A new treatment system for animal waste water has been developed as an alternative to the activated sludge process. It consists of two treatments; one is operated with 7 tanks, and the other is soil and plant cultivation bed. Aerobic microorganisms are added to the influent water in the tanks where the water is aerated so that the microbes utilize the pollutants, while sedimentation removes the indigestible solids. In the secondary treatment the water, which has already received a primary treatment, is filtered through soil where it also receives treatment by soil organisms. In addition there is transpiration of water and absorption of minerals by plants. In the primary treatment BOD, SS, coliforms (E. coli), TP and total bacteria were removed 79-99%, but COD and TN were removed only 58% and 36%, respectively. In the secondary treatment removal of nutrients proceeded further, and 93-99% of pollutants were removed. The treated waters met the quality standard of discharge water in Japan except for TN, which was in too great a concentration to meet discharge standards. This problem requires further study.
Supported by : Ministry of Education, Science and Culture
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