Present situation and treatment of rural sewage treatment

(2) Biofilm method (integrated equipment commonly used). Common anaerobic filter, biological contact oxidation process (BCO), biological aerated filter (BAF), denitrification filter, biological turntable, moving bed biofilm reactor (MBBR) and so on.

The advantage of biofilm method is that the operation and maintenance requirements are low, can be unmanned management, only a small number of biofilm fall off, most of the integrated equipment is used anaerobic filter + biological contact oxidation process, etc., but can not remove phosphorus, where there are phosphorus removal requirements need to add chemical phosphorus removal or electric phosphorus removal (iron and aluminum electrodes). The purification tank technology based on the biofilm method has been widely used in Japan, and in China, it is also the most widely used process technology for integrated equipment, which is suitable for small-scale sewage treatment (several tons to dozens of tons).

(3) Ecological treatment method. The common ones are constructed wetland, micro-ecological filter bed, artificial fast infiltration, land treatment and so on. The advantages are ecological sustainability and low energy consumption. It has a landscape effect, but the disadvantage is that the pollutant removal load is low and a large area of land is required.

(4) Other methods. Common septic tanks, stabilization ponds, biogas digesters and so on. This kind of method has limited pollutant removal ability and poor effect. It is generally used in remote areas with poor economy or as a pre-treatment measure.

1.4 Rural sewage treatment and discharge standards: there is no unified standard, resulting in a variety of problems in design, construction, operation and supervision

Because there is no unified emission standard, it causes difficulties in process and construction standards. There is also a lack of unified technical standards and specifications for the design, construction, evaluation, acceptance, operation and supervision of the project, and some places copy urban standards, resulting in high costs and problems such as abnormal operation.

The formulation of standards and norms should first consider the regional differences of villages and towns, and make corresponding design adjustments according to different regions, different terrain, different geographical and climatic conditions and economic development levels. Secondly, priority should be given to resource utilization. Due to the scarcity of water resources in our country, priority should be given to the treatment of sewage in villages and towns and the utilization of local resources, especially for the arid areas in the north and east of our country. Moreover, economic and efficient, the village sewage treatment system should invest in the province, low energy consumption, and adapt to the economic development level of the village and village and the economic affordability of the villagers. The process design is reliable and stable, and the effluent meets the discharge standard requirements.

Taking into account the economic capacity and operation and maintenance of rural areas, emission standards should not be too stringent. The formulation of rural sewage standards should first consider organic matter and SS, effectively control the black and odor of water, should not be excessively harsh TN and TP standards, in fact, many Western developed countries in rural sewage treatment and no nitrogen and phosphorus requirements, discharge standards should be formulated according to local conditions, to take into account the environmental capacity (self-purification capacity of receiving water) and discharge road. And the local social economy and other comprehensive consideration.

1.5 The operation and maintenance level of rural sewage treatment facilities is low

(1) Lack of operation and maintenance funds and management system, heavy construction and light operation. Due to the lack of operation and maintenance funds and effective operation management assessment system, supervision is absent, and there is still a lack of effective assessment means for the implementation of sewage treatment facilities, management effects, water quality testing and discharge, leading to some sewage treatment facilities idle or abnormal operation.

(2) Lack of operation and maintenance technology and personnel. At present, the operation technology of rural domestic sewage treatment facilities is lacking, and most of the management personnel are local villagers, who lack relevant knowledge of environmental protection and skills related to equipment operation and management. They can only be responsible for the daily care work of equipment, and are not qualified for professional system maintenance, which leads to problems such as fluctuating sewage treatment effect and substandard effluent water quality.

1.6 Construction and operating costs of rural sewage treatment: large investment and operating costs, and high electricity consumption per ton of water

According to the "Rural domestic sewage treatment Project construction and investment Guide" issued by the Ministry of Ecology and Environment, because the amount of water is small, under the same circumstances, the ton of water investment and power consumption of rural sewage and operating costs are slightly higher than that of municipal sewage plants. But the use of ecological treatment technology can reduce costs.