Water treatment is the process of improving water quality by means of physical, chemical or biological methods. The target of water treatment is the water that does not meet the quality requirements.
The ways humans do water treatment has been for many years. The methods of water treatment include physical water treatment, chemical water treatment and biological water treatment.
Physical methods include filtration using a variety of filter media with different pore sizes. Also, the method of adsorption and the method of blocking are utilized. To exclude impurities in the water by adsorption or blocking. A more important adsorption method is adsorption with activated carbon. The blocking method is to pass water through the filter material. So that the bulky impurities cannot pass, and thus the clean water is got.
In addition, physical methods also include precipitation methods. It is to let the impurities with smaller specific gravity float on the surface of the water. Or let the impurities with larger specific gravity are deposited underneath. So as to obtain relatively clean water.
2 ways to treat water mentioned above are commen methods. Now, let’s talk about the biological water treatment method.
Biological water treatment mainly uses microorganisms that grow and reproduce under natural conditions to treat sewage. The ecosystem can make full use of the nutrients in the sewage, which is beneficial to the growth of green plants. Finally, the reclamation, harmlessness and stabilization of sewage are realized.
Biological water treatment methods mainly include stabilization pond, wetland, land treatment system and the combination system of these processes. Stabilization ponds utilize naturally growing microorganisms (aerobic, facultative and anaerobic) in pond water to decompose organic matter in wastewater. Oxygen is supplied to the pond by the photosynthesis of algae growing in the pond and the reoxygenation of the atmosphere, and its biochemical process is similar to that of natural water purification.
The chemical method uses various water treatment chemicals to convert impurities into substances that are less harmful to the human. Or to use water treatment chemicals to concentrate impurities. The oldest chemical water treatment method should be an alum. The alum is added to the water. And after the impurities in the water are collected, the volume becomes large. And the impurities can be removed by a filtration method.
The minimum standards for drinking water are set by the environmental protection department. Industrial water has its own requirements. The physical properties of water are the basic criteria for judging the quality of water. Such as temperature, color, transparency, smell, taste, etc. The chemical properties of water are also important indicators for judging water quality. Such as its pH, dissolved solids concentration, oxygen content, etc.
Some natural waters have a total dissolved solids concentration of up to 1000 mg/L. Canada requires that the concentration of total dissolved solids in drinking water should not exceed 500 mg/L. Much industrial water is also required to be at concentrations not higher than 200 mg/L. This kind of industrial water cannot be used casually even if its physical properties meet the requirements. In addition, the radioactive element content in water is also an important characteristic that must be monitored.
The purpose of water treatment is to improve water quality to a certain standard. There are various types of physical water treatment, chemical water treatment, and biological water treatment depending on the water treatment method. According to the treatment target, there are two major categories of water supply treatment and wastewater treatment. Water supply treatment includes domestic drinking water treatment and industrial water treatment. Wastewater treatment includes domestic sewage treatment and industrial wastewater treatment.
There are several types of industrial water treatments that are particularly closely related to thermal technology. They are boiler feedwater treatment, make-up water treatment, steam turbine main condensate treatment and circulating water treatment. Water treatment is of great significance to industrial production, product quality, and environmental ecology.