Biofiltration nitrification design overview

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Biofiltration - nitrfification

Text of Biofiltration nitrification design overview

  • 1. Biofiltration-Nitrification Design Overview James M. Ebeling, Ph.D. Environmental Engineer Aquaculture Systems Technologies, LLC New Orleans, LA Recirculating Aquaculture Systems Short Course
  • 2. Overview of System Design Carbon Dioxide Aeration Removal Air/Oxygen Monitoring & System Control Disinfection Fish Culture Tank Fine & Dissolved Biofiltration Solids Removal Nitrification 5% 95% Sludge Settable Suspended Solids Solids Biosecurity Sludge Sludge Program Recirculating Aquaculture Systems
  • 3. Nitrification Biofiltration NitrificationInorganic Nitrogen Compounds NH4+-N (ionized ammonia nitrogen) NH3N (un-ionized ammonia nitrogen) NO2N (nitrite nitrogen) NO3N (nitrate nitrogen) Recirculating Aquaculture Systems
  • 4. Nitrification Biofiltration NitrificationNitrosomones Bacteria Catabolize un-ionized ammonia to nitrite Nitrobacter Bacteria Oxidize nitrite to nitrateHeterotrophic Bacteria Metabolize biologically degradable organic compounds Recirculating Aquaculture Systems
  • 5. Nitrification Biofiltration NitrificationNitrosomones Bacteria 2 NH4+ + OH - + 3 O2 2 H + + 2 NO2- + 4 H2ONitrobacter Bacteria 2 NO2 + 1 O2 2 NO3- Recirculating Aquaculture Systems
  • 6. Nitrification Biofiltration Nitrification Nitrifying Bacteria Overall ReactionNH4+ + 1.83 O2 + 1.97 HCO3- 0.0244 C5H7O2N + 0.976 NO3- + 2.90 H2O + 1.86 CO2 Recirculating Aquaculture Systems
  • 7. Nitrification (1 kg of feed @ 35% protein) Consumes C organic C inorganic NConsumables Stoichiometry (g) (g) (g) (g) NH4+-N 50.4 ----- ----- 50.4 Alkalinity 7.05 g Alk/ g N 355 ----- 85.6 ----- Oxygen 4.18 g O2/ g N 211 ----- ----- ----- Yields C organic C inorganic NProducts Stoichiometry (g) (g) (g) (g) VSSA 0.20 g VSSA / g N 10.1 5.35 ----- 1.25 NO3--N 0.976 g NO3--N /g N 0.976 ----- ----- 49.2 CO2 5.85 g CO2/ g N 295 ----- 80.1 ----- Recirculating Aquaculture Systems
  • 8. Nitrification BiofiltrationStart-up Curve for a Biological Filter Nitrification 15 TAN NO2 Concentration (ppm) 10 NO3 5 0 0 7 14 21 28 35 42 Time (days) Recirculating Aquaculture Systems
  • 9. Nitrification BiofiltrationAmmonia Production Nitrification1 kg feed about 0.03 kg ammonia nitrogen 1 g of ammonia yields: 4.42 g nitrate NO3- 5.93 g carbon dioxide 0.17 g cell mass 1 g of ammonia consumes: 4.57 g oxygen 7.14 g alkalinity Recirculating Aquaculture Systems
  • 10. Nitrification Biofiltration NitrificationEquilibrium Reaction - Ammonia NH4+ + OH - NH3 + H2O (ionized) (unionized) TOXIC Increase in pH Increase in temperatureNote: NH4+-N + NH3-N TAN NH4--N Ammonia - nitrogen Recirculating Aquaculture Systems
  • 11. Nitrification Biofiltration NitrificationPercent unionized ammonia-nitrogen pH Temp. 6.0 6.5 7.0 7.5 8.0 9.0 10 - 0.1 0.2 0.6 1.8 15.7 15 - 0.1 0.3 0.9 2.7 21.5 20 - 0.1 0.4 1.2 3.8 28.4 25 0.1 0.2 0.6 1.8 5.4 36.3 30 0.1 0.3 0.8 2.5 7.5 44.6 Recirculating Aquaculture Systems
  • 12. Nitrification Biofiltration Nitrification Equilibrium Reaction Nitrite NO2- + H2O HNO2 + OH - Decrease in pHNote: NO2--N Nitrite - nitrogenmitigated by adding salt (chlorides) Recirculating Aquaculture Systems
  • 13. Nitrification Biofiltration NitrificationHigh levels of nitrite can be produced under conditions when there is an imbalance between populations of Nitrosomonas and Nitrobacter, which can occur: within the first 4-8 weeks of biofilter startup if inadequate surface area or dissolved oxygen if ozone is used for an extended period and then turned-off (O3 + NO2- NO3- + O2) Recirculating Aquaculture Systems
  • 14. Nitrification Biofiltration Nitrification Equilibrium Reaction Nitrate NO3-N Non-toxic (freshwater systems)Note: NO3--N Nitrate - nitrogen Recirculating Aquaculture Systems
  • 15. Nitrification Biofiltration NitrificationFACTORS AFFECTING NITRIFICATION pH Alkalinity Temperature Oxygen Salinity Light Recirculating Aquaculture Systems
  • 16. Nitrification Biofiltration Nitrification pH Optimum range 6 - 9 (7.2-7.8) Recirculating Aquaculture Systems
  • 17. Nitrification Biofiltration Nitrification Alkalinity (50 -150 mg/l as Ca CO3)Formula Common Name Equivalent WeightNaOH sodium hydroxide 40Na2CO3 sodium carbonate 53 10.0 350NaHCO3 sodium bicarbonate 83CaCO3 Calcium Carbonate 50 300

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