The choice of urban drainage system and management of the shallow discussion?

City drainage system is the town of sewage and rainwater organized exclusion and treatment of engineering facilities, is an important part of urban infrastructure construction, it is usually composed of drainage network and sewage treatment plant. Drainage system should be selected according to local conditions, from the overall situation, through technical and economic comparison of comprehensive consideration to determine; at the same time. To strengthen the management of rainwater runoff from urban water systems and pollution control.

One, the classification of urban drainage system

Urban drainage system is generally divided into two types of combined system and diversion system:

(a) combined system drainage system

Combined system drainage system is the city's domestic sewage, industrial wastewater and rainwater runoff pooled in a canal to be transported, treated and discharged. According to the order of its generation and the degree of sewage treatment, combined system drainage system can be divided into direct drainage combined system, intercepting combined system and full treatment combined system.

Urban sewage and rainwater runoff without any treatment is directly discharged into the nearby water bodies of the combined flow system is called direct drainage combined flow system drainage system. The combined flow drainage systems in old urban areas at home and abroad belong to this category.

With the continuous development of industrialization, sewage pollution of the environment is becoming more and more serious, it is necessary to carry out appropriate treatment of sewage in order to reduce the urban sewage and stormwater runoff pollution of the water environment, which has produced the interception of the combined flow system. The intercepting combined flow system is based on the direct-drain combined flow system, the construction of intercepting trunk pipes along the river, and overflow wells are set up at appropriate locations, and a sewage treatment plant is built at the end of the intercepting trunk pipes (canals). This system can ensure that all the sewage in sunny days into the sewage treatment plant, the rainy season, through the interception facilities, intercepting combined flow drainage system can collect part of the rainwater (especially the heavy pollution of the initial rainwater runoff) to the sewage treatment plant. However, on the other hand, if the rainfall is too heavy and the volume of mixed sewage exceeds the design flow rate of the interceptor, the excess will overflow into the urban river, which will inevitably cause localized and short-term pollution to the water body. And, into the sewage treatment plant, mixed with a large number of rainwater, so that the quality of raw water, water fluctuations are large, is bound to the sewage treatment plant of the impact of each treatment unit, which puts forward a higher demand for sewage treatment plant process.

In the smaller rainfall and water quality requirements of the water body in the region, can be used to fully integrated system. Domestic sewage, industrial wastewater and precipitation runoff are all sent to the sewage treatment plant for treatment and discharge. This way of environmental water quality pollution is minimized, but the sewage treatment plant treatment capacity requirements are high, and requires substantial investment and operating costs.

(B) diversion system drainage system

When the domestic sewage, industrial wastewater and rainwater with two or more drains, known as diversion system drainage system.

The exclusion of domestic sewage, industrial wastewater system known as sewage drainage system; exclusion of rainwater system known as stormwater drainage system. According to the exclusion of rainwater in different ways, but also divided into complete diversion system, incomplete diversion system and interceptor diversion system.

Complete diversion system drainage system is divided into sewage and rainwater two pipe system, the former collection of domestic sewage, industrial wastewater, sent to the treatment plant, after treatment or discharge or use. The latter collects rainwater and part of the industrial wastewater (which is cleaner) in the city through various drainage facilities and discharges it into water bodies nearby. But the initial rainwater untreated directly discharged into the water body, will cause pollution to the water body.

In recent years, the water quality of rainwater runoff survey found that the rainwater runoff, especially the initial rainfall runoff on the water pollution is quite serious, and therefore put forward to rainwater runoff should also be strictly controlled by the interception of the diversion system drainage system. Interceptor type diversion system has both sewage drainage system, and rainwater drainage system, and complete diversion system is different is that it has the initial rainfall into the sewage pipe special facilities, called rainwater interceptor well. When it rains lightly, the rainwater through the initial rainwater interceptor trunk and sewage together into the sewage treatment plant; when it rains heavily, the rainwater jumps the interceptor trunk through the storm drain into the water body. Interceptor diversion system is the key to the early rainfall interceptor, it should ensure that the early rainfall can enter the interceptor, and after the middle of the rain can be directly discharged into the water body, while the interceptor in the sewage can not overflow into the water body. Interceptor diversion system can better protect the water body from pollution. Due to only accept sewage and early rainfall, interceptor cross-section is smaller than the interceptor system, into the interceptor in the flow and water quality is relatively stable, but also reduce the sewage pumping station and sewage treatment plant operation and management costs.

Incomplete diversion system only built sewage drainage system, not built rainwater drainage system, rainwater along the ground, roadside ditches and nullahs into the water body. Or in the original channel drainage capacity is insufficient to build part of the stormwater pipeline, to be further development of the city or have the funds to build a stormwater drainage system. This drainage system is a low-investment system that is mainly used in places where there is suitable terrain and a relatively sound system of open nullahs for the smooth drainage of rainwater. It is still in use in many cities, but because of the lack of complete storm drains, it is prone to runoff pollution and flooding during the rainy season, so it will eventually have to be converted to a full diversion system. For the year-round rainfall, dry climate of the city can use this system, and for the terrain is flat, rainy areas prone to waterlogging, should not be used incomplete diversion system.

