|RILEY, KENNETH - HBOI
Submitted to: Global Aquaculture Advocate
Publication Type: Trade Journal
Publication Acceptance Date: 6/6/2005
Publication Date: 8/12/2005
Citation: Pfeiffer, T.J., Riley, K. 2005. Filter performance study evaluates combined performance of bead, sand filters in RAS. Global Aquaculture Advocate. 8:39-42.
Technical Abstract: The ammonia removal performance of a propeller-washed bead filter and fluidized sand filter in a demonstration recirculating aquaculture system was evaluated as the daily feed rates applied to tilapia fingerlings progressively increased from 0.9 kg to 4.5 kg per day. The system consisted of two culture tanks, each 3.65 m in diameter with a culture voume of approximately 12.5 m3. Solids removal was accomplished in part by a 625 liter swirl separator that captured the solids from the effluent flow from the center drain of each tank. The flow from the swirl separators joined the high volume flow from the elevated sidewall drain of each tank and flowed into a sump. Water from the sump was pumped through a 0.28 m3 propeller-washed bead filter with standard plastic floating media. From the PWBF water flowed into a 2.2 m3 fluidized sand filter before gravity flowing back into the tanks. System recirculation flow rate was approximately 300 Lpm. Supplemental aeration was provided by air diffusers in the tank. Filter evaluation was conducted several weeks after the daily feed rates were increased and the system stabilized. Filter ammonia removal performance increased with the progressive increase in the daily feed amount. Greatest ammonia removal rates (140 g TAN/m3 of media-day) were observed at the highest daily feed rate, 4.5 kg/day. Ammonia removal rates were limited by decreasing dissolved oxygen levels into the filters and a lack of system CO2 degassing abilities.