Do you know which of the seven commonly used chemicals for water treatment?

"Water Treatment agents (also known as water treatment agents, water treatment Chemicals, Water Treatment Chemicals) are chemical agents commonly required for the disposal of industrial water, domestic water, and wastewater."

The main function is to control the formation of scale and sludge, reduce the corrosion of materials in contact with water, remove suspended solids and toxic substances in water, deodorize and decolorize, soften and stabilize water quality. Water treatment agents are widely used in chemical, petroleum, light industry, daily chemical, textile, printing and dyeing, construction, metallurgy, machinery, medicine and health, transportation, urban and rural environmental protection and other industries, including wastewater and sewage treatment, cooling water and boiler water treatment, seawater and brackish water desalination, membrane separation, biological treatment, flocculation and ion exchange technology required agents.

1. Polyacrylamide (PAM)

Polyacrylamide is a linear polymer. The biggest difference between PAC and PAC is that one is organic and one is inorganic. PAM is a glassy solid at room temperature and can be dissolved in water in any proportion, and its aqueous solution is a transparent liquid, which is generally used in the flocculation process. However, the actual use of PAM is complex. After the optimal amount is determined, it needs to be added in batches, constantly stirred, and completely melted before it can be put into use.

2. Polyaluminum chloride

Polyaluminum chloride (PAC) is a water-soluble inorganic polymer between ALCL3 and AL(OH)3. This product has a strong bridge adsorption performance. During the hydrolysis process, physical and chemical processes such as coagulation, adsorption and precipitation occur, which are generally used in the coagulation process.

PAC comes in a variety of colors, such as white, pale yellow, golden, brown, tan and coffee. According to different raw materials and processes, the PAC produced has different colors, of which white has the highest purity and the highest price. Light yellow is more high-end, often used for drinking water treatment; Gold is widely used and moderately priced; The rest are used in special environments such as industry.

3. Alkali tablets

Caustic soda, also known as sodium hydroxide, is an inorganic compound that is mainly used to adjust the PH value, because caustic soda is a strong alkaline substance, and conventional sewage is mostly acidic. It is mainly used in the air floating pool or regulating pool, and a reasonable PH environment can also avoid the phenomenon of sludge floating. In addition, caustic soda can filter heavy metal ions to a certain extent by precipitation. Caustic soda is also one of the common chemicals used in sewage treatment.

4. Biological antibacterial agent

Biological agents refer to the target microorganisms (effective bacteria) through industrial production and reproduction, the use of porous substances as adsorbents (such as peat, vermiculite) made of live bacteria preparations, adsorption of bacteria fermentation fluid. Generally liquid, powder, particles, etc. Microbial supplementation for biological treatment in wastewater treatment.

5. Carbon source

Nutrients that contain carbon and can be used by microorganisms for growth and reproduction are collectively referred to as carbon sources. We often have sugars, fats, organic acids, etc. The carbon source is equivalent to food for microorganisms, a carbon shelf that provides them with energy and synthetic products.

6. Citric acid

Citric acid is an important organic acid. It is colorless crystal, odorless, has a strong sour taste, easily soluble in water. It is mainly used for backwashing of MBR system, which can dissolve the salt compound dirt on the surface of MBR film.

7. Sodium hypochlorite

Sodium hypochlorite is an inorganic compound, which is mainly used in bleaching, industrial wastewater treatment, textile, manufacturing and many other fields. In water treatment, it is used as water purifier, fungicide, disinfectant and backwash of organic pollution of MBR membrane.

01. Application field

The application field of water treatment agents can be divided into industrial water treatment, municipal and drinking water treatment, sewage and wastewater treatment, and seawater desalination according to the different objects and ways of water treatment of the end customers. Industrial water treatment Water treatment agents are mainly used in circulating water cooling systems and industrial boiler water. Circulating cooling water is used to cool the used water through the cooling tower, and the whole water system is in a dynamic process of continuous circulation, which belongs to multiple uses. Circulating water cooling systems need to address coalescence, corrosion and microbial issues in lines and equipment. The chemicals used in industrial circulating water treatment mainly include scale inhibitor, corrosion inhibitor, bactericidal and algicidal agent, cleaning agent and pre-film agent. The common methods of industrial boiler water treatment are water treatment outside the pot and water treatment inside the pot, the main agents used are corrosion and scale inhibitor, oxygen removal agent, feedwater alkali reduction agent, ion exchange agent, regenerant, softener, alkalicity regulator, scale cleaning agent and so on. In the process of producing qualified domestic water, appropriate water treatment chemicals must be added to make the water quality of the factory meet the national standard. Key areas to be addressed are: algal control to reduce toxic or odorous algae in reservoirs; Flocculation process, removal of suspended and colloidal solids such as clay; Softening process, removal of calcium and magnesium salts, especially carbonate and bicarbonate; Corrosion control, used to reduce the corrosion of pipelines; Sterilization and disinfection. Municipal and drinking water treatment involved in the water treatment agents are generally bactericidal algaecide, flocculant, corrosion inhibitor and so on. Sewage and wastewater treatment If the sewage or wastewater is discharged directly into the natural environment, the pollutants contained in it will pollute the ecological environment, so it is necessary to remove all the pollutants in the sewage. It is usually necessary to combine a variety of sewage treatment methods to achieve layer by layer purification and step by step filtration until the pollutants in the water are completely removed. The water treatment agents involved in sewage treatment are generally flocculant, sludge dehydrating agent, defoamer, chelating agent, decolorizing agent and so on. The development of seawater desalination began in the 1960s, and after the development of recent decades, seawater desalination technology has been relatively mature. Among them, distillation method and membrane method have become the mainstream technology. For the membrane process, in order to reduce the impact of scale deposition on the reverse osmosis membrane, it is necessary to add scale inhibitor, detergent, flocculant, scale inhibitor and dispersant to the water. For distillation method, it is easy to produce pot scale and thus reduce the evaporation efficiency. Seawater can be pre-treated to reduce the impact, and polyphosphate, organic phosphoric acid, phosphate-based polycarboxylic acid, etc. can be added to raw water to soften the water quality. Calcium, magnesium ions and other metal ions can be chelated to make it difficult to precipitate, thus preventing the formation of scale.

