In order to win the battle against pollution, the "Implementation Plan for Strengthening and Weaknesses of Urban Domestic Sewage Treatment Facilities" was issued recently, requiring that by 2023, the capacity of urban facilities at the county level and above basically meets the needs of domestic sewage treatment——

Does sewage treatment capacity limit urban development? Make up the shortcomings of facilities!

  Recently, the Haigang District of Qinhuangdao City, Hebei Province has incorporated domestic sewage from 7 villages in Donggang Town’s jurisdiction into the urban pipeline network in the flood drainage river ecological improvement project, comprehensively harnessed the entire river basin, and built 240 acres of artificial wetlands. Improved the water quality of rivers entering the sea. Photo by Xinhua News Agency reporter Yang Shiyao

  According to statistics from the Ministry of Housing and Urban-Rural Development, in 2019, the sewage treatment capacity of cities and counties in my country exceeded 210 million cubic meters per day, and the length of sewage pipe networks reached 570,000 kilometers. Nevertheless, the shortcomings of the sewage collection pipe network in China are more prominent, the "capillaries" are missing, the pipe network is old and damaged, and the problems of mixed connections are widespread; the phenomenon of "heavy water and light mud" is more common, and the construction of sludge treatment and disposal facilities is lagging behind. The harmless and resource-based disposal is not yet standardized and the level is generally not high.

  In order to make up for the shortcomings and weaknesses of facility construction and win the battle against pollution prevention, the National Development and Reform Commission and the Ministry of Housing and Urban-Rural Development have recently jointly issued the "Implementation Plan for Strengthening and Weaknesses of Urban Domestic Sewage Treatment Facilities" (hereinafter referred to as the "Implementation Plan"). In 2023, the capacity of urban facilities at county level and above will basically meet the demand for domestic sewage treatment; the harmless disposal rate and resource utilization rate of urban sludge will be further improved, and the level of sewage resource utilization in water-scarce areas and water-sensitive areas will be significantly improved.

Insufficient sewage treatment capacity has become a bottleneck for urban development

  According to the national surface water quality status reported by the Ministry of Ecology and Environment in the first half of 2020, among the 1940 national surface water assessment sections, 80.1% have good water quality, an increase of 5.6 percentage points year-on-year; the proportion of sections with poor grade V is 1.1%, year-on-year A decrease of 3.2 percentage points. Compared with the significant improvement in the quality of the water environment, the urban domestic sewage treatment capacity has become a prominent shortcoming in the comprehensive promotion of water pollution prevention and control.

  Liu Bo, secretary general of the Sponge City Ecological Industry Technology Innovation Strategic Alliance of Changsha City, Hunan Province, told the reporter of Science and Technology Daily that the two departments issued the "Implementation Plan" because of the long-term insufficient capacity of sewage treatment facilities in cities above the county level in China, which has become a bottleneck for urban development. The water ecological environment urgently needs to be improved. "A large number of sewage treatment facilities built during the'Twelfth Five-Year Plan' period have solved the problem of insufficient sewage treatment capacity in some cities. However, due to unmatched pipe networks, misconnection of pipe networks, mixed rain and sewage, and low pollution load of influent water, etc. Many cities have not achieved the desired treatment effect, and pollution caused by sewage overflow is widespread."

  "Although on the whole, the sewage treatment rate indicators of cities and counties in the country are relatively high, many central and western cities and towns have problems with sewage treatment facilities such as incomplete coverage and uneven distribution. Due to the rapid growth of urban area and population, some areas have It is difficult for the layout and construction of treatment facilities to match the local sewage discharge in a timely manner. And in some poverty alleviation areas, due to lack of sufficient funds, many sewage treatment facilities are not yet available." Zhu Zhu, Director of Resources and Environment Business Department of China International Engineering Consulting Co., Ltd. Li Yang said that the unmatched pipe network, leakage, and poor operation and maintenance have caused problems such as the influent quality and instability of the sewage treatment plant, and the sewage treatment plant has low treatment efficiency. With the increasingly strict national discharge standards, the cost of sewage treatment continues to rise.

  Carrying out the strengths and weaknesses of urban domestic sewage treatment to make up for the shortcomings, and constructing systematic projects covering sewage collection pipelines, sewage treatment plants, sludge treatment and disposal, and sewage recycling, which can not only form current investment, but also attract industrial investment, and promote green industries development of. The relevant person in charge of the National Development and Reform Commission said that this is of positive significance for promoting the formation of a strong domestic market and promoting economic and social development. The implementation of the "Implementation Plan" can also promote the continuous improvement of the quality of the water environment, meet the people's growing health needs and beautiful ecological environment needs, and enhance the people's sense of happiness, sense of gain and security.

Encourage biomass utilization methods to find a way out for sludge

  In view of the main shortcomings of urban sewage treatment facilities, the "Implementation Plan" proposes to strengthen the shortcomings of urban sewage treatment plants, make up for the shortcomings of urban sewage collection pipe network, accelerate the promotion of the harmless disposal and resource utilization of sludge, and promote the information system Four major tasks of construction.

