According to the treatment method, the water treatment process is generally divided into 3 types:
1. Physical treatment method:
Membrane filtration method, suitable for water quality changes.
The use of this process is characterized by: compact device, easy to operate, as well as by the load change of small impact.
Membrane filtration is under the action of external forces, the solution to be separated at a certain flow rate along the surface of the filter membrane, the solvent and low molecular weight substances in solution, inorganic ions from the high-pressure side of the filter membrane into the low-pressure side, and as a filtrate and discharged; and high molecular weight substances, colloidal particles and microorganisms in the solution by the ultrafiltration membrane to intercept the solution is concentrated and discharged in the form of concentrated.
2. Physicochemical method:
Suitable for sewage water quality changes. The methods generally used are: sand filtration, activated carbon adsorption, flotation, coagulation and precipitation. This process is characterized by: the use of hollow fiber ultrafilter for treatment, advanced technology, compact structure, occupies less space, intermittent operation of the system, simple management.
3. Biological treatment method
Suitable for sewage with high organic content. Generally use the activated sludge method, contact oxidation, biological turntable and other biological treatment methods. Or used alone, or a combination of several biological treatment methods, such as contact oxidation + biofilter; biofilter + activated carbon adsorption; turntable ten sand filtration and other processes. This process has the advantages of strong adaptability to changes in hydraulic load, less sludge, easy maintenance and management.
At present, due to some countries and regions in excessive, unrestrained development of water resources at the same time, environmental protection awareness is relatively poor, so that the surface water and groundwater are subject to varying degrees of contamination, so that the original fresh water supply with good water quality is limited; secondly, to be developed fresh water from the centralized water supply point is far away from the one-time investment costs are high, so that some of the water-scarce areas can not afford to expand the water supply capacity. Expanding water supply capacity. The concept of water is introduced here to the extent that it is non-drinkable. Water is also used in the life and production of people in the quality of miscellaneous drainage (excluding feces and kitchen drainage), miscellaneous drainage (excluding fecal waste water) and domestic sewage (waste) water through the regeneration of water collection and reuse, as ground cleaning, watering flowers, car washing, air-conditioning, cooling, flushing commode, firefighting, and other miscellaneous water does not come into direct contact with the human body. Because of its water quality indicators lower than the city's water supply in the drinking water quality standards, but higher than the sewage allowed to be discharged into the ground water discharge standards, i.e., its water quality in the drinking water quality and allow the discharge of sewage water quality standards, it is named "water".
Water development and reuse technology has recently been the rapid development of the United States, Japan, India, the United Kingdom and other countries (especially Japan for the prominent) has been widely used. These countries are based on the national degree, the characteristics of the region to determine the national situation suitable for its national strength of the water reuse technology, so that the water reuse technology is more and more perfect. In China, this technology has been emphasized by all levels of government and relevant departments and the building of water reuse has done a lot of theoretical research and practical work in many cities across the country, such as Shenzhen, Beijing, Qingdao, Tianjin, Taiyuan, etc. to carry out the operation of the water project and achieved remarkable results.