Theses and Dissertations


Title: Studies of Channel Catfish Ictalurus punctatus pond effluent characteristics and treatment options

Name: Ozbay, Gulnihal

Degree: PhD

Chair: Claude E. Boyd

Resides:

University: Auburn University

Location: Auburn, Alabama

Date: 2002

Pages: 108

Keywords: Channel Catfish,pond effluent characteristics,treatment options

Abstract:

A series of studies on channel catfish pond effluent characteristics and treatment options were conducted at the Auburn University Fisheries Research Station (FRU), Auburn, Alabama in 2000 and 2001. In the first year, the size distribution of particles in storm overflow from catfish ponds and the settling rates for these particles were determined. The benefits of sedimentation and dirt-bag filtration for treating effluents also were studied. In the second year, information on concentrations of total, organic and inorganic suspended particles in channel catfish pond waters was obtained, and the relationship between suspended solids concentration and turbidity was estimated. The effectiveness of coagulants to treat catfish pond effluents was also determined in the second year. In the first year, findings from serial filtration showed that a small reduction in concentrations of most water quality variables of interest occurred when samples passed a 41 µMS Office filter. The decline in concentrations of variables were: total suspended solids, 21%: particulate organic matter, 21%: 5-day biochemical oxygen demand, 26%: total phosphorus, 27%. The settling time to remove 21% of mineral particles was 0.18 hours, while 5.09 hours would be necessary to settle 21% of organic particles. The sedimentation time to remove particles larger than 5 µn and reduce concentrations of some water quality variables by 50% would be around 120 hours for mineral particles and 3,423 hours for organic particles. Therefore, sedimentation does not appear to be useful method to remove potential pollutants in pond overflow after rains. In the sedimentation study, differences (P < 0.05) were observed in the water quality variables for both surface and bottom pond effluents between the settling ponds used for each effluent type over a 72-hour settling interval. However, the effectiveness of sedimentation was much greater for the bottom effluents released during pond draining because this effluent contained a high concentration of coarse mineral particles. Where space is available for sedimentation basins, this method could be used to treat draining effluents from aquaculture ponds and improve their quality. The dirt bag technique for removing suspended solids from wastewater was not effective for improving pond effluent quality. In the second year, 46% of 141 pond samples exceeded the usual limit for total suspended solids in typical National Pollution Discharge Elimination System permits. This variable is likely to be included in aquaculture pond effluent regulations. Most samples contained less than 50 mg/L inorganic suspended solids. The particulate organic matter comprised, on average, 43.5% of the total suspended solids. Inorganic suspended solids accounted for a little over half of the total suspended solids. Hence, water in catfish ponds has nearly equal proportions of organic and inorganic suspended solids.

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