for the dimension of the two future glass fiber tanks is then presented and summarized in the output sheet as can be seen in figure 33. In addition to the dimensions for the glass fiber tanks, the number of needed buffer tanks as well as the choice of water reclamation unit is provided. 42

51 Figure 33: The output summary page of the design tool. Here all theoretical lengths of the cylinder segments for each compartment of each tank are presented as well as the theoretical total length of the respective tanks. Then the number of needed predefined cylinder segments for each tank is presented followed by the final practical/real length and volume of the future tank when constructing the tanks with the right amount of cylinder segments. Now the user knows how big, either with the real length or the dry/empty volume, the tanks need to be. Additionally, the dimensions of the general tank from the configuration part of the datasheet is also seen so that the user can get a better feel for the size of the tanks as well as being able to control that the tank design is the desired one. The user can also at any time go back and change any value in the input pages to later return to the output sheet with updated values. In addition to the now known design dimensions and schematics regarding the tank design of the two glass fiber tanks, the user can continue using the design tool and access a simple additional tool by pressing the pipe calculator button. Otherwise, the Excel document is saved and ready to be linked with a CAD program (Inventor in this case), this is further described in chapter Pipe calculator The last sheet in the design tool is the pipe calculator sheet which has a pipe diameter calculator for straight smooth pipes. This tool is meant to give the user a basic estimate of the size of the connecting pipes between each section in the water reclamation system. In this sheet, that can be seen in figure 34, the user can insert an arbitrary volume flow in liter per minute in the striped box to receive an approximate minimum pipe diameter in mm. This striped box is complimented with a spin button like the ones mentioned in previous chapters. 43

52 Figure 34: The page regarding the pipe calculator in the design tool. The equations used in the pipe tool is described in chapter To enable the user to access the equations and constants relevant for the pipe diameter an Advanced button has been added, which when clicked, unhides a section with the equations and constants relevant for the pipe calculations. The advanced options can be seen in figure 35 and as seen in the figure, an additional button Hide advanced comes apparent and the function of this button is to simply hide the advanced section again. Figure 35: Program response for advanced options regarding pipe calculations. 44

53 The code responsible for the hide/show behavior works in the same way as in figure 27 where two lines of code target relative columns and the Hide advanced button. This code can be seen in appendix B in the module named Pipe_Advanced. Since the calculation of the pipe diameter needs to be done in both laminar and turbulent cases as mentioned in chapter 2.2.9, a logic test seen in figure 35 is conducted. The argument in this cell (True/False) determines if the used pipe diameter should be then from the laminar or turbulent equation results. The result in the cell under the liter per minute input is rounded up to the closest whole mm to make the output of the pipe calculator more practical. 4.7 Help page As mentioned, in addition to all the previous pages a help page can be found. This page can be accessed at any time by clicking on the hyperlink connected to both the? -icon and Help text. The help page is located in its sheet seen in figure 36. Figure 36: The help page provided in the design tool 45

