How to treat industrial polluted sewage with imported flocculants

The flocculation principle of imported flocculant can be divided into two types: chemical flocculation and physical flocculation. The former assumes that the particles agglutinate in a well-defined chemical structure and cause an unstable state of glial particles due to their chemical reaction with each other. The latter is due to the presence of an electric double layer and certain physical factors, and when an ionic solution with different electrical properties from colloidal particles is added, condensation will occur.

When condensation occurs, colloidal particles will lose their stabilizing effect or be electrically neutralized, and the unstable colloidal particles will collide with each other to form larger particles. When a flocculant is added, it ionizes and forms a valence bond with the ionic surface. In order to overcome the repulsive force of the ions, the flocculant will cause the particles to collide with each other due to agitation and Brownian motion, and as the particles gradually approach, hydrogen bonds and van der Waals forces will cause the particles to form larger particles.

Once the collision begins, the particles begin to agglutinate through different physical and chemical processes, and the larger particles are separated from the water and settled.

If the pollutants in the water are mainly in a colloidal state, inorganic flocculants should be preferred to destabilize and coagulate, and if the flocs are small, it is necessary to add polymer flocculants or use coagulants such as activated silica gel. In many cases, the combination of inorganic flocculants and polymer flocculants can significantly improve the coagulation effect and expand the scope of application. For polymers, the larger the amount of charge on the chain molecule, the higher the charge density, the more fully the chain can be extended, the larger the range of adsorption and bridging, and the better the coagulation effect.

Imported flocculants are used in many industries, including in the field of water treatment, the effective disposal of sewage and sludge in printing and dyeing factories has caused headaches for many manufacturers.

Therefore, our preferred imported flocculants for sludge treatment are polyaluminum chloride and polyacrylamide, and polyacrylamide flocculants are generally divided into anionic type, cationic type and non-ionic type. The choice of ionic flocculant should be tested and screened according to the characteristics of the sludge and the different treatment methods. However, if polyacrylamide is selected as the dehydrating agent for dehydration, the solid content of the dry sludge after dehydration can generally be greater than 25%, which can meet the transportation requirements, and the manufacturer can also accept the investment, operating costs and sludge disposal methods.

With the continuous intensification of pollution, the increase of pollution sources, water pollution has also become a problem that must be saved, water quality treatment requires a lot of processes and materials to complete, flocculant has become an indispensable product in the process of water purification. At present, most sewage treatment plants use flocculants in the treatment of sewage, generally polyacrylamide, polyaluminum chloride and so on. Moreover, in recent years, the research and development and application of new high-efficiency flocculants have made rapid progress.

Two types of flocculants are of interest. One is inorganic polymer flocculants; The other type is organic polymer flocculants.

Inorganic polymer flocculants include: basic polyaluminum chloride (PAC), polyaluminum sulfate (PAS), polysulfur aluminum chloride (PACS) and polyferric sulfate (PFS). Among them, the most representative PAC and PAS have the characteristics of wide adaptability to the water quality change of raw water treatment agents, good coagulation and purification effect, and low cost of chemicals.

The use of polyaluminium chloride in water treatment in Japan has surpassed that of aluminium sulphate. According to relevant information, there are also some water plants in China.

Countries attach great importance to the research and application of organic polymer flocculants. At present, the most widely used is polyacrylamide. Generally, according to its different functions, it is divided into anionic type, cationic type and non-ionic polyacrylamide.

Organic polymer flocculant has the advantages of low dosage, large floc and less sludge. As a result, it is developing rapidly. However, scholars from various countries have different opinions on its toxicity, and it needs to be used with caution in drinking water.

The use of polymer flocculants is becoming more and more widespread, because this not only reduces the amount of chemicals and reduces the amount of mud, but also increases the physical strength of the flocs, which is necessary for high-speed filtration. Anionic and nonionic polymers are also commonly used as coagulants and filter aids.

At present, the main coagulant used is inorganic activated silicic acid, which is used to increase the skeleton strength of the flocculant and improve the floc structure. In particular, it is more effective for the treatment of low-temperature and low-turbidity water. At the same time, ferrous sulfate is oxidized to ** iron with chlorine to improve the purification effect of the coagulant.

However, for the contaminated raw water, halogenated organic compounds represented by trihalomethanes are easy to be generated. This class of substances has mutagenic activity, so it needs to be analyzed and studied in depth.

The industrial solid-liquid separation process is generally made of polyacrylamide to use imported flocculants, which can be better treated, including sedimentation, clarification, concentration and sludge dewatering processes, and the application of industries is also relatively wide, according to the ** of sewage, it is mainly divided into two types: industrial wastewater and urban sewage.

Industrial wastewater: According to the chemical properties of the main pollutants contained in industrial wastewater, it is mainly divided into: organic wastewater containing mainly organic pollutants, inorganic wastewater containing inorganic pollutants, mixed wastewater containing both organic and inorganic substances, wastewater containing radioactive substances and cooling water contaminated by heat only, and heavy metal wastewater.

For example, the wastewater from the processing of food or crude oil is organic wastewater, while the wastewater from mineral processing and electroplating is inorganic wastewater.

