According to its function, wastewater treatment can be divided into physical method, biological method and chemical method.
Physical method: The main use of physical action to separate insoluble substances in wastewater, in the treatment process does not change the chemical properties. Commonly used are gravity separation, centrifugal separation, reverse osmosis, air flotation and so on. Physical treatment is simple and economical, which can be used in the case of large capacity of water body, strong self-purification ability and low requirement of wastewater treatment in villages and towns.
(2) Biological method: By utilizing the metabolic function of microorganisms, the dissolved or colloidal organic matter in wastewater can be decomposed and oxidized into stable inorganic matter, so that the wastewater can be purified. Activated sludge process and biofilm process are commonly used. The degree of biological treatment is higher than that of physical treatment.
(3) Chemical method: It is a method of treating or recovering dissolved or colloidal substances from wastewater by chemical reaction, which is mostly used in industrial wastewater. The commonly used methods are coagulation, neutralization, redox and ion exchange. Chemical treatment method has good treatment effect and high cost. It is mostly used as effluent after biochemical treatment for further treatment to improve the quality of effluent.
According to the degree of treatment
Wastewater treatment can be divided into primary treatment, secondary treatment and tertiary treatment according to the degree of treatment.
The primary treatment is mainly to remove suspended solid substances from wastewater, which is commonly used by physical methods. The BOD removal rate of wastewater after primary treatment is only 20%, which is not suitable for discharge, and secondary treatment is also needed. The main task of secondary treatment is to remove colloidal and dissolved organic matter from wastewater by a large margin. The removal rate of BOD is 80%-90%. Generally, the wastewater after secondary treatment can meet the discharge standard. Activated sludge method and biofilm treatment method are commonly used. The purpose of tertiary treatment is to further remove some special pollutants, such as fluoride and phosphorus, which belong to advanced treatment and commonly used chemical methods.
废水工艺流程选型要求 1、对现有一级处理工艺进行加强处理效果的改造 改造应根据实际情况，充分利用现有处理设施，对现有医院中应用较多的化粪池、接触池在结构或运行方式上进行改造，必要时增设部分设施，尽可能地提高处理效果，以达到医院废水处理的排放标准。
Requirements of wastewater process selection 1. To improve the treatment effect of existing primary treatment processes, we should make full use of the existing treatment facilities according to the actual situation, transform the structure or operation mode of septic tanks and contact tanks which are widely used in existing hospitals, add some facilities when necessary, and try our best to make full use of the existing treatment facilities. Improve the treatment effect to meet the discharge standard of hospital wastewater treatment.