I. Saving industrial water
In industry, water is mainly used for cooling, boiler water, raw material water and processing washing products, among which cooling water accounts for the largest proportion, accounting for about 60% of the total industrial water consumption. For example, the annual industrial water consumption in Beijing is about10 ~1300 million cubic meters, of which the cooling water consumption is about 600 ~ 800 million cubic meters. The main measures of industrial water saving are:
1. Cooling water reuse: A large amount of cooling water can be reused by implementing cooling tower and cooling pool technology in the factory, with less investment and quick results. For example, after a plastic factory invested tens of thousands of yuan to set up a cooling tower, the water consumption for producing 1 ton of plastic decreased from more than 300 cubic meters to 40 cubic meters, and the water recovery rate reached 80-90%, saving nearly 30,000 yuan a year.
2. Waste water recycling, establishing a closed-loop system of industrial water: After a paper mill in Tianjin adopted this method to realize industrial recycling, the daily water consumption was reduced from 3,000 cubic meters to 300 cubic meters, saving 90% water.
3. Circulating water: In the production process of chemical industry, electroplating, printing and dyeing, textile and other industries, the circulating water technology of countercurrent rinsing can be implemented, and the clean water discharged from the latter process can be used in the former process, which can save water by more than 30%.
4. Innovative technology, adopting new technology: air cooling, steam cooling instead of water cooling, and hot water instead of steam heating. A refinery in Canada used steam cooling instead of water cooling, which reduced the water consumption per ton of crude oil from about 100 cubic meter to 0.2 cubic meter. Using hot water instead of steam for heating can also save water by more than 30%.
5. Replace good water with secondary water, and exchange waste water: factories with high water consumption in coastal cities can use seawater instead of fresh water to cool down. For example, Dalian chemical, petroleum, power generation and other 13 factories use seawater for cooling machinery and equipment10.68 million cubic meters, equivalent to 56% of the city's total water consumption. Shallow groundwater with poor water quality can also replace high-quality deep groundwater for industrial cooling and construction water. Factory wastewater can also be used interchangeably. For example, a paper mill in Qingdao uses 600 cubic meters of bottle washing wastewater from a neighboring brewery every day for pulp washing, ball filling and grass steaming. According to the statistics of 22 factories in Qingdao, after wastewater exchange, the daily water saving reached 3400 cubic meters.
Second, save agricultural water.
Beijing's agricultural water consumption is about 2.5 billion cubic meters per year, accounting for more than 60% of the city's total water consumption. At present, the effective utilization rate of agricultural irrigation water is low, generally only 25 ~ 40%, and most of the water is wasted. The main measures of agricultural water saving are:
1. Seepage prevention of water conveyance channel: lining and tamping the channel with concrete, concrete and stone can generally reduce the leakage by 30% or even double the water utilization rate. Plastic film can also be used to lay the channel, which is not only simple in construction, low in cost, but also quick in effect.
2. Replacing open channels with underground water pipelines: it can reduce leakage and evaporation losses in channels and save water by more than 20%. For example, building a 1.500m underground cement pipe in a certain place can save water by 23%, and the irrigation of two wells can be shortened from 15 days to 7 days.
3. Spray drip irrigation instead of flood irrigation: it can save water by 40-60%, increase production by more than 20-50%, and improve land utilization rate by 5- 10%. The effect of saving water, land and increasing production is very obvious. For example, a township, located in the deep mountains, is short of water resources. After the construction of 2600 mu of sprinkler irrigation field, the irrigation water consumption per mu increased from 65438+. However, the effect of drip irrigation technology on saving water and increasing production is more obvious than that of sprinkler irrigation. For example, in a mountain village, the water resources are scarce and scattered. There are only 1 1 Koizumi in the village, and the water gushes out 2 cubic meters per hour. The crops are short of water, and the yield is extremely low. The yield per mu of wheat is only 128 kg. Since the construction of 50 mu drip irrigation field, the yield has increased by 4.6 times, and the yield has increased year after year. The investment of drip irrigation equipment can be calculated according to the output value of increasing production, and the cost can be recovered in two or three years. The agricultural water consumption in Beijing and Tianjin is about 4.5 billion cubic meters per year. If spray and drip irrigation are fully implemented, at least1.50 ~ 200 million cubic meters of water can be saved, which is equivalent to the sum of domestic and industrial water consumption in Beijing for one year, and the investment cost can be recovered after spray and drip irrigation for 3 ~ 5 years. In addition, we can also expand the cultivation of crops with less water consumption, such as changing rice into upland rice and various crops with less water consumption such as wheat and corn.
Third, save domestic water.
The urban tap water supply in Beijing is about 500 million cubic meters per year, and it is increasing at a rate of more than 30 million cubic meters per year. Due to insufficient publicity and poor management, urban domestic water is seriously wasted. The daily water consumption of some units and residents is as high as 0.5 ~ 2 cubic meters, which is more than 10 times higher than that of ordinary urban residents. The main measures to save water in urban life are:
1. Strengthen publicity and water-saving education: carry out water-saving education for urban workers and student residents, and commend and reward water-saving models; People and collectives who waste water should be criticized and punished.
2. Strict management and maintenance: improve the water meter, improve the water quota and progressive charging system, save water with prizes, and impose heavy penalties for excess; Strengthen the maintenance of water pipelines to prevent water leakage losses.
3. Research and popularize all kinds of water-saving devices: Take effective measures to popularize all kinds of water-saving devices, such as foot valve shower, automatic hand washing faucet, water-saving urinal flusher, mop washing and dewatering vehicle, controllable car washing nozzle, etc.
4. Advocate multi-purpose and differentiated water use: in areas where high-quality deep groundwater is over-exploited, shallow groundwater with poor water quality can be developed for cleaning, landscaping and fire fighting; Domestic water can also be reused, for example, the water after washing rice can be used to flush toilets, water flowers and plant trees. In coastal cities, seawater can be used for cleaning and sanitation, such as Dalian Shipyard flushing toilets with seawater, which saves a lot of fresh water.