  The relevant person in charge of the National Development and Reform Commission stated that the pipeline network is the top priority to make up for shortcomings, including speeding up the elimination of blank areas in the pipeline network in urban villages, old urban areas, and urban-rural junctions, and speeding up the filling of the "capillaries" in the pipeline network; Outside the region, new pipe networks should strictly divert rain and sewage; the Yangtze River Basin and cities in the south of the region should promote the transformation of rain and sewage combined pipe networks to reduce the frequency of overflow pollution.

  Liu Bo believes that according to the "Implementation Plan", to truly divert rain and sewage, we need to build sponge cities in accordance with the principle of decentralized treatment at the source to realize rainwater storage, purification, and utilization. You can refer to the price of tap water to price purified rainwater and make rainwater widely available. It is used for toilet flushing, landscaping, etc., so as to completely reduce the pressure of sewage pipe network transmission and treatment. At the same time, gradually implement a rainwater discharge and treatment fee system, separate rainwater and sewage treatment fees, and separately use them for rainwater and sewage collection and treatment capacity building, and control rainwater runoff non-point source pollution and sewage overflow pollution from the source to eliminate the largest urban water environment. Source of pollution.

  As a product of sewage treatment, sludge can be said to be the "last mile" of sewage treatment. According to data released by the E20 Water Industry Research Center, my country’s urban wet sludge production was 46.46 million tons in 2018, and it will climb to 52.92 million tons in 2020.

  Promoting the harmless and resourceful treatment and disposal of sludge is considered to be the difficulty of making up for the shortcomings. Hang Shijun, the former deputy chief engineer of Beijing Municipal Engineering Design and Research Institute, said that at present, one of the key problems in the harmless treatment and disposal of sludge in China is to systematically solve the problem of sludge outlets and make sludge treatment and disposal become municipal waste. A link in the ecological recycling industry chain to form a sustainable sludge utilization and consumption model.

  The "Implementation Plan" encourages large and medium-sized cities with scarce land resources to adopt the "biomass utilization + incineration" disposal mode. Biogas generated from biomass utilization can be used for power generation and heat generation, and incineration is a key process route to solve the sludge problem. At present, large amounts of sludge accumulate and the way to dissipate is limited. Some cities with conditions can use kilns for co-incineration, and incineration ash can be used as building materials or for phosphorus recovery.

Guide social capital to participate to achieve the goal of water ecological restoration

  In order to ensure the implementation of the "Implementation Plan", the National Development and Reform Commission requires strengthening of organization and coordination, with cities and counties as the first responsible persons, speeding up project planning and reserves, clarifying the construction sequence, etc.; localities should include the land for sewage treatment facilities in the protection scope of the urban yellow line. Reasonably reserve land space; increase the collection of sewage treatment fees and promote the determination of sewage treatment service fees through market-based methods; promote the supervision of the entire process of sewage collection and treatment, resource utilization and sludge treatment and disposal, and establish scientific and reasonable performance Assessment system, etc.

  Liu Bo emphasized that the "Implementation Plan" requires rectification and regulation of pipe network construction, and solves the problems of rain and sewage diversion and missing and misconnected pipe networks. "It needs to be pointed out that the pipe network problem is an old problem left over from the urban construction process for decades. In addition to the pipe network problem itself, it is more a problem that the pipe network management mechanism and quality effect supervision mechanism cannot function. According to the " "Implementation Plan", strengthen supervision and management, it is necessary to investigate and hold the engineering construction unit responsible. If you only focus on construction, regardless of management, you will not bear the responsibility, and you will not be able to bear the consequences of blind advancement and low investment efficiency."

  The "Implementation Plan" proposes to attract financial institutions and social capital investment, and guide social capital to actively participate in construction and operation. Liu Bo suggested that when social capital is introduced and social capital is truly involved, the government should strengthen supervision. At the same time, establish a long-term investment return mechanism for municipal infrastructure, issue green bonds, return social capital, and achieve a virtuous circle.

  "The "Implementation Plan" emphasizes the strengths and weaknesses of the shortcomings, and it is foreseeable that it will promote the construction of urban rain and sewage pipelines and is worthy of high recognition." Liu Bo said that the treatment capacity of the sewage treatment plant is improved, even if the discharge reaches the standard, the tail water It is still inferior to Grade V. In the long run, it will have a great impact on the fundamental improvement of the water environment and water ecology. It is necessary to conduct ecological treatment through artificial wetlands and other methods. This also requires upgrading the existing sewage treatment plants, reducing the floor space, and using the saved land space to transform it into constructed wetlands.

  "To build an urban sewage treatment system, we must combine the higher goals of water environment and water ecological restoration, and do a good job of top-level design. This also requires a more scientific construction plan, more integration of multidisciplinary expertise, and high-tech informatization. To improve the efficiency of construction management, at the same time we must pay attention to management system and mechanism, investment and financing model innovation." Liu Bo said.

  Our reporter Li He