There are three main methods:
1. Chemical method
Simply put, it means adding chemical agents to wastewater to allow the dirt inside to react and become easily removable.
Coagulation method：The working principle of coagulation method is to add chemical agents to water, causing small suspended particles to aggregate and form larger flocs, and then settle down by gravity. This method can effectively remove chromaticity, bacteria, and some organic matter from water. However, its treatment effect on substances completely dissolved in water is limited, and the treatment effect is easily affected by fluctuations in water temperature and pH value.
Oxidation method: Using oxidants (such as chlorine, ozone) to decompose toxic substances into harmless ones. Ozone has good effects and no secondary pollution, but the cost is high; Chlorine is commonly used and suitable for treating wastewater containing phenol and cyanide; The air oxidation effect is slightly poor and is generally used in wastewater where pollutants are easily oxidized.
Electrochemical method: Electricity is applied to allow pollutants to react on the electrode surface for removal, and sometimes sodium chloride is added to enhance the effect. This method has good processing effect, but its disadvantages are also obvious: on the one hand, it consumes a lot of electricity and has high operating costs; On the other hand, some side reactions may also occur during the process, leading to secondary pollution.
2. Physical Method
Separate solid impurities from water through physical methods.
The filtration method uses filter media with micropores (such as microporous filters) to intercept suspended solids in water.
The sedimentation rule is to use gravity to allow heavier suspended particles in sewage to naturally settle to the bottom of the water.
The air flotation method introduces a large number of tiny bubbles into the water, causing them to adhere to impurity particles and form a floating body with an overall density lower than water. It then rises to the water surface by buoyancy and is removed by scraping equipment.
These methods are simple and easy to manage, but they cannot remove pollutants dissolved in water and have limitations in their use.
3. Photocatalytic oxidation technology
By using ultraviolet light and oxidizing agents (such as hydrogen peroxide), difficult to decompose pollutants (such as polychlorinated biphenyls) can be completely destroyed.
There is a method called 'photocatalytic Fenton', which can rapidly produce a large amount of active substances and efficiently decompose organic matter under the combined action of light and iron ions.
Another method is to add photosensitive semiconductor materials (such as titanium dioxide), which generate highly oxidizing free radicals under light irradiation, completely decomposing pollutants into harmless substances such as carbon dioxide and water. This method has great potential for treating recalcitrant pollutants.
Post time: Nov-11-2025
