2007 Annual Report
An internal disinfection process to control the accumulation of pathogens and other microbial populations was developed for fish culture systems that recirculate water. Process requirements to achieve full-flow disinfection using ozonation followed by ultraviolet irradiation were determined. The design guidelines and performance of these two processes in water reuse systems have been made available to the aquaculture community and the findings are predicted to produce more biosecure and better environments in aquatic production systems
Rainbow trout health and performance was studied in replicated water reuse systems operated at high feed rates but low system flushing rates. Preliminary results indicate that rainbow trout health, growth, and survival were no different between replicated systems operated at feed loading rates of 3.5 or 0.35 kg/m3 of makeup water exchange. This work will result in the identification and amelioration of substances that can accumulate within controlled intensive aquaculture systems and affect fish health.
Wastes contained in the backwash discharged from intensive recirculating aquaculture systems were removed and dewatered in simple geotextile bag filters. Three chemical coagulation aids, i.e., aluminum sulfate, ferric chloride, and calcium hydroxide, were tested in combination with a polymer flocculation aid to determine the most cost effective and efficient treatment combination. In addition, studies were completed to compare the capture and dewatering of wastes from intensive recirculating aquaculture systems by a gravity thickening tank, an inclined belt filter, and a geotextile bag filter. The design and management guidelines will improve waste capture, dewatering, and disposal at aquaculture facilities.
Trials to evaluate performance and waste production characteristics of rainbow trout fed a new USDA ARS formulated grain-based diet began. Fish farmers and aquacultural engineers will use the results from this research to identify changes in controlled intensive aquaculture system technology required to accommodate the changes in waste production characteristics encountered when feeding these diets. Finally, growth and survival data on selected rainbow trout families from NCCCWA were collected during culture in commercial-scale intensive water reuse systems to evaluate their performance.
Geotextile filters for dewatering aquaculture biosolids.
More effective technologies are required to improve waste capture, dewatering, and disposal at intensive aquaculture facilities. Scientists at The Conservation Fund's Freshwater Institute (Shepherdstown, WV) used pilot-scale geotextile tube filters to treat the wastes contained in the backwash discharged from intensive aquaculture systems. The geotextile filters removed approximately 95% of the suspended solids from the backwash flow and dewatered the solids to > 20% dry content, which presents a form that fish farmers could readily transport, store, or send for disposal. Three chemical coagulation aids, i.e., aluminum sulfate (alum), ferric chloride, and calcium hydroxide (slaked lime), were tested in combination with a polymer flocculation aid to determine the most cost effective and efficient treatment combination; alum was identified as the most cost effective chemical for coagulation, but slaked lime ws the most effective at phosphorus removal. Geotextile filter design and management recommendations were developed to improve waste capture, dewatering and disposal at aquaculture facilities. This accomplishment aligns wit the Sustainability and Environmental Compatibility of Aquaculture (Water Use and Reuse; Effluent Management Control; Environmental Sustainability) component of NP 106
Bebak, J.A., Welch, T.J., Starliper, C.E., Baya, A.M., Garner, M.M. 2007. An Outbreak of Rainbow Trout Fry Syndrome at a West Virginia Farm Controlled through Improved Husbandry. Journal of the American Veterinary Medical Association 231, 114-116. Davidson, J., Frankel, A., Ellison, W., Summerfelt, S.T., Popper, A.N., Mazik, P., Bebak, J. 2007. Minimizing noise in fiberglass aquaculture tanks: Noise reduction potential of various retrofits. Aquacultural Engineering 37, 125-131. Draghi, A., Bebak, J., Popov, V.L., Noble, A.C., Geary, S.J., West, A.B., Byrne, P., Frasca Jr., S. 2007. Characterization of a Neochlamydia-like Bacterium Associated with Epitheliocystis in Cultured Arctic Char Salvelinus alpinus. Diseases of Aquatic Organisms. 76, 27-38. Ebeling, J.M., Timmons, M.B., Bisogni, J.J., 2006. Engineering analysis of the stoichiometry of photoautotrophic, autotrophic, and heterotrophic control of ammonia-nitrogen in aquaculture production systems. Aquaculture 257, 346-358. Labatut, R.A., Ebeling, J.M., Bhaskaran, R., Timmons, M.B. 2007. Effects of inlet and outlet flow characteristics on mixed-cell raceway (MCR) hydrodynamics. Aquacultural Engineering 37, 158-170. Labatut, R.A., Ebeling, J.M., Bhaskaran, R., Timmons, M.B. 2007. Hydrodynamics of a large-scale mixed-cell raceway (MCR): Experimental studies. Aquacultural Engineering 37, 132-143. Sharrer, M.J., Tal, Y., Ferrier, D., Hankins, J.A., Summerfelt, S.T. 2007. Membrane biological reactor treatment of a saline backwash flow from a recirculating aquaculture system. Aquacultural Engineering 35, 159–176. Sharrer, M.J., Summerfelt, S.T. 2007. Ozonation followed by ultraviolet irradiation provides effective bacteria inactivation in a freshwater recirculating system. Aquacultural Engineering 37, 180-191.