Investigation in Reuse of Decommissioned Wastewater Facility and Reclaimed Water for Culturing Paddlefish Fingerlings

Abstract

AbstractReclaimed water is treated wastewater that has received at least secondary treatment and basic disinfection and is reused for beneficial purposes. The goal of this study was to develop a safe and reliable sustainable aquaculture system for producing stocker fish using reclaimed water in decommissioned wastewater treatment plants (WWTP) in Kentucky. The specific objectives were (1) to monitor paddlefish, Polyodon spathula, growth and survival and water quality in experimental tanks with static or flow‐through reclaimed water, (2) to evaluate the use of decommissioned tanks for large‐scale production of phase II paddlefish, and (3) to biomonitor paddlefish grown in reclaimed water for contaminants. Phase I paddlefish (11 ± 2.6 g) were produced by feeding live Daphnia collected daily from the clarifier tanks with hand‐pulled nets for 27 d. Phase II paddlefish were produced in four replicated 5600‐L experimental tanks with static and flow‐through reclaimed water. Paddlefish from the flow‐through system were significantly larger (199.2 ± 61 g) and had better feed conversion ratios (2.8 ± 2.1) than those from the static system (135.5 ± 51 g; 4.1 ± 1.6). For the large‐scale trial, two 1125 m3 decommissioned digester tanks were stocked with 50,000 paddlefish larvae per tank. One tank was treated as a flow‐through system with reclaimed water flowing at a rate of 280 L/min, while the other tank was treated as a static system where water was just added to replace that lost by evaporation. Survival rate (40%) and weight (194.1 ± 25.4 g) from the flow‐through system were significantly different from those of the static system (31%; 147.1 ± 6.5 g). This difference could be linked to better water quality in the flow‐through systems. Analyses for 38 contaminants were conducted on Daphnia, prepared diets, and paddlefish. All the concentration levels detected were at levels well below the FDA action limits and their permissible limits in edible food. The result from this project showed that paddlefish can be successfully produced in large-scale as stocker fish using reclaimed water in decommissioned tanks at WWTP.