Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 28, 2002
Publication Date: N/A
Technical Abstract: The success of biological filtration depends on careful control and maintenance of the bacterial biomass on the filter media during the maturation period and backwashing. For biological filters, an effective backwashing strategy involves removing excess biomass while not totally removing the attached biomass essential for the next filter cycle. A PC- controlled small-scale recirculating aquaculture system was constructed and operated in a greenhouse facility for evaluating the air-scour/filter purge strategy on the floating bead biofilter performance. The culture tank is a round polyethylene tank with a total volume of 795 liters. The tank was stocked with approximately 14 kg of tilapia fish (100-g avg. wt.) The water is recirculated through a 0.014 m3 (0.5 ft3) floating bead biofilter at a flow rate of 75 Lpm. A diaphragm air pump provides air for culture aeration and filter media scrubbing. The computer-control system for the recirculating systems conducts filter media cleaning and purging, refilling of the culture system tank water, and daily feeding. The small purge volume allows several air-scrubbings per day with the equivalent volumetric loss of a single backflush. Several filter media air- scrub/solids purging per day increases the solids removal rate, allows for a higher feed loading rate, and maintains an adequate flow through the filter bead.