Assessing Permeate Water Quality in Recirculating Aquaculture Systems Using Nanofiltration Membrane Technology and Various Pre-Treatment Configurations

The nanofiltration (NF) membrane technology used in recirculating aquaculture systems (RAS) encounters fouling issues. Fouling can be mitigated by incorporating pre-treatment units such as multimedia filters (MMF) and activated carbon filters (CF). This research aims to optimize the RAS configuration using MMF, CF, and NF90-4040 membranes to identify the most effective treatment system for reducing organic contaminants in aquaculture water. The performance of RAS was monitored and evaluated by the decrease in membrane flux and the efficiency of each configuration in reducing concentrations of ammonia, nitrite, and total suspended solids (TSS). The combination of MMF, CF, and NF (V1) demonstrated the highest overall efficiency, reducing ammonia concentration by 97.5% and nitrite by 100%. The MMF unit in V1 reduced ammonia and nitrite levels by 36.25% and 35.48%, respectively, while the CF unit further reduced ammonia and nitrite levels by 86.27% and 10%, respectively. The NF unit reduced ammonia by 71.43% and nitrite by 100%. Moreover, V1 exhibited a smaller decrease in flux value compared to the combination of MMF and NF (V2) and CF and NF (V3). The optimized RAS reactor in V1 achieved a 100% reduction in nitrate and TSS, highlighting its superior performance in treating aquaculture water effectively.