What are the ways to increase revenue and reduce expenditure?

It is urgent to rationally allocate water resources, save water, protect existing water resources and develop new water resources. Relevant international agencies and organizations have held many meetings and adopted a series of resolutions or regulations to ensure the normal use of water. More and more countries in the world are actively taking measures to increase income and reduce expenditure.

Water resources are not inexhaustible. If there is not enough water, we should increase revenue and reduce expenditure. Open source is the most important thing, but the construction of new water source projects is affected by financial resources, and the construction period is long, so it is difficult to benefit in the short term. Therefore, water saving is the key to alleviate the contradiction of water resources, and water saving and open source are the only feasible ways. This is also a basic national policy of China's economic construction.

Mankind has made gratifying achievements in finding new water sources. At present, there are more than 1000 desalination plants in the Middle East, with a daily output of about 5 million tons of fresh water. According to the principle that cobwebs can absorb fog dew, Canadian experts invented a new method of intercepting fog and taking water. A fog water treatment plant can supply 1. 1000 liters of water every day, and it can reach 13000 liters in dense fog season. This technology has been extended to more than 20 countries. Scientists have also found that there is at least 70 billion cubic meters of fresh water at the bottom of sub-Saharan Africa at 1300 meters. Once developed and utilized, it is expected to alleviate the drought and water shortage in the Sahara region.

The history of Saudi Arabia's demand for fresh water from the ocean can be traced back to the beginning of this century. In order to solve the drinking water problem of Jeddah residents, 1928 set up two sets of distillation equipment there to desalinate seawater. Although the equipment is simple and the production capacity is limited, we did find a solution to the water source.

Most of Saudi Arabia is covered by desert, and it is a country with poor fresh water resources. However, Saudi Arabia's agriculture has developed rapidly, with a cultivated area of more than 3 million hectares and self-sufficiency in food. As early as 199 1, Saudi Arabia ranked sixth among the world's wheat exporters. The key to this miracle lies in the desalination plant in Saudi Arabia. Seawater desalination is to separate salt from seawater by chemical methods to obtain fresh water. Its methods include flash evaporation, electrodialysis and reverse osmosis. Saudi Arabia basically adopts the traditional flash evaporation method. Although the cost of flash evaporation method is high, because the equipment and pipelines used in flash evaporation method are all copper-nickel alloy, this method can kill two birds with one stone, which can not only obtain fresh water, but also drive the turbine to generate electricity when seawater evaporates.

After decades of construction, the desalination project in Saudi Arabia has made great progress. Compared with 1970, the number of plants has grown from a few to 23 modern plants at present, and the fresh water output has doubled again, from 1970 to 23.64 million liters/day, while generating 3600 MW. The problem of fresh water that has long plagued the Saudis has been solved to a considerable extent.

The potential for saving water resources is also considerable. At present, the annual water consumption of agricultural irrigation in China is more than 400 billion cubic meters, and the effective utilization rate is very low. The effective utilization rate of canal irrigation is only 30% ~ 40%, and that of well irrigation area is only about 60%. Israel has the best water-saving agriculture in the world, and its irrigation efficiency is 70% to 80%. If China improves the utilization rate of water resources 10%, it can save more than 40 billion cubic meters of water every year. What a huge number this is! Since 1980s, Israel has adopted computer-controlled drip irrigation and sprinkler irrigation technology, which has reduced agricultural water consumption by 30%. At the same time, nearly 70% of the country's wastewater has been treated and used for agricultural irrigation, and the agricultural output ratio per cubic meter of fresh water has quadrupled 1950.

Japan's industry adopts water-saving production mode and wastewater recycling, and the industrial water consumption is reduced by 25% compared with the past, and the reuse rate remains above 70%.

The reuse rate of industrial water in Germany is also above 60%. Many of its paper mills adopt new technologies. Seven kilograms of water can produce 1 kg of paper, and the water consumption only accounts for about 1% of some old factories. Saving domestic water is equally effective.

Through public education, installation of water-saving equipment and water inspection of the company in Boston, USA, the urban domestic water consumption is reduced by 16% every year.

Mexico has reformed the national toilets, reducing the flushing volume by more than half and saving about 3.2 billion liters of water every year.

Sewage treatment has also become the conscious requirement of all mankind. Many countries have enacted Environmental Protection Law or Water Pollution Prevention Law, and adopted advanced technology to change the polluted water quality, among which "microfiltration method" is more effective. At the beginning of 1996, Professor Dolao, a sewage treatment expert at the Institute of Water, Soil and Air Hygiene of the Federal Environment Agency in Berlin, said: "The current problem is caused by purification methods." He said that the focus is on the final stage of purification, that is, precipitation.

Technically, it is impossible to remove suspended solids including bacteria, viruses and parasites by precipitation. However, microfiltration makes this possible. This method has passed the first test. In the Luleben purification plant in Berlin, the purified wastewater will flow through the microfiltration test device before being discharged into the river, and all the larger particles will be blocked. This is an insurmountable obstacle for bacteria and parasites. Even smaller viruses will be blocked by the membrane, because most viruses are adsorbed on larger particles.

In addition, this method can also make the content of phosphate in the discharged wastewater particularly low. Phosphate is a nutrient for plants, which will lead to the proliferation of algae in water and make the water green. Moreover, this method can effectively filter out Escherichia coli.

Mankind is constantly exploring, trying to learn from each other's strengths and strengthen international exchanges and technical cooperation. We believe that with the awakening of mankind and the progress of science and technology, one day, mankind will get rid of the predicament of "water shortage"!