What are the advantages of nanofiltration membranes for treating paper mill wastewater?

What are the advantages of nanofiltration membranes for treating paper mill wastewater?

Papermaking wastewater is an important factor causing environmental pollution, membrane separation technology to treat pulp and paper industry wastewater has been more mature in foreign countries, mainly using nanofiltration and ultrafiltration to treat pulping wastewater and useful by-products. Nanofiltration membranes can replace absorption and electrochemical methods to remove the chlorinated lignin produced in the process of dark lignin and wood pulp bleaching, because many colored substances in the pollutants are negatively charged, which is easy to be intercepted by the negatively charged nanofiltration membrane, and does not pollute the membrane.

Nanofiltration membranes treat paper mill wastewater to obtain colorless, transparent, anionic waste-free permeate water. Moreover, the removal rate of COD and inorganic content of permeate water can reach more than 80%. The combination of nanofiltration and electrodialysis was used to treat the rinse effluent of the kenaf pulp mill, and as a result, almost all the anions were removed, which can basically be reused in the papermaking process.

Nanofiltration membrane is a technology of advanced treatment, in the sewage treatment plant, it is basically the last process, and the wastewater of the general paper mill is mixed in the comprehensive pool of the sewage plant, so the last nanofiltration membrane treatment can make the water quality reach the level of pure water, and the disadvantage is that the cost is too high.

The electroplating industry will produce a large amount of heavy metal ion wastewater containing copper, nickel, zinc, cadmium and other heavy metal ions in the production process, how to treat these wastewater cost-effectively and effectively reuse is of great significance for reducing environmental pollution and technological progress in the industry. The nanofiltration process is a pressure-driven membrane process between ultrafiltration and reverse osmosis, and its core element, the nanofiltration membrane material, can not only intercept low-molecular-weight substances, but also have a certain interception effect on ions due to its nano-sized micropores and surface charge. This property makes it promising for the treatment of electroplating wastewater.

Dow nanofiltration membranes offer the following benefits:1.Cross-flow filtration is commonly used in nanofiltration systems.

Cross-flow avoids clogging in the dead-end filtration process: the material passes through the membrane surface, liquids and small molecules pass through the nanofiltration membrane under pressure, and insoluble and macromolecules are retained.

2.With sufficient flow rate, the remaining material on the membrane can be stripped from the membrane surface. Continuous peeling reduces the degree of fouling of the membrane, thus maintaining a high permeability flux over time.

3.Cross-flow filtration is an effective, reliable, and cost-effective method for membrane separation.

4.In the process of dead-end filtration (e.g. plate and frame filter presses, rotary drum vacuum filters), it is also avoided to rely on the filter cake layer filtration. The separation takes place on the surface of the membrane, not on the cake layer, so the quality of the filtrate is uniform and stable throughout the process.

The quality of the filtrate depends on the membrane itself, so that the production process can be effectively controlled.

If you want to purify the wastewater discharged from a paper mill, you must first understand the water quality characteristics of the paper mill. The content of COD and suspended solids (SS) in papermaking wastewater is high, and the color is serious. The concentration of SS and COD in papermaking wastewater is high, and COD is composed of two parts: insoluble COD and dissolved COD, usually non-soluble COD accounts for most of the total COD composition, and when SS is removed in wastewater, most of the insoluble COD is removed at the same time.

Therefore, the main problem to be solved in waste paper wastewater treatment is the removal of SS and COD.

By adding cationic polyacrylamide, most of the SS can be removed, and most of the insoluble COD and partially dissolved COD and BOD can be removed by air flotation or precipitation method. The typical treatment process is as follows:

Waste water, screens, sumps, air flotation or sedimentation discharge.

Air flotation and sedimentation are both physicochemical treatment methods, and the treatment effect is related to the selected equipment, process parameters, coagulants, etc., and the COD removal rate is generally higher than that of the water in the middle of pulping, which can usually reach 70% to 85%. For small and medium-sized waste paper enterprises with a low concentration of 150m3 per ton of paper wastewater, the effluent water quality index can meet or approach the national discharge standard through air flotation or sedimentation treatment.

