Experimental Study On Reusing Domestic Sewage Treated For Scenic Water

With the development of living quality, the landscapes design of the residential districts is under the spotlight at present. Among them, the waterscapes become a very important part because of their unique and various styles. At present, tap water is used for headwater of many waterscapes while the precipitation is prepared rarely in our county. Thus, most of them can't achieve the expected effect because of water quota. So it is an urgent issue to improve the state by exploring new means of water supplement for waterscapes.Wastewater reuse provides an effective way to solve the problem of shortage of water. Nowadays, the foreign and domestic researches on reusing sewage treated for scenic water always focus on reusing the discharged water of the effluent treatment plant which flows back to river or lake after the advanced treatment as the supplement of the scenic water. And researches on reusing of the middle water for landscapes are limited to the greening of the residential district. The feasibility of reusing domestic sewage treated for scenic water on the spot was studied in this paper to the present scenic water situation.The domestic sewage has steady quality and quantity. In other hand, the pollutants in it are mainly composed of organic compounds which can be removed by biologic methods easily. Domestic sewage may be feasible source for scenic water.The main obstacle of reusing sewage treated for scenic water is that the concentration of phosphorus and nitrogen exceed standard (GB/T18921-2002) to form eutrophication of the scenic water. Thus, the key to the sewage reusing for scenic water is how to remove nitrogen and phosphorus. In this paper, the A~2/O process was selected as secondary treatment process to base on analysis of the P/N removal processes in synchronism, and the traditional A~2/O process was improved. The stuff was putted in every reaction phase of the traditional A~2/O process to increase the microorganism quantity and strengthen reaction function. The aerobic phase was improved by adopting biological contact oxidation process to solve the sludge age problem of traditional A~2/O process and the deflect baffleplate was set at the aerobic phase to forma plugflow biological contact oxidation aeration basin. The sludge recycle was concealed to solve nitrate problem of the traditional A2/O process and reduce equipment and operation costs.The effluent of the improved A2/O process had good quality, especially had high denitrification efficiency. When the system came to a steady state, the removal rate of the CODcr, NH3-N, TP, turbidity could achieve 65.0%, 82.1%, 56.1%, 89.8%, respectively. The removal of the TP was not remarkable. So coagulating sedimentation which could remove TP efficiently was employed as the advanced treatment. The removal rate of the TP in advanced treatment could achieve 88.4%. The experimental result showed the water after the advanced treatment was transparent and had no odor. The average value of tested quality index could meet the Standard for scenic environment use (GB/T18921-2002). In this paper, the economic and social benefit was assessed, and the feasibility was also proved.In order to test the eutrophication, an experiment was employed to simulate the scenic water. Through this experiment, the eutrophication process and the variety of the water quality was indicated.