2010 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)
1. The minimum 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 using oxygen and ph feedback control sytems will determine whether carbon dioxide gradients will induce fish to swim out of the culture tank during a harvest event. Sound levels and frequency ranges typically produced in the CIAS environment will be identified and analyzed to determine sound levels and frequencies that can cause hearing loss, damage fish ears and result in reduced growth rates. Controlled ozone and UV systems will be used to determine the combined ozone and UV irradiation dosages required to inactivate total heterotrophic bacteria and total coliform bacteria within a CIAS. Variable feeding rates per make-up water flow rates, fish health indicators and chemical analyses of organic carbon constituent will be used to determine whether advanced oxidation techniques can reduce accumulations of organic carbon constituents that impair fish health. Carbon dioxide removal across forced-ventilated cascade columns in a marine system will be characterized and modeled as a function of air: water loading, packing height, and salinity. Molecular techniques will be used to investigate reservoirs of infection for an emerging chlamydia-like bacterium that causes respiratory disease in Artic char.
2. The solids and nutrients capture and dewatering efficiency of a new bag filter system used to treat microscreen backwash will be determined. Biological nutrient removal will be evalutated within a commercial membrane biological reactor system using seperate stages for aerobic nitrification and anoxic denitrification. In conrolled, replicated feeding studies, the 'low fish meal and high grain proportion' feeds developed by ARS nutritionists at SGPGRU will be evaluated to determine differences in the amount of solid and nutrient waste excreted in comparison with standard fish meal and fish oil based diets, and determine if these grain-based feeds impact water quality in CIAS.
3. Growth and survival data on selected rainbow trout germplasm cohorts or families provided by NCCCWA will be collected. Replicated and commercial scale intensive recirculating aquaculture systems will be operated as performance trial platforms for the evaluation of singular and mixed stocks of trout. Aquaculture systems will simulate conditions found in commercial production environments or will be modified to create enhanced challenges. Trout will be tagged to allow either individual, family or cohort identification as appropriate. Linkage with specific research objectives at the NCCCWA will be maintained.
This is the final report for 1930-32000-003-00D which terminated December 1, 2009. Project was replaced by 1930-31320-001-00D. The overall goal of this project has been to develop and improve technologies that enhance the sustainability and reduce the environmental impacts of the modern fish farming industry. Progress was made in several areas.
Research on rainbow trout performance, health, and welfare, and water quality, was carried out in WRAS operated at close to zero water exchange, with or without ozone. This work has provided valuable insight into water quality parameters that accumulate (with or without ozone) in near-zero exchange WRAS, and has stimulated hypotheses regarding, among other things, nitrate levels that will be explored in controlled research in the next 5-year cycle.
The cost and effectiveness of three solids thickening processes, i.e., gravity thickening cone, geotextile filter, and belt filter, were determined and published in the refereed journal Bioresource Technologies. This research will provide design and management recommendations that can be used by fish farmers to improve waste capture, dewatering, and disposal, which will reduce the risk of potentially adverse interactions between aquaculture operations and the surrounding aquatic environment.
Performance of a novel aerated geotextile filter system that combines biological nutrient removal, sludge stabilization, and solids thickening in one membrane filter process was determined. This research has determined the engineering criteria and performance expectations for solids and nutrient capture within a relatively primitive but inexpensive membrane biological reactor system.
Data collection was concluded in a study that determined the capacity of a membrane biological reactor to provide nitrification, denitrification, and enhanced biological phosphorus removal of a high-strength aquaculture backwash flow (control condition), or the same flow amended with 100 mg/L of NO3–N and 3 mg/L of dissolved P (test condition) using only endogenous carbon. A paper summarizing these findings was written and published in the journal Bioresource Technologies. Our findings suggest that permeate flow could be reclaimed to recycle alkalinity, salts, and heat for fish culture and that the waste activated sludge does not produce metals concentrations that would prevent its land application (reclaiming phosphorus) or prevent its use as a protein source in animal feeds.
Two year class of select rainbow trout germplasm that were provided by the NCCCWA were reared at the Freshwater Institute during this reporting period. These fish serve as a back-up repository for NCCCWA rainbow trout broodfish.
A select strain of rainbow trout developed by Troutlodge was reared in two water reuse systems at the Freshwater Institute to provide fish performance and survival data to this key industry stakeholder.