The environment is people's livelihood, and continuously improving the quality of the water environment is one of the important tasks for Nanjing to promote high-quality economic and social development. After successively completing the elimination of black-smelling water bodies, the basic elimination of poor V-class water bodies two major water environment management objectives.Nanjing's water treatment goal at this stage is that the water quality of the river is stable and meets the standard.
To achieve "stable standards", to solve the "overflow pollution" is a priority. To this end, Nanjing last year to try to the eastern section of the Inner Qinhuai River, Ri Wei River and other river interception facilities to optimize the transformation, to achieve normalization of the "open", so that the rainwater is released directly into the river, and no longer through the interception facilities into the sewage system, so as to solve the problem of overflow pollution in rainy days.
"Overflow Pollution" means that when it rains, sewage from the interception facilities built along the river enters the river under the rapid wash of rainwater, resulting in poor water quality.
This year the city will further promote this work. It is understood that the city will implement 103 water environment management projects during the year, in which the six main city districts have led to the optimization of river interception facilities, demolition of the task, involving the interception of more than 30 outfalls.
interceptor
This former "hero" of pollution control.
Why has it been reversed at this stage to become a "source of pollution"?
Optimization of retrofitting or dismantling
What are the requirements?
What is the effect of "opening"?
The former "hero" of pollution control has become a "source of pollution".
Blue water, grass and trees, spring in the Qinhuai River is full of cozy. Although the "blue wave" has been the norm, but to heavy rainstorms, some of the waters will instantly return to the black, there will be an odor, which is derived from the interception facilities along the river on both sides.
The so-called interception facilities, i.e. facilities installed in the inspection wells of the stormwater drains or on the stormwater outfalls, are used to intercept dry weather sewage and part of the mixed stormwater from the stormwater system and to divert it to the sewer network.
In 2015, the state promulgated the Water Pollution Prevention and Control Plan, and Nanjing set off the climax of large-scale remediation of black-smelling rivers in the city.
"Elimination of black smelly water bodies, must realize the sewage does not go down the river, but at that time, rain sewage diversion, sewage pipe network system and other relatively weak, 'make up' will take many years, a considerable part of the interception system built along the river, it is the product of this context, but also at that time, the treatment of sewage and interception of sewage 'merit'." Municipal Water Affairs Bureau of the Water Environment Division of the relevant person in charge of the introduction.
"In the case where rainwater and sewage diversion is not thorough enough, the interception facilities usually take on the function of intercepting dry weather sewage. However, in order to ensure rainy day drainage, the interception facilities are bound to occur under certain rainfall conditions to drain the river, a process that inevitably carries some of the sewage down the river, resulting in poorer water quality in the city's inland waterways on rainy days. In addition, not only rainwater through the interception system into the sewage system, some areas of groundwater, river water, construction pit water, etc. will also run into the sewage network through the interception facilities, resulting in long-term sewage network 'high water level, low concentration', affecting the efficacy of sewage treatment." With the quality of the water environment to improve the requirements of more and more high, once the "merit", now all the drawbacks are increasingly prominent.
Normalization "open", a system-wide "major surgery"
According to reports, the normalization of "open" the path of the interception facilities, there are mainly two kinds: one is to ensure that the outlet has no sewage inflow under the premise of the interception facilities to completely open or demolition; one in the interception facilities at the mouth of a separate rainwater pipe to realize the direct discharge of rainwater to the river, and no longer rainwater and sewage flow into the sewage network in one head.
The work required to achieve normalized "openness" is "massive".
Located in the Longjiang area of the Ri Wei River directly connected to the outside of the Qinhuai River, Ri Wei River waters within 0.5 square kilometers of the district, the unit compound all completed the rainwater and sewage diversion, municipal roads, rainwater and sewage main and secondary trunk pipelines to complete the renovation and repair, and the completion of the Longjiang River sewage discharge two channels. Since June last year, the interception facilities to realize the normalization of "open".
The same is the outlet traceability, rain sewage pipe network "physical examination", repair ...... After several years of investigation and mapping, the Inner Qinhuai River Yixianqiao to Changfu Street section of the banks of the 10 outlets, in line with the "surgery "The conditions are 4, and in the last year completed 2.
Around the Jiangning District, two longitudinal ditch Shuanglong Avenue along the interceptor ditch "surgery", but also lasted for many years, including: the upstream of each drainage household survey, to ensure that each drainage unit rain sewage diversion in place, to determine the node wells do not drain on sunny days; municipal pipeline network desilting and dredging testing and repair, the outlet upstream of municipal rain sewage pipe network testing ......
How effective is "opening up"?
From the Inner Qinhuai River to the Rixu River, and then to the Pearl River, etc., last year, the city to solve the overflow pollution, in a number of rivers at a number of points for the pilot. How effective is it?
Gulou District Water Affairs Bureau of the Water Environment Construction Section responsible person, previously every heavy rainfall, it is faced with the "dilemma": if the interception facilities are not opened in a timely manner scheduling, rainwater discharge is blocked, some of the neighborhoods and units along the street compound will have a cumulative flooding; if the opening of the interception facilities, the sewage is instantly flushed down the river, will cause the instantaneous quality of the river waterway! deterioration. "Ri Wei River interception facilities open, we have carried out a long time tracking observation, sunny days basically no sewage out, even if there is, but also the tap water leakage or groundwater infiltration. The most critical thing is that the rainy day state can discharge rainwater normally, reducing the risk of the area accumulating flood water."
Large area "open", Nanjing has the strength but challenges
Make stormwater discharge into the river smoother, reduce the impact of overflow pollution on water quality fluctuations in the river, reduce the pressure of sewage network long-term high water level and low concentration of the operation of the ...... interception facilities to optimize the renovation and demolition of a series of heavy responsibility, but also in the next few years Nanjing to improve the quality of the water environment is a key initiative.On the basis of last year's pilot, the city has lined up a list of tasks for further promotion this year.
From the list, the task of each district is not light: Xuanwu District will optimize and renovate the Pearl River, Neiqinhuai River channel around the access to the interceptor ditch of the five outfalls; Qinhuai District will implement the Neiqinhuai River east section of the head of the Lane, the Cotton Shoes Camp section, and other four points of the outfalls of the interceptor renovation; Jianye District will be the interception of the Yikang River, the three rivers of the South Lake, the Moqi pumping station intake canal, etc., which is the renovation of interceptors, including demolition of two, the controlled transformation of the four ......
The key to keeping sewage out of the river and producing less overflow pollution is to improve sewage collection and treatment capacity. In recent years, Nanjing has done a lot of work in this regard.
On the one hand, in accordance with the standard of one area per 2 square kilometers, the built-up area is delineated into 400 areas for the creation of sewage treatment quality improvement and efficiency standard area, in order to eliminate the urban black stinky water, eliminate sewage outlets, and eliminate the sewage pipe network blank area;
On the other hand, the main city of Jiangxinzhou, north, east, iron north, south, Xianlin and other six sewage treatment system as a "unit", the implementation of sewage main and secondary pipeline rectification and repair in batches and areas, and from 2021 onwards on the 280 kilometers of defective pipelines, defective inspection wells, rain and sewage wrong mixing, inverted slopes, and other issues to focus on remediation! As of the end of last year, the rehabilitation of 160 kilometers of sewage main and secondary trunk pipes has been completed, and another 60 kilometers will be completed by the end of this year.
In addition, in recent years, the city has continued to promote the sewage treatment plant renovation and expansion projects to enhance the end of the treatment capacity. By the end of this year, the city's sewage treatment capacity will reach 3.68 million tons per day.
