COMBINATION OF A BEAD FILTER AND ROTATING BIOLOGICAL CONTACTOR IN A RECIRCULATING FISH CULTURE SYSTEM

The performance of the combination of a floating bead filter and an RB C employing I-inch diameter Norpac(R) tube media was evaluated in an i ntensive pilot scale recirculating system stocked with tilapia. The co mbination maintained favorable water quality, attaining practically co mplete TAN and NO2-N removal. The average overall removal across the F BF-RBC combination was 60.6 g TAN/day and 59.6 g NO2-N/day, which was 30.7 and 51.7% of the influent loaning, respectively. At a feeding lev el of 2 kg/day with backwashing every 2 days, the bend filter function ed primarily as a solids capture device, while the RBC performed the b ulk of the nitrification. Areal removal for the bend filter was 56.2 m g TAN/m(2)-day at 5% efficiency and 13.1 mg NO2-N/m(2)-day at 1.1% eff iciency, while for the RBC it was 257 mg TAN/m(2)-day at 52% efficienc y, and 282 mg NO2-N/m(2)-day at 51% efficiency.