Release of ammonia, phosphate and organic matter during process of co-controlling excess sludge with acid and alkaline
酸碱联合调节剩余污泥过程中氮、磷和有机质的释放

Municipal sludge reduction and reutilization is one of the problems in WWTPs. Two kinds of co-control methods were taken to study the release of such soluble items as ammonia, phosphate, chemical oxygen demand, carbonhydrate, protein, and volatile fatty acids during the hydrolysis and acidification of excess sludge. One was acid-alkali, acidity control (pH=3) for 8 days and then alkalinity (pH=10) for 8 days, the other was alkali-acid, alkalinity control (pH=10) for 8 days and then acidity (pH=3) for 8 days, meanwhile with pH uncontrolled as contrast. The results show that more release amounts of all matters mentioned above are achieved with the co-control methods than those with the contrast. Besides, compared with alkaline condition, the release amounts of ammonia and phosphate are greater under acidic condition, but those of the organic matters are greater under alkaline condition. Ammonia arrives at the maximum release amount of 17.28 mg/g TS through 1 day after acidity is converted to with the alkali-acid method. And, the optimal release amount of phosphate, 14.16 mg/g TS, is attained after 7 days with the acid-alkali method. The release amounts of those organic matters, except volatile fatty acids, get to the top through 6 days or so. The production of total volatile fatty acids is seriously influenced by reaction time.