| Changchun northern sewage treatment plant is located in downstream of thenortheastern Yitong River in Changchun City. The secondary treatment process usesmodified A~2/O process, and the design capacity is390,000tons/day. At present the plantis the largest sewage treatment plant in Changchun City, and it plays a key role not onlyin water pollution control of Yitong River, which is mother of the Changchun City people,but also in guarantee the quality of the Songhua River water. Since the plant putting intooperation, for various reasons, effect of sewage treatment operation is unstable, and itsenergy consumption is relatively high, and the sludge which is generated by sewagetreatment plants can not be properly handled. We need optimize operation parameters,and seek energy-saving technical way, and solve problem of sludge disposal. By this waywe can ensure that the sewage plant can be run in the best condition. For these reasons,Combined with environmental characteristics of the cold regions of northern China, byanalyze effect of the system in different conditions, we establish the optimum parametersand optimize the system operation conditions on the basis of full investigation andstudying on the plant. In order to solve the sludge whereabouts problem of the sewagetreatment plant and achieve sludge harmless, reduction, recycling, combined withrunning of the new Changchun sludge disposal plant, by analyze moisture content,temperature, pH, seed germination rate and other control indicators in the sludge aerobicthermophilic fermentation process, we investigate running effect of the sludge aerobiccomposting process under low temperature conditions in cold regions of northern China.The test results show that, dissolved oxygen concentration has a greater impact tothe processing power of the Modified A~2/O biological treatment system system in the endof the aerobic tank. And it is significant for energy-saving of the sewage treatment plant,these parameters need to be optimized. When dissolved oxygen concentration of the endof the aerobic tank is in the1.5~2.5mg/L, indicators of treated water comply with qualitystandards, nitrification capacity is very high in the aerobic pool, ammonia nitrogen removal rate is about80.75%. Total phosphorus and total nitrogen removal rate is thehighest, they are88.79%and59%. Removal efficiency of COD is at a high level, it canbe up to83.06%.When sludge recycling ratio are60%,80%and100%, the test results show that thebest sludge recycling ratio is80%. Its MLSS concentration is higher than other, and itsSVI is moderate. Compared to other sludge recycling ratio, the treatment effect of CODand ammonia nitrogen has no difference, removal efficiency of COD is84.52%, removalefficiency of ammonia nitrogen is81.28%. Its total nitrogen removal rate is59.72%, it isonly3.39%lower than100%sludge recycling ratio, and it is7.34%higher than60%sludge recycling ratio. Pre-denitrification tank can effectively solve the problem whichanaerobic phosphorus release is suppressed, where it set before anaerobic tank, totalphosphorus removal rate is84.54%.When inner recycling ratio are100%,150%,180%,200%, the test results show thatthe treatment effect of COD is little away from each other, and they all meet thestandards. Average total nitrogen removal rate is the highest of all when inner recyclingratio is180%, it is63.50%. Denitrification is the better, nitrate nitrogen which is returnedto the anaerobic tank is the less, the more favorable to remove total phosphorus andimprove total phosphorus removal rate.Due to dissolved oxygen concentration in the end of the aerobic tank, sludgerecycling ratio and inner recycling ratio is proportional to energy consumption ofwastewater treatment plant. Consolidating removal efficiency of water quality indicatorsand energy consumption, the best dissolved oxygen concentration in the end of theaerobic tank, sludge recycling ratio and inner recycling ratio should be chosen as1.5~2.5mg/L、80%and180%.Analysis on running test results of sludge aerobic pile fermentation in the northernsewage treatment plant shows that, when we use forced ventilation and mechanical turnerprocess based on CTB Technical intelligent control in cold regions in northern China,sludge aerobic pile temperature, PH value, moisture content and etc basically meet therequirements of microbial decomposition during fermentation in low temperature environment in winter. By the effective control of ventilation flow, time interval and piletemperature, pile moisture content quickly decreases from63.36%to44.50%during thefirst fermentation with intelligent control of CTB system, and it slowly decreases to39.2%during the secondary fermentation. Seed germination rate increases from21%to82%. Compost product indexes meet <the landscaping argillaceous standard GB/T23486-2009> and <agricultural muddy standard CJ/T309-2009>.this effectively solve the sludgewhereabouts problem of the sewage treatment plant and achieve sludge harmless,reduction, recycling. |
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