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Purification and treatment of collected rainwater


Purification and treatment of collected rainwater

The influencing factors of rainwater and sewage diversion treatment process of rainwater and sewage diversion system include: rainwater recoverable amount, rainwater raw water quality and water quality requirements of rainwater and sewage diversion parts.

These three factors are interrelated and affect the water treatment and operation cost of rainwater reuse.

Other factors should also be fully considered in the process selection, such as large randomness of rainfall, unstable source of rainwater recovery, short storage period of rainwater, frequent idle equipment, etc. at present, the control and utilization of general rainwater should simplify the treatment procedure as far as possible, so as to meet the seasonality of rainwater control and utilization and save investment and operation cost.

Bluslot specially developed filter elements for rainwater collection and filtration.

The collection of rainwater will be affected by the season. It is suggested to adopt physical and chemical treatment methods to adapt to the seasonal discontinuous operation. The separation of rainwater and sewage is to discharge rainwater into the reservoir, and then concentrate on physical and chemical treatment. Many existing water supply and sewage treatment technologies can be used for rainwater treatment. Generally, rainwater with better water quality is selected for collection and recycling. The treatment process is simple and the combination of filtration and sedimentation is adopted.

When there are higher requirements for water quality, the corresponding advanced treatment measures should be added. This condition is mainly for the places where users have higher requirements for water quality. The water quality should meet the relevant national water quality standards, such as air conditioning circulating cooling water make-up water and other industrial water, etc. the water treatment process should be based on the water quality for advanced treatment, such as coagulation, sedimentation, sedimentation After filtration, treatment units such as activated carbon filtration or membrane filtration are added.

When rainwater is collected, especially the surface rainwater contains more sediment. After sediment separation, it can reduce the scouring work of the reservoir (sink). Sedimentation separation can be finished equipment, can also be built like the primary sedimentation tank.

When the effluent can not meet the requirements of landscape water quality, the natural purification capacity of landscape water and water quality maintenance purification facilities can be used to purify the water mixed with rainwater. When landscape water has accurate water quality index requirements, purification facilities are generally required.

If the surface rainwater is diffused into the water body, the rainwater can be discharged through the gravel ditch on the grassland or the river bank, so that it can be preliminarily purified before entering the water body, so as to save the initial rainwater disposal facilities. Landscape water body is an economic rainwater storage facility. When the water body has conditions to set rainwater storage capacity, it should use landscape water body to store rainwater instead of building another rainwater storage pool.

Grit chamber and reservoir can be used to settle the natural precipitation during rainwater storage. When the filter screen is used for rapid filtration, the pore size should be 100 ~ 500 μm。

The water quality of this kind of water is higher than that of green space irrigation, so flocculation filtration or air flotation is needed.

Sand filtration should be adopted for coagulation filtration with particle size of D and thickness of filter layer of H = 800mm ~ 1000mm. The flocculant is polyaluminum chloride, and the feed concentration is 10mg / L. Filter at 350m3 / h. Fiber ball filter element can also be selected, and water air combination mode is adopted for backwashing.

When users have higher requirements for water quality, corresponding advanced treatment measures should be added. This item is mainly aimed at places with higher requirements for water quality. The water quality should meet the provisions of relevant national standards, such as air conditioning circulating cooling water, domestic water and other industrial water. The water treatment process should be based on the water quality for advanced treatment, such as coagulation, sedimentation, sedimentation After filtration, treatment units such as activated carbon filtration or membrane filtration are added.

The sediment produced in the process of rainwater treatment is mostly inorganic matter, which can be treated simply. When the composition of sediment is complex, it should be treated according to relevant standards.

Rainwater stays in the reservoir for a long time, generally about 1-3 days, which has a good precipitation removal effect. The setting of the reservoir should give full play to its precipitation effect. The rainwater pump should absorb the supernatant as much as possible from the water tank.

The rapid filtration device composed of quartz sand, anthracite, heavy ore and other filter materials is a mature treatment equipment and technology in the current construction sewage treatment, which can be used as a reference for rainwater treatment. The design parameters should be determined according to the test data when new filter materials and process are used. When it is used for circulating cooling water after rain, advanced treatment should be carried out. Deep processing equipment can adopt membrane filtration, reverse osmosis and other processes.

According to the experience, it is suggested to adopt the filtration method of rainwater reuse. Generally, the chlorination amount of rainwater reuse can refer to the chlorination amount of water supply enterprises. According to the operation experience of foreign countries, the chlorination dosage is about 2mg / L ~ 4mg / L, and the effluent can meet the water quality requirements of urban miscellaneous water. When the green space and road surface are irrigated at night, no filtration is needed.

Through the new drainage ditch, rainwater collection pipeline, water storage module, emergency overflow, ecological purification community and other facilities, a comprehensive rainwater collection and utilization system integrating rainwater collection, purification, accommodation and utilization is formed. In this project, the roofs, landscape stones and hardened roads of the six stadiums and gymnasiums are used as water collecting surfaces, drainage ditches, linear drainage ditches and drainage pipes are used as water conveyance pipelines, and artificial lakes are used as reservoirs. After the rainwater is collected, it goes through the water supply pipeline and enters into the flow well, settlement well and sedimentation tank for filtration and sedimentation, and then it is pumped into the ecological purification community by retaining the water storage module. The purified rainwater is directly discharged into the lake for storage, and the rest is discharged into the municipal pipe network.

Water shortage, environmental pollution, ecological damage and other problems are becoming increasingly serious. Rainwater, as a clean, economic and convenient green water source, is getting more and more attention. Rainwater module is an integral part of rainwater collection and utilization system, which is composed of several rainwater module units to form an underground reservoir. According to the needs of the project, the impermeable geotextile or permeable geotextile is wrapped around the pool to form different types of reservoirs, seepage pools and flood regulating pools. The equipment is suitable for rainwater collection and utilization in large building communities, industrial parks, squares, factories and other places. The rainwater pool can effectively store the collected rainwater. After treatment, these rainwater resources can be used to flush the toilet, clean the road, water the lawn, water the waterscape and so on.

The annual total water resources amount to 100 million cubic meters, but the per capita share is only 442 cubic meters. The annual precipitation distribution is uneven. Affected by the monsoon climate, 37% of the annual precipitation is concentrated in July to September, mainly due to rainstorms, frequent floods, and most of them are discharged into the sea, which is a resource shortage area. It has become very important to improve water use efficiency and comprehensively use various water-saving measures. Recycling rainwater is a new direction to alleviate flood disaster and save water resources. Nowadays, the urban population is highly concentrated, the demand for water is increasing, but the urban anti-seepage area has increased significantly. Under the same rainfall condition, the increase of runoff coefficient, rainfall flood flow and drainage ditch load often cause serious ground water accumulation and local flood disaster, and also interfere with the natural hydrological cycle, reduce rainfall infiltration, so that groundwater can not be effectively replenished. Therefore, the city in flood control and drainage at the same time, also faces the problem of water shortage.

The rainwater is slightly polluted water, which can be used as landscape water, greening water, industrial cooling water and domestic miscellaneous water to replenish urban ecological water and groundwater to alleviate land subsidence. Moreover, the cost of rainwater treatment is low and the economic benefit is significant; After collecting rainwater, the rainwater is discarded, filtered, stored and utilized, and initial results have been achieved.