The Full-scale Running And Conditioning Management Of Intermittent Aeration Process

The water pollution problem caused by nitrogen and phosphorus becomes seriously day-by-day, along with the development of social economy. The domestic secondary WWTP constructed almost doesn't put nitrogen and phosphorus removal into consideration. Moreover, many problems exist in the operational management of the WWTP. It is the key for making the WWTP run efficiently that good daily operational management. How to make the management efficiently and make the role of the WWTP develop completely is the important duty at present. This article focuses on municipal sewage treatment using a full-scale complete mixed continuous flow activated sludge unit, in which operation scheme of intermittent aeration is executed to promote the performance of wastewater treatment plant, and also focuses on the detailed regulation requirement of full-scale operation process on auto-controlling.Results of the research indicate that when an operation cycle of which aeration lasts 3 hours and intermission lasts 2 hours and with the rotation velocity of 950 r/min is adopted, the average removal ratios of COD, NH3-N, TN and SS of effluent were 84.6%, 86.9%, 53.8%, 78.6% respectively. And the effluent can achieve the first grade B discharge standard of GB18918—2002. If chemical method were applied in the operation to removal phosphorus, the concentration of TP of effluent would reach the standard.The fixed time controlling method was applied in this trial. Under the optimized condition, the dissolved oxygen concentration in the mixed liquid was controlled by rotation velocity of aeration equipment, with the concentration of DO at the range of 2.0mg/L to 2.5 mg/L at aeration stage and at the range of 0.0mg/L to 0.2mg/L at no-aeration stage. Excess sludge discharging controlled the mixed liquid suspended solid. When the sludge age was at the range of 15 to 20 days, the amount of excess sludge discharging was from 5.56 to 8.90 m3/d and the mixed liquid suspended solids was controlled at the range of 2 500 mg/L to 3 000mg/L.In order to make auto-control of the intermittent aeration process perfect, it was suggested that DO, ORP and PH may be used to be the auto-control parameter of continuous flow intermittent-aeration process.