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Biofiltration-Nitrification Design Overview

Biofiltration-Nitrification Design Overview. James M. Ebeling, Ph.D. Environmental Engineer Aquaculture Systems Technologies, LLC New Orleans, LA. Overview of System Design. Carbon Dioxide Removal. Aeration Air/Oxygen. Fish Culture Tank. Monitoring & System Control. Disinfection.

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Biofiltration-Nitrification Design Overview

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  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 Removal Aeration Air/Oxygen Fish Culture Tank Monitoring & System Control Disinfection Fine & Dissolved Solids Removal Biofiltration Nitrification 5% 95% Sludge Settable Solids Suspended Solids Biosecurity Program Sludge Sludge Recirculating Aquaculture Systems Short Course

  3. Nitrification Biofiltration Nitrification • Inorganic Nitrogen Compounds • NH4+-N (ionized ammonia nitrogen) • NH3–N (un-ionized ammonia nitrogen) • NO2–N (nitrite nitrogen) • NO3–N (nitrate nitrogen) Recirculating Aquaculture Systems Short Course

  4. Nitrification Biofiltration Nitrification Nitrosomones Bacteria Catabolize un-ionized ammonia to nitrite Nitrobacter Bacteria Oxidize nitrite to nitrate Heterotrophic Bacteria Metabolize biologically degradable organic compounds Recirculating Aquaculture Systems Short Course

  5. Nitrification Biofiltration Nitrification Nitrosomones Bacteria 2 NH4+ + OH - + 3 O2  2H + +2 NO2- + 4 H2O Nitrobacter Bacteria 2 NO2 + 1 O2 2 NO3- Recirculating Aquaculture Systems Short Course

  6. Nitrification Nitrifying Bacteria – Overall Reaction Biofiltration Nitrification NH4+ + 1.83 O2 + 1.97 HCO3- → 0.0244 C5H7O2N + 0.976 NO3- + 2.90 H2O + 1.86 CO2 Recirculating Aquaculture Systems Short Course

  7. Nitrification (1 kg of feed @ 35% protein) Recirculating Aquaculture Systems Short Course

  8. Nitrification Start-up Curve for a Biological Filter Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  9. Nitrification Ammonia Production Biofiltration Nitrification 1 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 Short Course

  10. Nitrification Equilibrium Reaction - Ammonia Biofiltration Nitrification NH4+ + OH - NH3+ H2O (ionized) (unionized) TOXIC Increase in pH Increase in temperature Note: NH4+-N + NH3-N  TAN NH4--N  Ammonia - nitrogen Recirculating Aquaculture Systems Short Course

  11. Nitrification Percent unionized ammonia-nitrogen Biofiltration Nitrification 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 Short Course

  12. Nitrification Equilibrium Reaction – Nitrite Biofiltration Nitrification NO2- + H2O HNO2+ OH - Decrease in pH Note: NO2--N  Nitrite - nitrogen mitigated by adding salt (chlorides) Recirculating Aquaculture Systems Short Course

  13. Nitrification Biofiltration Nitrification High 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 Short Course

  14. Nitrification Equilibrium Reaction – Nitrate Biofiltration Nitrification NO3-N Non-toxic (freshwater systems) Note: NO3--N  Nitrate - nitrogen Recirculating Aquaculture Systems Short Course

  15. Nitrification FACTORS AFFECTING NITRIFICATION Biofiltration Nitrification • pH • Alkalinity • Temperature • Oxygen • Salinity • Light Recirculating Aquaculture Systems Short Course

  16. Nitrification pH Biofiltration Nitrification Optimum range 6 - 9 (7.2-7.8) Recirculating Aquaculture Systems Short Course

  17. Nitrification Alkalinity (50 -150 mg/l as Ca CO3) Biofiltration Nitrification Formula Common Name Equivalent Weight NaOH sodium hydroxide 40 Na2CO3 sodium carbonate 53 NaHCO3 sodium bicarbonate 83 CaCO3 Calcium Carbonate 50 CaO slaked lime 28 Ca(OH) 2 hydrated lime 37 Rule of Thumb: 0.25 lbs of baking soda per pound of feed Recirculating Aquaculture Systems Short Course

  18. Nitrification Temperature Biofiltration Nitrification Determined by the species cultured not biofilter needs “Nitrification rates at 17 Deg. C would be 77% of the rates obtained at 27 Deg. C, or a 27% reduction in rate” Recirculating Aquaculture Systems Short Course

  19. Nitrification Oxygen Biofiltration Nitrification 4.57 g O2 for each gram of TAN -> NO3 Rule of Thumb: Effluent from biofilter at least 2 mg/L Dissolved Oxygen (DO) Recirculating Aquaculture Systems Short Course

  20. Nitrification Salinity Biofiltration Nitrification Bacteria can acclimate to almost any salinity range. Recirculating Aquaculture Systems Short Course

  21. Nitrification Light Biofiltration Nitrification Light has been shown to inhibit the growth of nitrifying bacteria. Recirculating Aquaculture Systems Short Course

  22. Nitrification Ammonia Concentration Biofiltration Nitrification Ammonia concentration itself will affect the nitrification rate directly. Recirculating Aquaculture Systems Short Course

