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United States Department of Agriculture

Agricultural Research Service

2007 Annual Report

1a.Objectives (from AD-416)
1. Develop and evaluate solutions that improve efficiencies of scale and reduce water quality constraints for sustainable production. Sub-objectives are to overcome obstacles associated with managing hydraulics and harvests within large (600 m3) tanks, and control of noise, dissolved organic compounds, micro-organisms, and dissolved carbon dioxide.

2. Develop and evaluate sustainable waste management technologies that result in environmentally compatible CIAS. Sub-objectives include work on treatment processes for solids, nutrient removal from aquaculture effluents and mitigation of the impact of feed on water quality.

3. Field test selected rainbow trout germplasm resources for performance in intensive recirculating aquaculture systems.

1b.Approach (from AD-416)
To investigate approaches for enhancing economics of scale and to reduce water quality and other environmental contraints, the minumum bottom-center drain surface loading rate and the water inlet structure design required to produce rapid solids flushing and safe fish swimming speeds will be identified using a 600 m3 experimental tank. Studies will be conducted to determine if noise levels in the water produced by water pumping and treatment equipment affect hearing in fish and result in reduced growth. In addition, fish health will be assessed in conjunction with controlled ozone and UV treatment to determine treatment levels required to reduce bacterial load and organic carbon load; further, the utilization of bacteriophage to specifically mitigate pathogenic bacterial load in CIAS will be tested. Water quality control using new technology that facilitates carbon dioxide removal and enhances oxygen absorption will be tested and operating parameters defined. More sustainable waste management technologies for CIAS will be developed by testing several new and promising approaches to the capture and concentration of solid wastes and to their stabilization and denitrification. Further, new diets utilizing plant proteins as a substitute for fish meal proteins will be evaluated to determine if there is a differential impact on water quality of the wastes produced from feeding these diets in CIAS. Growth and survival data on selected rainbow trout germplasm cohorts or families provided by NCCCWA will be collected. Linkage with specific research objective at NCCCWA will be maintained.

3.Progress Report
This report documents research conducted under an Assistance Type Cooperative Agreement between ARS and the Conservation Fund’s Freshwater Institute entitled, "Development of Sustainable Land-based Aquaculture Systems" (1930-32000-003-01G). A novel technique was developed to herd fish in large culture tanks during harvest or fish transfer events. In addition, a model was developed and calibrated with empirical data so that the solids flushing rate and water rotational velocity profile across a culture tank can be estimated from culture tank volume and exchange rate, inlet nozzle velocity and orientation, and the bottom-center drain surface loading rate. These results will yield operational cost savings with the use commercial-scale circular culture tanks.

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.

Disinfection in recirculating fish culture systems. Pathogens and other microbial populations can accumulate and compromise fish health in fish culture systems that recirculate water. Scientists at The Conservation Fund’s Freshwater Institute (Shepherdstown, WV) determined the process requirements necessary to achieve full-flow disinfection of recycled water using ozonation followed immediately by ultraviolet irradiation. We found that the entire recirculating flow could be effectively disinfected when the ozone dose was controlled in a feed-back loop using real-time probes that measured either dissolved ozone concentration or oxidation reduction potential. Thus, combining ozone with ultraviolet irradiation in a recirculating system can prevent the accumulation of most fish pathogens and significantly reduce the risk of spreading fish disease. These findings are predicted to produce more biosecure aquatic production systems that sustain healthier and more growth promoting environments. This accomplishment aligns with the NP 106 Aquaculture Program Components: Aquaculture Production Systems (Production Intensity) and Sustainability and Environmental Compatibility of Aquaculture (Water Use & Reuse).

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 was 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 with 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.

5.Significant Activities that Support Special Target Populations
Freshwater Institute scientists have provided technical support in aquaculture engineering, fish health and biosecurity, and trout and Arctic char culture across the Appalachian region. This work supports economic development in a region where many counties are rated as economically distressed and unemployment rates are greater than 10%. Across the Appalachian states of West Virginia, Kentucky, Virginia, Maryland and Pennsylvania, there are many natural resources that appear to represent potential development opportunities. Current production figures indicate that the Mid-Atlantic Highlands region has not yet participated in the general expansion of the aquaculture industry in the U.S.

6.Technology Transfer

Number of web sites managed1
Number of non-peer reviewed presentations and proceedings28
Number of newspaper articles and other presentations for non-science audiences6

Last Modified: 10/25/2014
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