Study On Sludge Disposal Scheme Of Municipal Sewage Treatment Plant In Changchun

With the economic development of Changchun and the increasingpopulation of the city, huge amount of sludge is produced in municipalsewage treatment. It is a potential threaten to the ecological environmentand public health. It is imperative to construct the sludge disposal projectin Changchun to avoid the secondary pollution and realize sludgestabilization, reduction, safety and recycling.Through investigating the sludge disposal technology research at homeand abroad and considering the properties of sludge from Changchun’ssewage treatment plants, the effect of sludge disposal, construction costand the environmental impact factors, this papaer selects turner andaerobic aeration technology to compost sludge which obtains good effectin actual operation. By studying, it concludes following conclusions:(1)Comparing with hot drying and incineration technology, compostingoccupies a small area, consumes low energy, has good effect on sludgedisposal and avoids the secondary pollution.(2)Turner and aerobic aeration composting technology has lowengineering investment and occupies a small area. The compostingconditions is easy to control and the amount of organic matter is large.Besides more oxygen is provided for microorganism to degrade therefractory organics whose degradation can reach more the50%.(3)The main influence factors in the process of composting sludge arewater content, organic matter content and carbon and nitrogen ratio,temperature and ventilation. It is concluded that the best water content ofcomposting is50%-60%. The process cycles some disposed sludge andadds suitable amount of crushing plant straw to adjust the water contentwhich is approximately60%. By adding plant straw, the ratio of C/N iscontrolled at25-35:1and organic matter content is adjusted between 40%to60%. The process uses the temperature-gas supply feedbacksystem to control the composting temperature. Through the turner and thefan of temperature-supply system the process controls flow at about0.1m~3air per min·m~3material.(4) Changchun sludge treatment plant has been using turner aerobicaeration composting process for sludge disposal. Sludge samples takenfrom the actual operation process result that the average moisture contentof the sludge disposal rate is36.7%, the pollutants in sludge decreasessignificantly meeting the technical requirements and the effect of sludgedisposal is good. Treatment sludge power consumption is14.67kwh/ton,that indicates the process has lower energy consumption, lower operatingcosts and significant economic benefits.