600 likes | 863 Views
Recirculation Aquaculture. Why Recirculation. Water use Climate Quality Predation. Environmental impact Land Disease Exotic species (or control thereof…. Cost of Labor : $7/day. Solids Siphon. Near Ensenada, Mexico; 2002. Near Ensenada, Mexico; 2002. Near Ensenada, Mexico; 2002.
E N D
Why Recirculation • Water use • Climate • Quality • Predation • Environmental impact • Land • Disease • Exotic species (or control thereof…
Cost of Labor : $7/day Solids Siphon Near Ensenada, Mexico; 2002
Definitions Recirculating System: A production system that reconditions water to extend it’s reuse A technique that increases the value of a limited resource An artificial well that never ceases to flow A stable platform forming a reliable base for commercial production
Five Major Processes 1) Circulation 2) Clarification (Solids capture) 3) Biofiltration (BOD reduction/nitrification) 4) Aeration (Oxygen replacement) 5) Degasification (CO2 stripping)
Five Major Treatment Objectives The Five Major Processes in a Recirculating System Feeding Circulation Aeration Fish Tank Degasification Biofiltration Solids Capture
Return to Tank Double Drain at Center of Tank
Inlet Outlet Sludge outlet From Under-drain
From Microscreen Micro-Bead Filter
Pressure line from Centrifugal Pumps Oxygen Bubbles 02 Flow Meter Pressure Gauge Water Return to Tanks
Solids Capture Feeding Circulation Aeration Fish Tank Degasification Biofiltration Solids Capture
Solids Capture Impact of Solids on Recirculating Systems • Increased BOD load (organic solids) causes problems with Biofilters • Increased system turbidity (fine particles) • Gill damage in fish (fine particles)
Solids Capture Particle Size Distribution (microns) Settleable 10-4 10-3 10-2 10-1 1 10 100 Dissolved Colloidal Suspended
Tilapia No Fine Solids Capture
Coarse Screens Cartridge Filter Plain Sedimentation Tube Settler Microscreen Granular Filter Foam Fractionation 100 30 75 10 Particle Size, microns SOLIDS REMOVAL PROCESSES AND PARTICLE SIZES
Solids Capture SEDIMENTATION Vh OUTFLOW Vs Settling Zone Inlet Zone INFLOW Outlet Zone (Vs> Overflow Rate to settle) Sludge Zone
Solids Capture Solid Removal Technologies • Effective for selected particle size • Differ in headloss…energy $$$ • Differ in labor for upkeep • Sensitive to organic loading
“BYPASS” FILTRATION TANKS Pump Liquid O2 Bead Filter Packed Column Fluidized Bed Packed Column Lime Addition
“IN-LINE” FILTRATION TANKS Shrimp Maturation in South America Pump Bead Filter Fluidized Bed Packed Column
Feeding Circulation Aeration Fish Tank Degasification Biofiltration Solids Capture
Biofiltration Types of Biofilters
0.45 kg/m3 USDA - SBIR/AST, 97
Broodstock Return Anti-siphon valve Bypass Sludge View Port Pressure Gauge Sludge Intake
Gas Exchange Feeding Circulation Aeration Fish Tank Degasification Biofiltration Solids Capture
Oxygen 21% of air Saturation 10 mg/l Poorly soluble Transfer H20 limited Carbon Dioxide 0.035% of air Saturation 0.5 mg/l Highly soluble 50 mg/l + Transfer gas limited Gas Exchange Different Behavior Oxygen goes in easier than CO2 comes out
Gas Exchange No CO2 Removal Enrichment Devices • Commonly used for large scale applications • Self-generates pressure (150-200 psi) • 1 m3 liquid860 m3 gas • Dependent on local source of liquid oxygen • Not impacted by power failure • 15-35cents/kg typical Liquid Oxygen Timmons and Lorsordo (1994) pg. 188
Gas Exchange • Air stones • Paddle wheels • Surface Agitators • Spray nozzles • Packed columns Ambient Air –Oxygen Addition and Carbon Dioxide removal are balanced
Gas Exchange Ambient Air Options
Circulation Feeding Aeration Circulation Fish Tank Biofiltration Degasification Solids Capture