Biological N and P removal in activated sludge processes

Transkript

1 Biological N and P removal in activated sludge processes Sara Hallin Department of Microbiology, SLU Sara Hallin

2 Metabolism

3 Oxidation: KOLFÖRENING KOLDIOXID + ELEKTRONER + VÄTEJONER Reduktion: SYRE + ELEKTRONER + VÄTEJONER VATTEN Fullständig reaktion: KOLFÖRENING + SYRE KOLDIOXID + VATTEN BIOKEMISKT BUNDEN ENERGI

4 Fermentation: GLUKOS ETANOL + KOLDIOXID BIOKEMISKT BUNDEN ENERGI Fermentation av socker till etanol och koldioxid. En del av kolet i sockret har oxiderats till koldioxid medan en del har reducerats till etanol (vanlig sprit).

5 Traditionell ASP Organiskt material bryts ner av mikroorganismer i luftningsbassängen. Slammet (biomassa och organiskt material)avskiljs från det renade vattnet i sedimenteringsbassängen..

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7 Microbiological reactions in the N cycle ATMOSPHERE Denitrification N 2 SOIL/WATER Nitrogen fixation N 2 O Organically bound nitrogen orgnh 2 NO Assimilation Mineralization/ Ammonification Assimilation NO 2 NH 4 + NO 2 NO 3 Nitrification Dissimilatory nitrate reduction to ammonium

8 Nitrification in water treatment Nitrification lowers BOD load in recipient Nitrification coupled to denitrification lowers N load in recipient Nitrogen removal systems: natural wetlands constructed wetlands wastewater treatment plants Process problems with inhibition: Microbial sensors for detecting nitrification inhibitors

9 Nitrification Nitrification involves several reactions and two different bacteria: 1. Dissociation of ammonium 2. Oxidation of ammonia Ammonia monooxygenase (AMO): Integral membrane protein Can oxidize methane Cometabolize halogenated compounds 3. Oxidation of hydroxylamine Hydroxylamine oxidoreductase (HAO): Soluble, periplasmic protein Nitrosomonas 4. Oxidation of nitrite

10 Ammonia oxidation: NH 3 + 1,5O 2 NO 2 + H + + H 2 O

11 Nitrite oxidation: NO 2 + ½ O 2 NO 3 Periplams OH

12 Carbon metabolism Cell constituents Growth

13 Energetic constraints ATP and NADPH (reducing power) requirements in Calvin cycle 2. NAD(P)H formed by reverse e flow: e NAD(P) + 2e Cyt c e Cyt c O 2

14 The organisms Ammonia oxidizing archaea and bacteria (AOA and AOB) NH 3 oxidizers Proteobacteria: Nitrosomonas Nitrosococcus Nitrosospira Thaumarchaeota: Nitrosopumilis NO 2 oxidizers Bacteria: Nitrobacter Nitrospira

15 Microbiological reactions in the N cycle ATMOSPHERE Denitrification N 2 SOIL/WATER Nitrogen fixation N 2 O Organically bound nitrogen orgnh 2 NO Assimilation Mineralization/ Ammonification Assimilation NO 2 NH 4 + NO 2 NO 3 Nitrification Dissimilatory nitrate reduction to ammonium

16 Denitrifikation är en andningsprocess som där nitrat omvandlas till kvävgas i flera komplicerade steg inom en och samma bakteriecell: nitrat nitrit kväveoxid lustgas kvävgas (NO 3 NO 2 NO N 2 O N 2 )

17 Denitrification pathway Pathway NO / + 3 = O NO 2 2

18 Denitrification: anaerobic respiration ATP Organic compound CO 2 Carbon flow Electron flow Biosynthesis NO 3, (NO 2, N 2 O)

19 Denitrification Cytoplasma NO 2 NO 3 NADH 2 NAD + nar 2e 2e 2enor e NO 3 Periplasma H + Proton motive force nir NO 2 NO NO N 2 O nos N 2 O N 2