54 The help page consists of four parts that illustrate parts of the design tool to clarify how to use them and what they consist of. The first part relates to the navigation of the design tool, here the navigation field is highlighted and described. An example of a function button that takes the user forward or backward in the Excel document is shown and its function is described. The second part relates to the input pages, here the first input sheet is described where a description of the spin buttons/drop-down list and how they are used are described. The second to fourth input page is then described and information on how the option buttons operate on these pages is described. The third part of the help page relates to the output page, here a general description of the output sheet is provided. The last part of the help page relates to the pipe calculator, and just like for the output part, a general description is provided. To exit the help page either the navigation field can be used to return to any of the available sheets or the function button on the bottom of the page can be used to return to the previous sheet the user viewed. The function of this function button differs somewhat from the other function buttons in the design tool. Instead, to direct the user to a specific/predefined page, this button calls on the macro Lastsheet seen in appendix B in the module Module_LastPage. This macro activates the sheet that was active before the sheet that is currently active (the help sheet). To be able to do this, the program must keep track of what sheet that where activated before the currently active sheet. This is done with a macro located in the workbook itself called Workbook_SheetDeactivate seen in appendix B in the ThisWorkBook window. These two macros/sections of code enable the user to return to the page the user was on previously to the help page. For example, if the user access the help page from the Dashboard and then clicks on the Back to previous page button, the user will return to the Dashboard, if instead the help page was accessed from the Onboard Machine sheet the user will return to this page upon clicking on the Back to previous page button. 4.8 CAD extension As described in the sub-aims in chapter the output of the Excel document will be used in a 3D CAD environment to produce parametric models and accompanied blueprints. How the Excel document should be structured depends on what CAD program the information will be used in. In this thesis work Inventor is the CAD program of choice since this was desired from the customer that primarily will use the outcome of this thesis work. Inventor can read information directly from a.xlxm file (Excel Macro-Enabled Workbook) but the information/parameters need to be structured in a certain way. The table with dimensions can be placed anywhere on the sheet but the structure of the table must follow the following structure and be present on the very first sheet of the document: Parameter Name, Equation, Unit/Value, and Comment. This structure can be seen in figure 37 and in this case the information starts in cell A2. The way Inventor reads information is defined so that dimensions are defined from the start cell and all the rows below until an empty row is found. This means that it is important that there are no gaps when defining the table with information. To make the dimensions more practical, all dimensions is rounded up to whole millimeters. 46

55 Figure 37: Sheet one with dimension data to be imported to Inventor (ul = unitless). Headers aren t necessary on the page but have been provided in this case to clarify each column since the structure is important to the functionality of the cooperation of Excel and Inventor. Start cell A1 can be used even though this row contains the headlines, in this case the user will be met by a warning in Inventor with the information that Inventor can t read the first row and will skip over it. This warning can be discarded and will not affect the dimensions provided that there are no empty rows between the headlines and dimensions. In Inventor, 3D models are defined with dimensions that depend directly or indirectly on user-parameters with the same name as the dimensions defined in the column Parameter Name in figure 37. In this way, when the design tool/excel document is linked to Inventor from the Parameters module seen in figure 38 either linked or embedded, the dimensions will be updated with the values from Excel and the 3D models will update to the most current dimensions. 47

56 Figure 38: Parameter page in Inventor. If Inventor is linked with the Excel file with the linked option, the information is still stored in Excel, and information is dynamically updated in Inventor if both programs are running at the same time. In this way one Excel file can control multiple files at the same time and/or a CAD model can be changed multiple times from Excel without the need to link the files together again. This also allows the CAD file size to be small. If instead Inventor is linked with the embed option, the information is imported and stored in Inventor internally which makes the file size bigger. If the Excel file is changed in this case, the model in Inventor will not change and the new information needs to be imported to Inventor again. The accompanied blueprints with the two CAD files (one for each tank) will follow the 3D models independent of the options regarding the Excel-Inventor connection. Here only minor adjustment is needed for each new iteration of imported to finalize the blueprints D models When designing the 3D models in Inventor certain assumptions and adjustments have to be made. When regarding the first glass fiber tank, since the real cylinder lengths are almost always longer than the sum of cylinder length of each of the three sections, the placement of the separating walls can be defined in several different ways. One approach is to define the separating wall between the fine sludge compartment and the oil separator on the theoretical length of the oil separator and define the other separating wall from the theoretical length of the fine sludge compartment with a reference towards the first separating wall. In this way the course sludge compartment will have a longer cylindrical length than the theoretical value and this volume will get the extra volume resulting from the implementation of predefined cylindrical length (in combination with the number of segments). This case is visualized in figure

57 Figure 39: One approach on separating wall placements in the first glass fiber tank. Another approach, that is used in this thesis work, is to divide the extra volume over all three segments and let the real cylindrical length of the tank define the placement of dividing walls. In this case is the dividing wall between the two sludge compartments are placed in the middle of the whole tank and the second dividing wall between the fine sludge compartment and the oil separator is placed in the middle of the remaining half of the tank. This is visualized in figure 40. This approach is chosen to better fit Westmatic s needs. Figure 40: The used approach on separating wall placements in the first glass fiber tank. For the second glass fiber tank similar cases can be investigated. Here only one separation wall need to be defined and the approach chosen here (again to fit Westmatic s needs in the best way), is to define the pump chamber with the theoretical cylinder length. This so that, the depot chamber gets all the extra volume when designing the tanks with predefined cylindrical segments. This is visualized in figure 41. Figure 41: The used approach on separating wall placement in the second glass fiber tank. 49

