This article first clarifies the concept of water and its scope of utilization, and then analyzes the necessity and feasibility of water utilization and its significance, and finally points out that due to the serious shortage of water resources in our country, water utilization is imperative.
China is a country with serious water shortage, and there are three main ways to solve the water shortage: water conservation, water storage and water transfer. And water conservation is the most feasible and economical of the three. There are two main means of water conservation: total volume control and recycling. The use of water is the main form of recycling, is an effective way to alleviate the shortage of urban water resources, is an important measure to open up new sources of income and cut down on expenditure, is the most effective way to solve the shortage of water resources, is the water shortage of the city is imperative for the major decisions.
1 The concept of water and the scope of water utilization
1.1 The concept of water
The concept of "water" originated in Japan, mainly refers to the life and part of the industrial water after a certain process, reuse for agricultural irrigation, municipal landscaping, vehicle washing, construction, internal toilet flushing, landscape water, and industrial water requirements are not high. Internal toilet flushing, landscape water and industrial cooling water and other aspects of the water, because it is between the water (tap water) and the water (sewage), it is called water.
In China, on the concept of water, the Ministry of Construction in 1995 issued the "Interim Measures for Urban Water Facilities," the second article stipulates that: water is part of the life of high-quality miscellaneous drainage water after treatment and purification to meet the "water quality standards for miscellaneous water use," can be reused to a certain extent of non-potable water.
Beijing, Dalian, Shenzhen and other places in the "urban water facilities management approach" on the definition of water and the Ministry of Construction is basically similar to the definition of only "part of the life of high-quality miscellaneous drainage water" expressed as "sewage". Jinan City, Shandong Province, issued in August 2002, "Jinan City, Interim Measures for the Construction and Management of Urban Water Facilities" on the scope of water to further expand the water will be expressed as urban sewage and wastewater purification and treatment, to meet the national "miscellaneous water quality standards" or industrial water quality standards, can be reused within a certain range of non-drinking water.
Since our country is facing the threat of water shortage not only in large and medium-sized cities, many towns, villages and rural areas are also facing the same problem, as a legal concept, its definition should be forward-looking and universal. Therefore, the concept of water can be expressed as: sewage and wastewater produced in the process of life, production, after purification and treatment, to meet the national "miscellaneous water quality standards for life" or industrial water quality standards, can be reused within a certain range of non-potable water.
1.2 Scope of Water Utilization
The scope of water utilization, in accordance with the Ministry of Construction's "Interim Measures for the Management of Urban Water Facilities", is mainly used for flushing toilets, green areas, tree watering, road cleaning, vehicle washing, infrastructure construction, fountains, and other water that is acceptable to the quality standards of the water, the "Management of the Construction of Urban Water Facilities in Kunming" and the "Jinan City Water Facilities Construction". Interim Measures for the Construction and Management of Urban Water Facilities in Jinan City" and other local regulations add water for equipment cooling and industrial water. From the point of view of expanding the scope of water resources utilization and reducing waste, the scope of the latter is obviously more scientific.
1.3 Water utilization and water reuse
For water utilization, there is a "water reuse" concept. Water reuse refers to the community residents living wastewater (bathing, washing, laundry, kitchen, etc.) concentrated, after appropriate treatment to meet certain standards, and then reused in the community of green watering, vehicle washing, road washing, and family toilet flushing, etc., so as to achieve the purpose of saving water. From its concept can be seen, water reuse is only one aspect of water utilization.
2 the need to vigorously promote the use of water in our country
2.1 water scarcity, the situation is grim
China's current 668 cities in more than 400 cities have varying degrees of water shortage, of which 136 cities are seriously short of water, the daily shortage of water amounted to 16 million cubic meters, an annual shortage of 6 billion cubic meters of water due to the lack of water each year affects the value of industrial output The industrial output value is affected by the water shortage every year, amounting to more than RMB 200 billion. Especially the northern cities are generally short of water, water resources has become one of the limiting factors for the sustainable development of these cities.
According to the process of urbanization in China is expected, by the middle of the 21st century, China's urban population will increase from the current less than 400 million to about 900 million, the number of cities will increase to more than 1,000, the supply and demand of urban water resources will be in the current acute situation becomes more acute.
