Water treatment pretreatment process

After World War II With the rapid development of industry and cities, the water pollution situation worldwide has gradually worsened. Since the 1980s, China has also experienced a rapid deterioration of its water ecological environment, which has become very serious in recent years. In the face of changes in water source quality, especially pollutants such as organic matter, ammonia nitrogen, algae, and chromogenic substances, conventional drinking water treatment processes can no longer guarantee the hygiene and safety of the treated water Therefore, pretreatment of drinking water is necessary.

Pretreatment addresses the shortcomings of traditional processes In order to strengthen water treatment processes and improve the quality of treated water, before conventional treatment processes, certain physical, chemical, or biological methods are used to remove pollutants from the water, especially those that conventional processes cannot effectively remove; at the same time, it can enable conventional processes to function better, reduce the burden on conventional and advanced treatment, and better play the overall role of water treatment processes.

Pretreatment processes can be divided into oxidation methods and adsorption methods Among them, oxidation methods can be further divided into biological oxidation methods and chemical oxidation methods.

Various methods have different specific processes A brief introduction is given below.

Biological pretreatment mainly relies on the life activities of microorganisms (oxidation, adsorption, biological flocculation, etc.) to remove pollutants from water. Among these microorganisms the vast majority that play a major role in water purification belong to oligotrophic microorganisms, which have long generation cycles and slow reproduction rates. To ensure treatment effectiveness and accelerate purification efficiency sufficient microbial biomass (biological concentration) must be ensured. Because microorganisms adhere to the carrier filler in the biofilm method, a relatively stable growth environment can be obtained, which is suitable for the survival and reproduction of microorganisms with long generation cycles. Therefore, the vast majority of biological pretreatments use the biofilm method.

Currently used biofilm methods mainly include biological contact oxidation, ordinary biological filters, biofilters, biological rotating discs, and biological

fluidized beds, etc. Among them, biological contact oxidation has been the most extensively studied and applied. Biological contact oxidation is also called submerged (immersed) biological filtration. Fillers are placed in the pool as microbial carriers, and oxygenated water (or aeration in the pool) flows through the filler material forming a biofilm on the filler; during the contact between water and the biofilm, pollutants in the water are degraded and removed through the biofilm's biological flocculation, adsorption, and oxidation etc.

Biological contact oxidation was initially applied to wastewater treatment. With the pollution of water sources conventional water treatment processes cannot achieve the required drinking water quality or industrial water quality. In this case biological contact oxidation is applied to water pretreatment and has been extensively studied, achieving significant results.

Fillers and operating methods are the core of biological pretreatment contact oxidation The operating method is closely related to the specific filler, so the choice of filler is crucial for biological pretreatment contact oxidation. In the development of biological pretreatment contact oxidation, many different types of fillers have appeared. For example, according to shape, there are honeycomb, bundle, corrugated plate, circular spoke

shape, regular spherical, irregular granular, etc. According to properties, there are hard, soft, semi-soft...