INTEGRATING AQUACULTURE AND WATER REUSE FOR DECOMMISSIONED WASTEWATER TREATMENT FACILITIES IN LONDON, KY
Decommissioned waste water treatment facilities provide a unique infrastructure for aquaculture development. This project utilizes large concrete structures (formerly clarifiers and digesters) at the Water Resource Recovery Facility (WRRF) in London, KY. Features of these facilities include a secure location, vehicle access, readily available electric power, support structures, communication infrastructure, abundant continuous water supply, treatment for aquaculture discharge, personnel trained in water quality assessment, and other substantial industrial infrastructure. Facilities are not designed for aquaculture and represent challenges with regard to safety, economy of scale, water quality management, harvesting and marketing. Clarifiers used in this study are rectangular approximately 34.7 m by 9.5 m by 2.4 m deep with a volume of 800 m3 (0.65 acre-ft). Digesters are circular with a 10.7 m diameter and a depth of 9.1 m with a water volume of 617 m3 (0.5 acre-ft). Clarifiers have a flat bottom that can be seined, but digesters have a cone bottom that is not seinable. Good management practices for this facility include continuous aeration, periodic water exchange, confining the fish in net pens, routine water quality monitoring, feeding in relation to an established production plan, addition of salt after a water exchange, monitoring for disease, and systematic record keeping for each production unit. Paddlefish, Largemouth Bass, Hybrid Striped Bass, Hybrid Bluegill Sunfish, Channel Catfish, survive and grow well in this facility.
At this point, investigators working on this project have not observed a specific contaminant risk associated with growing food fish in water treated at these facilities. Previous work at a treatment plant in Winchester, KY found that fish produced there met FDA requirements with regard to metals and pesticides (i.e. mercury, selenium, Chlordane, Mirex, Aldrin, PCB's and more). A composite sample of 10 Largemouth bass grown in the London WRRF confirmed this conclusion with levels of metals or pesticides no higher than samples of bass taken from surface waters in the London area. While the objectives of this project do not include a study of contaminants in fish produced at this location it was deemed prudent from a marketing perspective.
As the value of water is recognized, it makes sense to develop methods that take greater advantage of existing resources to grow fish for food and recreation. Results from this project contribute to observations made at wastewater treatment plants in Winchester, Frankfort, Midway, and now, London, Kentucky.