[Impact of pH on the generation of COD, phosphorous and ammonia-nitrogen during the anaerobic fermentation of excess activated sludge].

There are mainly two kinds of sludge in the municipal wastewater treatment plant, i. e. , primary and secondary sludge. This study investigated the effect of pH, ranging from 4.0-11.0, on hydrolysis in terms of soluble chemical oxygen demand (SCOD) production in the anaerobic solubilization of excess activated sludge at 20-22 degrees C. It was found that when the value of pH was 8.0-10.0, the production quantity of SCOD were higher than pH = 5.0-7.0. Especially when the pH was 10.0 or 11.0, the value of SCOD was almost 10 times of pH = 6.0 during the whole fermentation of 20 days. And volatile fatty acids (VFA) production on the 8th day under alkaline condition was higher than that under acidic condition.