Study On Treatment City Sewage With Diatomite Enhanced A~2/O Process

With the development of society and economy and the acceleration of urbanization level, people’s livingstandard increases continually and the demand for water environment becomes more and more high.However, at present, the current domestic water pollution situation is still grim, a large parts of cities’ sewagetreatment can only meet the standards of level2, which can never meet the need of economic situationdevelopment. Therefore, nationwide sewage treatment plant upgrade is in full swing. Study of economic,reasonable, convenient, reliable upgrading and reconstruction technology is an urgent affair and also the needof the time.Diatomaceous earth has been applied in the activated sludge wastewater treatment improvement inrecent years, but it has not yet formed scales and the mechanism is also being further explored. In view ofthis, Diatomaceous earth reinforcement A~2/O process experimental study is conducted, which aims at theactual situation of A~2/O process upgrading in the cities of Hebei Province.This research is based on a university of Hebei Province, and improving A~2/O process by diatomite todeal with the research is adopted. The experiment is divided into three parts: the first part is the A~2/O processcommissioning phase. This stage is mainly to simulate the A~2/O process operation through A~2/O processsimulator in sewage treatment plant, and adjust all the index parameter in the A~2/O process to the bestoperation condition. The second part is the beaker experiment. In this stage, the goal is to determine the bestdosage concentration of diatomite through the beaker experiment. The third part is the strengthening phase ofdiatomaceous earth. Use dosing parameters of diatomite which has been designed for dosing diatomaceousearth, dosing after a period of time by adjusting the additive quantity of diatomite and water-qualitymeasurement to find the best dropping condition.Through experiments the optimum reaction parameters of A~2/O process is confirmed: control the DO ofwater between2mg/L~3mg/L, hydraulic retention time HRT for8h, the reflux ratio of the mixture is250%, the sludge reflux ratio is70%. The effluent water quality of the A~2/O process has improved afterputting diatomaceous earth into the process, while the quantity changes of diatomite dosing have littleinfluence on the quality of the output water. However when diatomite dosing quantity is25mg/L, theeffluent water quality is relatively stable, therefore diatomite dosing quantity is25mg/L for the optimaldosing quantity. Under the best parameters, process of CODcr, three indicators of NH+4-N and TP removalrate was90.3%,82%and92.2%, and the effluent water quality have reached the level of standard A.Through the study, it was found that the effluent water quality of A~2/O process reinforced bydiatomaceous earth has improved significantly; the effect on the various pollutants in the water treatment isobvious. This process can save resources and money, does not need too much established structures, and hasno pollution to the environment, so it is can be used in sewage treatment plant upgrading.