Author
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Pfeiffer, Tim |
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MALONE, RONALD - LOUISANA STATE UNIV |
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Submitted to: Journal of Aquaculture Engineering
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/1/2004 Publication Date: 5/1/2005 Citation: Pfeiffer, T.J., Malone, R.F. 2005. Performance characteristics of the floating bead bioclarifier in a recirculating aquaculture system. Journal of Aquaculture Engineering. p. 468. Interpretive Summary: The ammonia and solids removal performance of a propeller-wash floating media biofilters in a two-tank small-scale tilapia recirculating tilapia production system was evaluated. The culture units were two twelve foot diameter panel fiberglass circular tanks with a sloping bottom. Culture volume for each tank at 3.3 feet depth was 2775 gallons. Tilapia were stocked to provide a two-phase production system. One tank was stocked with thirty-five hundred 25-g fish stock and four hundred 350-g fish stocked into the second tank. Other system components included a 70 gallon swirl separator to capture the solids laden water from the tank bottom drain as water flows through the swirl separator, and on to the sump. Flow from the swirl separator joins the high volume flow from the elevated sidewall drain of each tank as it flows into the 260 gallon sump. Flow from the sump is pumped (1.5 hp) through a 10 ft) prop-washed floating bead (PWBF) bioclarifier for additionally solids removal. Backwashing of the bead filter was an automated process done daily. Additional ammonia removal was provided by a fluidized sand bed filter, (4.9 ft. diameter). Water gravity flows back to the culture tanks. The nitrification and solids removal performance of the PWBF was characterized with increasing feed loading rates ranging from 0.25 to 1.0 lbs of feed per cubic foot of filter media. Ammonia removal rates ranged of the bead filter increased with an increasing feed load and ranged from 40 to over 100 g of TAN removal per cubic meter of media per day. The solids removal by the PWBF was approximately 10 to 15% of the theoretical total dissolved load. Overall performance of the PWBF was less than the design criteria and potentially limited by the increasing system carbon dioxide concentration and decreasing dissolved oxygen concentrations in the filter media. Technical Abstract: In a recirculating aquaculture production system an important requirement is an efficient and effective process for water treatment. The objective of this study was to evaluate the nitrification and solids removal performance of a propeller-wash floating media biofilters in a two-tank small-scale tilapia recirculating tilapia production system. The culture units are two 3.65 meter (12 ft) diameter panel fiberglass circular tanks with a sloping bottom. Culture volume for each tank at 1.0 m depth is 10,500 L (2775 gal). Tilapia are produced through a two-phase system with 3500 25-g fish stock into the first tank and four hundred 350-g fish stocked into the second tank. Removal of the heavy settleable solids from the tank bottom is capture in a 0.6 m diameter (265 L) swirl separator as the solids laden water passes from the tank bottom drain, through the swirl separator, and on to the sump. Flow from the swirl separator joins the high volume flow from the elevated sidewall drain of each tank as it flows into the 1000 L sump. Flow from the sump is pumped (1.5 hp) through a 0.3 m**3 (10 ft**3) prop-washed floating bead bioclarifier (PWBF) for additionally solids removal. Backwashing of the bioclarifier is an automated process. Supplemental biological filtration is provided by a fluidized bed biological filter, FBB (1.5 m diameter) which uses a silica sand media. Water gravity flows back to the culture tanks. The nitrification and solids removal performance of the PWBF was characterized with increasing feed loading rates. The solids removal, nitrification, and oxygen demands of this system were measured at five feed rates ranging from 0.9 to 4.5 kg feed per day. |
