The construction and transformation of domestic sewage pipe network in Nanchang City is lagging, and the problem of direct sewage discharge is not effectively rectified
The news pointed out that the second round of the third batch of the central ecological and environmental protection inspection team went deep into the front line and on-site, and verified a number of prominent ecological and environmental problems, and verified a number of inactions, slow actions, non-accountability, and non-responsibility. They even deal with formalism and bureaucracy issues such as perfunctory response and fraud. In order to play a warning role and effectively promote the rectification of problems, the inspection team conducted a centralized public notification of the fourth batch of 8 typical cases.
Among them, the construction and renovation of the domestic sewage pipe network in Nanchang City, Jiangxi Province is lagging behind, and the problem of direct sewage discharge is ineffective. The details of this typical case are as follows:
The built-up area of Nanchang City is 302 square kilometers, the population is 2.57 million, and the daily domestic sewage is about 1.1 million tons. There are 7 sewage treatment plants with a processing capacity of 1.525 million tons. /Day, construct a sewage pipe network of 2,114 kilometers. In 2018, the Central Ecological Environmental Protection Inspector “Looking Back” and the Poyang Lake Water Environment Special Inspector, the ecological environment warning film of the Yangtze River Economic Zone in 2018, 2019, and 2020 all pointed out that a large number of domestic sewage direct discharge problems in Nanchang City have not caused Nanchang Municipal Party Committee or City The government attaches great importance to it, and the problem still exists.
(1) Inadequate ideological understanding and poor water pollution prevention and control
First, the implementation of national decision-making and deployment is not in place. The State Council’s “Water Pollution Prevention and Control Action Plan” requires that the sewage in the built-up areas of provincial capital cities be basically fully collected and treated by 2017. In July 2018, Jiangxi Province’s “Implementation Opinions on Comprehensively Strengthening Ecological Environmental Protection and Resolutely Fighting Pollution Prevention and Control” again required that by the end of 2020, the domestic sewage in the built-up areas of the districts and cities will be basically collected and treated. Faced with a serious shortage of sewage collection, Nanchang has been slow to act. It was not until the end of June 2019 that the “Special Plan for Nanchang Central City Sewage (2019-2035)” was completed. The plan still proposes to retain the combined drainage system before 2025. , And gradually realize the diversion of rain and sewage by 2035, and relax the requirements again. According to calculations by relevant departments, the domestic sewage collection rate in the built-up area of Nanchang City in 2019 was only 49.7%, and the sewage collection rate in the built-up area in 2020 was 50.78%, which was only 1 percentage point higher than the previous year, far from reaching the target requirements.
The second is the incomplete rectification work. In 2018, the Central Ecological Environmental Protection Inspector “Looking Back” and the Poyang Lake Special Inspector pointed out that there was an illegal sewage discharge problem at the Diyixiang Gate in the secondary protection area of the water source of Nanchang Niuhang Water Plant. Although the Municipal Urban Management Bureau carried out rectification, it did not fundamentally solve it. The problem is that only sewage can be intercepted on sunny days, and overflow and discharge can still be achieved on rainy days. The 2019 Yangtze River Economic Zone ecological environment warning film disclosed the water pollution problem of Wusha River. Nanchang City’s rectification plan proposed to intercept sewage and sediment dredging of the pipeline network along the river section, and completely solve the sewage pollution problem of Wusha River by the end of 2020. However, the water department did not work hard on the interception and renovation of the pipe network. Instead, it built a new water intake pump station on the Gan River. In the name of ecological water replenishment, the water was pumped from the Gan River to wash the river, and the Wusha River was solved by diluting the river water.
The third is the sewage pipe network The investigation and remediation are lagging behind. In January, February, and November 2019, the three thematic meetings of the Nanchang Municipal Government all put forward requirements on the responsible department and completion time limit for the investigation of the city’s sewage pipe network problems. However, due to the ineffective implementation of the responsible department, it caused repeated requests and repeated requests. Not implemented. In March 2019, the Nanchang Municipal Government approved the “Nanchang City Urban Wastewater Complete Collection and Treatment Standard Remediation Project Plan”, requiring the completion of the pipeline network status analysis and the establishment of a ledger by the end of April 2019, but the investigation work was not completed until August 2020 , Due to insufficient investigation depth, incomplete conditions, inaccurate problems and other reasons, the city’s pipeline network construction and transformation lacks systematic and pertinence. The inspection and repairs are performed while the repairs are made, and the rectification effect is poor.
(2) Domestic sewage is discharged directly, and black and smelly water bodies show a rebound trend.
