Characterization and Treatment of Waste
Discharged from High Density Catfish Cultures
RICHARD J. RUANE, Supervisor
TIEN-YUNG J. CHU, Environmental Engineer
VIRGIL E. VANDERGRIFF, Engineering Associate
Water Quality and Ecology Branch
Division of Environmental Planning
Tennessee Valley Authority
Chattanooga, Tennessee 37401
INTRODUCTION
For the past three years, the Tennessee Valley Authority (TVA) has been conducting a
cooperative interdisciplinary research program with private industry to determine the
feasibility of high-density raceway production of catfish using heated water discharges from
a steam-electric generating plant. A pilot-scale raceway facility located on the bank of
TVA's Gallatin Steam Plant condenser discharge canal has been used for the research.
Condenser circulating water averaging 7 Celsius degrees above the ambient temperature of
the plant intake water is pumped from the discharge canal through the facility and returned
to the canal. Results to date have proven the benefits of heated water in extending the
catfish growing season, increasing growth rates, and increasing production poundage.
As part of this study during 1973 and 1974, the following wastewater characteristics
were investigated: settleable solids, suspended solids, five-day biochemical oxygen demand
(BOD5), chemical oxygen demand (COD), total and soluble phosphates, ammonia
nitrogen, organic nitrogen, and nitrite plus nitrate nitrogen. The results of four 12-hour
surveys at various times during the 1973 growing season were reported previously (1).
During 1974, four 72-hour surveys were conducted to evaluate the hourly and daily
variations of these waste characteristics, the generation of fecal coliform bacteria, and the
effects of feeding on waste production. Also, in 1974, a pilot-scale sedimentation tank was
constructed to evaluate removal of settleable solids, suspended solids, BOD5, COD, total
phosphates, and fecal coliform bacteria. The results of the 1974 studies are reported herein.
DESCRIPTION OF PROJECT
Approximately 190 1/sec of heated water were pumped continuously from the steam
plant once-through cooling water discharge canal, passed through ten concrete raceways,
and discharged back into the canal downstream from the intake. As shown in Figure I. each
raceway (1.22 m wide, 1.22 mdeep, 15.24 m long) was divided into four equivalent sections
by screens. Water depth within the raceways was maintained at 1.07 m. A concrete baffle
0.39 m from the discharge end of the raceway extended down to within 0.30 m of the
bottom. A 1.3 cm mesh screen was installed between the baffle and the bottom of the
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