2.2 serious pollution of water resources
China's water pollution has long been ineffective control, according to the country's seven major water systems and inland rivers more than 110 key river statistics, in line with the "Environmental Quality Standards for Surface Water," I, Ⅱ class accounted for 32%, Ⅲ accounted for 29%, belonging to the Ⅳ, V class accounted for 39%. The main pollution indicators are ammonia nitrogen, COD, volatile phenol and BOD. The water quality of the Yellow River, Songhua River and Liaohe River belongs to Ⅳ, V class water quality has exceeded 60%; the water quality of Huaihe River has reached Ⅲ class during the dry season, and the water quality of most of its tributaries is above V class all the year round. The water quality of the Yangtze River and the Pearl River has exceeded 20% of the Ⅳ and V river sections. At the same time, serious eutrophication prevails in the city and nearby lakes. 97% of the groundwater in large and medium-sized cities is seriously polluted, and the groundwater pollutants are generally dominated by phenol, cyanide, arsenic, nitrate, chromium, sulfur, and mercury to a lesser extent. At present, 80% of China's waters, 45% of the groundwater is contaminated, more than 90% of urban water sources are seriously polluted.
2.3 Serious waste of water resources
Washing water in the daily life of urban families (mainly including washing clothes, washing vegetables and other water), its emissions accounted for 75% -80% of the amount of domestic sewage discharged. On the other hand, most cities in urban greening, road surface spraying water, car flushing, toilet flushing water, fire water, etc. are used in the tap water, toilet flushing alone, China's annual consumption of more than 10 billion cubic meters of tap water, which is equivalent to 50 medium-sized cities in the annual tap water consumption! In fact, not all water occasions need quality water, but only to meet certain water quality requirements. To domestic water, for example, there is a considerable part of the life does not require direct contact with the human body miscellaneous water does not require high water quality requirements. If the city's domestic sewage in the original treatment process on the basis of the depth of treatment, so that it meets certain water quality standards, and then reused in the water quality requirements are not high, the demand for a large number of industries, such as industrial cold, landscaping, automobile flushing, miscellaneous residential life, etc., can save a lot of clean water, alleviate the contradiction between the city's supply and demand for water, but also reduce sewage, sewage recycling, in the economic, social and environmental benefits have a In terms of economic, social and environmental benefits, it has practical and long-term significance. It can be seen that for water-scarce cities, this water source is a valuable asset. The development of this potential is very worthwhile.
2.4 The necessity of water utilization
The countermeasures to solve the large-scale water shortage in China's cities are mainly focused on two aspects, one is the "open source", i.e., through the construction of water diversion projects, the exploitation of groundwater, seawater desalination, and even the import of fresh water from abroad and other methods to increase the supply of water resources. The second is "cutting back", that is, through various methods to improve the efficiency of water resources utilization, reduce the efficiency of water resources utilization.
We must note that a variety of "open source" measures to meet the demand for urban water supply at the same time also caused great side effects, the construction of water diversion projects not only cost a huge amount of money, time-consuming and long-lasting, at the same time, the ecological environment has caused a huge impact and damage; and large-scale exploitation of groundwater is the result of the lowering of the groundwater level, the formation of geological funnels, ground subsidence. The large-scale exploitation of groundwater has led to the lowering of the groundwater level, resulting in the formation of geological funnels, ground subsidence, cracks and other serious geological disasters; desalination is not only costly, but also limited to the scope of application of the coastal cities; the import of freshwater from foreign countries is even more difficult to quench the thirst of the immediate water from afar. In contrast, to solve the problem of urban water shortage, "open source" is only the symptom, the root of the problem has to be solved by "cutting back". In a variety of "cost-cutting" measures, the implementation of water use in the city is an extremely important aspect of the most effective way to solve the problem of water shortages, water-scarce cities are imperative to the major decisions.
3 in China to vigorously promote the feasibility of water utilization
3.1 National policy support
2000 the State Council held a "national urban water supply, water conservation and water pollution prevention and control work" put forward: vigorously advocate the reuse of urban wastewater, such as the development and utilization of non-traditional water resources and water resources into the unified management and deployment. It can be seen that the increase in the rate of urban sewage treatment, the construction of a large number of urban sewage treatment plants, the gradual improvement of the reuse policy for the reuse of urban sewage to create an unprecedented opportunity. Water utilization is indeed a large market and promising, great potential, broad prospects.