02. Future opportunities

Development prospect

Energy conservation and emission reduction needs China's vast territory, a large population, the per capita occupancy of fresh water resources is less, and the reuse rate is relatively low, especially in recent years due to the rapid development of the national economy, people in the production and living activities of the water consumption is larger, the pollution problem has continued to intensify. In the process of industrial cooling water treatment, the application of water treatment agents can play a very high quality application effect. In addition, the application of water treatment agents in urban sewage treatment can also play a great auxiliary role, which is of great significance for the improvement of water resource utilization efficiency, so as to alleviate the shortage of water resources. The improvement of environmental standards In order to manage and improve the water environment quality in China's river basin, the state has introduced various policies and gradually raised the standards of sewage discharge. This also points out a very clear direction in the research and development of the new water treatment agent, which brings a good opportunity for the development of the industry. In terms of the current overall situation of China's industrial development, the most widely used scale inhibitors are mainly phosphorus products, and the country needs to consume about 100,000 tons of scale inhibitors every year. Most of these phosphorus-containing compounds end up in natural water bodies, causing eutrophication in rivers and lakes, posing a serious threat to the ecological environment. Therefore, at present, the research and promotion of non-toxic, non-phosphating and biodegradable water treatment agents is very important. Technical system support At present, China's water environment management is gradually changing from the previous total control to the target management of specific basins, the state is vigorously promoting the construction of water pollution treatment technology system and integrated management system, the development of water treatment agents has formed a very high quality technical support, showing a broader development platform.

03. Development opportunities

Innovation is the driving force for the sustainable development of water treatment agents, green is the future direction of development of water treatment agents, the development of low phosphorus, non-nitrogen, biodegradable, non-toxic and harmless, low-cost green water treatment agents suitable for China's environmental protection requirements, will become the future direction of development of water treatment agents in China. In recent years, with the formation of the depletion flocculation mechanism of organic polymer flocculants such as adsorption bridging, adsorption electric neutralization, and polymer-particulate surface complex formation, And the research on the mechanism of polyelectrolyte complex flocculation and adsorption micelle flocculation of refractory organic compounds to strengthen the flocculation mechanism provides a theoretical basis for the development and application of organic polymer flocculants and multiple composite flocculants, a number of new efficient and environmentally friendly organic polymer flocculants and multiple composite flocculants have been developed, achieving a new breakthrough in water treatment agents. Green water treatment agents The development of green water treatment agents has experienced the process from natural polymer green water treatment agents to artificial synthetic polymer green water treatment agents. The development of new green water treatment agents with high scale inhibition, good biodegradability, non-toxic, phosphorus free or low phosphorus is the development direction of water treatment agents in the 21st century. 

However, at present, only scale inhibitors and corrosion inhibitors have made certain progress in greening, while flocculants, as the most important and the most used reagents, still have secondary pollution problems in the inorganic and organic flocculants currently used, and are easy to cause significant harm to human health, so the research and development of their greening process should be increased. In the development process, natural products such as agricultural and forest products are used as raw materials, supplemented by W/W emulsion polymerization technology, so that the production and use of green, and no secondary pollution. Multi-component composite water treatment agent multi-component composite water treatment agent is a kind of water treatment agent with one dose of multi-effect, such as polysilicic acid and aluminum salt composite flocculant, is a new type of inorganic polymer coagulant, is developed on the basis of activated silicic acid (that is, polysilicic acid) and aluminum salt coagulant composite product, and has electric neutralization and adsorption bridging effect. This kind of coagulant has the advantages of good coagulation effect, low price and low amount of residual aluminum in the treated water. Another example is the polyhalogenated alcohol thiazaline quaternary ammonium salt flocculant, which has the characteristics of strong flocculation ability, especially suitable for the separation of ore and water in beneficiation operations, and also has certain bactericidal and slow-release effects. The characteristics of multiple compound water treatment agents with multiple effects in one dose attract more and more researchers to engage in the research and application development of its preparation technology. Nanomaterials, microbial flocculants and other new high-efficiency water treatment agents 

(1) Nanomaterials have small size effect, surface effect, quantum size effect, macro quantum tunnel effect, etc., as a new high-efficiency water treatment agent, they are placed on high hopes. At present, the use of nano TiO2 photocatalytic degradation of toxic organic matter, carbon nanotube modification to remove heavy metals and other research has made a breakthrough, which has set a precedent for the development of nanomaterial water treatment agents. 

 (2) Microbial flocculants are non-toxic biomolecular compounds, including functional proteins or functional polysaccharides, with unique properties of biodegradation. Compared with other flocculants, microbial flocculants have the advantages of easy solid-liquid separation, less precipitate formation, easy to be degraded by microorganisms, non-toxic and harmless, and strong practicability. At present, there are many researches on microbial flocculants, and some researchers have used inorganic - organic polymer flocculants in combination, and achieved good results.