Passive Self-Regulating Denitrification Technology for Aquaculture

Commercial-scale marine aquaculture has the potential to close the gap between an increasing demand for high quality seafood products and marine fisheries near maximum sustainable yields. In flow through aquaculture systems, the release of nitrate to nearby streams, lakes, etc. can be detrimental to the ecology of the receiving water body. Similarly, in recirculating aquaculture and/or aquarium systems (RAS), high nitrate levels are toxic to many species. Therefore, the reduction of nitrate by denitrification is of major concern. Denitrification is normally achieved by adding methanol or a similar chemical to act as the necessary carbon source, which requires sophisticated computer monitoring and control systems. This project proposes to investigate the potential for using Polyhydroxyalkanotes (PHAs), a biodegradable biopolymer, produced from sugar fermentation, as an alternative carbon source for denitrification in recirculating aquaculture systems. The denitrification capability of PHA will be quantified and a predictive computer model will be developed for estimating PHA carbon release as a system design tool. Additionally, the commercial feasibility of employing PHAs as a simple, low-cost alternative to the relatively complex existing treatment methods will be investigated.