1. Wastewater quality
The quality of domestic sewage is usually relatively stable, and general treatment methods include acidification, aerobic biological treatment, disinfection, etc. The reasonable selection of process flow for industrial wastewater should be based on specific water quality conditions. It should be noted that when using aerobic biological treatment technology to treat wastewater, attention should be paid to the biodegradability of the wastewater, usually requiring COD/BOD5>0.3. If this requirement cannot be met, anaerobic biological hydrolysis acidification can be considered to improve the biodegradability of the wastewater, or non biological treatment physical or chemical methods can be considered
2. Degree of sewage treatment
This is the main basis for selecting the sewage treatment process flow. The degree of sewage treatment generally depends on the water quality characteristics of the sewage, the direction of the treated water, and the self purification capacity of the water body into which the sewage flows. However, currently, the determination of the degree of sewage treatment mainly depends on the requirements of the relevant legal system and technical policies of the country. Usually, environmental management departments control the concentration of wastewater discharge based on the Comprehensive Wastewater Discharge Standards and related industry discharge standards. Some regions with higher levels of economic development also have stricter local discharge standards. Therefore, regardless of the type of wastewater that needs to be treated, and regardless of the treatment process and degree adopted, it should be based on the premise that the effluent of the treatment system can meet the standards. Prevent and control water environmental pollution in accordance with the requirements of laws, regulations, and policies.
3. Construction and operation costs
When considering construction and operation costs, it should be a prerequisite for treating water to meet water quality standards. Under this premise, the low cost process of engineering construction and operation should be given due attention. In addition, reducing the footprint is also an important measure to lower construction costs
4. Difficulty level of engineering construction
The difficulty level of engineering construction is also one of the influencing factors in choosing the process flow. If the groundwater level is high and the geological conditions are poor, it is not suitable to use deep and difficult to construct treatment structures.
5. Local natural and social conditions
The local terrain, climate, and other natural conditions also have a certain impact on the selection of wastewater treatment processes. If the local climate is cold, a process that can operate normally during low temperature seasons and ensure water quality standards should be adopted. Local social conditions such as raw materials, water resources, and electricity supply are also factors that should be considered in process selection.
6. The amount of sewage
In addition to water quality, the amount of sewage is also one of the influencing factors. For wastewater with significant changes in water quantity and quality, the first consideration should be to adopt processes with strong shock load resistance, or to establish buffer facilities such as regulating tanks to minimize adverse effects.
7. Did any new conflicts arise during the processing
During the sewage treatment process, attention should be paid to whether it will cause secondary pollution problems. For example, pharmaceutical factory wastewater contains a large amount of organic substances (such as benzene, toluene, artemisinin, etc.), which will result in exhaust emissions during the aeration process and have an impact on the surrounding atmospheric environment; The production wastewater from fertilizer plants is recycled after sedimentation and cooling treatment. The tail gas from the cooling tower contains cyanide, which pollutes the atmosphere; In the treatment of LeGuo wastewater in pesticide factories, the use of alkalization method to degrade LeGuo, such as using lime as alkalizing agent, will result in secondary pollution of the generated sludge; When treating wastewater from printing and dyeing or dye factories, the disposal of sludge becomes a key consideration.
