Starting Up And Operation Of Modified Carrousel Oxidation Ditch

Carrousel oxidation ditch has the advantages of strong impact resistance,good effluent quality,convenient management and low energy consumption.It is mostly used in small and medium-sized urban sewage treatment plants.However,due to the large differences in water quality,water quantity,climate,etc.of different regions,it is necessary to appropriately improve the traditional Carrousel oxidation ditch process and formulate a start debugging plan according to local conditions.The second sewage treatment plant in Dabancheng District,Urumqi,Xinjiang is a newly built urban sewage treatment plant in 2020,and the main process is the improved Carrousel 2000 oxidation ditch.Aiming at the wastewater treatment plant’s low water intake,large fluctuations in water quality,sludge floating,poor removal of TP and TN and other issues,the cultivation,operation performance and operation parameter control of activated sludge were studied during the start debugging of the sewage treatment plant,as well as the treatment effect,environmental benefits and operating costs during the trial operation.Combined with the problems in the process of start debugging,the improved Carrousel oxidation ditch process start debuggingand operational optimization control method were discussed,which provides a basis for the stable operation of the sewage treatment plant in the later stage and the start debugging and operation of the same type of sewage treatment plant.The results of the study are as follows:（1）During the commissioning period of the Dabancheng No.2 Sewage Treatment Plant,the influent water quality was COD:211.33～532.33mg/L;TN:42.34～67.24mg/L;NH₄⁺-N:29.12～59.44mg/L;TP:3.42～7.95mg/L.It has the characteristics of"small water inflow,large fluctuations in water quality,and average concentrations of COD,NH₄⁺-N,and TP are higher than the design value"The sludge culture method of inoculation,suffocation and intermittent culture was adopted,which lasted 31 days.The effluent COD is 15.08mg/L,TN is 7.57mg/L,NH₄⁺-N is 3.90mg/L,and TP is 0.11mg/L,reaching the first-level A standard.（2）During the floating of sludge,the reason why TN failure to meet the standard is that the alkalinity and carbon source are not supplemented in time,and the high level of DO in the hypoxic section causes the denitrification process to fail to proceed normally;the reason why the failure of TP is that the sludge age is too long;Long-term low-load operation of the system,excessive sludge age,and excessive aeration are the main reason for the aging and floating of the sludge in the oxidation ditch.The above problems can be solved by adjusting the p H of the aerobic section of the oxidation ditch,increasing the carbon source dosage,and controlling the DO and sludge age in the aerobic zone.The aeration mode and SRT of the modified Carrousel oxidation ditch were debugged.The results showed that the aeration mode of"start aeration with water intake,stop aeration with water stop"was adopted,and when SRT was controlled at 16days,the removal effect of the system was relatively good.（3）It has been proved by stable operation for 6 months that the effluent quality of the sewage treatment plant is stable,and under seasonal influent water quality concentration and temperature changes,it can effectively remove pollutants,so that the effluent quality of the sewage treatment plant can reach first-level A standard.The monthly water treatment volume is 46387.70 tons and the emission reduction of COD,TP,TN and the NH₄⁺-N is 13.65,0.23,2.37 and 2.10 tons,respectively.During the trial operation,the operating cost is 1.51yuan/m³.