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CE421/521 Environmental Biotechnology

CE421/521 Environmental Biotechnology. Nitrogen and Phosphorus Cycles Lecture 9-26-06 Tim Ellis. Nitrification Kinetics. 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

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CE421/521 Environmental Biotechnology

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  1. CE421/521 Environmental Biotechnology Nitrogen and Phosphorus Cycles Lecture 9-26-06 Tim Ellis

  2. Nitrification Kinetics where μmax = maximum specific growth rate, h-1 KS = half saturation coefficient for ammonia, mg/L as NH4-N KO = half saturation coefficient, mg/L as O2 Yield = mg biomass formed/mg ammonia utilized

  3. Nitrification Kinetics

  4. Nitrifiers are sensitive to • d____________ o_____________ • t______________ • p___ • i_____________________ where I = concentration of inhibitor, mg/L KI = inhibition coeficient, mg/L

  5. Effects of Temperature • derivation of the • A____________ equation • where k1,2 = reaction rate coefficient at temperature T1,2 • θ = t___________ c__________

  6. Typical Theta Values ln θ ln k Temp (deg C or K)

  7. Calculating Theta • given the following measured data, calculate the theta value

  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. NO3- ➔ NO2- ➔ NO ➔ N2O ➔ N2 summarized as: NO3- ➔ NO2- ➔ N2

  9. DENITRIFICATION • requires o______________ m________________(example: methanol) • kinetics for denitrification similar to those for heterotrophic aerobic growth

  10. DENITRIFICATION 6NO3- + 5CH3OH ➔ 3N2 + 5 CO2 + 7 H2O + 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 • Biological • n_______________ • d________________ • ANAMMOX: ammonium is the electron donor, nitrite is the TEA NH4+ + NO2- ➔ N2 + 2 H2O Suitable for high ammonia loads (typically greater than 400 mg/L) and low organic carbon • Chemical/Physical • air s_______________ • breakpoint c__________________ • ion e_____________________ • 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 Activated Sludge Aeration Basin Bar Rack/ Screens Primary Settling Tank Grit Tank Diffusers Screenings Grit Air or Oxygen Primary Sludge Secondary Settling Tank Waste Activated Sludge (WAS) Cl2 Tertiary Filtration (Optional) to receiving stream Chlorine Contact Basin (optional) wastewater flow Return Activated Sludge (RAS) residuals flow

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

  17. Completely Mixed Activated Sludge (CMAS)

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

  19. Conventional Activated Sludge

  20. Conventional Activated Sludge

  21. Step Feed Activated Sludge Feed Feed RAS

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

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

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

  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 7- 10 mg/L as P • o__________________ • i______________: orthophosphate

  26. Removal of Phosphorus • Chemical precipitation: • traditional p____________________ reactions Al+3 + PO4-3 ➔ AlPO4 Fe+3 + PO4-3 ➔ FePO4 • as s_______________ (magnesium ammonium phosphate, MAP) Mg+2 + NH4+ + PO4-3 ➔ MgNH4PO4

  27. Struvite as a problem • Scale build-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, 1976) • Used for high-value crops For ISU study on removing ammonia from hog waste see: www.public.iastate.edu/~tge/miles_and_ellis_2000.pdf

  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 NO3-) 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 granule • When BOD is depleted, PAO continue to grow on stored reserves (PHB) and continue to store poly-P

  33. Anaerobic Zone (initial) H3CCOOH H3CCOO- + H+ ATP PHB polymer ADP+Pi ATP ADP+Pi Pi Pi Polyphosphate Granule ADP+Pi H+ ATP

  34. Anaerobic Zone (later) H3CCOOH H3CCOO- + H+ ATP ADP+Pi PHB polymer ATP ADP ADP+Pi Pi Polyphosphate Granule Pi ADP+Pi H+ ATP

  35. Aerobic Zone (initial) substrate H+ substrate CO2 + NADH ADP+Pi ATP NAD ATP Polyphosphate Granule ADP+Pi PHB polymer Pi H2O Pi ATP 2H+ + 1/2O2 ADP+Pi H+

  36. Aerobic Zone (later) H+ NAD CO2 + NADH ATP PHB polymer ADP+Pi ATP ADP+Pi Polyphosphate Granule Pi H2O Pi ATP 2H+ + 1/2O2 ADP+Pi H+

  37. Bio-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 Alum, Fe+3 (optional) air Anaerobic Selector Secondary Clarifier Aeration Basin return activated sludge (RAS) waste activated sludge (WAS) Phosphate Storage “Battery”

  39. Combined N and P Removal • Competition between bio-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 Removal nitrate rich recirculation Secondary Settling Tank Anaerobic Selector Anoxic Selector Aeration Basin (nitrification zone) air return activated sludge (RAS) waste activated sludge (WAS) A2O

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

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

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

  44. Sulfur • inorganic: SO4-2 S° H2S • organic: R — O — SO3-2 four key reactions: • H2S o__________________ — can occur aerobically or anaerobically to elemental sulfur (S°) • a___________________ : Thiobaccilus thioparus oxidizes S-2 to S° • S-2 + ½ O2 + 2H+ ➔ S° + H2O • a_______________________: — phototrophs use H2S as electron donor • filamentous sulfur bacteria oxidize H2S to S° in sulfur granules: Beggiatoa, Thiothrix

  45. Sulfur 2. Oxidation of E_______________ Sulfur (Thiobacillus thiooxidans at low pH) 2S° + 3 O2 + 2 H2O ➔ 2 H2SO4 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 SO4-2 + Organics ➔ S-2 + H2O + CO2 S-2 + 2H+ ➔ H2S • 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

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