Water Treatment agents are necessary chemicals in the process of industrial water, domestic water and waste water treatment. Through the use of these chemicals, water can reach the inevitable quality requirements. Its primary effect is to control scale and sludge composition, reduce foam, reduce erosion of water contact data, remove suspended solids and toxic substances in water, deodorization, decolorization and softening water quality. At present, due to the rapid increase of water consumption in countries around the world, various environmental protection laws (water purification law) have been formulated one after another, and the requirements are increasingly stringent. Therefore, the development of efficient water treatment chemicals is very fast. In China, the contradiction with the increasingly serious water capital crisis is that the production ability of water treatment chemicals is very low, and the quality is not guaranteed. Therefore, it is urgent to speed up the development of water treatment chemicals, an environmental protection information property.
Water treatment chemicals include flocculant, corrosion inhibitor, scale inhibitor, biocide, laxative agent, cleaning agent, prefilming agent, defoamer, decolorizing agent, chelating agent, deoxidizing agent and ion exchange Resin. In this paper, flocculants and biocides are introduced systematically.
It was only after the introduction of large-scale chemical fertilizer plants in the 1970s that water treatment chemicals were paid attention to and gradually developed in China. There are several kinds of water treatment agents in China, such as scale inhibitor, corrosion inhibitor, bactericide and algaecide, inorganic coagulant and organic flocculant.
Water treatment chemicals can be divided into three categories
1、 Sewage Treatment chemicals
2、 Chemicals for industrial circulating water treatment
3、 Oil water separator
The commonly used water treatment chemicals are: scale inhibitor, corrosion inhibitor, bactericide (water treatment bactericide), cleaning agent, slime stripping agent, flocculant, coagulant, dispersant and other water treatment agents. Sodium Hexametaphosphate is also a kind of water treatment.
4. green water treatment chemicals PASP polyaspartic ACID
Water treatment chemicals, water quality testing agents, water quality testing instruments
The characteristics of the new water treatment agent are as follows
1. The reaction speed is fast, and it only takes half an hour to several hours to treat ordinary industrial wastewater.
2. It has a wide range of effects on organic pollutants, and has good degradation effect for refractory organic substances.
3. The process is simple, less investment, long service life, convenient operation and maintenance, ideal treatment effect and less consumption of micro electrolysis reagent.
4. After micro electrolysis treatment, the wastewater will form original ferrous or iron ions in the water, which has better coagulation effect than ordinary coagulants, and there is no need to add iron salt and other coagulants. The removal rate of COD is high, and it will not cause secondary pollution to the water.
5. It has good coagulation effect, can effectively remove chroma and COD, and greatly improve the biodegradability of wastewater.
6. This method can achieve the effect of chemical precipitation and heavy metal removal by reduction.
7. This paper analyzes the opportunities faced by the development of water treatment agents in China, and expounds the application status of environmental protection water treatment agents. It is considered that water treatment agents will develop rapidly in the direction of green water treatment agents, multi-component composite water treatment agents, nano materials, microbial flocculants and other new high-efficiency water treatment agents on the basis of continuous innovation of coagulation theory.
characteristic
Natural mineral wastewater treatment agent is a new product made of composite aluminosilicate non-metallic mineral as the main raw material and processed by special technology. It is essentially different from chemical synthetic water treatment agent. There are two states of slurry and powder. It is acid in nature and pH value is 3-4. The specific gravity of slurry is 1.5-1.6, and that of powder is 1.2-1.3. Color gray to dark gray.
Natural mineral wastewater treatment agent has five properties: adsorption, ion exchange, catalytic cracking, chemical conversion, physiological fertility. Application advantages:
(1) The most important advantage is that it can treat all kinds of refractory, especially toxic sewage;
(2) It can remove a little floating matter;
(3) It has the advantages of fast flocculation, low moisture content, high compactness and good dehydration, and is easy to be treated by pressure filtration;
(4) Sewage treatment facilities and processes are simple and easy to operate, which greatly reduces the one-time investment of project construction, and the operation cost is not high;
(5) The sludge produced by sewage treatment can be used as agricultural fertilizer additive, because the mineral raw material is heavy fertilizer additive. Thus, the secondary pollution is completely eliminated.
In the water treatment industry, not only all kinds of water treatment equipment are widely used, but also water treatment chemicals make great contributions to various industries. Water treatment chemicals include corrosion and scale inhibitor, flocculant, reducing agent, bactericide, catalyst, cleaning agent, etc. each agent has its own function and characteristics.
Flocculant property
The molecular formula of flocculant is + CH2 CHN, which belongs to linear polymer with molecular weight between 4 million and 20 million. The flocculant can make the high-efficiency mixed bacteria with flocculation and degradation function separated from urban domestic sewage to treat domestic sewage, and ensure that the removal rate of COD and BOD reaches 100%.
