Research On The Performance Of Enhanced Hydrolysis-AICS Process For Small Town Sewage Under Low Temperature

Along with China’s urbanization construction and increasing number of smalltowns, and the construction of sewage disposal engineering in small towns lagsbehind town development and construction. After then the water environmentpollution of small town is more and more serious. The sewage treatment plants ofsmall towns in cold north area are facing low temperature. Low temperature has aserious impact on the sewage treatment plant, especially for phosphorus andnitrogen removal. In order to study how to strengthen the hydrolysis-Alternatedinternal Cyclic System（AICS） process to treat small towns sewage,the test chosePanShi sewage treatment plant as site. The test simulated the hydrolysis-AICSprocess on the scene with using wastewater in PanShi sewage treatment plant.In the field experiment conditions, the remove of COD in hydrolysis-AICSsystem is good and stable, the removal rate of80%or more. Hydrolysis acidificationpool has a fine pretreatment effect. The removal rate of COD was30%, and theremoval rate of COD was70%, so it reduced the adverse impact of low temperature.Return sludge ratio, nitrification liquid reflux ratio and HRT had a certain effect onthe effect of system denitrification and phosphorus, when return sludge ratio was75%, and nitration liquid reflux ratio was200%, HRT=13.9h, the whole systemoperation condition was best. Phosphor removal effect of hydrolysis-AICS systemwas better in the situation of low temperature. TP concentration in the effluent was0.7¹.0mg/L, NH₄⁺-N concentration was4¹2mg/L, and TN concentration in theeffluent was15²5mg/L. It showed that hydrolysis-AICS system could not reach thesewage discharge level1A（GB18918-2002） standard only by biologicaldenitrification and phosphorus, it needed to take measures to strengthen.In contrast research of hydrolysis-AICS process and A²/O process, it showedthat the two system were similar to remove pollutants effect. Both had a fineremoval effect of COD, SS and NH₄⁺-N, and a general removal effect of TN.Compared to A²/O process, hydrolysis-AICS process has advantages, such as lessoxygen demand, sludge production less, impact resistance of load.The experiment also studied coagulation precipitate and adding media to AICSpool. It shows that with dosing quantity of PAC and Ferric chloride increases, theinfluence is stronger in the coagulation precipitate study. When dosing quantity was20mg/L, the effect of coagulation precipitate was best. Both of the two coagulantscould make the system achieve1A level. Porous rotating ball suspension media wereadded to oxygen pool to maintain a high concentration of nitrifying bacteria andnitrification rate. The results showed that the removal rate of TN increased significantly, and the removal rate of TN growed from45%to75%in hangmembrane process.The experiment studied the engineering effect of PanShi sewage treatmentplant in winter to konw the actual effect of the hydrolysis-AICS process. The effectof low temperature on COD,SS and TP removal efficiency were little, besides TN.The subject also made a technical and economic analysis about PanShi sewagetreatment plant and a A²/O process engineering with equal scale. The results showedthat the engineering-total investment and running costs of hydrolysis-AICS processwere lower than the A²/O process.