Studies on the Treatment of Animal Excreta. I. Treatment of High-Concentration Swine Waste by Aerobic Digestion

Abstract

Fresh excreta of a swine (40-60 kg in body weight, which was bred with arranged feed) was analysed for physical and chemical nature. Analytical data were as follows : in the fresh feces, BOD value, 61800 ppm ; COD value, 63200 ppm ; albumin-N, 6320 ppm ; kjeldahl-N, 11400 ppm. In the freshurine, BOD value, 4790 ppm ; COD value, 3640 ppm ; albuminoid-N, 775 ppm ; Kjeldahl-N, 4510 ppm. By the activated sludge treatment of high-concentration swine waste, stable treated effluent was obtained after 3 days. Aeration of high-concentration swine waste gave activated sludge after 6 days, and it had good purification ability. The more activated sludge was added, the quicker the waste was purified. By aeration, BOD substances were almost removed, but about 30-40% of COD remained in the supernatant. When BOD load was 5 kg/m³·d, the treatment results were not good. With low aeration (325 m³ air/m³·d), effluent water was not good, while with high aeration (650 m³ air/m³·d), SV value was not good. When BOD load was 2.5 kg/m³·d and aeration volume was 650 m³ air/m³·d, the treatment result was good. The quality of effluent water showed the following mean value : BOD value, 66 ppm ; SS value, 12 ppm. Their removal rate was both over 99%. Air temperature of injecter was higher than that around the plants, and this might be one cause for the rise of liquor temperature.