Papermaking wastewater can not be treated only by biochemical system, it needs to be treated with pretreatment or back-end treatment, pretreatment needs to be treated to a certain extent of effluent to achieve stable standards, and ferrous iron, PAC, decolorizing agent and other water treatment agents can be added at the front end for pretreatment.

The odor emitted by paper mill sewage is generally hydrogen sulfide and ammonia gas, which is relatively toxic. When the weather is hot, the sewage in the pond is acidified, and the sewage with the smell of acidification evaporates and diffuses in the air and drifts away with the wind. A sour smell often permeates the community, the smell is sometimes strong and sometimes faint, and the residents are unable to resist the stench, so they all hold their breath and cover their noses.

13,82,558 special 8916 paper mill sewage deodorant and papermaking sewage deodorant use a variety of plant extracts, and the application of modern technology is a high-efficiency deodorant, which not only has a high content of sterilization and disinfection substances, but also has a strong sterilization, disinfection and deodorization function. The sewage deodorant quickly undergoes polymerization and decomposition reaction after contact with the odor source, inhibiting the protein synthesis process of fungal substances, thereby killing and decomposing microorganisms, bacteria and viruses. So as to achieve the purpose of eliminating odors and maintaining fresh air.

Wright. Ryder's wastewater treatment methods can be roughly divided into chemical methods, physical methods, physical and chemical methods, and biochemical methods, among which the chemical method mainly uses the role of chemicals to adjust the pH value of the waste liquid, reduce and eliminate the color, and also has the effect of removing part of the biochemical oxygen consumption and solid suspended solids. Chemical methods include redox, ozonation, and photocatalytic oxidation.

Physicochemical methods include coagulation, adsorption, membrane separation, and some other methods. The physical method is based on the principle of physical action, mainly to remove insoluble solid suspended solids, but also to remove part of the substances that produce biochemical oxygen consumption, reduce and eliminate the color of wastewater. The biochemical method is to use microorganisms to degrade metabolic organic matter into inorganic matter to treat wastewater.

By artificially creating an environment suitable for the survival and reproduction of microorganisms, so that they can multiply in large numbers, so as to improve their efficiency of oxidative decomposition of organic matter. According to the types of microorganisms used, it can be divided into aerobic method, anaerobic method and biological enzymatic method, in which the method of wastewater treatment can be roughly divided into chemical method, physical method, physicochemical method, and biochemical method, in which the chemical method mainly uses the role of chemicals to adjust the pH value of the waste liquid, reduce and eliminate the color, and also has the effect of removing part of the biochemical oxygen consumption and solid suspended solids. Chemical methods include redox, ozonation, and photocatalytic oxidation.

Physicochemical methods include coagulation, adsorption, membrane separation, and some other methods. The physical method is based on the principle of physical action, mainly to remove insoluble solid suspended solids, but also to remove part of the substances that produce biochemical oxygen consumption, reduce and eliminate the color of wastewater. The biochemical method is to use microorganisms to degrade metabolic organic matter into inorganic matter to treat wastewater.

By artificially creating an environment suitable for the survival and reproduction of microorganisms, so that they can multiply in large numbers, so as to improve their efficiency of oxidative decomposition of organic matter. According to the type of microorganisms used, it can be divided into aerobic method, anaerobic method and biological enzymatic method.

It depends on what you want to do with it.

I know that one is to use a sewage heat exchanger and refrigeration, but it requires a sewage heat exchanger.

If you are interested in this, you can go to Renault** to find out.

There's that sewage treatment facility that can be purified.

Nanofiltration membrane separation technology is often applied to the treatment of industrial heavy metal wastewater, and the application of nanofiltration membrane separation technology is used to treat the wastewater generated in the production process of heavy industry: on the one hand, it can realize the first performance of more than 90% of the wastewater and passivate it; On the other hand, it can concentrate the metal ion content of pulmonary edema by about 10 times. The application of nanofiltration membranes in papermaking wastewater treatment can not only achieve the treatment of COD (about 90%) in wastewater, but also have a higher membrane flux compared to traditional polysulfone ultrafiltration membranes.

