In southern China, especially in the city of Shanghai and Shenzhen, the sewage treatment plant faces the situation of the shortcomings of carbon source of biological nitrogen removal process. While the anaerobic acidification of sludge from city sewage can produce a high concentration of dissolved organic matter (called dissolved Chemical Oxygen Demand, SCOD). It not only can provide carbon source for biological denitrification system but also improve the nitrogen removal efficiency. More and more concern i...