Properties of corrosion and scale inhibitors
It is a kind of corrosion inhibitor for boiler. The agent is composed of alkaline substance and organic compound, and corrosion inhibitor is added to prevent the heating surface from being corroded. The alkaline substance in the agent reacts with calcium and magnesium salts in water through chemical reaction in the boiler to form water slag, which is discharged out of the boiler through sewage discharge function after precipitation, so as to reduce the concentration of calcium and magnesium ions in water, so as to avoid scale formation in the boiler.
Detergent property
Cleaning agent is a kind of volatile solvent which can dissolve the penetrant, which is used to remove the surplus penetrant on the surface of the workpiece to be inspected. Some cleaning agents are specially designed to remove metal hydroxides, calcium carbonate and other similar scales attached to the surfaces of polyamide, polysulfone and membrane component membranes. Before using the cleaning agent, check the cleaning tank, pipeline, security filter and install new filter element.
Fungicide
Fungicide. Its function can be seen by its name. Bactericide is mainly a kind of medicament to eliminate bacteria, microorganisms and other harmful bacteria. In the world, it is usually used as a general term for the control of various pathogenic microorganisms. Fungicides do not produce potential hazards such as bromine, iodine, peroxide or peracetic acid.
Common technology
1. Sterilization and disinfection: the disinfection methods of water can be divided into chemical and physical methods. Physical disinfection methods include heating method, ultraviolet method and ultrasonic method; chemical methods include chlorination method, ozone method, heavy metal ion method and other oxidant methods.
2. Magnetization: the treatment of water by magnetic field effect is called magnetization treatment of water.
3. Precision filtration technology: microporous filter element and membrane made of special materials are used to intercept particles and bacteria in water by using their uniform pore size, so that they can not be removed and intercepted through filter element and filter membrane. Precision filtration can filter micron (μ m) or nanometer (nm) particles and bacteria. It is also widely used in advanced water treatment.
4. Ultrafiltration technology: ultrafiltration is a membrane separation technology. Under a certain pressure (the pressure is 0.07-0.7mpa, the maximum is not more than 1.05mpa), water flows on the membrane surface, water, dissolved salt and other electrolytes are small particles, which can penetrate the ultrafiltration membrane, and the particles with large molecular weight and colloidal substances are blocked by the ultrafiltration membrane, so that some particles in the water can be separated. The pore size of ultrafiltration membrane is determined by the interception test of certain molecular weight material, and expressed by the value of molecular weight.
5. Ozone: it is a kind of gas with special fishy smell and blue color at room temperature. Its molecular formula is O3. Ozone is an allotrope of oxygen, which can be decomposed into single oxygen atom at room temperature, and the single oxygen atom has strong oxidizability. Ozone can oxidize and denaturate the proteins of bacteria and fungi, which makes electrolytes lose their function, kill bacterial propagation and spores, viruses, fungi, etc., and destroy botulinum toxin. It can remove and kill toxic substances and bacteria in air, water and food, and remove peculiar smell. It is widely used in disinfection and sterilization of food production. In the process of disinfection and sterilization, ozone only produces non-toxic oxides, and the excess ozone is finally reduced to oxygen. There is no residue on the sterilized articles, so it can be directly used for food disinfection and sterilization.
6. Ion exchange: the so-called ion exchange is the equal charge reaction between ions in water and ions on ion exchange resin. The reaction process of ion exchange can take the H + type cation exchange resin HR and the Na + exchange reaction process in water as an example: HR + Na + = Na + + H +. From the above formula, the cation in water (such as Na) is transferred to the resin, and an exchangeable H on the ion exchange resin is transferred to the water. The transfer of Na from water to resin is a process of ion replacement. The process of H exchange from resin to water is called free process. Therefore, due to the results of dissociation and replacement process, Na and H exchange positions. This change is called ion exchange.
7. Ultraviolet: when the mercury lamp is ignited, it can emit ultraviolet light with the wavelength of 1400nm-4900nm (1nm = 10-10m). This light can penetrate the cell wall of bacteria, kill microorganisms, and achieve the purpose of disinfection and sterilization. The best UV wavelength is about 2600 nm. Ultraviolet disinfection is mainly used in drinking water with small treatment capacity. Its characteristics are: strong killing capacity, short contact time; simple equipment, convenient operation and management, the treated water is colorless, tasteless and free of toxic hazards; it will not increase the chlorine ions like chlorine gas in the process of disinfection.
8. Adsorption water purification technology: mainly refers to Activated Carbon and other substances with adsorption capacity. Here are only some characteristics of activated carbon, do a brief introduction: activated carbon is widely used in drinking water and food industry, chemical industry, electric power and other industrial water purification, dehydrogenation, deodorization and so on. Generally, it can remove 63% - 86% colloidal substances; about 50% iron; and 47% - 60% organic substances.
