The potential for integrated biological treatment systems in recirculating fish culture-A review

Intensive aquaculture in recirculating systems is rapidly developing, and with it arises the need for reliable treatment systems. To enable reuse of water in these systems, biological treatment is considered the most economically feasible approach. In this review the advantages and disadvantages of some of the most commonly used biological treatment systems are examined. Using as a comparator the main biological processes in extensive static fish ponds, it is explained how most treatment facilities in recirculating systems achieve only partial water purification as sludge and nitrate are produced. Methods for reducing the accumulation of these materials are discussed. It is concluded that incorporation of such methods would result in more stable water quality conditions within the culture units, and also in a considerable reduction of pollution.