CE421/521 Environmental Biotechnology. Nitrogen and Phosphorus Cycles Lecture Tim Ellis

Transcription

1 CE421/521 Environmental Biotechnology Nitrogen and Phosphorus Cycles Lecture Tim Ellis

2 Nitrification Kinetics µ = µ K maxs NH 4 S + S NH4 K O S O2 + S O2 where µ max = maximum specific growth rate, h-1 K S = half saturation coefficient for ammonia, mg/l as NH 4 -N K O = half saturation coefficient, mg/l as O2 Yield = mg biomass formed/mg ammonia utilized

3 Nitrification Kinetics Nitrosomonas parameter range typical 20 C) µ max K S K O Yield Nitrobacter range typical (@ 20 C) Optimum ph for nitrifiers is around 8.0, range (higher than for most other biological processes).

4 Nitrifiers are sensitive to d o t p i µ = µ K maxs NH 4 S + S NH4 K K I I + I where I = concentration of inhibitor, mg/l K I = inhibition coeficient,, mg/l

5 Effects of Temperature derivation of the A equation k k = Ae RT = k θ ( T2 T1 ) 2 1 where k 1,2 = reaction rate coefficient at temperature T 1,2 θ = t c µ

6 Typical Theta Values theta values µmax KS kd Nitrosomonas Nitrobacter ln k ln θ Temp (deg C or K)

7 Calculating Theta given the following measured data, calculate the theta value T, C b, h

8 DENITRIFICATION 1. A nitrate reduction: NO3- NH4+ nitrate is incorporated into cell material and reduced inside the cell 2. D nitrate reduction (denitrification) NO3- serves as the t e a (TEA) in an anoxic (anaerobic) environment nitrate reductase nitrite r. nitric oxide r. nitrous oxide r. - - NO 3 NO 2 NO N 2 O N 2 summarized as: NO 3 - NO 2 - N 2

9 DENITRIFICATION requires o m (example: methanol) kinetics for denitrification similar to those for heterotrophic aerobic growth µ = µ K maxs S + S K NO 3 NO3 + NO3

10 DENITRIFICATION 6NO CH 3 OH 3N CO H 2 O + 6 OH - calculate COD of methanol: calculate alkalinity:

11 Nitrogen Removal in Wastewater Treatment Plants Total Kjeldahl Nitrogen (TKN) = o n + a (measured by digesting sample with sulfuric acid to convert all nitrogen to ammonia) TKN ~ 35 mg/l in influent p t removes approximately 15% additional removal with biomass w

12 Methods for Nitrogen Removal 1. Biological n d ANAMMOX: ammonium is the electron donor, nitrite is the TEA + NH NO 2 N H 2 O Suitable for high ammonia loads (typically greater than 400 mg/l) and low organic carbon 2. Chemical/Physical 1. air s 2. breakpoint c 3. ion e 4. reverse o

13 Concerns for nitrogen discharge: 1. T 2. D of DO 3. E 4. Nitrate in d water causes methemoglobinemia (blue baby) oxidizes hemoglobin to methemoglobin

14 System Configurations Completely mixed activated sludge (CMAS) Conventional activated sludge (CAS) Sequencing Batch Reactor (SBR) Extended aeration, oxidation ditch, others

15 Activated Sludge Wastewater Treatment Plant Influent Force Main Bar Rack/ Screens Grit Tank Primary Settling Tank Activated Sludge Aeration Basin Screenings Secondary Settling Tank Grit Primary Sludge Air or Oxygen Waste Activated Sludge (WAS) Cl 2 Tertiary Filtration (Optional) Diffusers to receiving stream Return Activated Sludge (RAS) wastewater flow residuals flow Chlorine Contact Basin (optional)

16 Completely Mixed Activated Sludge (CMAS) to tertiary treatment or surface discharge aeration basin RAS air or oxygen clarifier WAS

17 Completely Mixed Activated Sludge (CMAS)

18 Conventional (plug flow) Activated Sludge (CAS) Primary effl. plan view RAS to secondary clarifier

19 Conventional Activated Sludge

20 Conventional Activated Sludge

21 Step Feed Activated Sludge Feed RAS Feed

22 CMAS with Selector High F/M Selector Low F/M CMAS with Selector

23 Contact Stabilization Activated Sludge contact tank aeration basin air or oxygen RAS air or oxygen clarifier WAS

24 Sequencing Batch Reactor WASTEWATER AIR TREATED EFFLUENT FILL REACT SETTLE DECANT Sludge wastage at end of decant cycle

25 Phosphorus limiting n in algae (at approximately 1/5 the nitrogen requirement) 15% of population in US discharges to l wastewater discharge contains approximately mg/l as P o i : orthophosphate

26 Removal of Phosphorus Chemical precipitation: traditional p reactions Al + PO -3 4 AlPO 4 Fe + PO -3 4 FePO 4 as s (magnesium ammonium phosphate, MAP) Mg +2 + NH 4+ + PO -3 4 MgNH 4 PO 4

27 Struvite as a problem Scale build-up up chokes pipelines, clogs aerators, reduces heat exchange capacity Canned king crab industry Kidney stones