  23. Biofilters Terms Used To Describe Biofilters Biofiltration Nitrification • Void Space / porosity • Cross-sectional Area • Hydraulic Loading Rate • Specific Surface Area Recirculating Aquaculture Systems Short Course

  24. Biofilters Void Space / porosity Biofiltration Nitrification Terms Used To Describe Biofilters Ratio of the volume of void spaces between media particles and filter media volume High void ratios reduce clogging Recirculating Aquaculture Systems Short Course

  25. Biofilters Cross-sectional Area Biofiltration Nitrification Terms Used To Describe Biofilters Area of the filter bed material looking in the direction of the water flow. Recirculating Aquaculture Systems Short Course

  26. Biofilters Hydraulic Loading Rate Biofiltration Nitrification Terms Used To Describe Biofilters Volume of water flowing through the filter per unit of cross-sectional area of the filter bed per unit of time (m3/m2/day) (gal/ft2/min) Recirculating Aquaculture Systems Short Course

  27. Biofilters Specific Surface Area Biofiltration Nitrification Terms Used To Describe Biofilters Surface area of the media per unit volume (m2/m3) (ft2/ft3 ) Recirculating Aquaculture Systems Short Course

  28. Biofilter Performance Volumetric TAN conversion rate Biofiltration Nitrification Terms Used To Describe Biofilter Performance Ammonia-nitrogen removal rate per unit volume of filter [kg TAN /m3 day] Recirculating Aquaculture Systems Short Course

  29. Biofilter Performance Areal TAN conversion rate Biofiltration Nitrification Terms Used To Describe Biofilter Performance Ammonia-nitrogen removal rate per unit surface area of filter [g TAN /m2 day] Recirculating Aquaculture Systems Short Course

  30. (15 to 20 Deg. C) Granular (bead/sand) (> 500 m2/m3) Media Type Trickling or RBC (100 – 300 m2/m3) (25 to 30 Deg. C) Surface area of media Volume of media TAN Conversion Basis 0.2 to 1.0 g/m2 day TAN Conversion Rate 0.6 to 0.7 kg/m3 day 1.0 to 2.0 g/m2 day 1.0 to 1.5 kg/m3 day TAN Conversion Rate Biofilter Performance Ammonia Assimilation Rates Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  31. Sizing Nitrifying Biofilters • Biofilter is sized to remove a given daily TAN production (kg TAN/day). • You must know or assume • daily TAN production, kg TAN/day. • Arial TAN removal rate, g TAN removal/day per m2 • Sp Surface Area in m2/m3 • Biofilter Volume in m3 Recirculating Aquaculture Systems Short Course

  32. Biofilter Surface Area Specific surface area typical for different biofilter typesm2/m3 • Trickling & RBC 100-300 • Kjaldness moving bed biofilter 500 • Pressurized-bead filter 1,150-1,475 • Polystyrene micro-bead biofilter 3,900 • Sand biofilter 5,000-11,000 Recirculating Aquaculture Systems Short Course

  33. Biofilter Media Classified according to packing characteristics, i.e., • Random packing: • aggregate sand, crushed rock, or river gravel; • plastic or ceramic beads, spheres, rings, or saddles; • Structured packing: • plastic blocks of corrugated plates or tubes.

  34. Structured Packing It is important to consider: • Large void spaces • Non-plugging • Easy to maintain NORPAC ACCUPAC Recirculating Aquaculture Systems Short Course

  35. Structured Packing Structured packings are not limited to rectangular tower designs! – circular cut packing blocks AccuPac CF-3000: 3 cm flute, 95% void ratio, 102 m2/m3 , Crossflow design Recirculating Aquaculture Systems Short Course Courtesy of LS Enterprises (FL)

  36. Random Packing Random packing below a rotary spray nozzle. Recirculating Aquaculture Systems Short Course

  37. Biofilter Design To provide good performance and avoid solids plugging & dead zones requires proper: • media selection, • media support or retention mechanisms • flow distribution, • flow collection.

  38. Biofilter Classification Recirculating Aquaculture Systems Short Course

  39. Biofilter Classification microbial floc systems fixed-film bioreactors Recirculating Aquaculture Systems Short Course

  40. Biofilters Biofilter Options – Emergent Filters● Rotating Biological Contactor● Trickling Biofilters Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  41. Biofilters Rotating Biological Contactor Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  42. Biofilters Rotating Biological Contactor Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  43. Biofilters Biofiltration Nitrification Trickling Biofilters Recirculating Aquaculture Systems Short Course

  44. Biofilters Trickling Biofilters – Media Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  45. Biofilters Trickling Biofilters – Spray Bar Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  46. Biofilters Biofilter Options – Submerged Biofilters Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  47. Biofilters Submerged Biofilters – Static Packed Bed Biofiltration Nitrification Random Packed Plastic Media Gravel Bed Biofilter Recirculating Aquaculture Systems Short Course

  48. Biofilters Submerged Biofilters - Expandable Filters● Upflow Sand Filters● Floating-Bead Bioclarifiers Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  49. Biofilters Up Flow Sand Filters Biofiltration Nitrification Recirculating Aquaculture Systems Short Course

  50. Biofilters Floating Bead Bioclarifiers Biofiltration Nitrification Propeller-washed Bioclarifiers Recirculating Aquaculture Systems Short Course

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