Current situation and development trend of municipal sewage treatment and reuse in China

In recent years, China has accelerated the process of social urbanization, and the number of people has also shown a trend of rapid growth, the contradiction between sewage treatment and residents' life in urban development has been highlighted, and has received extensive attention from all walks of life. According to relevant data, as of the end of June 2019, the sewage treatment plants of cities in China have reached more than 5,000 (excluding township sewage treatment plants and industries), and the sewage treatment capacity has reached 2.1×108 m3/d. Although the number of urban sewage treatment plants is gradually increasing, it can not meet the current needs of urban development, and the current status of sewage treatment in urban agglomerations in China is still not optimistic. Only by effectively solving the problem of urban sewage treatment can we effectively guarantee the steady improvement of the quality of life of urban residents and ensure the ecological and sustainable development of the city.

First, the current situation of urban sewage treatment and recycling in China

The state increasingly attaches importance to urban sewage treatment and reuse, and sewage treatment plants actively innovate A variety of effective solutions for the treatment and reuse of urban sewage, such as A-A-O process, A-O process, oxidation ditch process and SBR process, and even the deep sewage treatment and reuse technology that has been widely used in urban sewage treatment plants. But at present, the situation of municipal sewage reuse is still not objective. The main reasons for the low efficiency in the reuse of municipal sewage are as follows:

1. Shortage of funds for sewage treatment and reuse

Urban sewage treatment and reuse can be used for flushing toilets, urban road greening, domestic water, landscape water, etc. According to the relevant regulations of reuse water, the requirements of fecal Escherichia coli, residual chlorine, suspended matter and other indicators are stricter than Grade A, and the effluent of most sewage treatment plants has not yet met the requirements. In order to improve the capacity of reuse water for sewage treatment, it is necessary to strengthen the construction of the sewage treatment plant. However, in the process of establishing the plant, a large amount of financial support is urgently needed, such as site construction funds, equipment introduction funds and machinery and equipment maintenance funds. In addition, when purchasing related chemical reagents and updating technical means, it is necessary to improve the quality of the plant. Strong financial backing is needed everywhere. However, at the current stage, the financial support given to urban sewage treatment plants by local government departments in China is not sufficient, which leads to insufficient construction of urban sewage treatment plants and low technical level, and ultimately leads to China's urban sewage treatment plants in the performance of sewage treatment capacity can not get the ideal effect.

2. Technical problems of sewage treatment and reuse

China has a vast area, the urban division is very detailed, at present, the process of urban sewage treatment and reuse is often limited by the level of urban economic development and scientific and technological input, and even affected by the urban geographical environment, resulting in our city in the reuse of sewage is relatively slow. If the technical problems can not be solved in the sewage treatment and reuse of the urban sewage treatment plant, it will lead to the difficulty of the designed sewage treatment and recycling scheme, and it will not be able to successfully achieve the goal of urban sewage treatment and reuse. Most urban sewage factory sewage treatment technology is introduced from abroad, resulting in sewage treatment technology can not match the actual situation of our city, the actual treatment capacity may not be able to reach the design treatment capacity.

Second, China's sewage treatment and reuse process technical support

At present, most domestic and foreign sewage treatment in the use of secondary treatment method, the core is the traditional activated sludge method. The processes used in the treatment of sewage include A-A-O process, A-O process, oxidation ditch process and SBR process. At present, these processes are relatively mature, and the effect of treating sewage is also relatively good.

1, A-A-O sewage treatment process

A-a-o wastewater treatment process is also known as anaerobic - anoxic - aerobic process, this process has A wide range of applications, the southern region of China is more common use of such technology. The principle is to set up anaerobic areas, anoxic areas and aerobic areas in the sewage treatment system to achieve the purpose of biological nitrogen and phosphorus removal.

2. SBR process

SBR process is also known as the continuous batch activated sludge treatment process, this process requires the use of a pool as a tool, the pool as an aeration tank to develop secondary precipitation, this method is different from the traditional way of space or time segmentation, more suitable for sewage treatment in small-scale cities.