Nowadays there are generally two ways both in China and abroad for disposing the domestic sewage, centralized processing and in-site decentralized processing with handy facilities. Centralized processing is a way to first gather the dispersal waste water by laying sewage pipe network and then transport it to the downstream sewage treatment station for an uniform treatment, while decentralized processing is applied into the situation when the sources of pollution are relatively concentrated in a range, where the handy sewage processing facilities will be established for in-site treatment.
       In China, town sewage, especially village sewage lack appropriate governance since the local infrastructure for environmental protection seriously lags behind, while in some economically underdeveloped areas, even the rain sewage streaming network is incomplete. With the social development, some economically underdeveloped areas always need to explore local tourism resources and sell the land to obtain area developing funs. In such context, traditional sewage processing technology will be limited by its technical characteristics, which requires high operational fees, a complete sewage pipe network and which therefore will occupy a lot of social resources. However, the counterpart funds from central financial authorities are far from enough for completing the pipe network and establishing sewage processing facilities. Besides, the expenditure for pipe network tends to account for one second to one third of the whole engineering investment，and its operational fee is shouldered by local financial authorities. As the traditional technology is characterized by its high operational cost, many existing sewage plants are running at half capacity or have directly terminated the operation. According to the investigation, only 20% sewage plants in villages can run properly. The traditional sewage processing technology requires quite high professionalism of the personnel, who will observe the machine’s running state while doing adjusting for the running parameters at any time. In total, its operation management is relatively complex and has a higher requirement for managers’ basic qualities, which also leads to a higher cost of operation. Whether the management personnel concerned is responsible for his job will directly affect the result of sewage treatment, however, due to the lack of automation and automatic monitoring facilities, it’s relatively hard for the relevant administrative departments to supervise the running of the sewage plants.
       In such a general background, the advantages of PASG Technology such as the low operational fee, in-site dispersed, landfilled, high-tech network management and so on (please refer to Chapter II for details) can well make up for the deficiencies of traditional technology so as to be fit for town sewage treatment.