Influence of Sewage Pipe Network on COD Reduction Efficiency in Sewage Treatment Plant

One of the most important functions for sewage treatment plant is COD (Chemical Oxygen Demand) reduction. As an auxiliary of the plant, sewage pipe network plays an important role on COD reduction efficiency. Taking a town of Pearl River delta region for example, by comparing the domestic sewage COD with the influent COD of the plant, and investigating the sewage network amply, different kinds of unpolluted water has been found entering the sewage pipe network continually, leading to low influent COD concentration and COD reduction efficiency of the sewage treatment plant. Feasible engineering solutions, including outfalls plugging, flap valve reform, river-crossing pipes renewal, bursting supply pipe repairing, were proposed. Suggestions to perfect the management of sewage network were also given. The concentration of influent COD reached higher than 180 mg/L, demanded by the government, after implementing the measures mentioned above, and kept stable in such a level for more than one year. COD reduction efficiency was improved greatly.