What are the wastewater treatment methods?

The wastewater treatment method comprises the following steps:

1. Physical method: treating, separating and recovering pollutants in wastewater by physical action. For example, precipitation method (gravity separation method) is used to remove suspended solids with relative density greater than 1; Filtering method (sand activated carbon with filter screen) can remove suspended solids from water; Evaporation is used to concentrate insoluble and soluble substances in wastewater, and there are other methods such as centrifugal separation, steam flotation (flotation) and high gradient magnetic separation.

2. Chemical method: treating and recycling soluble wastes or colloidal substances by chemical reaction or physical and chemical action. For example, neutralization method is used to neutralize acidic or alkaline wastewater; The extraction method uses the "distribution" of soluble wastes with different solubility in the two-phase interaction to recover phenols and heavy metals; Redox method is used to remove reducing or oxidizing pollutants in wastewater and kill pathogenic bacteria in natural water. In addition, there are coagulation and chemical precipitation.

3. Physical and chemical methods: adsorption, ion exchange, extraction, membrane separation and evaporation.

4. Biological method: using the biochemical action of microorganisms to treat organic pollutants in wastewater. For example, biological filtration and activated sludge process are used to treat domestic sewage or organic production wastewater, so that organic matter can be transformed and degraded into inorganic salts and purified. There are also biofilm method and biological pond method.

5. Sludge land treatment method: used for organic matter treatment. Sewage irrigation, slow infiltration and rapid infiltration must be treated by sewage treatment plant and then recycled for flushing toilets.