58 5 Result and program example This chapter presents one of the possible results of this thesis work with the help of a collection of sample input. Since this thesis work consists of a dynamic program for a modular solution, there isn t one specific result. Instead the following chapter will describe an input example and the result relevant for that specific example. The following example input described in table 6 will be used in this example. Table 6: Input data example. Function/information Value Unit Number of washes per hour 5 Minimum time between washes 4 min Vehicle type to be washed Trucks Type of trench (wet/dry) Dry Minimum depot volume 6000 liter Zone 1: total fresh water flow 310 l/min Zone 1: total reclaimed water flow 620 l/min Zone 2: Total fresh water flow 215 l/min Zone 2: Total reclaimed water flow 400 l/min Zone 3: Total fresh water flow 200 l/min Zone 3: Total reclaimed water flow 0 l/min With this example data, the following Excel output described in table 7 is produced. 50

59 Dimension Table 7: Resulting output example. Value Unit Theoretical cylindrical length of the course sludge compartment 3369 mm Theoretical cylindrical length of the fine sludge compartment 1795 mm Theoretical cylindrical length of the oil separator 1149 mm Theoretical length of the first tank 7113 mm Number of cylindrical segments for the first tank 3 Real cylindrical length of the first tank 8340 mm Real total length of the first tank 9140 mm Dry/Empty volume of the first tank liter Theoretical cylindrical length of the pump chamber 1838 mm Theoretical cylindrical length of the depot compartment 2654 mm Theoretical length of the second tank 5292 mm Number of cylindrical segments for the second tank 2 Real cylindrical length of the second tank 5560 mm Real total length of the second tank 6360 mm Dry/Empty volume of the second tank liter Tank Diameter 2000 mm Cylindrical segment length 2780 mm Cylindrical wall thickness 10 mm Spherical cap length 400 mm Spherical cap wall thickness 10 mm Joint length 400 mm Joint wall thickness 10 mm Partition wall thickness 10 mm Volume of buffer tank type liter Number of type 1 buffer tanks 1 WWR unit to use WWR When this result from the design tool is used in Inventor, the following 3D models and blueprints in figure are produced. In figure 42, the sections from left to right are as follows: Coarse sludge tank - Fine sludge tank - Oil separator. In figure 43, the sections from left to right are as follows: Pump chamber - Depot. Figure 42: A half-view of the 3D model from Inventor of the first glass fiber tank with the output example described in table 7. 51

60 Figure 43: A half-view of the 3D model from Inventor of the second glass fiber tank with the output example described in table D (9140) D 2000 A A C C B A-A B A Designed by Checked by Approved by Date Date Scale PM /50 Glass fiber tank w/ sludge & oil separator A First_Tank Edition 1 Sheet 1 / 1 Figure 44: The blueprint of the CAD model in figure

61 (6360) B B ,00 B-B Designed by Checked by Approved by Date Date Scale PM /50 Glass fiber tank w/ pumpchamber & depot Second_tank Edition Sheet 1 / 1 Figure 45: The blueprint of the CAD model in figure 43. Additionally, an example result for the pipe calculator would be to take the maximum peak flow form table 6 and insert that into the pipe calculator. The result of this case is presented in table 8. Table 8: Pipe calculator example. Dimension/flow Maximum peak volume flow Minimum pipe diameter Value Unit 930 l/min 113 mm 53