20 Denitrifier diversity Diversity Bacteria Eukarya Archaea Denitrifiers

21 Nitrifikation Redox Denitrifikation Glucose Glykolysis 2 Pyruvate 2 ATP 2 NADH 8 NADH 2 FADH TCA cycle 2 GTP 6 CO 2 NH 4 + NO 2 ATP NADH FADH ATP ATP O 2 H 2 0 NO 3 NO 2 NO N 2 O N 2 +

22 Kvävrening + NH 4 NH NO 2 OH NO NO NO N 2 O N 2

23 Nitrifierande bakterier Denitrifierande bakterier Nitrifierare finns i mark och vatten Denitrifierare finns nästan överallt Bara några få arter Nitrifikation är två energigivande processer som utförs av två olika grupper av bakterier Nitrifierare växer långsamt Många bakteriesläkten Denitrifikation är en alternativ andningsprocess i frånvaro av syre Denitrifierare är växer oftast snabbt

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28 Effekt av extern kolkälla på kvävereningen 1. Kvävereningsgrad (%): 2. Denitrifikastionskapacitet: E 60 E R R Tid (dagar) Tid (dagar) R = Fördenitrifikation utan extern kolkälla E = Fördenitrifikation med etanoltillsats

29 Intermittent dosering av etanol i en fördenitrifikationsprocess Hasselblad & Hallin Wat. Sci.Technol.

30 Kvävrening + NH 4 NH NO 2 OH NO NO NO N 2 O N 2

31 D I E T A G R I C U L T U R E E N V I R O N M E N T

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33 Microber med och utan nosz (N 2 O reduktase gen) 1/3 of denitrifier genomes lack nosz (Jones et al Molec Biol Evol) Some organisms only have nosz and are potential N 2 O sinks. (Graf et al. in prep.) Manipulation of soil denitrifier community showed direct causality link between the community composition and potential N 2 O emissions. (Philippot et al Global Change Biol.) N 2 O/(N 2 O+ N 2 ) 0,8 0,6 0,4 0,2 0 Ratio of N 2 Oproducers

34 World greenhouse gas emissions by sector

35 Biological phosphorus removal ANAEROBIC AEROBIC Short chain fatty acids Energy Phosphate O 2 CO 2 +H 2 O Energy Phosphate Energy consumption for uptake of soluble organics. ATP and PO43 is released. Energy is conserved as polyphosphate granules. Uptake of PO 4 3. Consumption of stored products (PHB).

36 PHB synthesis & degradation Acetic acid AcetylCoA AcetoacetylCoA Acetoacetate ßhyroxybutyrylCoA ßhydroxybutyrate Polyßhyroxybutyrate (PHB)

37 Biological phosphorus removal Recirculation of NO 3 ANAEROBIC REACTOR AEROBIC REACTOR SEDIMENTATION Organics Energy PO 4 3 Denitrification O 2 CO 2 +H 2 O Energy PO 4 3

38 Nremoval in wetlands

39 Constructed wetlands Diffusion through aerenchyma CH 4 O 2 CO 2 CH 4 N 2 O N 2 O 2 Water CO 2 O 2 O 2 +NH 3 NO 3 O 2 NO 3 N 2 O N 2 Aerobic zone NO 3 Reduction zone SO 2 4 Reduction zone CO 2 Reduction zone Acetate NO 3 O 2 + NH 3 Anaerobic zone CH 4 Root exudates H 2 +CO 2

40 Plants affect denitrification µg N/g DW/h Ruiz et al., 2009, FEMS Microbiol. Ecol.

41 DGGE of nosz Wetland plants effects Typha and Fragmites select nosz communities Rhizospehere Sediment Low rates High rates Seasonal differences Ruiz et al., 2009, FEMS Microbiol. Ecol.

42 Conclusions and outlook Typha and Phragmites select nosz communities Typha and Phragmites increase denitrification activity Seasonal differences Is increase in rhizosphere enough for increased capacity of wetland? What about the abundance of denitrifiers?

43 Ekeby wetland in Eskilstuna Ekeby Constructed Wetland Total area: 36 ha Flow: ~45000m 3 /day

44 Waterflow paths Kjellin et al., 2007, Wat. Res.

45 Denitrification rates Multiple regressions: PDA = T R CN Kjellin et al., 2007, Wat. Res.

46 Nremoval in mining impacted waters