Xiong Yuehui, Director of Science and Technology Standards Department of MEP, pointed out that the treatment of black and smelly urban rivers should follow the technical route of "external emission reduction, internal dredging, water purification, water supply and ecological restoration". Exogenous emission reduction and endogenous dredging are the basis and premise. Water purification is a phased approach. Hydrodynamic improvement technologies and ecological restoration are long-term safeguards.
First, exogenous blocking technology. For the water body lacking the perfect sewage collection system, the sewage interception should be incorporated into the sewage collection and treatment system by constructing and rebuilding the sewage pipeline along the water body to reduce the direct discharge of pollutants from the source. In view of the sewage which is not yet subject to the interception of pollutants, it can adopt an efficient first-level enhanced sewage treatment technology or process in situ to rapidly and efficiently remove pollutants in the water and avoid direct pollution of the effluents to the water body.
The urban non-point source pollution mainly comes from the pollutants contained in the runoff. The control technologies mainly include various low-impact urban development (such as sponge city) technology, initial rainwater control technology and ecological revetment technology.
Second, endogenous control technology. There are usually two types of dredging dredging technologies: one is dredging lake / river dredging; the other is dredging silt directly from the water.
Third, water purification technology. Aeration aeration artificial, water can increase the dissolved oxygen concentration and redox potential, ease the water black and smelly conditions. It should be noted that chemical flocculation costs more and produces more sediment. Some chemicals are toxic and can cause secondary pollution when environmental conditions change. Artificial wetland technology is the use of soil - microbial - plant ecosystems for nutrient removal technology, the use of surface wet or underflow wetlands, wetland plants can choose submerged plants or emergent plants. Ecological floating island is a bio-ecological facility that is constructed, floated on the surface of the water for the growth, reproduction and habitat of animals, plants and microorganisms to achieve water quality purification by building a water ecosystem that feeds, digests and degrades pollutants in the water body . Stabilization pond is a kind of water purification technology that combines artificial enhancement measures and natural purification functions to purify the polluted water with multiple natural reservoirs or artificial ponds along the water.
Fourth, hydrodynamic improvement technology. Water diversion can not only dilute the concentration of pollutants in the black-odor water with a large amount of clean water, but also enhance the diffusion, purification and output of pollutants. For the treatment effect of urban black-odor water with high pollutant load, insufficient hydrodynamic force and low environmental capacity Obvious, but a waste of water resources, should try to use unconventional water sources, such as reclaimed water and rainwater utilization.
Fifth, ecological restoration technology. Where conditions permit, it is necessary to implement the regional limit of phosphorus or increase the total phosphorus discharge standard of sewage. Artificial algae growth control technologies include a variety of physical, chemical and biological technologies. Physical control technologies include direct collection of algae and UV disinfection. Chemical control technologies include the addition of inorganic or organic algaecides. Biological control technologies include the cultivation of algal blooms or algal blooms. These measures are generally used in emergency situations.
Governance black smelly water, to take the following management countermeasures.
First, the establishment of dissolved oxygen as the core indicator of the evaluation system. The key to the treatment of black and smelly water is to improve the dissolved oxygen status of the water so that the water can recover from the low oxygen / anaerobic status to the normal aerobic status. Proposed dissolved oxygen as the core, the establishment of odor threshold, transparency, color and other indicators of black-odor water evaluation system. The threshold is: Dissolved oxygen 1mg / L, Stink threshold 100, Transparency 25cm, Chroma 20, When any one of the index value exceeds the threshold, then it can be judged as black stink water body. According to the "Water Pollution Prevention Action Plan" task decomposition, evaluation system will be responsible for the preparation of housing urban and rural construction department.
Second, after the interception of sewage repair, a comprehensive means of governance black smelly water body. Taking pollution control measures such as pollution source treatment at the basin scale can greatly reduce the pollution load into the river and is the primary measure to eliminate the problem of black-odor. At the same time, engineering measures such as riparian restoration and artificial oxygenation will be taken as an important supplementary means to reduce pollution load. On the basis of effective improvement of river water quality, ecological restoration of rivers will be gradually realized through the restoration of aquatic organisms and the black-odor will be eliminated.
Third, improve the ecological conditions, let the water flow. Under normal circumstances, to maintain the flow velocity of river water 0.4m3 / s ~ 1.0m3 / s, you can break the physicochemical conditions of the dissolved oxygen transition layer formation, making the water and soil interface dissolved oxygen maintained above 3mg / L, you can effectively control the bottom of the water Pollution. Water does not rot, is to reduce or even eliminate the key black river smelly key factors.
Fourth, build a green belt on the shore to enhance self-purification capacity of the water body. We must thoroughly remove rubbish along the river, strictly control the sources of colored and odorous pollution sources, carry out afforestation on the banks of the shore, restore their natural state, and establish a long-term operation and management mechanism for river cleaning. The use of shore plants, emergent plants and submerged plants with the construction of the landscape restoration approach to effectively change the water ecosystem energy and material flow patterns, the formation of a self-cleaning water body.
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