62 6 Discussion This chapter discusses and compares the old and new water reclamation system, the use and selection of buffer tanks/wwr unit, as well as the use of Excel and CAD. How well the outcomes correlate with the proposed aims are also presented in this chapter along with future work and improvements. 6.1 Old vs New solution Old water reclamation system The old water reclamation system that is used today consists mainly of prefabricated concrete sections that are glued together. This Solution is not very efficient in terms of height and installation. The solution is large and heavy which makes shipping inconvenient and expensive. Larger and better cranes are required to install these solutions that again makes the process unnecessary expensive. On top of this, there isn t any well-defined methodology when choosing and designing the different sections in the concrete construction and the manufacturing process have long lead times. The solution will then lack any degree of modularity and all sections will be oversized and be deemed sufficient as long as the solution is in regulations of the SS-EN 858 standard. One advantage of the older solution is that, due to its weight and rigidity, when installed vehicles can run over the tanks without risking any damage to the system. Additionally, the tank system doesn t risk rising to the surface in cases where high groundwater is present. The lack of modularity is a big problem since the customer demands and requests differ much, for example the type of vehicle and the environment the vehicle is subjected to will not only affect what kind of dirt and how much dirt is present but also what kind of cleaning processes is needed. For example, a bus for public transport that is washed every day has no noticeable volume of dirt other than some dust while large trucks in mining processes can have up towards tenths of kilograms of hard gravel and dirt that is being discharged in the washing process. New water reclamation system The new water reclamation system that has been defined in this master thesis is highly modular with quicker manufacturing times and easier handling. As previously mentioned, the new solution will consist of glass fiber tanks that are casted in a centrifugal process and laminated together in segments to fit more specific needs. This will solve the problem with the variance in customer specifications. The glass fiber tanks will also be significantly lighter than the tank solution in concrete, mainly due to that glass fiber - epoxy laminar have generally a lower density than concrete but the glass fiber tanks will also be casted with a much thinner wall thickness than the older solution. These two factors together result in a significant weight loss and this will enable much easier handling in shipping processes. Since there are two tanks, these can also be shipped individually if that makes the shipping process more efficient. When installing the tanks, a smaller crane can be used which is beneficial. However, since the tanks are much lighter than the concrete solution, buoyancy becomes a potential problem. Win cases where there is a low amount of water in the tank and/or the groundwater level is high, the glass fiber tanks are in danger to rise to the surface over time. This is taken care of with reinforced anchor points either connected to concrete anchors on a flattened shaft bottom or to a pre-molded concrete ground plate that the glass fiber tank rests upon. One other problem with underground glass fiber thanks, due to their relevantly low rigidity, the surface above the tanks needs to be reinforced so that the tanks don t get damaged by high loads from above. This reinforcement is practically made with a pressure equalization plate that consists of a reinforced concrete plate that surrounds the tank throats. It is also important that the ditch/excavation lacks sharp or pointy tips that can puncture or otherwise damage the glass fiber tanks in the install [27]. 54

63 In addition to the oil separator unit that is installed in the oil separator chamber, other functions can be added to the tank design to help with dimensional restrictions. For example, some glass fiber tank manufacturers offer water testing solutions internally inside the tanks, this means that height difference restrictions between inlet and outlet can be relaxed in accordance with the SS-EN 858 standard. When the glass fiber reinforced tanks are manufactured in centrifugal manufacturing processes, it is possible to reuse old thermoset products in the new product as reinforcements. The company, bia HÄRDPLAST AB, that collaborates with Westmatic with the manufacturing of the glass fiber uses 30% recycled thermoset in the manufacturing of the cylindrical segments as an example. While the specific plastic used in the manufacturing of the glass fiber reinforced tanks can vary depending on price and demand, bia uses ortho polyester as of 2011 in their tanks [35]. What is important when selecting the plastic to be used in the glass fiber tanks, is that these tanks in the application relevant for this master thesis, is in contact with different harmful oils, detergents, and petrol. Therefore, the material used must have some degree of chemical resistance. This is also a restriction valid for other components in the system like pipes, coalescing material, and for different seals throughout the system. 6.2 Buffer tanks and WWR unit Beyond the detailed design of the glass fiber tanks, it is important to choose the appropriate water reclamation unit in relation to the size of the buffer volume and vice versa. The optimization of these components is taken into consideration to be able the reduce the volume of fresh water significantly as discussed in chapter 1.1. In this study, with equation 17, a smaller reclamation unit is prioritized with the potential cost of using a larger buffer volume. Another approach would to reformulate equation 17 to equation 67 and let WWR be chosen when this condition is true and WWR otherwise, with this formulation, a larger WWR unit is prioritized to potentially reduce the need for one more buffer tank. Q W Rmin 3ÿ 3ÿ t cyci ă pq reci t cyci q (67) i 1 i 1 However, in this stage of the calculations, the internal volume of the WWR-110 unit is not taken in consideration and this factor will alleviate the difference between the two approaches. 6.3 Excel and CAD As mentioned, Excel is the program of choice to house the design tool. For all intends and purposes any other user-friendly program can be used for this application but Microsoft Excel is a widely used program and have a good balance between simple and advanced functions to be used. When handling a lot of mathematical equations however, the arguments in Excel can be somewhat hard to follow. While developing the equations for this master thesis, the equations have been formulated in Wolfram Matheamtica instead where test values can be evaluated and developed. The code used in Mathematica can be found in appendix C. One other aspect that is beneficial by using a program like Excel is that many other programs are adapted to take input from Excel. Regarding computer aided design programs, many CAD programs (like Autodesk Inventor) can import, export, or be dynamically connected the Excel documents. In the cases where programs are not adapted for Excel, this problem can most often be overcome by letting Excel output data to another program and/or file format that will act like a bridge between the two programs. This new program/file will then be connected to the desired CAD program of choice. Beyond this, there is drawbacks with using Excel as the design tool program. One problem that has affected this particular case is that Microsoft Excel cannot handle more advanced equations 55