28 Struvite as a Fertilizer Nonburning and long lasting source of nitrogen and phosphorus Found in natural fertilizers such as guano Heavy applications have not burned crops or depressed seed germination (Rothbaum( Rothbaum, 1976) Used for high-value crops For ISU study on removing ammonia from hog waste see:

29 Full Scale ASBR 2300 head operation in central Iowa, USA methane recovery for energy generation site for full-scale study for struvite precipitation

30 Biological P Removal Discovered in plug flow A.S. systems Requires anaerobic (low DO and NO - 3 ) zone and aerobic zone Biological battery Grow phosphate accumulating organisms (PAO) with 7% P content Need to remove TSS

31 Key Reactions in Anaerobic Environment Uptake of acetic acid Storage polymer (PHB) is formed Polyphosphate granule is consumed Phosphate is released

32 Key Reactions in Aerobic Environment Energy (ATP) is regenerated as bacteria consume BOD Phosphorus is taken into the cell and stored as poly-p P granule When BOD is depleted, PAO continue to grow on stored reserves (PHB) and continue to store poly-p

33 Anaerobic Zone (initial) H 3 CCOOH H 3 CCOO - + H + ATP ATP ADP+P i ADP+P i PHB polymer P i Polyphosphate Granule H + ADP+P i ATP P i

34 Anaerobic Zone (later) H 3 CCOOH H 3 CCOO - + H + ATP ATP ADP+P i ADP+P i PHB polymer Polyphosphate Granule P i P i ADP+P i H + ATP

35 Aerobic Zone (initial) substrate H + substrate ADP+P i ATP CO 2 + NADH NAD ATP Polyphosphate Granule ADP+P i P i PHB polymer H 2 O ATP P i 2H + + 1/2O 2 ADP+P i H +

36 Aerobic Zone (later) H + NAD CO 2 + NADH ATP ADP+P i PHB polymer Polyphosphate Granule ATP ADP+P i P i H 2 O ATP P i 2H + + 1/2O 2 ADP+P i H +

37 Bio-P P Operational Considerations Need adequate supply of acetic acid Nitrate recycled in RAS will compete for acetic acid May need a trim dose of coagulant to meet permit Subsequent sludge treatment may return soluble phosphorus to A.S.

38 A/O EBPR air Alum, Fe +3 (optional) Anaerobic Selector Aeration Basin Secondary Clarifier return activated sludge (RAS) Anaerobic Selector Release of phosphorus Uptake of acetic acid ATP ADP Phosphate Storage Battery Aeration Basin Uptake of phosphorus Formation of phosphorus storage granules (up to 7% P) ADP ATP waste activated sludge (WAS)

39 Combined N and P Removal Competition between bio-p P and denitrification BOD becomes valuable resource required for both N and P removal Operation depends on treatment goals One reaction will limit difficult to eliminate all BOD, N, and P Commercial models (BioWin, ASIM, etc.) useful to predict performance

40 Combined Biological Phosphorus & Nitrogen Anaerobic Selector Removal nitrate rich recirculation Secondary Settling Tank Anoxic Selector Aeration Basin (nitrification zone) air return activated sludge (RAS) A 2 O waste activated sludge (WAS)

41 Combined EBPR & Nitrogen Removal Anaerobic Selector nitrate rich recirculation Secondary Settling Tank Anoxic Selector Primary Aeration Basin Anoxic Tank Secondary Aeration Basin air air return activated sludge (RAS) 5-Stage Bardenpho waste activated sludge (WAS)

42 Combined Biological Phosphorus & Nitrogen nitrate free recirculation Removal nitrate rich recirculation Secondary Settling Tank Anaerobic Selector First Anoxic Tank Second Anoxic Tank Aeration Basin air return activated sludge (RAS) Modified UCT waste activated sludge (WAS)

43 Combined Biological Phosphorus & Nitrogen nitrate free recirculation Removal nitrate rich recirculation Secondary Settling Tank Anaerobic Selector Anoxic Selector Aeration Basin (nitrification zone) air return activated sludge (RAS) waste activated sludge (WAS) Virginia Initiative Plant (VIP)

44 Sulfur inorganic: SO -2 4 S H 2 S organic: R O SO -2 3 four key reactions: 1. H 2 S o can occur aerobically or anaerobically to elemental sulfur (S ) a : Thiobaccilus thioparus oxidizes S-2 S to S S S -2 + ½ O 2 + 2H + S + H 2 O a : phototrophs use H2S as electron donor filamentous sulfur bacteria oxidize H 2 S to S S in sulfur granules: Beggiatoa, Thiothrix

45 Sulfur 2. Oxidation of E Sulfur (Thiobacillus( thiooxidans at low ph) 2S + 3 O H 2 O 2 H 2 SO 4 3. A sulfate reduction: proteolytic bacteria breakdown organic matter containing sulfur (e.g. amino acids: methionine, cysteine, cystine) 4. D sulfate reduction: under anaerobic conditions s r b (SR SO Organics S -2 + H 2 O + CO 2 S H + H 2 S Desulvibrio and others Sulfate is used as a TEA & l m w organics serve as the electron donors Low cell y P of SRB depends on COD:S ratio, particularly readily degradable (e.g., VFA) COD SRB compete with m for substrate: high COD:S favors methanogens,, low COD:S favors SRB

46 Crown Sewer Corrosion