2. Chemical method: the conversion process of adding chemicals to react with harmful substances in sewage. Neutralization, oxidation, reduction, decomposition, coagulation, chemical precipitation and so on.
3. Physical chemistry method: the separation process of physical chemistry. Gas stripping, stripping, adsorption, extraction, ion exchange, electrolytic electrodialysis, reverse osmosis, etc.
Extended data
Sewage treatment is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical care, catering and other fields. Urban sewage treatment technology should be optimized after comprehensive technical and economic comparison according to the treatment scale, water quality characteristics, environmental functions of receiving water bodies and local actual conditions and requirements.
Village sewage is mainly composed of domestic sewage and agricultural wastewater. The composition of domestic sewage is relatively fixed, mainly containing carbohydrates, protein, amino acids, fats and other organic substances, which is more suitable for the growth of bacteria and becomes a place for the survival and reproduction of bacteria and viruses; Domestic sewage is generally non-toxic and has certain fertilizer efficiency, so it can be used to irrigate farmland.
The composition of agricultural wastewater is varied. Different seasons, different places and villages with different development goals need different treatment methods. When treating sewage, in order to reduce the sewage discharge and its complexity, the toilet flushing water (black water) should be separated from other domestic water (gray water) in combination with the construction of biogas digesters that the country is vigorously promoting.
Grey water is treated by natural purification system, while black water and human and animal manure are treated by anaerobic biogas digesters, which can not only reduce the discharge, complexity and treatment cost of sewage, but also have great significance for developing clean new energy in rural areas, protecting human settlements and promoting sustainable development of rural economy and society.