Analysis on Construction and Operation Effectiveness of County Sewage Treatment Plant in Guangxi

The statistics about construction, process, investment, treatment effect of 72 sewage treatment plants show that the plant scale of county sewage treatment plants are less than 50,000m?/d in Guangxi. The mainly treatment processes are SBR and its variants process, A2/O, Oxidation ditch. The sewage treatment plant´s investment of unit total construction and operating costs are reduced with the treatment scale increases. While the treatment scales are below 10,000 m3/d, the investment of unit total construction is among 17,300-4,700 yuan/m3, but to scales in 10,000~20,000m?/d is 4,700-3,500 yuan/m3, and to scales 20,000 ~ 50,000 m3/d is about 3,500 yuan/m3. The average operating costs of scales below 20,000 m3/d and 20,000 ~ 50,000 m3/d is 0.48 and 0.36 yuan/m3, respectively. The pipe network actual investment is significantly lower than the municipal treatment plant construction investment. In 2010, the average load rate of the municipal treatment plant is only 60.8%, which is lower than national online average level. 96% of average wastewater treatment plant´s efficiency reaches the standard, COD, BOD of the effluent are all reach the standards, but a few sewage treatment plants appear to ammonia nitrogen exceed standards for the less of technology, and shortage of carbon source.