In 2020, the average daily water supply in the built-up area of Nanchang City is about 1.25 million tons. According to the calculation of the sewage collection rate in that year, Every day, more than 500,000 tons of domestic sewage in Nanchang City is not collected and discharged directly into urban rivers, lakes and Gan River. Inspectors found that urban rivers and inner lakes in some urban areas of Nanchang were seriously polluted. Domestic sewage near the Tianshui Huadu Community in Qingshan Lake District was directly discharged into the river beside Changdong Avenue. Monitoring showed that the ammonia nitrogen concentration was 12.9 mg/L, which exceeded the surface water level III standard by 11.9 times. The domestic sewage in the surrounding communities of the Happy People Group was directly discharged into the rainwater pipe network, and the monitoring showed that the ammonia nitrogen concentration was 12.5 mg/L, which exceeded the surface water Class III standard by 11.5 times. The concentration of ammonia nitrogen in the river beside Tengwang Pavilion in Donghu District is 5.9 mg/L, which is 4.9 times higher than the Grade III standard for surface water. The concentration of ammonia nitrogen in the river beside Gaoxin Avenue in Qingshan Lake District, the river opposite to Longsheng Industrial, and the river in Jiaoqiao Town of Honggutan New District of Longtan Canal reached 11.2, 11.2, and 14.4 mg/L, respectively, exceeding the surface water level III standard by 10.2 times, 10.2 times and 13.4 times. . There is a large amount of oil pollution on the water surface of Mingshan Canal, which is discharged into the Ganjiang River through the Yuwei Gate.
The water quality of the Ganjiang River in Nanchang City is mostly inferior to Grade V. In 2020, the monitoring results of the main outlets of the Ganjiang River show that 9 monitored outlets of Category V and worse than Category V accounted for 54.9%. Among them, the chemical oxygen demand and ammonia nitrogen concentration at the outlet of Lijing intersection in February were 186 mg/L and 30 mg/L, respectively, which exceeded the Class III standard by 8.3 times and 29 times; in November, the ammonia nitrogen concentration at the outlet of the World Trade Intersection was 12.6 mg/L. , 11.6 times more than the Class III standard. In 2020, the water quality evaluation results of 20 cities in Nanchang showed that Grade V and worse than Grade V accounted for 71.68%, among which Diezi Lake and Sangan Canal were inferior Grade V throughout the year. The masses have strongly reacted to the problem of urban water pollution. In November 2020, according to public feedback, relevant departments conducted water quality tests on the inner lakes of 5 cities including Aixi Lake in Nanchang. The results showed that the water quality of Aixi Lake, Qingshan Lake, Xianghu Lake and Qianhu Lake was Grade V or worse than Grade V. Blue algae blooms appeared on the surface of East Lake, Qingshan Lake, Xianghu Lake and Qianhu Lake.
(3) Rain The problem of mixed flow is prominent and the sewage treatment plant operates inefficiently
The population and domestic sewage discharge in the old city of Nanchang (Donghu District, Xihu District, Qingyunpu District, Qingshan Lake District) account for 2/3 of the city’s built-up area. Sewage The pipeline network is 1,068 kilometers, of which 724 kilometers are combined with rain and sewage, accounting for 67.8%. From 2018 to 2020, Nanchang City will invest a total of 3.081 billion yuan to build and renovate a sewage pipe network with a length of 922.59 kilometers, of which 116.24 kilometers of rain-sewage combined pipe network in the old urban area will be transformed, accounting for only 16% of the old urban area. According to the survey results of the Municipal Urban Management Bureau in August 2020, there are as many as 12,300 old pipe networks in the old city of Nanchang with 415.85 kilometers of rupture, misconnection, disconnection, deformation, and corrosion. However, the transformation of the old sewage pipe network is progressing slowly. The “Thirteenth Five-Year Plan for Urban Sewage Treatment and Reclaimed Water Utilization Facilities Construction Plan in Jiangxi Province” requires Nanchang City to complete the renovation of 305 kilometers of old sewage pipe network in the built-up area. By the end of 2020, Nanchang City has completed 171.55 kilometers and only completed the planning target of 56.2. %. From 2018 to 2020, the annual sewage treatment volume and influent concentration of the sewage treatment plant in the built-up area of Nanchang City will not increase significantly.
A large amount of domestic sewage cannot be collected effectively, and rainwater is mixed into the sewage pipe network, resulting in a generally low concentration of influent water from urban sewage treatment plants, which affects the sewage treatment plant’s ability to control pollution. In February and March 2021, sampling and monitoring of five sewage treatment plants in Qingshan Lake, Xianghu Lake, Baishui Lake, Honggutan and Chaoyang within the built-up area found that the influent chemical oxygen demand concentration was less than 100 mg/L. Among them, the Qingshan Lake Sewage Treatment Plant handles about 500,000 tons of sewage per day, which is the largest domestic sewage treatment plant in Nanchang. The two sampling and monitoring results show that the influent chemical oxygen demand is only 15 mg/liter and 48 mg/liter respectively. , The influent concentration is even lower than the sewage discharge standard, and the clean water enters the clean water out. A survey of data found that the chemical oxygen demand concentration of influent water from the Qingshan Lake Wastewater Treatment Plant from 2018 to 2020 has been decreasing year by year. The influent chemical oxygen demand of Xianghu Sewage Treatment Plant is only 42 mg/L.
Insufficient understanding of major national decision-making and deployment, insufficient attention to the central ecological and environmental protection inspection and rectification work, lack of systematic thinking and overall planning in the construction and transformation of domestic sewage pipe network, poor operation of domestic sewage collection and treatment mechanism, and construction of sewage pipe network The lack of determination and low standards for the renovation has led to the long-term failure to completely solve the problem of environmental pollution caused by domestic sewage.
The inspection team will further investigate and verify the situation, and follow-up inspection work as required.