Laboratory Scale Evaluation of a Treatment System for Effluents from Hybrid Catfish Ponds

Abstract

Results from laboratory scale investigation indicated that treatment of hybrid catfish pond effluent in treatment system consisting of one day sedimentation followed by four days aeration and nine days absorption by water hyacinth was very effective in removing pollutants from the effluent.  Initial concertrations of pollutants in the effluents used for the experiments were between 9.58 and 40.14 mg-N/l for ammonia, 0.02 and 1.67 mg-N/l for nitrite, 12.35 and 56.59 mg-N/l for total kjeldahl nitrogen, 1.50 and 2.15 mg/l for total phosphorus, 0.001 and 0.022 mg-S/l for hydrogen sulfide, 41.5 and 61.7 mg/l BOD₅, and 568.3 and 826.7 mg/l for total suspended solids. Average removal rates of 1 day sedimentation were 81.2% for total suspended solids, 54.7% for BOD₅, 72.7% for total phosphorus, 26.5% for total ammonia nitrogen, 33.3% for total kjeldahl nitrogen, and 100% for hydrogen sulfide while 4 days aeration removed 6.5% of total suspended solids, 6.9% of BOD₅, 6.2% of total phosphorus, 51.2% of total ammonia nitrogen, and 14.1% of total kjeldahl nitrogen, by average. Treatment by water hyacinth for 9 days removed 9.9% of total suspended solids, 28.4% of BOD₅, 11.7% of total phosphorus, 22.2% of total ammonia nitrogen, and 32.9% of total kjeldahl nitrogen. The whole treatment system was able to reduce 97.6% of total suspended solids, 90.0% of BOD₅, 90.6% of total phosphorus, 99.9% of total ammonia nitrogen, 80.3% of total kjeldahl nitrogen, and 100% of hydrogen sulfide.