Abstract
Conventional treatment alternatives for phosphorus in wastewater, whether they employ chemical precipitation, physical removal, or land application technologies, represent a significant additional cost to the owner of an aquaculture operation. Plant-based removal of nutrients has the potential to generate additional revenues, which can offset treatment costs. The objective of this analysis was to describe the economic relationship between a 22,680 kg per year recirculating rainbow trout (Oncorhynchus mykiss Walbaum) production system and a hydroponic treatment unit, growing 'Ostinata' lettuce (Lactuca sativa L.) and sweet basil (Ocimum basilicum L.), capable of reducing phosphorus concentration levels in the fish farm effluent to less than 0.1 mg/L. The integration of the fish and plant production system (aquaponics) produces economic cost savings over either system alone. Shared cost savings come from spreading out operating costs (e.g., management, water, nutrients, and overhead charges) and capital costs (e.g., backup generator, used truck, and office equipment) over the two systems. The investment analysis demonstrates the profitability of this combined system over its 20-year expected life. Net present values are positive for a wide range of discount'rates. Internal rate of return analysis shows that for a total investment of $244,720 this system can potentially provide a return of 12.5%. The hydroponic system drives the potential profitability of the combined system with 67% of annual returns derived from plant production.
Highlights
Consumer demand for fish has been increasing, but ocean fish catches continue to decline
All states in the Northeastern U.S have regulations regarding the discharge of aquacultural effluents (Ewart et al 1995)
Technologies are available to reduce the concentration of nutrient discharge from these facilities to regulated levels based on United States EPA (Environmental Protection Agency) water quality drinking standards
Summary
Consumer demand for fish has been increasing, but ocean fish catches continue to decline. A conveyor production system made it possible for plants to remove >95% of the P (to< 0.01 ppm P) in the rainbow trout effluent while producing a marketable product The objective of this analysis was to describe the economic relationship between a 22,680-kg per year recirculating trout production system and a hydroponic treatment unit capable of reducing phosphorus concentration levels in the fish farm effluent to less than 0.1 mg/L. Adler et al (2000) conducted a study which compared the cost of alternative nutrient discharge treatment options includi~g chemical and filtration methods and hydroponics It did not describe the International Journal of Recirculating Aquaculture, vol l, no. The economics of this integrated relationship must be quantified to properly assess the viability of this technology
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