64 like integers and derivatives. This problem hinders all equations to work automatically when parameters is changed. As an example, the volume of the air-filled portion of the spherical end caps (V ) is calculated by an integer in equation 49. This calculation must be calculated outside of Excel and manually updated by a user when affecting parameters are changed. To solve this kind of problem, there is different Excel plugin programs available online that can handle more complex mathematical formulations. But for the purpose of this thesis where the only affected equation won t change very often, the design tool is deemed sufficient in the general/vanilla version of Excel to keep the program simple. One other complication when using the same Excel document on different computers with different system settings, is the handling of decimal separation sign. Most computers use comma as the decimal separator and as consequence, separates lists of information with a semicolon. However, some computers use a simple punctuation as a decimal separator and a comma as a list separator. This can cause some problems when opening the same file on two different computer that differs in the for mentioned settings. This can however be changed in the advanced options section when opening a Excel file and thus avoiding said problem. 6.4 Outcome and aims The outcome of the thesis work described in the previous chapters correlates well with the presented aims of the project described in chapter 1.3. The use of VBA macros enables the program to operate mainly automatically without the need for user interference, this in combination with the fact that the document can be linked to Inventor without the need of an intermediate file makes the whole process efficient. On that note, with the implementation of parametric 3D models in Inventor, the sub-aims described in the chapter is fulfilled. Even though the name of all the parameters are manually defined in the CAD program, the values of these parameters are updated from data that originates from the most recently used Excel file. The manual definition in the CAD program is done once when constructing the models. The blueprints mentioned in chapter will in turn depend on the CAD files, hence the blueprints indirectly depend on the data from the Excel file. Depending on how strict the overall quality of the blueprints must be, some manual adjustment to certain elements might be needed. 6.5 Future Work The possible level of complexity when regarding the design and optimization of a water reclamation system can be endless. The following text touches on some recommended/possible improvements that can be investigated to make the design tool more extensive/efficient. Beyond the obvious improvements by including the points in the delimitation list in chapter 1.4 the tank design can be optimized further than what have been described in previous chapters. When regarding the sludge tanks, while the SS-EN 858 standard must be uphold, further research can be done to optimize the tank dimensions by letting the needed volume depend on additional factors. One proposal would be to investigate the residence time of the particles to be separated in the course and fine section of the tank. This residence time will then depend on the settling velocity in combination with settling distance and the flow rate through the tank. To be able to calculate the settling velocity, information regarding the geometry of the particles as well as the typical size must be gathered. These studies that investigates aspects like geometry, size and material of particles from different wastewater that can be beneficial to preform. Here the type of vehicle as well as environmental factors could be in effect. Additionally, if other cross-sections than circular of the tanks can be considered, the settling distance can be influenced in a positive manor by choosing a wider and shorter cross-section which in turn will decrees the needed residence time (higher sedimentation rate) in the tanks. 56

