The treatment of black and odorous water bodies is an old problem of water pollution prevention and control. After several years of work progress, it should be almost treated. However, in the central ecological and environmental protection inspection, there are still many places where the inspection and rectification of black and odorous water bodies is not in place. The problem of water turning black and smelling is still very prominent.
Recently, the Central Ecological and Environmental Protection Inspectors concentrated on a number of typical cases discovered in the second round of the fourth batch of inspections. Among them, the black and odorous water bodies in Jilin, Shandong and other places were not properly treated. The inspectors found that in the above-mentioned areas, there is a long-term delay in the improvement of black and odorous water bodies. The construction of sewage treatment plants in some areas and the transformation of rain and sewage diversion are still lagging behind. The phenomenon of direct sewage discharge is more prominent. Problems such as black and odorous water turning black and odor.
Coincidentally, as early as April this year, the second round of the third batch of inspections by the supervision group of the Central Ministry of Ecology and Environment also found that there were four black and smelly puddles in Chongzuo City, Guangxi, and the sewage was directly discharged into a branch of the Xijiang River. Zuo Jiang and other issues. The confluence of rain and sewage, direct discharge of sewage, and ineffective supervision and rectification have become the fundamental problems of "long-term governance and long-term cleanliness" that cannot be controlled for black and odorous water.
In 2018, the relevant national departments jointly issued the "Implementation Plan for the Battle of Urban Black and Odorous Water Bodies", which clearly stated that provincial capital cities should achieve the goal of eliminating black and odorous water bodies by the end of 2018, and by accelerating the construction of urban environmental infrastructure and improving long-term mechanisms, fundamentally Solve the relevant environmental problems that lead to black and odorous water bodies. It can be found in the report of the Central Environmental Protection Supervision Group that the current lag in the construction of pipe network facilities is a relatively prominent hidden danger. Problems such as insufficient construction and maintenance of rainwater and sewage pipe networks have seriously restricted the progress and effectiveness of black and odorous water treatment.
"Black odor lies in the water, its roots lie on the shore, its core lies in the pipe network, and the key lies in the outlet." This is an accepted view today. The root cause of the black and odorous water body is that the sewage has not been cut and intercepted to enter the river and lake water bodies. In the case reported by the inspector this time, this problem is particularly obvious.
The inspector found that the problem of direct sewage discharge in Jilin Province is still outstanding. The two sewage outfalls under the bridge of Zhongheng Road and under the bridge of Guanggu Street in Changchun City total about 40,000 tons of domestic sewage every day and discharge it directly into the Yongchun River. On-site sampling and monitoring showed that the highest concentration of chemical oxygen demand, ammonia nitrogen and total phosphorus in sewage was 263 mg/L, 25.4 mg/L and 2.38 mg/L, respectively, seriously polluting the water quality of Yongchun River. In addition, in some areas such as under the Fourth Ring Bridge, Lvyuan Minggou, and Zhonghai Community, a large amount of domestic sewage is mixed with rainwater in rainy days, and overflows into rivers through open channel overflow weirs and sewage wells.
In Shandong, problems such as mixed connection and wrong connection of the sewage pipe network in Heze City, silting of the pipe network, and mixed flow of rain and sewage are still prominent. In 2020, the urban domestic sewage collection rate in Heze City was only 51.9%. There are still 53 kilometers of combined rain and sewage pipe network. There are obvious shortcomings in sewage collection, and the repeated treatment of black and odorous water bodies has led to a significant decline in the environmental quality of surface water in Heze City.
The low rate of pollutant collection and treatment is also a problem that we must attach great importance to in our current sewage treatment. Wang Jiazhuo, director of the Ecological Municipal Institute of the Planning and Design Company of the China Institute of Planning and Design (Beijing), once pointed out at the "2018 (16th) Water Industry Strategy Forum" that emphasizing factories and ignoring networks has led to low efficiency of sewage collection systems and low influent concentrations , is one of the more prominent problems in the current water environment governance.
Over the past period of time, we have attached great importance to the construction of urban sewage treatment plants, but we have not paid enough attention to the pipe network, resulting in low efficiency of the current sewage collection system and low influent concentration.
From 2007 to 2017, the number and scale of urban sewage treatment plants in my country continued to grow. In 2007, there were 1,148 sewage treatment plants across the country. By 2017, the number of sewage treatment plants in operation reached 4,802, and the total treatment scale also increased from 75.54 million tons per day to 185.58 million tons per day.
This means that the sewage plant was originally used to treat sewage, but now it processes sewage that has been diluted in a large proportion. River water, groundwater, mountain spring water, etc. are mixed with sewage and enter the sewage treatment plant together, which not only occupies the sewage pipes The collection capacity of the net also squeezed the treatment capacity of the sewage treatment plant, and also wasted a lot of sewage treatment costs of the local government.
At the regular press conference of the Ministry of Environment in March this year, Zhang Bo, director of the Water Department of the Ministry of Ecology and Environment, emphasized that the first priority in the next step in the treatment of black and odorous water bodies is to solve the problem of the pipe network. At present, although the urban pipe network seems to have been built, the quality is not high. There are some wrong connections, some mixed connections, and some leaks. "In some places, the influent concentration of sewage treatment plants is extremely low, and it is close to reaching the standard without any treatment. A considerable part of the treated water is not sewage."
