Location: Cool and Cold Water Aquaculture Research
2015 Annual Report
Objectives
Objective 1. Develop technically advanced, environmentally compatible, and sustainable closed production systems and techniques
Sub-objective 1.1 Optimize the cost and effectiveness of technologies to remove nitrogen and phosphorus from recirculating aquaculture systems and their effluent.
a) Optimize system water quality and evaluate salmonid performance when using membrane biological reactors to digest biosolids, remove nitrate, and practically eliminate water flushing requirements in each water recirculating system module.
b) Evaluate effectiveness of woodchip bioreactors for treating the effluent from water recirculating systems.
Sub-objective 1.2 Increase the energy efficiency of CO2 degassing technologies.
Sub-objective 1.3 Use refinements in water treatment process design and economies of scale to decrease the capital cost required per tonne of fish produced within water recirculating systems.
Objective 2: Improve salmonid performance, health and well-being in land-based systems through research on nutrition, rearing environment, and control of pathogens and fin erosion.
Sub-objective 2.1 Field-test rainbow trout germplasm resources when reared to 2kg harvest size within intensive water reuse systems and ID top performing individuals and families.
Sub-objective 2.2 Compare the effects of alternate protein (zero fish meal) versus fishmeal-based diets on growth performance and welfare of select families of Troutlodge rainbow trout when reared to 2 kg. We will also measure water quality, water treatment process performance, and waste production rates in recirculating aquaculture systems operated at low flushing rates.
Sub-objective 2.3 Identify strategies to minimize losses of Atlantic salmon smolt to Saprolegnia infections following vaccination in water recirculating systems.
Approach
The ability to provide U.S. consumers with high-quality, sustainably-produced seafood hinges upon research that supports increased domestic aquaculture production and the development of new and improved technologies. This proposed work encompasses several USDA ARS Action Plan components, primarily technology development for sustainable production systems (Component 4), alternative protein
investigation (Component 2), and disease prevention (Component 3). The first objective, which is focused on recirculating aquaculture system (WRAS) technology development, will investigate two water qualityimprovement technologies: (1) low-cost woodchip bioreactors for nitrate removal from aquaculture effluents, and (2) membrane biological reactors that produce a clean filtrate for reuse in the WRAS, which eliminates makeup water flushing and the point-source discharge. Refinement of water treatment processes and use of economies of scale to reduce capital costs of WRAS will also be a key focus. This
work will also investigate a new and potentially more energy efficient and cost-effective carbon dioxide stripping technology. Within the second overarching objective, we will evaluate the performance of commercially available rainbow trout strains (fingerling to 2 kg) cultured in WRAS, and will identify
strategies to minimize Saprolegnia infections in Atlantic salmon smolt cultured in WRAS after vaccinations. In addition, pressing societal concerns about the sustainability of fish feed and the rising cost of fish meal provide the emphasis to compare the effects of alternate protein (zero fish meal) and
fishmeal-based feed formulations on trout health and performance, waste production, and water quality. Through this work plan, we are eager to support the USDA in their forward-thinking efforts.
Progress Report
The overall goal of this project was to develop and improve technologies that enhance the sustainability and reduce the environmental impacts of the modern fish farming industry. Progress was made in many areas.
A research study was conducted to compare the effects of chronically elevated nitrate nitrogen on performance, health, and welfare of Atlantic salmon post-smolt cultured in freshwater recirculating aquaculture system (RAS) at 14C. No significant difference in growth, survival, and maturation were identified between the high (100 mg/L) and low (10 mg/L) nitrate nitrogen treatments. Findings are critically important in establishing boundary design criteria for rearing system water quality in water recirculating systems. This study was conducted in advance of the membrane biological reactors (MBR) in RAS study (sub-objective 1.1.a). Additional concurrent research was carried out examining the presence of hormonally active compounds in RAS water and spring makeup water, in collaboration with USDA-ARS National Cool and Coldwater Aquaculture (NCCCWA) and U.S. Geological Survery-Organic Geochemistry Research Laboratory scientists. The findings of these studies will assist in understanding and potentially remediating the most significant problem in RAS Atlantic salmon growout; namely, decreased growth and product quality related to early male maturation. Components were ordered to allow construction of the MBR test systems (sub-objective 1.1.a).
It was prudent to explore several critical design issues at a smaller scale prior to the construction of full-scale woodchip bioreactors detailed in the work plan (sub-objective 1.1.b). Four pilot-scale woodchip bioreactors (L x W x D: 3.8 x 0.76 x 0.76m) were constructed on-site and operated for 268 d, beginning in FY14 and running into FY15, to determine the optimal range of design hydraulic retention times (HRTs) for nitrogen removal from aquaculture wastewater. Results indicated that an optimized design HRT may not be the same based on metrics of nitrogen removal rate versus nitrogen removal efficiency. Balancing these metrics for this water chemistry with an optimized design HRT of approximately 24 h would result in a 65% nitrogen removal efficiency and removal rates of at least 18 g N removed per m3 of woodchips per day. Determination of this critical design parameter (HRT) will better inform the design of the planned full-scale woodchip bioreactors. Notable results from these pilot-scale bioreactors include some of the highest nitrogen removal rates ever reported for this simple woodchip-based technology. Proposed monitoring activities for the full-scale bioreactors (FY15 milestones for “…water quality and hydraulic grade line monitoring; Sample woodchips to measure degradation”) were performed for the pilot-scale bioreactors to further refine evaluation efforts once the full-scale bioreactors are constructed. The research study was completed and the findings have been summarized in a manuscript that is currently in review at the Journal of Environmental Quality.