65 Beyond the properties of the wastewater, other constructional solutions can be added to lower the turbulence of the flow and/or the flow velocity. This will increase the separating efficiency of the tanks, this can also be implemented in multiple sections of the system and not just the sludge tanks. For example, an implementation of additional baffles to break the flow och wider entrance channels/pipes can be implemented and investigated. The evaluations of these studies as well as the one conducted in this thesis work can be enforced worth mass flow simulations (CFD analysis) to identify possible improvements. In the compartments in the water reclamation system where a submerged pump is located, in this case the fine sludge compartment and the pump chamber, there will be a residual water volume left if these sections is pumped dry. The influence on the final design for this scenario can further be investigated and affect the final formulations regarding the size of these sections. When regarding the buffer tanks, the buffer tank can only be filled with the volume that resides in the fine sludge compartment. This volume that depends on the location and type of the submerged pump and the geometrical factors of the fine sludge compartment can be taken into consideration when defining the needed number of buffer tanks in the system. This is especially of interest under the rest period when the washing section is inactivate and the fine sludge compartment ceases to be filled. One additional natural future implementation when regarding the buffer tanks is the implementation of additional type of buffer tanks and their influence on the system. Westmatic provides larger buffer tanks than the ones defined in this thesis work, these tanks have a volume of 3600 liters and these can be used alone or in combination with the 1600 liter tanks currently used in this thesis work. This is also why the currently used buffer tank is refereed as tank type 1 in the Excel file. When regarding the water reclamation unit, a more advanced set of criteria that involves both the equations 17 and 67 or more advanced versions of these equations can be used to evaluate the choice of WWR unit. One more advanced development would be to look at what happens for when each wash zone is active in more detail when developing a criteria which the choice rest upon. In the pipe calculator there is great potential for further development. One addition would be to include the different types of one-time resistance components in the K L factor. Another addition could be to include data for some pre-defined flows in the system depending on the outcome from the input pages in addition to the user defined flow that in included in this version of the design tool. The tool can also be developed more to fit the specific restriction when installing the tanks for a specific customer to get more conclusive information regarding the design of the whole system. For the Excel document, this file has great potential be worked on further or to be used in a larger context. In addition to increase the number of inputs and general length of the program, one addition to the output page would be to ad an Export button that exports the output data in different formats, so that this information can be used in several other CAD programs. Another example of specific further developments on this version of the design tool would be to add multiple more data validation criteria like a restriction of input in the number of washing cycles and rest time so that their combined time doesn t exceed one hour. One other important input parameter that the design tool could be extended with is a number of wash cycles per day/per week. Other additions would be that the deign tool collaborates with other modules, either before this deign tool (like letting the user chose from a library of washing configurations that then will act like the input for this design tool), or after the design tool (like continuing to work the output to fit a product data place from the manufacturer). The overall price for the tanks/system could be calculated and provided to the user if sufficient data is available. 57

66 The overall tank design used in this thesis work could also be developed further. As for this version, the design only has the essential dimensions and the separating walls are linked to simple assumptions. The design of the well/throats could be implemented as well as the holes for pipe fittings for the flows entering and exiting the different compartments of the tanks. The constraints and design associated with the oil separator could also be implemented in the current 3D models and/or blueprints. This to ensure that the final design is valid. One data validation function that could be needed when including the dimensions for the oil separator is a restriction of the length of the oil separator compartment, so that the length isn t to short for the oil separator unit to fit in the compartment. In the blueprints produced in the current tool version, the header information is kept short. Information to be entered into different cells in the header could be implemented in earlier steps of the design tool to make the whole use more conclusive. 58

