Effluent water quality of fish laboratory at Norwegian University of Life Science (NMBU)

Abstract

The fish laboratory at Norwegian University of Life Science (NMBU) is a modern center for fish experiment with a recirculation aquaculture system. The main effluent water is overflow from recirculation aquaculture system (RAS), the quality of overflow is equal to system water. However, the main effluent water (overflow) is required to be pump to the municipal water treatment plant. The objective of this study is to understand the water quality of the main effluent water by measuring concentration total nitrogen (TN), total phosphorus (TP), total suspended solid (TSS) and chemical oxygen demand (COD). Samples was taken every 2 hours from 7:00 to 19:00 at January 18th and February 15th2018. The result showed that the average TN, TP, TSS and COD concentration at January 18th was 5.59 mg/l, 0.21 mg/l, 0.61 mg/l and 16.03 mg/l respectively. The TN, TP, TSS and COD concentration at February 15th was 5.2 mg/l, 0.152 mg/l, 0.472 mg/l and 5.83 mg/l. The concentration of these parameters was lower compare with the outlet water of municipal waste treatment plant (Søndre Follo) in Vestby. This suggests that the treatment in Søndre Follo does not significantly increase the water quality of the main effluent water from fish laboratory at NMBU. However, it will load the municipal plant with water that is cleaner than the outlet. The amount of TP, TN TSS and COD produced by 1kg feed supplied was 17.17 g, 0.56 g, 1.71 g and 33.2 g, respectively. In addition, the amount of TP, TN, TSS and COD discharged with main effluent water was estimated at 23.9 kg, 0.79 kg, 2.37 kg and 46.1 kg per year. One possible solution is to set the effluent water to lake in close area called Årungen. The amount of TP discharge to Årungen with stream will be increased with 0.025%.