| Title |
The Effect of pH on the Efficiency of Biological Wastewater Treatment |
| Abstract |
To determine the pH range which permits acid or alkaline wastewaters be treated by biological processes without preneutralization, experiments were performed by feeding completely mixed activated sludge reactors with synthetic organic wastewaters, the pHs of which were adjusted with sulfuric acid or sodium hydroxide. Results of the research showed that wastewater treatment efficiencies deteriorated as the pHs of wastewaters became too acid or alkaline due to the bulking and poor settleability of microbial sludge, and that the pH at which sludge bulking initiates was affected by the F/M ratio in the reactors. Therefore, it is advised to reduce F/M ratio by increasing MLSS concentration or hydraulic detention time in reactors in order to alleviate the effect of wastewater pHs on sludge bulking. It was also found that the pH and alkalinity of treated effluent increased through biological treatment, and that microbial yield coefficient and endogenous respiration rate decreased as the influent becomes more acid or alkaline. |