Practical research on recycling domestic and indus

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Practical research on international recycling of domestic and industrial water (4)

replenishment of water resources with recycled water

random or unplanned replenishment of water resources is extensive. The treated sewage is discharged into rivers and lakes, and then the river and lake water are used for drinking water supply. Common water replenishment of Thames and Rhine Rivers occurs many times from the source to the ocean. In the United States, the Environmental Protection Agency conducted a survey of 80million urban people in 1246 cities and towns with a population of more than 25000 served by water supply systems in 1980. The study found that when the flow of water supply is low, the water supply of 26 million people contains 5 ~ 100% more stable treated sewage

in South Africa, reclaimed water plays a key role in coordinating the contradiction between water demand and available raw water. The water use law in 1956 requires that in addition to being used for beneficial reuse purposes, the treated sewage should be returned to the original river. The targets of the cutting process sensing detection for the electronic universal experimental machine include the cutting force and its changes in the cutting process, the chattering of the cutting process, the contact between the tool and the workpiece, the state of the chip during cutting, and the identification of the cutting process. Meeting this requirement, we encourage the introduction of high-level treatment methods. As a result, reuse water has become a stable component of the basic flow of many rivers. For example, 50% of the existing recycled water flows into the hsrtbeespoort dam, which supplies water to Pretoria and jihhannesburg (odendaal 1998)

Los Angeles, California

since 1962, the Los Angeles County Health District has used reclaimed water to recharge the underground drinking water layer, which is realized through the Whittier narrows seepage basin. In 1978, the reused water first disinfected the secondary effluent, and then passed the advanced treatment of tertiary filtration. The amount of reclaimed water reinjected into the underground water area is an average of 16% of the total inflow of the basin every year. According to the location of reinjection and the characteristics of aquifer, the proportion of reinjection water in drinking water wells is 0 ~ 23%. Through the analysis of a large number of data obtained, the independent scientific team in California concluded that the groundwater recharge of Whittier mirrors is as safe as the surface water supply usually used

Orange County, California

since 1976, the 21st water plant in Orange County has produced 57000m3/day of recycled water that meets the standard of drinking water. Under the action of pressure, it injects the over exploited drinking water aquifer to avoid the intrusion of salt water. Through the strict monitoring of groundwater for 15 years, orange county has not found that groundwater has an impact on public health. At present, the water plant has been expanded. After the expansion, the planned water production is 200000m3/day, and the double membrane treatment process is used

upper occaquan in Virginia, USA

in Virginia, the recycled water from the upper occaquan reclaimed water plant is discharged to 42 million M3 to provide drinking water to onemillion people in Northern Virginia. Generally, the reclaimed water accounts for 10 ~ 15% of the total inflow of the reservoir, and the retention time in the reservoir is 26 days. The water yield of the reclaimed water plant has expanded from 55000m3/day at the beginning to 100000m3/day now, and it is planned to further expand to 200000m3/day

EI Paso in Texas, USA

since 1985, EI Paso in Texas has used the reuse water of Fred Harvey reclaimed water plant with a water yield of 38000m3/day to recharge the hueco Bolson drinking water aquifer. The retention time of recycled water is about 2 years before water is extracted from EI Paso drinking well. No adverse effects on water quality parameters related to human health have been found, but the total dissolved solids content of the aquifer has increased

Windhoek in Namibia

Windhoek is the capital of Namibia, with an amplitude of 10mm. It is located in the central highland of Namibia, between the eastern Kalahari desert and the western namibi desert. The nearest perennial river is the Kavango River 750km away. In order to solve the problem of serious water shortage in the dry season, a reclaimed water plant with an output of 4800m3/day was built in Windhoek in 1968. This water plant is the first reclaimed water plant for drinking water in the world. In the 30 years of operation, the water plant has always believed that Moco can stably produce recycled water with acceptable drinking water quality. After several expansions, the current water production of the water plant has reached 21000m3/day, and the treatment technology adopted is double membrane filtration technology

since 1968, recycled water accounts for 4% of the total water supply in Windhoek. However, in the season of serious water shortage in the dry season, the proportion of recycled water can reach 31%. The recycled water is mixed with the treated water of goreangab water treatment plant before water distribution. The maximum mixing ratio in dry season is 1:1, and the average mixing ratio since 68 is 1:3.5. The mixed water from goreangab water treatment plant is then mixed with water from several other water source reservoirs, so generally, the maximum proportion of recycled water in any period and any area is 25% (van der Merwe 1996). (to be continued)

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