Small sewage purification at room temperature anaerobic digester technology applications, in accordance with "multi-level gravity, level-degradation" principle, the establishment of anaerobic fermentation of grade Ⅰ - Ⅱ level and digestion of the new filtration device. It consists of anaerobic fermentation, digestion and filtration, sewage backflow and fillers such as process components. Most organic matter in sewage by the anaerobic fermentation to produce biogas, fermentation and digestion of sewage into the filter tank, part of the decomposition of organic matter is not further degraded. Settling down part of the organic matter and return activated sludge to anaerobic digestion anaerobic fermentation tanks to improve the effectiveness, reach the purpose of purification. 
 Sewage Biogas is a small decentralized wastewater treatment plant, with less investment, the effect is good, run without energy support and so on. Lianshui present the technology in the East China Sea and other places are widely used, results are more significant.