The function of nanofiltration membrane filtration is one of the reasons why many people choose it, because it can be retained.

microns between the particles. It allows macromolecules and dissolved solids (inorganic salts) to pass through, but retains suspended solids, bacteria, and large molecular weight colloids. The operating pressure of nanofiltration membrane is lower than that of reverse osmosis, but it is more expensive than reverse osmosis, so the general household water purifier is mainly ultrafiltration and reverse osmosis water dispenser.

In the industry, to see the specific requirements of water, if you want to meet the requirements of pure water, you must use reverse osmosis.

Ceramic membrane characteristics:

1. Good chemical stability, acid resistance, alkali resistance, organic solvent resistance; High mechanical strength, backwashable;

2. Strong antimicrobial ability; High temperature resistance;

3. Narrow pore size distribution and high separation efficiency.

The nanofiltration membrane can filter more than divalent metal ions in the water (the content of monovalent ions in the general water is very small, and they are all minerals beneficial to the human body), and the operating pressure of the nanofiltration membrane is much lower than that of reverse osmosis, and the water output is much higher than that of reverse osmosis, which can completely remove the calcium and magnesium ions that are easy to scale in the water, and the use of nanofiltration membrane is enough to meet the needs of drinking water.

Nanofiltration technology is a new generation of membrane technology, its membrane pores are not as small as reverse osmosis membranes, but it can effectively filter harmful substances in water, and its advantage is that it can retain some beneficial trace elements, such as potassium, calcium, sodium, magnesium, etc. Like my Haier Strauss Runquan water purifier HSNF2901-700 adopts this technology, the purification effect is good, and it is also very water-saving and core-saving, purifying 3 cups of water purification to produce a cup of wastewater, which is 9 times that of other water purifiers on the market, and the life of the nanofiltration membrane has also reached 2 years. The point is that it has a fast flow rate, and it takes less than 7s to receive a glass of 200ml of water, which can easily meet the daily washing, cooking, and direct drinking, and I am quite satisfied with it for a while.

Application areas of Heidenener nanofiltration membranes:

1.Applications in the food processing industry. At the same time, the nanofiltration membrane also has good desalination performance, which can effectively reduce the corrosion of salt to the evaporator, so it has been well used in the processing of cheese and yeast.

2.It is used in drinking water treatment equipment. In general, there are many applications for nanofiltration membranes in the field of softening and removal of organic matter in drinking water.

With the deterioration of the environment and the aggravation of water pollution, water quality problems have begun to receive more and more attention. Experiments have proved that nanofiltration membranes can remove pesticides, sulfates and nitrates produced during the disinfection process of drinking water, and its produced water quality standards are high and stable.

3.Applications in the pharmaceutical industry. The application of nanofiltration membranes can effectively purify and concentrate biochemical reagents, while also removing trace organic contamination and some low molecular weight salts.

4.Extraction and refining in the petroleum industry. In the process of offshore oil exploitation, nanofiltration membranes can be applied to separate and filter the wastewater discharged after the separation of seawater and **.

5.** and removal of small molecule organic matter. Nanofiltration membranes have the ability to separate small organic molecules.

Softened water treatment.

It can effectively intercept divalent ions, with low operating pressure and large water flux. Its main advantages are no sludge, no need for regeneration, complete removal of suspended solids and organic matter, simple operation, less land occupation, etc.

Drinking water purification.

Hyde Nanofiltration membranes can remove microtoxic by-products, trace amounts of herbicides, insecticides, heavy metals, natural organic matter and hardness, sulfates and nitrates generated by the disinfection process. At the same time, it has the advantages of good and stable treatment water quality, less chemical dosage, less land occupation, energy saving, easy management and maintenance, and basically zero discharge.

Nitrate removal from groundwater.

The permeate of the HEDENENER membrane contains a high content of nitrate, and after passing through the ion exchange column, the nitrate ions are exchanged by chloride ions, and the nitrate content in the water meets the requirements of drinking water.

Papermaking wastewater treatment.

Paper mill flushing wastewater contains a large number of pollutants, and Heidenener nanofiltration membranes can replace absorption and electrochemical methods to remove dark lignin and chlorinated lignin from the pulp bleaching process, because many of the organic matter in the pollutants is negatively charged, they are easily trapped by positively charged nanofiltration membranes, and do not cause large pollution to the membrane.