The advantage of the diversion system is that it can be constructed and implemented in phases, generally in the early stages of urban construction to build urban sewers, in the urban construction to reach a certain scale and then build rainwater channels, collection, treatment and discharge of precipitation, especially storm water runoff.

In a city, sometimes the use of a composite drainage system, that is, both diversion system and combined flow system of drainage system. Compound system drainage system is generally in the city by the combined system of the need to expand the drainage system. In large cities, because of the natural conditions of each area and the construction of the situation may vary greatly, according to the local conditions in each area to adopt different drainage system is also reasonable.

Second, the choice of urban drainage system

In order to further improve the quality of receiving water bodies, the establishment of an ideal diversion system or the combined system into a completely diversion system, the choice of drainage system should be a change of concepts, allowing part of the region in a long time to use the combined system of interception system and focus on improving the rate of sewage treatment, which is the fundamental way to protect water bodies. This is the fundamental way to protect water bodies. In the old city of combined flow system drainage system renovation should be combined with the actual development of feasible programs, in new development zones around the planning of drainage system is also necessary to fully analyze the local conditions, the rational operation of funds, but also from the management level, dynamic development point of view of the study, do not blindly imitation, raw terms. In the existing secondary sewage treatment plants in the combined flow system drainage network, the appropriate location to build a new type of regulation, treatment facilities (retention ponds, sedimentation and percolation ponds, ponds and wetlands, etc.) is to further reduce the pollution of urban water bodies of the key complementary measures. It can intercept the initial storm "first flush" of pollutants sent to the sewage plant, reduce the number of mixed sewage overflow, water and improve the quality of overflow water, as well as balanced into the sewage plant mixed sewage water and water quality, it can also be more pollutant content of storm water for initial treatment.

Three, the choice of drainage system and the construction of institutional problems and recommendations

(a) the construction of the drainage network

Many cities and regions, often only the sewage treatment plant as a key project to treat, and relax the construction of sewage pipe network with its matching. Often the sewage treatment plant was completed and put into operation according to plan, but the sewage network has only built part of the sewage trunk. Caused on the one hand, the sewage treatment plant treatment capacity is insufficient, on the one hand, sewage is still directly discharged into the river to pollute the environment. Therefore, the construction of drainage network and sewage treatment plant should be built as a whole, synchronized implementation.

(II) intercepting times

Whether combined or diversion system (storm drains), its drainage trunk or trunk canal, should be used to intercept the drainage system, at the end of the addition of overflow wells, the top of the overflow weir set up, the drainage trunk using the appropriate number of intercepting times; the size of its direct impact on the receiving body of water clean with or without too small will lead to the receiving body of water suffered serious pollution; too large will be Waste. Therefore, the reasonable selection of the intercepting times is the key, the value should be taken into account the water quality requirements of the receiving body of water, the receiving body of water self-purification capacity, the degree of civilization of the town (or level), population density, rainfall, investment and other factors.

(C) stormwater runoff pollutant content and control

With the rapid economic development, urban population density continues to increase, the capacity of the sewage collection system requirements also continue to increase, not only due to the ever-expanding city produces more and more sewage, but also due to the increase in impermeable drainage area led to an increase in the amount of urban stormwater runoff. Ultimately, the hydrological environment and urban water sources are seriously polluted and damaged in large residential areas, and more often in the neighborhoods of large cities and mega-cities. Therefore, regardless of the combined system or diversion system drainage system, should be intercepted rainwater runoff treatment.

(D) drainage network management

Strengthening management, for the effectiveness of the completed drainage network is crucial. If a drainage system has been rain, sewage diversion, and management measures to keep up with, along the street residents privately connected to the household pipe, or to save money for the convenience of the sewage pipe will be close to the rainwater pipe, will result in spending a lot of money to build a rainwater sewage diversion system to lose their role in the sewage discharged by the rainwater pipe directly into the water caused by the pollution of the river. Therefore, the urban drainage system can really play its due environmental benefits, social and economic benefits, we must take effective measures to strengthen the management of the drainage network, from the source to do a good job of rain, sewage diversion.

Four, conclusion

With the development of urbanization, the drainage system plays an increasingly important role in the sustainable development of society. Drainage system selection should be based on the planning of towns and industrial enterprises, environmental protection requirements, sewage utilization, the original drainage facilities, water quality, water quality, topography, climate and water and other conditions, from a holistic point of view, through the technical and economic comparisons of the comprehensive consideration of the determination of, at the same time, to strengthen the management of rainwater runoff from the urban water system and pollution control work.

More about the engineering/service/procurement category of the tender writing production, to enhance the winning rate, you can click on the bottom of the official website customer service free consultation:/#/?source=bdzd