The E20 Research Institute believes that the low sewage collection rate, the backward construction of the sewage pipe network, the serious phenomenon of combined overflow pollution, and the influent concentration of the sewage plant does not rise but falls, indicating that the construction and repair of the pipe network still has a lot of debts in the market However, the current payment model of the pipeline network is still purely government-paid, and the discussion on the business model of pipeline network operation and maintenance is still going on. At present, the length of drainage pipes in cities and counties is about 1 million kilometers, and the annual pipe network inspection and maintenance market is 20-30 billion. The market for pipe network repair exceeds 100 billion, and the market for new pipe network exceeds 150 billion.
In 2019, the "Three-Year Action Plan for Quality and Efficiency Improvement of Urban Sewage Treatment (2019-2021)" jointly issued by the Ministry of Housing and Urban-Rural Development and other three ministries and commissions focused on "speeding up the improvement of the shortcomings of urban sewage collection and treatment facilities, Realize full coverage, full collection, and full treatment of the sewage pipe network as soon as possible." In recent years, my country's sewage treatment infrastructure has made great progress. During the "13th Five-Year Plan" period, the national urban sewage treatment rate has reached more than 95%. However, the pipeline network has always been a shortcoming in my country's sewage treatment, and the pipeline network coverage is insufficient. , Leakage, passenger water crowding the pipe network, misconnection and mixed connection, overflow and other problems are common. This is the main reason why my country's sewage treatment rate is high but the sewage collection and treatment rate is still relatively low, and black and odorous water bodies occur frequently. Although a three-year action plan for improving the quality and efficiency of sewage treatment has been formulated, the problem of the pipe network cannot be solved in a short period of time. Network solution.
The inspector found that the long-term management and control mechanism of relevant districts, counties and departments in Changchun City was not in place. The river chief system in some river sections is ineffective. Although district-level and street-level river chiefs have been established, most of the river chiefs have not found any problems during the river patrol process. The water quality monitoring of black and odorous water bodies has not been effective. Judging from the monitoring reports reviewed by the inspection team, the monitoring data does not reflect the deterioration of water quality in some water bodies or even the problem of turning black and smelly. There is a problem of lax work. Changchun City lacks a systematic plan for the treatment of some black and odorous water bodies in the built-up area. The construction of water environment infrastructure such as sewage treatment plants and rainwater drainage pipe networks is relatively lagging behind. The implementation of some long-term control mechanisms is obviously not in place, and there are problems of dereliction of duty.
The inspectors found that Heze City had not completed the governance projects with clear implementation plans, and some projects were lagging behind for a long time, and some projects did not even start until the inspectors were stationed. According to statistics, among the 155 governance projects, 44 projects did not complete the construction as required by the end of 2020, involving half of the total project investment, and 17 of them had not yet completed construction by the time the inspectors arrived. The old city of Heze City is a rainwater and sewage confluence area. The sewage is raised to the first sewage treatment plant through the Chengyang Road pumping station. However, due to the blockage of the pipe network at the back end of the pumping station, the sewage in the old city can only be discharged directly through the overflow for a long time. Qingnian Lake Dongkeng. According to the remediation plan, Heze City should build a fifth sewage treatment plant before the end of 2020 to solve this problem. In June 2021, the inspection team found that thousands of tons of domestic sewage are still discharged directly into Qingnian Lake every day. The fifth sewage treatment plant As of the time the inspectors moved in, construction had not yet been completed. The Donggou of Juyang Road in the urban area flows into Qili River from south to north, and is one of the main pollution sources of Qili River. In June 2021, the inspection team found that there were still many direct sewage outlets along the ditch, and the ditch was full of garbage, and the black and smelly smell was serious. It was not until the inspectors were stationed that the relevant departments of Heze City began to build sewage interception pipelines along Juyang Road. .
During the "13th Five-Year Plan" period, an important task of water pollution prevention and control is the treatment of black and odorous water bodies. To this end, the Ministry of the Environment launched the "Battle for Urban Black and Odor Water Treatment". This year, at the regular press conference of the Ministry of Environment in March, Zhang Bo, director of the Water Department of the Ministry of Ecology and Environment, introduced that by the end of 2020, the elimination rate of 2,914 black and odorous water bodies in cities at the prefecture level and above across the country will reach 98.2%.
But in fact, as early as the beginning of 2018, when the "Battle for Urban Black and Odorous Water Treatment" just started, the completion rate of black and odorous water treatment dispatched by the Ministry of Environment from various places has reached 99.1%. Zhang Bo, director of the Water Department of the Ministry of Ecology and Environment, said frankly that this was because the figures at the time were inaccurate. In 2018, the Ministry of Environment and the Ministry of Housing and Urban-Rural Development launched a tough battle. Through reports from the masses and satellite remote sensing, it was found that many black and odorous water bodies have not been eliminated. Some even filled out the black and smelly water bodies. "Although after three years of hard work, it is still not as good as 99.1% at the beginning of 2018, but this 98.2% is relatively realistic, and the common people are quite satisfied."