Performance Study of Enhancing Pretreatment Process for Pre-Denitrification Aerated Filter

The performance and enhancement of pollutants removal in raw municipal sewage by a new pretreatment process were investigated in this study. The experiments were carried out with a GS sedimentation tank in full scale plant. The results revealed that average removal efficiency of TP, TSS, and TN achieved 49%, 67.3% and 20% respectively during stable running period. TSS removal rate could achieve about 90%, also NH₄-N, TP and COD removal increased about 15% and 5% by adding a specific coagulant aid. TP removal was explained by chemical coagulation, sludge layer interception and a small portion of assimilation by anaerobic and facultative bacteria from refluxing. TCOD removal was explained by degradation action, physical interception and bio-absorption for little granular COD by sludge layer. Through jar experiment, it was investigated that suspended sludge formed in GS sedimentation tank has characters of adsorbing even enriching NH₄-N of influent and enrichment coefficient was above 4. In addition, Hydrolysis in the GS sedimentation tank behaved as poor degree.