3.2 technically feasible
China in recent years, the relevant institutions and scientific research departments to organize scientific and technological research in the towns and residential areas of water reuse; urban sewage purification and reuse and gardening, municipal landscaping, road spraying, etc.; large-scale hotels and entertainment venues in the reuse of water systems; urban water reuse and industrial cooling water systems and water for the process of water and so on, in the study have achieved Fruitful results have been achieved, and a number of demonstration projects have been built. With the progress of science and technology, any wastewater can be treated by different process technologies to meet any needs. Generally speaking, the secondary effluent after disinfection, used as municipal miscellaneous water, life miscellaneous water, agricultural water and landscape water; on this basis, by mixing and filtering treatment, can be used as industrial circulating cooling water, etc.; and then further treatment, such as membrane technology or adsorption with activated carbon, can be used as industrial process water or ground water, groundwater recharge water, etc..
Domestic and foreign has had a lot of mature experience. In Tianjin, only in the water washing a car to save more than 5 million tons of tap water per year. In Dalian, Dalian Rolling Stock Factory in 1998 invested 1.5 million yuan on the sewage treatment plant renovation, the implementation of water reuse project. Now the daily reuse of water 800 cubic meters, plant greening, toilet flushing and cooling water are used in the water, saving 200,000 tons of water per year. The United States in 1926 for the first time recycled water, in 1971 there have been 358 factories and enterprises to use treated municipal wastewater, recycling volume of 510 million cubic meters. California, the United States, the annual use of purified sewage 270 million cubic meters, equivalent to 1 million people a year's water consumption. 1985, the former West Germany, 75% to 80% of the city's sewage has been secondary treatment to be utilized. Through the large-scale promotion of water use, many cities in developed countries in the expansion of urban development at the same time to achieve zero growth or even negative growth in water demand. Therefore, technically speaking, it is more mature.
3.3 Economically feasible
Water utilization occupies a very important position in urban water resources planning, and has a very considerable economic value.
(1) Providing a new source of water: the utilization of water in the case of no impact on health, provides us with a very economical new source of water. It reduces the amount of investment in engineering that would have been required to divert water from long distances.
(2) Water reuse can reduce the amount of fresh tap water while providing a new water source, thus reducing the investment in urban tap water treatment facilities accordingly.
(3) Water reuse can also reduce the amount of sewage discharge, reducing the cost of treatment caused by controlling water pollution. These economic benefits are factors that have prompted many cities at home and abroad to adopt water utilization.?
According to the statistics of domestic experts, when the use of community sewage as a source of water, the population is greater than 10,000 or water consumption of water to reach 750m3 / d or more for the economy; in the urban sewage treatment plant to add a water reuse system, mainly to build a new water purification room, its investment is only 30% of the investment in the construction of a new water purification plant, developed countries have proved the experience, the addition of water reuse system in urban sewage treatment plants Is the most feasible and effective mutual benefit project.
4 important significance of water utilization
First of all, lower cost than long-distance water diversion. As a result of the community water reuse treatment device installed in the district, reducing the infrastructure investment in water pipelines and operating costs, sewage treatment to the extent of miscellaneous water, its infrastructure investment is equivalent to only 30 km away from the water, if the treatment can be reused as a higher demand for process water, its infrastructure investment is equivalent to 40-60 km away from the water.
Secondly, the economy than desalination. Due to the low concentration of pollutants in the community sewage (less than 0.1%), biochemical better, less difficult to deal with, and the depth of treatment methods available to remove. Therefore, when the drainage of domestic sewage as a water source, the concentration of major pollutants indicators COD, BOD5, SS, NH3-N can meet the technical requirements of treatment. Seawater, on the other hand, contains 3.5% of dissolved salts and a large number of organic matter, the impurity content of the secondary treatment of sewage effluent for more than 35 times, so regardless of the infrastructure fee or unit cost, desalination of seawater are more than sewage reuse.
Subdivision reuse of sewage to open up a second source of water, reducing the amount of fresh water in the community to take, the treated sewage back to the community, reducing the discharge of sewage, reducing the pollution of the receiving body of water, but also reduces the governance of environmental pollution investment. So sewage reuse not only saves water resources, but also eliminates environmental pollution, with multiple benefits.
5 Conclusion
The use of water to achieve sewage resource utilization is the most effective way to solve the current water scarcity, water-scarce cities are imperative for major decisions, the feasibility of strong, with great significance and multiple benefits.
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