Aquaculture Research NSI 2010: An engineered multi-trophic approach to minimizing effluent impacts from marine recirculating aquaculture systems

End Date: 3/18/14


We will: 

  1. Develop a treatment system using geotextile bags in conjunction with coagulation and flocculation aids for the treatment of the effluent from marine recirculating systems
  2. Investigate the use of an engineered treatment system to facilitate the reuse of the liquid fraction of the effluent discharge back into the culture system
  3. Investigate the use of aquaponics for nutrient reduction in the liquid fraction of the effluent discharge through cultivation of environmentally and economically valuable salt tolerant plant species
  4. Investigate the use of solids recovered from effluent for cultivation of commercially important salt marsh species commonly used in marsh restoration efforts 


This project will address three of the focus areas identified in the Mississippi-Alabama Sea Grant Consortium Strategic Plan 2009-2013. The project will encourage healthy coastal ecosystems, sustainable coastal development, and a safe and sustainable seafood supply. The project will promote the technology required for a safe, sustainable domestic seafood industry compatible with the idea of sound coastal resource use and create healthier coastal ecosystems not only by reducing the risks associated with improper treatment of marine effluent discharge (pollutant nutrients and eutrophication) but also by using this discharge to grow the very plants that are vital to restoring coastal ecosystems.

Engineering designs for treatment of both primary (solids) and secondary (liquid) effluent from marine RAS will be produced. The use of the effluent in aquaponics (liquid fraction) and as a soil additive (solid fraction) to produce plants for coastal restoration, biofuel production, and/or human consumption will be evaluated experimentally. The outcomes will benefit commercial aquaculturists by decreasing the environmental impact of marine RAS, providing additional income from the potential cash crops produced from the effluent, reducing disposal costs, and reducing the cost of artificial seawater.

The project also will seek to facilitate the development of a well-informed public and advance scientific knowledge through an outreach campaign in conjunction with the Mississippi-Alabama Sea Grant Consortium that will include public education through website development and informational brochures, professional development through participation in scientific meetings and publications, and community development through the production of technical manuals that will serve as the basis for a training workshop for those interested in continuing education.


Aquaculture remains the fastest growing sector of food production, accounting for over half of the fish consumed as a food source worldwide. The U.S., however, imports about 80% of its seafood supply. Even though NOAA has set the goal for tripling U.S. aquaculture production by 2050, growth and expansion of the aquaculture industry in the U.S. has been limited by real and perceived issues that include regulatory, biological and environmental factors. Land-based recirculating aquaculture systems (RAS) do address many of the risks associated with offshore, open ocean aquaculture; however, the increased carrying capacity in large-scale commercial RAS aquaculture and the need for high water quality has complicated the issue of effluent waste management, particularly for marine aquaculture systems, whose effluent contains a considerable amount of salt. For marine RAS, therefore, it is critical that a significant percentage of the effluent by-products be recycled back into the production system to conserve salts and reduce and/or eliminate the environmental impact of salt discharges.  

Additionally, from an economical viewpoint, it is important to have some application for the solid component of the effluent discharge, since land application is impractical for marine systems. We propose to develop a system to minimize salt loss in recirculating aquaculture systems and repurpose the effluent discharge from filters for reuse in the system and for cultivation of important salt tolerant plant species that can be used for marsh restoration.