Improved Carrousel Oxidation Ditch Process Denitrification And Phosphorus Removal Performance Research

With the population growing bigger and the living standards getting better,emission of waste water continue to rise and the content of nitrogen and phosphorus and other nutrients in the sewage keeps algae breeding faster, resulting in eutrophication in water and aggravating the pollution of the water body. How to effectively reduce and remove the organic contents and nitrogen and phosphorus from sewage becomes a research objective in the field of water treatment.Among the ways in wastewater treatment, oxidation ditch is easy to operate, but effectiveness in nitrogen and phosphorus removal is far from satisfactory. Therefore, the improved Carrousel oxidation ditch process willenhance the effectiveness of nitrogen and phosphorus removal on the basis of the organic removal efficiency.The design of improved Carrousel oxidation ditch system is built on basis of the reaction cell of the oxidation ditch.In the front is set the pre-anoxic tank, front anaerobic tank and pre-biological selection pool. Rich NO3--N and NO2--N in water and return sludge will be degraded after pre-processing of the reaction cell, thereby increasing efficiency of nitrogen and phosphorus removal of the whole system. The pre-biological pool settings caneffectively improve the screening of bacteria in activated sludge and prevent bubbles,sludge floating or expansion phenomenon in sewage treatment process.When running the system, with campus sewage as feed water, by changing six kinds of operating parameters——HRT, DO, SRT, the MLSS, two-point water distribution ratio and two-point return sludge distribution——we can study the effect of the model of removing organic contents and nitrogen and phosphorus content. After confirming the using scope of each parameter, the test data derived from the orthogonal test can help to get the best sewage treatment operating parameters. Apply that set of data to the Carrousel oxidation ditch, compare the removal effect of the two processes and then analyze the features and advantages of this design.Study and analysis are carried out on the removal of COD, ammonia, NO3--N, NO2--N, TN and TP in two oxidation ditch.9kinds of conditions derived from the orthogonal experiments were used to determine the best conditions of the design, namely:HRT=9h,the average concentration of DO in the oxidation ditch aerobic zone=1.0mg/L, SRT=18d, MLSS=3.0g/L,two-point water distribution ratio (frontbiological selection pool:the pre-anoxic tank)=2:8, two-point sludge return distribution ratio (pre-anoxic tank:oxidation ditch)=3:7. Under this condition, the content of COD, ammonia, NO3--N,NO2--N, TN and TP in sewage treated by this design can fully meet the first-level standard of "Municipal wastewater treatment plant emission standards", and improve the oxidation ditch process in de-nitrogen and phosphorus removal ineffectiveness.