Problems in the utilization of sewage resources

The national level has attached great importance to water pollution control, sewage treatment technology has developed rapidly and achieved remarkable results, but the resource utilization of sewage is still in the preliminary stage, the development is not sufficient, and the utilization level is low. At present, the discharge of urban sewage is about 75 billion m³, and the amount of renewable water conservancy is less than 10 billion m³, which needs to be accelerated. Most coal chemical enterprises are built in water-scarce areas, and the resource utilization of industrial wastewater can minimize the shortage of water resources. At present, the main problems of sewage resource utilization are as follows:

1. Policies, regulations, management mechanisms and standard systems are not sound

At the national level, there are many laws and regulations on the policy of sewage resource utilization, but the connection of laws and regulations is not good, lack of coordination, and short board. The policies, planning, supervision and management of the relevant departments of the government lack coherence. There is a lack of coordination in sewage collection and recycling treatment, and some industrial wastewater is mixed into urban sewage systems, increasing the environmental risks of recycled water and sludge utilization. The problem is mainly reflected in the following aspects: First, the incentive mechanism and supervision system are not perfect, and the lack of reasonable charges and incentive mechanisms has led to the low enthusiasm of enterprises for regenerating water with thousands of ecological environment. Second, the lack of sewage resource utilization target determination mechanism, supervision and management system is not perfect, resulting in planning goals difficult to achieve. Third, the standard system is not perfect, the coverage of reclaimed water utilization water quality standard is not comprehensive, and the water quality classification standard is missing; The discharge standard of sewage treatment plant, water environment quality standard and water quality standard of reclaimed water ecological environment utilization lack coordination and coordination; Lack of sewage resource utilization benefit evaluation standards, ecological environmental risk management standards, technical standards, equipment standards and service and supervision standards.

2. The planning of reclaimed water utilization and the construction of facilities are not coordinated

The recycled water utilization plan lacks binding force, and the types of industrial projects introduced in the park often exceed the planning scope, affecting the normal operation of sewage treatment facilities. The positioning of industrial agglomeration area often changes with the situation of economic development, and the way out of "three wastes" is rarely considered from the perspective of the complementarity of circular economy and technological economy. Changes in the introduction of industrial projects have made it difficult for the centralized wastewater treatment facilities built according to the original plan to operate normally, and some even cannot operate normally. For the coal chemical industry and coal mine water problems, the more prominent is that the coupling degree is not enough, the distance is far, it belongs to thousands of different owner units, coordination is difficult, and the displacement and resource utilization are also difficult to match.

3. The theoretical research of sewage resource utilization is insufficient and the scientific and technological support is not strong

The research on the risk and control of sewage resource utilization is insufficient. The utilization of reclaimed water is a complex non-traditional water supply project. Compared with the standard discharge of sewage and traditional water supply, the risk factors, exposure pathways, exposure amounts and risk generation mechanisms need to be studied in a targeted and systematic way. There are some problems such as low efficiency of wastewater recycling treatment process, immature energy and resource conversion technology and lack of original technology.

4. The design of sewage treatment plant in industrial agglomeration area does not match the needs of enterprises in the park

The design and construction standard of sewage treatment plant in industrial agglomeration area can not meet the requirements of wastewater treatment in industrial park. In the construction of sewage treatment plants in many industrial agglomeration areas, the feasibility of industrial wastewater treatment and discharge up to standard is not demonstrated from a technical point of view, but the design idea of urban sewage treatment plant is adopted for construction, and the pollution control idea is rarely proposed from the characteristic pollutants of industrial wastewater, and the lack of pretreatment links and wastewater quality control means. Due to the lack of detailed provisions on toxic and harmful substances, especially organic poisons, in policies, regulations and related discharge indicators, and the lack of binding indicators on takeover conditions, many enterprises have blindly adopted various means, even adding water dilution, and pursued the "standard discharge" of wastewater indicators (especially COD). As a result, organic pollutants with biological toxicity, biological inhibition and difficult biodegradation in wastewater enter the park centralized sewage treatment plant without effective control. Some enterprises discharge wastewater with high biodegradability, which promotes the stable operation of the wastewater treatment plant in the industrial agglomeration area. However, in order to meet the unified take-over standards, biochemical pretreatment facilities have been built to remove useful components such as carbon sources, which is not conducive to the normal operation of the wastewater treatment plant in the park and the overall energy saving and emission reduction.