Extending water reuse in marine recirculating systems with DSC sludge digesters

This project will allow the expansion of tank-based production of marine fish and shrimp in many states by reducing production costs and discharge impacts. Nitrate accumulations irritate fish and can retard growth in recirculating aquaculture systems. The bacterial decay of feces withthe absence of oxygen, destroys the nitrate re-vitalizing the waters' ability to control pH. It is hypothesized that sludge can be held in a tank for a few days and manipulated by patterns of aeration and non-aeration to remove nitrate while reducing the volume of sludge that must be discharged from the facility. One specific objective is to demonstrate a high rate of nitrate removal, and the second, to reduce the volume of water that must be discharged to less than 4 liters for every kg of food fed. The target audience for this project is inland fish farmers producing marine food fish species in recirculating tank systems. It is projected that successful implementation of sludge-based nitrate removal will extend water reuse for inland marine systems to over 1 year while dramatically reducing the costs of marine salts and of chemicals currently added to control pH. ?