Water Treatment and Performance Characteristics Evaluation of a Pilot-Scale Recirculating Aquaculture System

To minimize the impact on the environment and land requirements, a pilot-scale recirculating aquaculture system was engineered and investigated in a greenhouse. The system included a three-step particulates separation device, fluidized bed reactors (FBR), UV treatment and cooling. Japanese flounder (Paralichthys olivaceus) were raised from initial mean weight 4.9 plusmn 0.6g to final mean weight 35.8 plusmn 14.6g after 140 days of growth. The specific growth rate was between 1.57 and 2.22 per day. Feed waste and excrement were removed by a three-step solids separation device. The sedimentation basin, hydrocyclone and foam fractionator showed 68.0%, 1.3% and 30.7% suspended solids removal efficiency, respectively, based on the influent and effluent concentrations. The measured solids concentrations in the fish tank were usually less than 8.24 mg/L. After fluidized bed biofilter maturation, the maximum TAN removal rate (R
_max
) was 1666.7 mgNH
₄
-N/m
²
/d and half saturation constant (K
_s
) was 1.67.The concentration of NH
₄
-N in the rearing water was variable cyclic fluctuation with lower than 0.505 mg/L. The concentration of NO
₂
-N was controlled of lower than 0.208 mg/L. Based on these results, the pilot-scale recirculating aquaculture system remained good water quality for Japanese flounder production.