洗濯洗剤を添加した都市下水を処理する活性汚泥中のポリリン酸蓄積細菌群の嫌気的有機物摂取

Abstract

An anaerobic aerobic sequencing batch reactor was operated for 185 days using municipal wastewater supplemented with a laundry detergent including LAS and AE to examine the efficiency of acetate uptake and the availability of the surfactants as a potential PHA source of PAOs under exposure to the detergent. Over the experimental period, the phosphate requirement for acetate uptake (+ΔP/-ΔAc ratio) was estimated by an anaerobic batch test with the addition of acetate. Consequently, it was found that the exposure to the detergent deteriorated the acetate uptake efficiency of PAOs. On the other hand, even though the detergent was added as a sole carbon source in the anaerobic batch test, a significant phosphate release was observed. The organic matter originating from the detergent was then divided into acetate and other organics, and their contributions to phosphate release were estimated using activated sludge collected on the 185th day. 60% of the total released phosphate was caused by the uptake of degradation products of LAS except lower fatty acids such as acetate. Comparing the maximum amounts of released phosphate between the two anaerobic batch tests in which acetate and the detergent were used, the latter was beyond the former after the start of the detergent addition. That is, PAOs that can not utilize acetate but can utilize degradation products of LAS contributed to phosphate removal gradually.