According to the classification of industrial processing objects, it can be divided into: metallurgical wastewater, textile wastewater, papermaking wastewater, tanning wastewater, pesticide wastewater, oil refining wastewater, mineral processing industry, dyeing industry and sugar industry.

Activated sludge treatment method is commonly used for municipal sewage and industrial wastewater, and biochemical sludge is often a very hydrophilic colloid, with high organic content and extremely difficult to dewater. Treated with cationic polyacrylamide, the dosage is small, the dehydration efficiency is high, and it is easy to separate.

Alcohol plant wastewater, brewery wastewater, monosodium glutamate factory wastewater, sugar factory wastewater, meat products factory wastewater, beverage factory wastewater, textile printing and dyeing factory wastewater, etc. The effect of using cationic polyacrylamide is several times or dozens of times higher than that of anionic polyacrylamide, nonionic polyacrylamide or inorganic salts. This is because this type of wastewater is generally negatively charged.

Urban sewage: refers to the general term of sewage discharged into the urban sewage system, at the same time, urban sewage also includes domestic sewage and industrial sewage, urban sewage in the selection of polyacrylamide as a flocculant use, generally use cationic polyacrylamide, the ionization degree is generally about 40% 60%, of course, according to the different water quality, but also specific problems have to be analyzed.

The selection of polyacrylamide flocculant is mainly based on the different charge types of the sewage water quality and the muqi belt, and the cationic polyacrylamide, anionic polyacrylamide, nonionic polyacrylamide, etc. are selected according to the characteristics of the water quality. No matter what industry and what water quality, choosing the right model is the most critical, mutation events occur from time to time, once the change, we must be calm, do not just look at the problem itself, to find a way to solve it, itself polyacrylamide selection is a very experimental process.

The use of flocculant in urban sewage treatment plant is an important part of sludge treatment and disposal, and the use of flocculant plays a key role. When selecting a flocculant, it is necessary to carry out an actual flocculation experiment according to the characteristics of the local sludge. Shanghai Tunbao specializes in the field of water treatment, focusing on polyacrylamide and flocculant products, and can choose the matching flocculant according to the customer's requirements with different on-site processes and equipment, and choose the most applicable and best solution for different industries and regions of the customer.

The selection of flocculant should be based on the type and nature of the sludge organic polymer flocculant. When VSS SS in the sludge is high, the flocculant with high cationic degree should be selected as much as possible, and the amount of flocculant should be increased. When the SS concentration in the sludge is high, a flocculant with high molecular weight should be selected, and when the SS concentration is low, a flocculant with a lower molecular weight can be used. When the pH value of the sludge is high, the flocculant with the functional group of quaternary ammonium salt structure should be selected, and when the pH value is low, the flocculant with tertiary amine salt and quaternary ammonium salt structure can be used. The sludge dewatering of China's municipal sewage treatment plants mainly uses two models, belt filter press and centrifuge, and the requirements for flocculants are different, among which the belt filter press requires the use of flocculants with medium molecular weight and medium and high cationic degrees, and the centrifuge requires the use of flocculants with high molecular weight, medium and low cationic degrees and moderate cross-linking.

Look at the nature of sludge, sludge conditioning, sludge dewatering agent is generally used cationic imported flocculant, cationic polyacrylamide is used in the concentration of acacia in the front, in one thousandth, the amount of its use, depending on the concentration of one ton of sludge treated.

The treatment principle of PAM: cationic polyacrylamide will adsorb multiple negatively charged colloidal particles or negatively charged particles on its chain through electrostatic action, and aggregate the dispersed small particles into large particles, which plays the role of flocculation and filtration aid. Similarly, anionic polyacrylamide bridges multiple positively charged colloidal particles or particles.

Some sand and gravel plants, mineral processing plants, coal washing plants, etc. can choose weak ionization; Domestic sewage treatment plants, chemical plants, and glass powder settling need to choose more than medium ionization.

It is used as a necessary agent for sludge dewatering after chemical conditioning of lead cleaning sludge. Sludge dewatering performance can be greatly improved. It is generally convenient to configure, as long as it is configured according to the concentration of 1-3 (depending on which range the comprehensive performance of your dispensing equipment meets, do not mix it with a thick or unwashed medicine box when changing the dressing), pre-training can be used for 1 2 hours after dispensing and stirring, and it is best to use warm water in winter.

For industrial wastewater with strong acid and alkali, the neutralization reaction is carried out first, and the sedimentation and other treatments are carried out by using imported flocculants; When the wastewater requirements of some characteristic industries cannot change the pH of sewage, it is necessary to use high-quality flocculants, or even imported high-quality sewage flocculants.

Strong acidic sewage: We can neutralize strong acidic sewage by adding industrial alkaline materials, lime, etc., and when the pH value reaches the ideal value, we can add imported flocculants (polyacrylamide, polyaluminum chloride) for treatment.

Strong alkaline sewage: We can neutralize strong alkaline sewage by adding polyferric sulfate, ferrous sulfate, and industrial hydrochloric acid. Weakly alkaline wastewater can be neutralized by adding polyaluminum chloride, and when the pH value is adjusted to the ideal value, a sewage treatment agent (polyacrylamide flocculant) is added for treatment.