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Warm Water System Design

Warm Water System Design. M.B. Timmons, Ph.D. Biological & Environmental Engineering Cornell University Ithaca, NY. James M. Ebeling, Ph.D. Research Engineer Aquaculture Systems Technologies, LLC New Orleans, LA. Overview of System Design. Carbon Dioxide Removal. Aeration Air/Oxygen.

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Warm Water System Design

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  1. Warm Water System Design M.B. Timmons, Ph.D. Biological & Environmental Engineering Cornell University Ithaca, NY James M. Ebeling, Ph.D. Research 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. Design Requirements • The Following Unit Process are required in any design: • Culture Tank Design • Circulation • Solids Removal • Biofiltration / Nitrification • Gas Transfer (Aeration / Oxygenation / CO2 Removal) Recirculating Aquaculture Systems Short Course

  4. Design Assumptions For any design, some assumptions need to be made, hopefully based either on actual experience or reputable research. Recirculating Aquaculture Systems Short Course

  5. Design Assumptions Assuming: 454,000 kg/yr production (1 million pounds/year) • Mean feeding rate: rfeed = 1.2% BW/day • Feed conversion rate: FCR = 1.3 kg feed/kg fish produced • Culture Density : 80 kg fish/m3 • Oxygen Demand: 0.75 kg O2/ kg feed (these rates are an average over entire year) Recirculating Aquaculture Systems Short Course

  6. System Biomass Estimation Estimate of system’s average feeding biomass : Recirculating Aquaculture Systems Short Course

  7. Total Oxygen Requirements • Estimate the oxygen demand of system’s feeding fish: • where: • RDO = average DO consumption Rate = kg DO consumed by fish per day) • aDO = average DO consumption proportionality constant = kg DO consumed per 1 kg feed Ranges from 0.4 to 1.0 kg O2/kg feed – cold water to warm water Recirculating Aquaculture Systems Short Course

  8. Total Flow Requirement – Oxygen Load • Estimate water flow (Q) required for fish’s O2 demand: • Assuming oxygen: • DOinlet = 18 mg/L • DOeffluent= 4 mg/L (@ steady state) Recirculating Aquaculture Systems Short Course

  9. Total Tank Volume Requirements Assume an average fish density across all culture tanks in the system: • culture density = 80 kg fish/m3 Recirculating Aquaculture Systems Short Course

  10. Check Culture Tank Exchange Rate Rule of Thumb a culture tank exchange every 30-60 minutes provides good flushing of waste metabolites while maintaining hydraulics within circular culture tanks Recirculating Aquaculture Systems Short Course

  11. Assuming 9 m (30 ft) dia tanks water depth 2.3 m 7.5 ft culture volume per tank 150 m3 40,000 gal 10-11 culture tanks required Assuming 15 m (50 ft) dia tanks water depth 3.7 m 12 ft culture volume per tank 670 m3 177,000 gal 2-3 culture tanks required Number of Tanks Required Recirculating Aquaculture Systems Short Course

  12. Ten Production Tanks Diameter 9.14 m ( 30 ft ) Water depth 2.3 m (7.5 ft) Culture volume per tank 150 m3 (40,000 gal) Oxygen Demand 117 kg O2/day (257 lbs/day) Tanks Design Summary • Flow Rate (30 min exchange) • 5,000 Lpm (1,320gpm) • Biomass Density • 86 kg/m3 (0.72 lbs/gal) Recirculating Aquaculture Systems Short Course

  13. Options for Solids Capture: Solids Capture • Dual-drain System • Settling Basin • Swirl Separator • Microscreen Filter • Propeller Washed Bead Filter Recirculating Aquaculture Systems Short Course

  14. One Options for Solids Capture: Solids Capture Dual-drain System (15% bottom Drain) Bottom Drain ▬►To a Swirl Separator Combine Flow (Swirl Separator & Side-wall Drain) ▬►To Microscreen Filter Recirculating Aquaculture Systems Short Course

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

  16. Biofilter Design – Step 1 Step 1: Calculate the dissolved oxygen requirement (RDO). Assume a DO consumption of 1.0 kg/kg feed Both the MBB and Trickling Tower provide O2 for Nitrification or approximately 0.25 kg. Thus 0.75 kg O2 /kg feed. Recirculating Aquaculture Systems Short Course

  17. Biofilter Design – Step 2 Step 2: Calculate water flow requirement (Qtank) required for fish DO demand. Assume: DOinlet = 18 mg/L (pure oxygen aeration system) DOtank = 4 mg/L (warm water 24 Deg. C, Tilapia!!) Recirculating Aquaculture Systems Short Course

  18. Biofilter Design – Step 2 (cont) Step 2: Check the Exchange rate (2-4 exchanges/hr) A tank exchange rate of 2 exchanges per hour is OK! Recirculating Aquaculture Systems Short Course

