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International Practical Research on recycling domestic and industrial water (1)

Abstract: the supply of fresh water in the world is limited and threatened by pollution. The increasing demand for water supply in agriculture, industry and cities has led to the distribution competition of limited freshwater water resources. In order to avoid water crisis, many countries must protect water resources according to the characteristics of electronic universal testing machine, manage water supply and demand, reduce pollution and reduce the impact of growing population on the environment

key words: reuse water, water cycle, international guidelines for water source management policy introduction

natural water cycle

in nature, like energy, water can neither be created nor disappear, but can only be transformed from one form to another. In the natural water cycle, most of the rainwater falling on the ground returns to the atmosphere through the evaporation of vegetation. Some rainwater seeps into the groundwater layer, and some rainwater flows to the river in the form of runoff into the ocean, and finally returns to the ground in the form of rainfall through evaporation. A small part of the water, as the drinking water of wild animals, is purified by natural processes

almost all the water in the world is salt water (97%). Of the remaining 3% of the water, 2/3 exists in the form of snow and ice in the polar and alpine regions. Only about 1% of the water in the world exists in the form of fresh water through the serial port of Chinese characters on the computer screen in the process of liquid experiment. More than 98% of the fresh water is groundwater, and less than 2% of the fresh water is usable River and lake water. Therefore, liquid fresh water is a very limited resource. (Bouwer 2000)

changed the water cycle

human beings have imposed many new water cycle factors, which has significantly changed the natural cycle of water. The imposed water cycle factors are as follows:

· grab river water and groundwater as urban and agricultural water

· return the treated and untreated sewage to the river

· recycle the sewage as a useful recycling

· desalinate the salt water in places with a shortage of fresh water

groundwater is the main water resource in many parts of the world. The exploitation rate of groundwater often seriously exceeds the recharge rate, so the groundwater level is constantly declining. The decline of the Aral Sea Surface in Central Asia caused by surface water diversion for irrigation can be used as an extreme example to illustrate the problems caused by water surface decline. This place used to be a prosperous fishing area, but now the Aral Sea has shrunk to a small part of its original size. The former seaside cities are now thousands of kilometers away from the sea. It can be seen that this problem has a serious impact on the economy, society and environment

the impact of urban development on water cycle is also serious. The water intake of urban water supply reduces the river flow. At the same time, the discharge of rainwater and sewage carrying a large number of pollutants leads to the decline of river water quality. In its catchment area, the water quality of the highly developed rivers in the city has declined more seriously

exposed water shortage problem

worldwide fresh water supply is limited and threatened by pollution. The increasing demand for water supply in agriculture, industry and cities has led to the distribution competition of limited freshwater water resources. In many countries, available freshwater resources have been heavily exploited, and in some cases may be overexploited. In order to avoid water source crisis, many countries must protect water resources, manage water supply and demand, reduce pollution and reduce the impact of the growing population on the environment from scratch (hinichsen et al 1999). For example:

· in the Nile Valley under the Aswan Dam, the current water demand exceeds the maximum water supply of the Aswan Dam. The shortage is made up by the reuse of sewage and discharged irrigation drainage (Croce 1998)

· lack of adequate water supply is the most important limiting factor for social and economic growth in South Africa in the 21st century. The existing plan indicates that the water demand will exceed the available water supply after 2020 (odendaal et al 1998)

water reuse meets the world's water demand

water reuse is a valuable water resource. After the water is used up, it is no longer discarded, but reasonably treated and reused, that is, reused, which will reduce the demand for high-quality fresh water sources. The reuse of water improves the reliability of water supply, and only less fresh water can meet the greater needs of mankind, thus reducing the impact of human survival on the world's water environment. The transformation of the old "one-time use and then discharge" method into a new sustainable "protection, rational use and recycling" method of water conservation will benefit the whole world

to the ABS produced by Alcoa mini mill outperforms the traditional ingot hot rolling process in terms of internal microstructure and surface quality. M Hannigan is the CEO of the California Department of water resources. He describes reclaimed water as the "brightest star" to meet California's future water needs. (to be continued)