Discussion on the application of rural sewage treatment technology in different regions of China

With the gradual acceleration of China's urbanization process, the construction of sewage treatment facilities in the majority of rural areas has also received greater attention. Due to the great differences in topography, climate, economy and living habits in different regions, the selection of rural sewage treatment technology needs to be adjusted according to the actual situation in each region to maximize its effectiveness. Based on the basic geographical characteristics of the six regions in China, this paper will make a comparative analysis of the generation characteristics of rural domestic sewage in the region, and briefly discuss the application conditions of the current major mainstream rural sewage treatment technologies in different areas of China, in order to provide references for exploring rural domestic sewage treatment technologies according to local conditions.

Regional characteristics of rural sewage treatment in China

According to the "Regional Rural sewage Treatment Technical Guide" issued by the Ministry of Housing and Urban-Rural Development, China's rural domestic sewage treatment work is divided into six regions: northeast, North China, Northwest, central and South, southeast and southwest. The reference index of domestic sewage quality applicable to localization in six regions is the basic reference for the construction of rural sewage treatment facilities. The characteristics and main problems of rural sewage production in each region are analyzed as follows.

Northeast region

China's northeast generally refers to the narrow sense of the northeast three provinces (Heilongjiang, Jilin, Liaoning) and the broad sense of Inner Mongolia East five league region. The whole region is located in the middle temperate zone and the cold temperate zone, which is a temperate monsoon climate, with mild and rainy summer and cold and dry winter. The terrain conditions are mainly in the vast northeast plain, but also distributed in the large and small Xingan Mountains, Changbai Mountains, Liaodong hills and other mountainous and hilly areas. Rural areas in Northeast China are mostly in economically underdeveloped areas, where villages are dispersed and sewage treatment levels are low. For example, in 2018, only 4.9% of rural areas in Jilin Province built centralized or partially centralized treatment facilities. Affected by the cold climate in winter, the average daily discharge of rural sewage in Northeast China is low, and the content of nitrogen and phosphorus in water is high. The extremely cold climate will greatly restrict the efficiency of the biochemical process of sewage treatment. Therefore, the selection of sewage treatment technology in northeast China should take low temperature adaptability, low cost, easy maintenance and high nitrogen and phosphorus removal efficiency as the main objectives.

North China

North China mainly refers to the North China Plain area of Beijing, Tianjin, Inner Mongolia, Hebei, Shanxi, Shandong, Henan and other provinces and cities most of the area. The whole is a temperate monsoon climate, hot and rainy in summer, cold and dry in winter. The terrain is mainly plain, and water resources are scarce. North China is the main agricultural producing area of China, with dense rural population, numerous villages and huge sewage production, but the per capita sewage production is less than that of the south. The level of economic development in the region is relatively unbalanced, the infrastructure of some arid areas is relatively backward, the phenomenon of disorderly discharge is common, the sewage treatment level in some rural areas is low, and the indicators of organic matter, nitrogen, phosphorus and suspended matter in the effluent are high. In North China, the whole year is relatively dry, and the precipitation is usually concentrated in summer. The selection of sewage treatment technology should focus on the circulation of water resources.

Northwest China

The northwest region mainly includes most of Xinjiang, Qinghai, Gansu, Ningxia, Shaanxi and other provinces. The region is mainly in the temperate and warm temperate continental climate, the local temperate monsoon climate, the overall drought, the average annual temperature is low. The terrain is mainly plateau, mountain and desert, and the population mainly gathers in Hetao plain and oasis. Rural areas in the northwest have traditionally used little water for living, with most villages still using dry latrines and lacking artificial drainage systems. And due to the large degree of rural population loss, many sewage treatment facilities are difficult to operate normally. For the arid areas in the northwest, the sewage treatment facilities should adopt the economical and simple technical route as far as possible.

Southeast region

The southeast region is mainly the provinces along the southeast coast of our country, the southeastern hills run through the whole region, the internal rivers are densely covered, and the countryside is usually distributed in the mountain valley zone. The whole is basically a subtropical monsoon climate, hot and rainy in summer, mild and humid in winter. The level of rural economic development in the southeast coastal areas is uneven, the economy of the Yangtze River Delta and the Pearl River Delta is developed, the rural population density is large, and the problems of water pollution and water shortage are obvious. Fujian, Guangdong, Hainan and other provinces have a large area of underdeveloped mountainous areas, a large number of rural population, and the cost of construction of sewage pipe network in hilly areas is high, and sewage is generally discharged directly into rivers in the early stage. Considering the rural water environment problem and the difference of economic development level in southeast China, targeted sewage treatment technology should be selected in practice.