Common drugs:
Polyaluminum chloride
Polyaluminum chloride is a kind of inorganic polymer coagulant. Due to the bridging effect of hydroxyl ions and the polymerization of multivalent anions, polyaluminum chloride is an inorganic polymer water treatment agent with large molecular weight and high charge.
characteristic
1. The floc has the advantages of quick forming, good activity and good filtration.
2. It does not need to add alkaline additives, and its effect will not change in case of deliquescence.
3. It has wide adaptability and wide application.
4. The treated water is less salty.
5. It can remove the pollution of heavy metals and radioactive substances to water.
6. High effective ingredients, easy to store and transport.
effect
The flocculation performance of polyaluminum chloride is as follows:
a. Strong electric neutralization of colloidal substances in water.
b. The hydrolysate has excellent bridging adsorption on suspended solids in water.
c. Selective adsorption of soluble substances.
Polyaluminum chloride is an inorganic polymer coagulant. Due to the bridging effect of hydroxyl ions and polymerization of multivalent anions, the characteristics of polyaluminum chloride water treatment agent with large molecular weight and high charge are mainly determined by the working principle of pressure atomizer, which makes this drying system have its own characteristics. Because the products obtained by pressure spray drying are porous particles or hollow particulates, the pressure type spray drying and anionic Polyacrylamide are mostly used to obtain granular products. The granular products have excellent dustproof and fluidity.
purpose
1. Urban water supply and drainage purification: River water, reservoir water and groundwater.
2. Industrial water purification.
3. Urban sewage treatment.
4. Recovery of useful substances in industrial wastewater and waste residue, promotion of coal dust settlement in coal washing wastewater, and starch recovery in starch manufacturing industry.
5. Various industrial wastewater treatment: printing and dyeing wastewater, leather wastewater, fluoride wastewater, heavy metal wastewater, oily wastewater, papermaking wastewater, coal washing wastewater, mine wastewater, brewing wastewater, metallurgical wastewater, meat processing wastewater F, sewage treatment.
6.Paper sizing
7.Refining of sugar liquor
8. Casting
9.Wrinkle proof cloth
⒑ catalyst support
⒒ pharmaceutical refining
12.Quick setting of cement
13.Cosmetics raw materials
Polyferric sulfate
The morphology of PFS is light yellow amorphous powder solid, easily soluble in water, 10% (weight) of aqueous solution is reddish brown transparent solution, hygroscopicity. Polyferric sulfate is widely used in the purification of drinking water, industrial water, various industrial wastewater, urban sewage, sludge dewatering and so on.
Application characteristics
Compared with other inorganic flocculants, PFS has the following characteristics:
1. New type, high quality and high efficiency inorganic polymer flocculant of iron salts;
2. Excellent coagulation performance, dense alum and fast settling speed;
3. The water purification effect is excellent and the water quality is good. It does not contain harmful substances such as aluminum, chlorine and heavy metal ions, and there is no water phase transfer of iron ions. It is non-toxic, harmless, safe and reliable;
4. Turbidity removal, decolorization, deoiling, dehydration, sterilization, deodorization, algae removal, COD, BOD and heavy metal ions in water are significant;
5. The pH value range of the water body is 4-11, and the best pH value is 6-9. After purification, the pH value and total alkalinity of the raw water change little, and the corrosion to the treatment equipment is small;
6. The purification effect of micro polluted, algae containing, low temperature and low turbidity raw water is remarkable, especially for high turbidity raw water;
7. The dosage is small, the cost is low, and the treatment cost can be saved by 20% - 50%.
Characteristics of oily wastewater treatment
Flocculation technology is widely used in the treatment of oily wastewater because of its strong adaptability, removal of emulsified oil and dissolved oil and some complex macromolecular organic compounds which are difficult to be biodegraded. The commonly used flocculants include inorganic flocculant, organic flocculant and composite flocculant.
Among inorganic polymer flocculants, polyaluminum chloride, polyferric sulfate and other low molecular weight inorganic flocculants have good treatment effect, low price, low dosage and high efficiency, so they are widely used.
polyacrylamide
Polyacrylamide (PAM) is a water-soluble polymer, insoluble in most organic solvents. It has good flocculation and can reduce the friction resistance between liquids. According to the ionic characteristics, PAM can be divided into four types: non-ionic, anionic, cationic and amphoteric.
Principle of action
1) Principle of flocculation: when PAM is used for flocculation, it is related to the surface properties of the flocs, especially the dynamic potential, viscosity, turbidity and the pH value of the suspension. The dynamic potential on the surface of the particles is the reason for the inhibition of agglomeration. Adding PAM with opposite surface charge can reduce the dynamic potential and coagulate.
2) Adsorption bridging: PAM molecular chain is fixed on the surface of different particles, and the polymer bridge is formed between the particles to form aggregates and settle.
3) Surface adsorption: various adsorption of polar group particles on PAM molecule.
4) Strengthening effect: PAM molecular chain and dispersed phase are linked together by various mechanical, physical and chemical actions to form a network, thus playing a reinforcing role.
Scope of application
1. It can be used as retention aid and reinforcing agent in papermaking process.
2. It is used as coagulant aid, flocculant and sludge dehydrating agent in water treatment.
3. It is used as dewatering agent and oil displacement agent in oil drilling and production.
4. PAM is also widely used in thickening, stabilizing colloids, drag reduction, bonding, film-forming, biomedical materials and so on.