67 7 Conclusion This final chapter summarizes the conclusions of this thesis work. In conclusion, the developed design tool will provide Westmatic s design engineers as well as their customers with a simple and efficient way to quantify their needs and turn their demands into practical plans in the form of blueprints and 3D models. The 3D CAD models as well as the accompanying blueprints are simple in detail with some non-essential information left out to create a good starting point for several different projects. The use of the available information from the SS-EN 858 standard enables the relevant equations to define the design tool at an appropriate level of complexity. This enables a wide variety of users and developers to navigate the tool. The use of glass fiber tanks rather than prefabricated concrete sections when defining the water reclamation system will reduce the production time and will make transport as well as the installation of the water reclamation system much simpler. The modularity of the glass fiber tanks will enable a wide variety of solutions to fit each customers specific needs more precisely than older solutions. 59

68 8 Acknowledgments Firstly, I would like to express my gratitude towards Semcon Karlstad for letting me write my master thesis in their facilities as well as lending me an equipped workplace. I would like to thank the employees at Semcon for a good and inviting working environment that helped me finish my master thesis in time despite the ongoing worldwide pandemic at the time of this thesis work. Specifically, I would like to thank my supervisor at Semcon, Mikael Johnsson for his continuous support and guidance when structuring the project. I would like to thank Stefan Törnqvist, who as a new employee at Semcon at the time, helped me with discussions and solutions to different problems along the way. I would also like to thank Martin Nordhal at Westmatic Arvika for being available throughout the project and provided me with the much-needed information regarding the project. Finally, I would like to thank Anders Gåård for his continuous support and guidance as my supervisor at Karlstads University. May 4 th, 2020 Pontus Marco 60

69 References [1] Naturvårdsverket, Fordonstvättar, 1st ed., [2] Westmatic, About Us, (visited on 01/28/2020). [3] H. A. Hasan, M. H. Muhammad, N. I. Ismail, A review of biological drinking water treatment technologies for contaminants removal from polluted water resources, Journal of Water Process Engineering 2020, 33, DOI [4] A. Holst, CWA, Federal Water Pollution Control Act Amendments of 1972, 2015, https: // (visited on 01/28/2020). [5] The History of water filters, https : / / www. historyofwaterfilters. com (visited on 01/28/2020). [6] F. R. Rijsberman, Water scarcity: Fact or fiction?, Agricultural Water Management 2006, 80, [7] J. Wallace, Increasing agricultural water use efficiency to meet future food production, Agriculture Ecosystems & Environment 2000, 82, [8] I. A. Shiklomanov, World water resources: a new appraisal and assessment for the 21st century, [9] R. Zaneti, R. Etchepare, J. Rubio, More environmentally friendly vehicle washes: water reclamation, Journal of Cleaner Production 2012, 37, [10] R. Zaneti, R. Etchepare, J. Rubio, Car wash wastewater reclamation. Full-scale application and upcoming features, Resources Conservation and Recycling 2011, 55, [11] J. Rubio, R. Zaneti, Treatment of washrack wastewater with water recycling by advanced flocculation-column flotation, Desalination and Water Treatment 2009, 8, [12] M. Panizza, G. Cerisola, Applicability of electrochemical methods to carwash wastewaters for reuse. Part 2: Electrocoagulation and anodic oxidation integrated process, Journal of Electroanalytical Chemistry 2010, 638, [13] Westmatic, Bruksanvisning vattenreningsanläggning, RE-1000/4, User manual, [14] Westmatic, RENAREN, Swedish, Pamphlet. [15] C. Jönsson, A.-S. Jönsson, The influence of degreasing agents used at car washes on the performance of ultrafiltration membranes, Desalination 1995, 100, [16] R. Rautenbach, K. Vossenkaul, T. Linn, T. Katz, Waste water treatment by membrane processes New development in ultrafiltration, nanofiltration and reverse osmosis, Desalination 1997, 108, Annual Meeting of the European Desalination Society of Desalination anf the Environment,

