Evaluation of Various Biofilters in an Intensive Recirculating Fish Production Facility

Various types and combinations of biofilters were evaluated in an operating, full-scale intensive recirculating fish production facility. Each of four tanks (18 900 L each) had a different combination of biofilters: 1) four upflow sand filters; 2) one upflow sand filter and two fluidized bed sand filters; 3) two prototype floating-bead filters; and 4) one upflow sand filter and one rotating biological contactor (RBC). The performance evaluation included the efficiency of each filter in removing total ammonia nitrogen (TAN), nitrite nitrogen (NO2-N), and suspended solids (SS). Removal was based on samples of the inflow and outflow of each filter taken once per day, two days per week for several weeks. Other water quality parameters measured were pH, alkalinity, carbon dioxide (CO2), and dissolved oxygen (DO).