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ARS Home » Southeast Area » Stuttgart, Arkansas » Harry K. Dupree Stuttgart National Aquaculture Research Cntr » Research » Publications at this Location » Publication #189932
Title: NITRIFICATION PERFORMANCE OF A PROPELLER-WASHED BEAD CLARIFIER SUPPORTING A FLUIDIZED SAND BIOFILTER IN A RECIRCULATING WARMWATER FISH SYSTEM

Author
item Pfeiffer, Tim
item MALONE, RON - LSU

Submitted to: Aquacultural Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2005
Publication Date: 1/2/2006
Citation: Pfeiffer, T.J., Malone, R. 2006. Nitrification performance of a propeller-washed bead clarifier supporting a fluidized sand biofilter in a recirculating warmwater fish system. Aquacultural Engineering. 31(1):80-92.

Interpretive Summary: A propeller-wash bead filter (PWBF) and a fluidized sand filter (FSF) on a 28 m3 recirculating system stocked with tilapia maintained favorable water quality at five different progressively higher feed rates, ranging from 0.9 to 4.5 kg feed per day. Total ammonia nitrogen (TAN) removal rates ranged up to about 200 g TAN per m3 of media per day for each of the biofilter units. When the system flow rate was increased by approximately 20% (a factor of new pump installation) peak rates of 244 g TAN per m3 of media per day were observed. Roughly 75% of the removal was accomplished by the fluidized sand filter, an observation that is consistent with the difference between the fluidized sand filter volume (0.92 m3) and the bead filter media volume (0.28 m3). The nitrification performance of the PWBF in this field setting was satisfactory but less than that reported from laboratory scale studies. However, for bead filters operated mainly for clarification, as in the system setup presented, nitrification will largely be supplemental. At the highest daily feed load, 4.5 kg/day, over 570 g dry weight of solids were removed during each daily bead filter backwashing event. A 20% increase in flow, at the same daily feed rate, improved solids removal to over 670 g dry weight per bead filter backwash event. The PWBF and FSF combination provided suitable water quality for fish production; however, further increases in feed loading were limited by carbon dioxide buildup and oxygen limitations.

Technical Abstract: A propeller-wash bead filter (PWBF) and a fluidized sand filter (FSF) on a 28 m3 recirculating system stocked with tilapia maintained favorable water quality at five different feed rates, ranging from 0.9 to 4.5 kg feed per day. TAN removal rates ranged up to about 200 g TAN per m3 of media per day for each of the units. Peak rates of 244 g TAN/m3 of media per day were observed when the recirculating flow was boosted by 20%. Roughly 75% of the removal was accomplished by the fluidized sand filter, an observation that is consistent with the difference between the fluidized sand filter volume (0.92 m3) and the bead filter media volume (0.28 m3). The bead filter's primary function was clarification. At the highest daily feed load, over 570 g dry weight of solids were removed during each daily bead filter backwashing event. A 20% increase in flow, at the same daily feed rate, improved solids removal to over 670 g dry weight per bead filter backwash event. The PWBF and FSF combination provided suitable water quality for fish production; however, further increases in feed loading were limited by carbon dioxide buildup and oxygen limitations.