70 [17] C. M. Marik, B. Anderson-Coughlin, S. Gartley, S. Craighead, R. Bradshaw, P. Kulkarni, M. Sharma, K. E. Kniel, The efficacy of zero valent iron-sand filtration on the reduction of Escherichia coli and Listeria monocytogenes in surface water for use in irrigation, Environmental Research 2019, 173, [18] M. Bruni, D. Spuhler, Rapid Sand Filtratio, SSWM University Course [19] E. Ghisi, D. da Fonseca Tavares, V. L. Rocha, Rainwater harvesting in petrol stations in Brasília: Potential for potable water savings and investment feasibility analysis, Resources Conservation and Recycling 2009, 54, [20] A. Al-Odwani, M. Ahmed, S. Bou-Hamad, Carwash water reclamation in Kuwait, Desalination 2007, 206, EuroMed 2006, [21] Westmatic, Westmatic Clean and Green, Westmatic AB, [22] M. Nordahl, Examensarbete: Tanksystem och Tvättbågar, Genomgång med Kandidater, Power Point Presentation, Westmatic, [23] Westmatic, Vattenåtervinningssystem, Westmatic AB, 2020, se/vattenatervinning (visited on 02/07/2020). [24] Westmatic, RENAREN - Vattenrening, Westmatic AB, 2020, se/vattenrening (visited on 02/07/2020). [25] Nelson, Grovsil i slamränna, Swedish, Drawing, Westmatic, [26] T. E. of Encyclopaedia Britannica, Stokes s law, Encyclopaedia Britannica, 1998, https: // [27] A. N. AB, Oljeavskiljare, Normer och anvisningar för projektering, dimensionering och installation, Catalog, [28] Naturvårdsverket, Oljeavskiljare, [29] P. Björklund, Utbildning på SS-EN 858 normen för oljeavskiljare, Bia härdplast AB, [30] Westmatic, Water Recycling System, WWR300, [31] Biovortex, Stainless Steel Hydrocyclones, [32] O. Isaksson, Grundläggande hydraulik, Luleå, [33] J. Berghel, R. Renström, Energitekniska Formler och Tabeller, Karlstad, [34] Microsoft, VBA programming in Office, Office VBA Reference [35] bia HÄRDPLAST AB, Bensin- och Oljeavskiljare CAM - I, product sheet,

71 Free standing equipment between entry and machine Appendices A Function library Function Water source Configuration Comments Chassis wash Reclaimed water Flow rate = 150 l/min Flow rate = 310 l/min Flow rate = 400 l/min Fresh water Flow rate = 150 l/min Flow rate = 310 l/min Flow rate = 400 l/min Wheel wash Reclaimed water Fresh water Shared with chassis wash Flow rate = 150 l/min Flow rate = 310 l/min Flow rate = 400 l/min Shared with chassis wash Flow rate = 150 l/min Flow rate = 310 l/min Flow rate = 400 l/min Only applicable for flow rate 310 and 400 l/min Only applicable for flow rate 310 and 400 l/min Pre-rinse Reclaimed water Fresh water Flow rate = 310 l/min Flow rate = 310 l/min Frame wash Reclaimed water Fresh water Flow rate = 150 l/min Flow rate = 310 l/min Flow rate = 400 l/min Flow rate = 150 l/min Flow rate = 310 l/min Flow rate = 400 l/min High pressure Reclaimed water Fresh water Flow rate = 300 l/min Flow rate = 310 l/min Flow rate = 400 l/min Flow rate = 300 l/min Flow rate = 310 l/min Flow rate = 400 l/min Detergent Frame wash Fresh water Reclaimed water Flow rate = 15 l/min 63

72 Free standing equipment between machine and exit Onboard equipment High pressure Detergent Wash water Rinse Spot-free rinse Rinse Fresh water Reclaimed water Fresh water Fresh water Reclaimed water Fresh water Fresh water Fresh water Fresh water Flow rate = 150 l/min Flow rate = 150 l/min Flow rate = 300 l/min Flow rate = 310 l/min Flow rate = 400 l/min Flow rate = 300 l/min Flow rate = 310 l/min Flow rate = 400 l/min Flow rate = 15 l/min Flow rate = 200 l/min Flow rate = 200 l/min Flow rate = 200 l/min Flow rate = 200 l/min Flow rate = 200 l/min Spot-free rinse Fresh water Flow rate = 200 l/min 64

73 B VBA summary 65