Recycling of water resources-advanced treatment, reuse and resource utilization of sewage and wastewater
It is very necessary to strengthen sewage treatment so that it not only meets the discharge standards, but also can be reused in large quantities. This is very important for eliminating pollution, improving the water environment, alleviating the shortage of water resources, saving valuable water resources, and promoting the development of environmental protection industries. Important; at the same time, the economic and social benefits of wastewater reuse, in turn, promote and drive the further development of wastewater reuse, which not only realizes the recycling of wastewater, but also promotes cleaner production.
Urban sewage is mainly composed of domestic sewage and industrial wastewater, roughly half of them. Currently, it is mainly treated by concentrated biological methods (conventional activated sludge method, A-B method, A2/0, hydrolysis monoxide, SBR, oxidation ditch, etc.) to make it meet the discharge standards. In order to implement sewage recycling and clean production, in addition to the recycling of centralized treatment and discharged sewage, the treatment and reuse of some point pollution sources are also very important. Point pollution source treatment can not only reduce the burden of centralized treatment, but also ensure centralized treatment. The water quality can sometimes achieve cleaner production. With the integration of traditional technology and membrane technology, sewage or wastewater can be turned into reused water with different water quality standards or recycled. This not only eases the contradiction between supply and demand, reduces pollution, and promotes the development of environmental protection industries. At present, wastewater reuse has been used as industrial cooling water, irrigation water and municipal water in a large number of practices, which has significant economic, social and environmental benefits.
The submerged membrane bioreactor treats sewage from domestic, food and pharmaceutical industries to make it reuse; ultrafiltration realizes the recovery of electrophoretic paint and leaching water in the coating industry (especially the automotive industry and aluminum processing industry); Filtering treatment of desizing waste liquid and printing and dyeing wastewater in the textile industry and printing and dyeing industry to return to the sizing system and printing and dyeing system for reuse. The effect is significant and it is an ideal treatment technology; reverse osmosis and nanofiltration make electroplating wastewater (nickel plating, Chromium plating, cadmium plating, gold plating, etc.) to realize the reuse of valuable electroplating agents in the rinse water and the reuse of rinse water, which can basically realize a closed circuit with zero discharge; dialysis and recovery of waste acid in metallurgy, chemical, mining and other industries , Reuse of alkali, greatly reducing pollution; ultrafiltration treatment of oily wastewater, such as oil field reinjection water, crude oil wastewater, emulsified oil wastewater and synthetic fiber oil wastewater, is also a process worth promoting.
In terms of comprehensive advanced treatment of sewage, the membrane technology used in sewage treatment can remove suspended particles, pathogenic bacteria, various organic and inorganic substances, etc., and the comprehensive advanced treatment of reverse osmosis secondary sewage. The obtained different levels of reclaimed water can be used for miscellaneous water (fire fighting, Car washing, road sprinkling…), irrigation water, construction water, industrial cooling water, groundwater reinjection, and even boiler water. These are technically and economically feasible. Economic and environmental benefits are significant. Groundwater reinjection not only prevents seawater intrusion, but also replenishes groundwater sources and improves the water quality of the river basin. Urban sewage reuse has a very significant effect on alleviating urban water supply shortage, saving precious water resources, reducing water pollution and improving water environment. A lot of practice has proved the feasibility and economics of wastewater reuse. With the enhancement of people’s environmental awareness and the improvement of living standards, the requirements for wastewater reuse will become higher and higher. Due to the characteristics of membrane technology, the technology continues to advance As the treatment cost continues to drop, membrane technology will be more useful in the field of wastewater reuse in the future and play a greater role.
As early as the 1950s, in order to solve the “water crisis”, membrane separation technology was proposed. With the continuous progress of membrane technology and the increasingly serious shortage of water resources, membrane technology, as one of the key common technologies for sustainable development, must be doubled. It is valued and continues to play a greater role in water resources development and protection, drinking water purification, transformation of traditional industries, and promotion of cleaner production.