Due to industrial development and the acceleration of urbanization, the height of the generated a lot of industrial wastewater and domestic sewage, the vast majority of sewage directly discharged into water bodies, causing 82% water and 93% of the underground water pollution, water quality significantly worse .
Drinking water pollution has long been a harm to human body caused by direct or indirect, drinking water purification technology and precipitation from the original simple water purification methods to traditional routine processing method, and the development of pretreatment and depth processing technology by now.
First people used natural sedimentation, grille intercept and simple water treatment method, and then found, using the method of sand filtration to remove fine suspended solids appeared reagent coagulation treatment at the same time, and began to build the city water treatment works, formed the early feed water treatment .
With the rapid development of industry and city, the water supply was more urban sewage and industrial wastewater pollution, drinking water needs on the basis of the conventional process for further purification can meet the requirements, which prompted people to seek a comprehensive measures to improve drinking water quality safety.
Currently, flocculation method, oxidation method, adsorption method and membrane separation method are used in drinking water treatment technology , and flocculation method includes strengthening mixing, flocculation, precipitation and filtration.
The oxidation method includes ozone, chlorine dioxide, hydrogen peroxide, potassium permanganate, ferric acid and photocatalytic oxidation, as well as the deep oxidation technology combined with ozone and hydrogen peroxide.
Adsorption method is divided into exchange adsorption, physical adsorption and chemical adsorption of three basic types, the main adsorbent is activated carbon, activated alumina, silica gel modified zeolite and organic resin adsorbent, such as a new type of adsorbent and carbon molecular sieve, the activated carbon fiber, metal adsorbent and various special adsorbent, etc.;
Membrane separation was originally applied in industrial water, sea water desalination of brackish water and desalination processing, now has been widely applied to remove the water turbidity, chroma, odor, disinfection by-products precursor dissolving organic matter, microorganism, etc.
Choose the appropriate membrane technology or membrane technology combination, can carry on the deep purification treatment to the drinking water, can even treat the raw water to the desired water quality level.
A wide scope of the technology to remove contaminants, compact and easy to realize automatic control equipment, can remove more tiny impurity, dissolved organic matter and inorganic matter, even the salt, water in polluted raw water treatment, disinfection by-products control by the epa recommended as one of the best technology .
But membrane before processing must carry on the strict pretreatment of raw water, and chemical cleaning on a regular basis, so the membrane filtration of infrastructure investment and operation cost is higher, and there is a membrane plugging and reverse osmosis and nanofiltration, membrane pollution concentration and other technical problems.
As high strength, long life, resistance to pollution, development and manufacturing of high flux membrane material, improvement of cleaning method, the membrane plugging and improvement of membrane pollution and various film falling prices, membrane filtration, as a new technology of water purification will be an important influence on feed water treatment, be distinguished as the most promising water treatment technology of the 21st century.