Abstract:
This research evaluated the efficiency of separated biofloc reactor on water quality control of the Closed Recirculating Aquaculture System (CRAS). The study consisted of 3 experiments. The first experiment was to evaluate ammonia removal and oxygen consumption rates of the biofloc. The results showed that, during 8 weeks experiment, the average ammonia removal rates at 1 mg.N/l ammonia concentration was 8.14±2.74 mg.N/g.TSS/day and the oxygen consumption rates was 141.59±18.78 mg.O2/g.TSS/day. The second experiment evaluated the efficiency of biofloc separator on suspended solids removal from fish tank. The results showed that 43 micron pore size of stainless screen could not be used as it was clogged within 1 hour of operation. On the other hand, 76, 100, 130 and 160 micron pore size had the average separation efficiency of 88.71±2.75, 86.73±2.08, 83.86±1.86 and 66.01±6.41 percent, respectively. Later, water recirculation flow rates were also estimated. It was found that 6,000 L./day flow rate was too high and caused the water overflow while other flow rates e.g. 1,500 3,000 and 4,500 L./day had the average separation efficiency of 91.25±1.81, 89.11±2.89 and 87.66±2.01 percent, respectively. The Third experiment was the comparison between separated biofloc reactor (Treatment) and non-separated biofloc reactor (Control) for inorganic nitrogen waste control in the CRAS for Tilapia. The results illustrated that the treatment with separated biofloc reactor had acceptable biofloc separation and better inorganic nitrogen waste treatment efficiency than the control.