Understand the principle of sewage treatment

With the development of economy, water pollution is becoming more and more serious, the state has gradually increased the intensity of urban sewage treatment, especially in recent years, the scale of its investment continues to expand, and the construction speed of sewage treatment plants has accelerated significantly. Many people are curious, what is the sewage package treatment process? Make it clear in an article. Understand the principle of sewage treatment

There are only two means of sewage treatment: one is separation, and the other is conversion.Understand the principle of sewage treatment

Separation is to separate some pollutants in sewage from the water body, the specific measures include precipitation, flocculation, centrifugation, air flotation, blowing and so on, the basic physical and chemical methods. Usually, the pollutants in sewage such as organic matter can be removed after preliminary separation and treatment, and the requirements are not high, so it can be directly discharged. This is called primary processing.

Some pollutants cannot be effectively separated, such as dissolved organic matter, ammonia nitrogen, phosphates, which need to be converted into harmless substances, or easily separated substances. The most important biochemical process in sewage treatment is the transformation work for example, dissolved organic matter is removed by converting organic matter into carbon dioxide (which is mostly harmless and easily separated from water) and biological sludge (harmful, but also easily precipitated and separated). This is called secondary processing. There are many means of conversion, such as various advanced oxidation, acid-base neutralization and so on. The cyanide sewage produced by the Tianjin explosion accident can only be broken by the strong oxidation of hydrogen peroxide to break the C-N bond and make it harmless.

The process of domestic sewage plant is usually 1 grid 2 primary precipitation 3 biochemical treatment 4 secondary precipitation 5 disinfection. From the above classification, 124 is separation and 35 is transformation. This separate type of process, although stable and easy, but occupies a large area, high construction costs, long residence time (can be understood as a large volume of structures occupy a large area).

Now new technologies are increasingly inclined to combine separation and conversion into a set of systems to reduce costs and improve efficiency, such as membrane biological treatment process (MBR), which is the biochemical process and primary and secondary sedimentation into a pool, so obviously the footprint is greatly reduced. Although the cost of the membrane process is still high, with the advancement of technology, the cost will be lower and lower, and it will be more and more popular.