Additionally, because phosphorus removing filters will be paired with the full-size woodchip bioreactors, it was practical to test phosphorus sorption media at a smaller scale first. A benchtop column experiment that pairs columns of woodchips for denitrification-based nitrogen removal with columns of either an iron or a calcium product (acid mine drainage treatment residuals or steel slag, respectively) to also remove phosphorus is currently ongoing. Design for the full-scale woodchip bioreactor set-up is being tested with this scaled experiment by asking the question: Is it better to remove N first in the woodchips (i.e., denitrification treatment upstream of phosphorus sorption treatment) or phosphorus first in the P-filters (i.e., phosphorus removal upstream of the denitrification treatment)?
Components were ordered and construction of the aeration pump test system (sub-objective 1.2) was completed. This experiment has been set up to test whether carbon dioxide can be stripped from water before reuse in a fish culture tank by adjusting floating aerator pumping rates to maintain CO2 within safe limits for fish culture, which will ultimately improve energy efficiency compared to traditional technologies.
In Phase 1 of the study to use refinements in water treatment process design and economies of scale to decrease the capital cost required per tonne of fish produced within water recirculating systems (sub-objective 1.3), we completed the identical bioplanning to be used in the three different system designs. We also completed the schematic design for the fluidized sand biofilter-based design. This portion of the study has used our most recent results on salmon growout performance as well as process design updates from work with commercial clients. In this phase of the study we are looking for refinements in tank scale, fish movements, and system loading in order to decrease costs and increase farm productivity and profitability.
A research study evaluating the relative performance of five independent lines of all female, diploid, rainbow trout (sub-objective 2.1) was completed at the Freshwater Institute, which was one of four locations where the lines were tested, each with unique rearing environments. The Freshwater Institute (TCFFI) provided a high-capacity intensive water reuse system where the trout were cultured in freshwater circular tanks, under 24-hr lighting, at oxygen saturation, and at 13°C, which is comparable to what is used by several domestic trout producers. The USDA select line grew as fast as or better than the other lines and achieved a mean size of 1, 2, and 3 kg at approximately 11, 14, and 17.5 months post-hatch. Similarities and differences in growth and other production traits, such as condition factor, fillet yield, color deposition, and lipid composition were determined for the independent lines of rainbow trout reared in this environment. Fin erosion in trout from the NCCCWA growth line was also measured when the fish reached a mean size of 2 kg, which ARS scientists at the NCCCWA will use to determine heritability estimates of susceptibility to fin erosion. Additional fin erosion data were collected on-site at the NCCCWA by Freshwater Institute staff in order to support the determination of fin erosion heritability estimates. This study is providing a more detailed understanding of how different trout strains interact with different environments, including the RAS environment; it has also identified top performing individuals and families.
In FY15, TCFFI prepared for the research study to compare the effects of alternate protein (zero fish meal) versus fishmeal-based diets on growth performance and welfare of select families of Troutlodge rainbow trout when reared to 2 kg (sub-objective 2.2). Troutlodge provided NCCCWA with 40 lots (single paired mating) of rainbow trout eyed eggs from selected production fish families. The NCCCWA incubated and hatched these eggs, and are continuing to rear the fish to 20-50 g before fin clipping, tagging and transfer to TCFFI where families of trout will be equally distributed among the six study tanks. The location re-verified the diet formulations and milled the feed, and shipped it to TCFFI. The study will begin in FY16. With widespread interest in “sustainably” formulated fish feeds, this work aims to push at the boundaries and determine how rainbow trout performance and resulting water quality and water treatment processes are impacted when a zero fishmeal versus a fishmeal-based diet is used. The focus of this sub-objective is to test a practical, near term, and relatively cost effective alternative protein diet compared to a traditional fishmeal diet.
Throughout the spring and early summer of FY15, twelve small (0.5m3) circular tanks in a flow-through system were retrofitted with fluidized sand biofilters and magnetic drive pumps to create the twelve replicated experimental RAS necessary to conduct the Atlantic salmon pre-smolt Saprolegnia spp. post-vaccination challenge in early FY16 (sub-objective 2.3). Following completion of all experimental RAS, several of these systems will be assessed in summer FY15 using small populations of rainbow trout in the culture tanks in order to establish and evaluate nitrification across the biofilters. Following this biofilter maturation, several daily low-dose regimes of hydrogen peroxide will be applied to the RAS culture tank water in order to assess their relative impact on biofilter nitrification and to inform subsequent studies to reduce Saprolegnia spp.-associated mortality post-vaccination. This first phase of this study is scheduled to be completed by the end of summer FY15; system dosing with peracetic acid and biofiltration evaluation will be carried out in autumn FY15, prior to the arrival of USDA-ARS pre-smolts in late FY15.
Accomplishments
Review Publications
Tsukuda, S., Christianson, L., Kolb, A., Saito, K., Summerfelt, S. 2014. Heterotrophic denitrification of aquaculture effluent using fluidized sand biofilters. Aquacultural Engineering. 64:49-59.
Summerfelt, S., Zuhlke, A., Kolarevic, J., Reiten, B., Selset, R., Gutierrez, X., Terjesen, B. 2014. Effects of alkalinity on ammonia removal, carbon dioxide stripping, and system pH in semi-commercial scale water recirculating aquaculture systems operated with moving bed bioreactors. Aquacultural Engineering. 65:46-54.
Summerfelt, S.T., Davidson, J., May, T., Good, C., Vinci, B. 2015. Emerging trends In salmonid RAS - Part I. Closed-containment culture advances. Global Aquaculture Advocate. 18(2):62-63.
Summerfelt, S.T., Davidson, J., May, T., Good, C., Vinci, B. 2015. Emerging trends in salmonid RAS - Part II. System enhancements. Global Aquaculture Advocate. 18(3):64-65.
