How to choose a wastewater treatment process, do you know?

The selection of wastewater treatment processes generally needs to consider the following factors.

 

 

 

1. Wastewater quality

The quality of domestic sewage is usually relatively stable, and common treatment methods include acidification, aerobic biological treatment, and disinfection. Industrial wastewater should be treated with a process reasonably selected according to its specific water quality. It is particularly important to note that for wastewater treatment using aerobic biological treatment processes, the biodegradability of the wastewater should be considered. Generally, COD/BOD5 > 0.3 is required. If this requirement is not met, anaerobic biological hydrolysis acidification can be considered to improve the biodegradability of the wastewater, or physical or chemical methods of non-biological treatment can be considered.

 

2. Wastewater treatment level

This is the main basis for selecting wastewater treatment processes. The degree of wastewater treatment depends on the water quality characteristics, the destination of the treated water, and the self-purification capacity of the water body into which the wastewater flows. However, at present, the determination of the degree of wastewater treatment mainly follows the requirements of relevant national laws, regulations, and technical policies. Usually, environmental management departments control the discharge concentration of wastewater according to the "Comprehensive Wastewater Discharge Standard" and related industry discharge standards. Some regions with higher economic development levels have also stipulated stricter local discharge standards. Therefore, regardless of the type of wastewater to be treated or the treatment process and degree adopted, the treated water must meet the standards as the basis and prerequisite. Pollution of the water environment should be prevented and controlled in accordance with laws, regulations, and policies.

 

3. Construction and operating costs

When considering construction and operating costs, the premise should be that the treated water meets the water quality standards. Under this premise, processes with low engineering construction and operating costs should be given priority. In addition, reducing the land area is also an important measure to reduce construction costs.

 

4. Difficulty of project construction

The difficulty of project construction is also one of the influencing factors in the selection of processes. For example, in places with high groundwater levels and poor geological conditions, treatment structures with large depths and high construction difficulty are not suitable.

 

5. Local natural and social conditions

Local natural conditions such as topography and climate also have a certain impact on the selection of wastewater treatment processes. For example, in areas with cold climates, processes that can operate normally in the cold season after taking appropriate technical measures and ensure that the water quality meets the standards should be adopted.

 

Local social conditions such as raw materials, water resources, and electricity supply are also factors that should be considered when selecting processes.

 

6. Wastewater volume

In addition to water quality, wastewater volume is also an influencing factor. For wastewater with large variations in volume and quality, processes with strong shock load resistance should be considered first, or buffer equipment such as regulating tanks should be considered to minimize adverse effects.

 

7. Whether the treatment process creates new contradictions

The wastewater treatment process should pay attention to whether it will cause secondary pollution problems. For example, pharmaceutical wastewater contains a large amount of organic matter (such as benzene, toluene, bromine, etc.), and organic waste gas will be emitted during aeration, affecting the surrounding atmospheric environment; the gasification wastewater from fertilizer plants is recycled after sedimentation and cooling treatment, and the cooling tower exhaust gas will contain cyanide, polluting the atmosphere; in the treatment of dimethoate wastewater from pesticide plants, the alkaline method is used to degrade dimethoate. If lime is used as an alkalizing agent, the resulting sludge will cause secondary pollution; when treating wastewater from printing and dyeing or dye factories, sludge disposal is a key issue to consider.

 

In short, the selection of wastewater treatment processes should comprehensively consider various factors, and technical and economic comparisons of multiple schemes should be carried out before a conclusion can be drawn.