  19. Biofilter Design – Step 3 Step 3: Calculate TAN production by fish (PTAN) (Note: Feed is 35% protein) PTAN = F * PC * 0.092 = F * 0.35 *0.092 = 0.032 where: PTAN = Production rate of total ammonia nitrogen, (kg/day) F = Feed rate (kg/day) PC = protein concentration in feed (decimal value) Recirculating Aquaculture Systems Short Course

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

  21. Biofilter Design – Step 4 (MBB) Step 4: Calculate volume of media, Vmedia based on the Volumetric nitrification rate (VTR) Consider a Moving Bed BioReactor (MBB) Curler Advance X-1 has a 605 g TAN/m3 (17.14 g TAN/ft3). Recirculating Aquaculture Systems Short Course

  22. Biofilter Design – Step 4 (MBB) Step 4: Calculate volume of biofilter, Vbiofiler based on a fill ratio of 65%. This would require a tank (3200 gal): 7 ft in diameter and 11 ft tall. Recirculating Aquaculture Systems Short Course

  23. Biofilter Design – Step 4 (Trickling Tower) Step 4:Calculate the surface area (Amedia) required to remove PTAN from the Areal TAN removal rate (ATR) (0.45 g TAN/m2 day) Recirculating Aquaculture Systems Short Course

  24. Biofilter Design – Step 5 (Trickling Tower) Step 5: Calculate volume of media based on the specific surface area (SSA), example BioBlock = 200 m2/m3 (61 ft2/ft3) Recirculating Aquaculture Systems Short Course

  25. Biofilter Design – Step 6 (Trickling Tower) Step 6: Calculate the biofilter cross-sectional area from required flow for the fish oxygen demand (Qtank) and the hydraulic loading rate, HLR of 250 m3/m2 day (4.4 gpm/ft2). Recirculating Aquaculture Systems Short Course

  26. Biofilter Design – Step 7 (Trickling Tower) From high school math class: area =  (Dia)2 / 4 diameter = [ 4 * area / ]1/2 The diameter of a two trickling towers, Dbiofilter, with this cross sectional area is: Recirculating Aquaculture Systems Short Course

  27. Biofilter Design – Step 8 (Trickling Tower) Step 8: Calculate the biofilter depth (Depthmedia) from the biofilter cross-sectional area (Amedia) and volume (Vmedia). The final Trickling Tower is 15 ft in diameter and 12 ft tall plus distribution plate, etc. Recirculating Aquaculture Systems Short Course

  28. Aeration / Oxygenation Options • Multi-staged low head oxygenators (LHO) • Packed or spray columns • Pressurized columns • Enclosed mechanical surface mixers Recirculating Aquaculture Systems Short Course

  29. Tank Oxygen Requirements • Estimate the oxygen demand of system: • where: • RDO = average DO consumption Rate • = kg DO consumed by fish per day) • aDO = average DO consumption proportionality constant • = kg DO consumed per 1 kg feed • Ranges from 0.4 to 1.0 kg O2/kg feed – cold water to warm water Recirculating Aquaculture Systems Short Course

  30. Tank Oxygen - Speece Cones (Design Requirement: 117 kg O2 / day or 4.88 kg / hr) From Aquatic Eco-Systems, Inc. Catalog: A single Speece Cone: OY140F is rated at: 4.5 kg O2 /hr @ 10 psi, 600 gpm, 40 mg/L Or two Speece Cones: OY60F is rated at 2.3 kg O2 /hr @ 15 psi, 260 gpm, 46 mg/L Recirculating Aquaculture Systems Short Course

  31. CO2 PRODUCTION • Molar basis • 1 mole of CO2 is produced for every1 mole O2 consumed • Mass basis • 1.38 g of CO2 is produced for every1 g O2 consumed Recirculating Aquaculture Systems Short Course

  32. CO2 Control Options • Packed Tower Stripping • Sodium Hydroxide Addition • Water Exchange • In-tank Surface Aeration • Side-stream Surface Aeration • In-tank Diffused Aeration • Side-stream Diffused Aeration Recirculating Aquaculture Systems Short Course

  33. Stripping Column Design • Design criteria used for the forced-ventilation cascade column: • hydraulic fall of about 1.0-1.5 m • hydraulic loading of 1.0-1.4 m3/min per m2 one stripping columns with diameter = 2.0 m = 6.6 ft Recirculating Aquaculture Systems Short Course

  34. Stripping Column Design • Design criteria used for the forced-ventilation cascade column: • volumetric G:L of 5:1 to 10:1 Fan requirement: 1770 scfm Recirculating Aquaculture Systems Short Course

  35. Ozone Requirements • Estimate the ozone requirement of system’s feeding fish: • where: • aozone = kg ozone added per 100 kg feed Recirculating Aquaculture Systems Short Course

  36. Putting It All Together Carbon Dioxide Removal Aeration Air/Oxygen Fish Culture Tank Disinfection Fine & Dissolved Solids Removal Biofiltration Nitrification Sludge Waste Solids Removal Monitoring & System Control Sludge Recirculating Aquaculture Systems Short Course

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