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The present study aimed at characterising the pollution potential of wastewater from fish breeding activities. Samples taken from various types of fishponds indicated that the concentration of TSS was the parameter, which did not meet the specification, being most of the time higher than 35mg/l. On the other hand the concentration of nitrate-N was below the 10mg/l and those of ammonia-N and phosphorus were also below the maximum allowable limits. During the normal flow, the concentration of COD and BOD5 were also below the maximum limits of 120mg/l and 40mg/l respectively. The sediments in the fishponds were also tested and it was noted that the COD of the sediments was quite high with a value of 545mg/l. A low cost pre-treatment filtration was proposed to lower the concentration of the TSS. A small treatment plant based upon a filtering mechanism using rock sand was tested, and this system was effective in removing up to 81% TSS. The study concluded that the TSS needed treatment before disposal in any watercourse, and this can be achieved with simple filtration mechanism. However, the sediment sludge is of high COD level and should not be disposed in river courses.
Keywords: fish breeding, wastewater treatment, rock sand filtration, total suspended solids removal