Can ultrafiltration membranes remove organic matter from water?

Can ultrafiltration membranes remove organics from water?

The answer is no. It is a misconception that ultrafiltration can easily remove organics from water.

1. On the morphology of organic matter in water.

According to the morphology, the organic matter in the water is also the same as the inorganic matter in the water, which can be divided into three categories: suspended, colloidal and dissolved.

The definition of dissolved organic matter is understood in terms of the method of determination. At present, the commonly used determination method is to filter the water sample through or filter membrane, and the organic matter in the water after passing through the filter membrane is regarded as dissolved organic matter, and the organic matter without passing through the filter membrane is used as suspended and colloidal organic matter. Some people choose filter membranes because the water that permeates the filter membrane is used as zero turbidity water in the preparation of turbidity-free water.

The test shows that after the water passes through or filters the membrane, it has little effect on the amount of organic matter in the water, so the organic matter in the water passing through the filter membrane is generally regarded as the dissolved organic matter.

According to this viewpoint, the COD measured in water analysis can also be divided into two parts: COD of suspended and colloidal organic compounds and COD of dissolved organic matter. The raw water is first coagulation, clarification, filtration before the ion exchange of the inlet water, reverse osmosis inlet water after filtration and then through secondary coagulation or fine sand filtration, such water, it should be said that the suspended and colloidal organic matter has been mostly removed, most of the COD of the water is the COD of dissolved organic matter. The test shows that the removal rate of dissolved organic matter in the water can reach more than 90% in the coagulation, clarification and filtration stages of raw water, sometimes even 0, while the removal rate of suspended and colloidal organic matter in water can reach more than 90%.

Therefore, it is not exact and comprehensive to talk about how much organic matter can be removed from the water by a certain treatment method, i.e., what is the COD removal rate. The difficulty in water treatment is not how much the total organic matter (COD) removal rate can be increased, because in suspended and colloidal organic content of high water, the general coagulation, clarification and filtration methods can be applied to increase the total organic matter (COD) removal rate to a very high value.

Therefore, the organic matter in the reverse osmosis (or ion exchange) influent water is mainly dissolved organic matter, and the COD index of reverse osmosis (or ion exchange) influent water mainly refers to the COD of dissolved organic matter. The main task of achieving COD compliance in reverse osmosis (or ion exchange) influent water is also to reduce the amount of dissolved organic matter in the water.

With the popularization of membrane technology, membranes are increasingly used in water treatment. In recent years, two membrane systems (UF+RO) and three membrane systems (UF+RO+EDR) often appear in pure water treatment, in which ultrafiltration is used as a pre-treatment for reverse osmosis, which can effectively remove particles (suspended solids and colloids) in the water, so that the SDI value of reverse osmosis influent water reaches the standard (<4, and can even be reduced to 1 2), effectively protecting the reverse osmosis membrane. However, in some seriously polluted raw water, some people also use ultrafiltration membrane, believing that it can not only reduce the SDI value, but also remove organic matter in the water, so that the COD value of the RO inlet water can be reduced or even reach the standard (COD<2 3mg L), thereby reducing the risk of organic matter pollution of the RO membrane.

However, the actual use shows that many raw water with serious pollution and high CODMN, after the use of ultrafiltration membrane, the COD of RO inlet water is not significantly reduced, and the ultrafiltration membrane itself is seriously polluted, frequent cleaning, and the ultrafiltration membrane is more expensive, which has a very adverse impact on the safety and economy of pure water preparation.

Therefore, it is a misconception that ultrafiltration can easily remove organics from water.

OK. The removal rate of ultrafiltration membranes is about 10%-70%. The main function of ultrafiltration membrane is that in addition to separating water molecules and ions, other substances can basically be filtered out.

Polymers can be removed, after all, ultrafiltration only has micron pores, and molecules below this pore size cannot be retained. Protein can basically intercept 95%, and the size of polypeptides basically begins to be unretained.

Commonly used in water treatment is the molecular weight cut-off of 15 300,000 ultrafiltration membrane, due to the low molecular weight of dissolved organic matter in water, large pore size ultrafiltration membrane can not intercept low molecular weight dissolved organic matter in water, the removal rate is very low, most of the molecular weight less than the membrane pore size of the organic matter will penetrate the ultrafiltration membrane in the treatment.

A method for the effective removal of harmful substances by ultrafiltration membranes.

What can be filtered by ultrafiltration membranesUltrafiltration membranes are mainly used in industrial water to separate bacteria, heat sources, colloids, suspended impurities and macromolecular organic matter; purification of drinking water and mineral water in the food and beverage industry; concentration, purification and clarification of fermentation, enzyme preparation industry, pharmaceutical industry; fruit juice concentration and separation; separation, concentration and clarification of soybeans, dairy, sugar industry, wine, tea, vinegar, etc.; purification of industrial wastewater and domestic sewage; Electrophoretic paint ** and other items.

Ultrafiltration membranes.

Organics, colloids, large suspended solids, particles, bacteria, etc.

Ultrafiltration membrane is a type of microporous filtration membrane with a nominal pore size range of less than microns. It is used in the separation, concentration and purification of biological products, pharmaceutical products and food industry. It is also used in terminal treatment units in blood treatment, wastewater treatment and ultrapure water preparation.

In the screening process of ultrafiltration membrane, the pressure difference between the two sides of the membrane is the driving force, and the ultrafiltration membrane is used as the filter medium, under a certain pressure, when the stock solution flows through the membrane surface, many small micropores densely covered on the surface of the ultrafiltration membrane only allow water and small molecule substances to pass through and become permeable liquid, and the substance with a volume larger than the micropore size on the membrane surface in the stock solution is intercepted on the inlet side of the membrane and becomes a concentrate, so as to achieve the purpose of purification, separation and concentration of the stock solution. There are about 6 billion micron pores on the wall of each meter-long ultrafiltration membrane filament, and its pore size only allows water molecules, beneficial minerals and trace elements in water to pass through, and the volume of the world's smallest bacteria is currently known to be in microns, so bacteria and colloids, rust, suspended solids, sediment, macromolecular organic matter, etc., which are much larger than the volume of bacteria, can be intercepted by the ultrafiltration membrane, so as to achieve the purification process.

What impurities can ultrafiltration membranes remolate?

The ultrafiltration membrane mainly filters the incoming water according to the pore size, and the pore size is usually between microns, which means that the ultrafiltration membrane can only filter impurities larger than its pore size, but cannot filter which impurities are smaller than the membrane pore size.

Substances filtered by ultrafiltration membranes in various industries:

1.Ultrafiltration membranes in the food industry can effectively filter proteins, lactose, colored proteins, polysaccharides and other colloidal impurities in milk or whey.

2.Biochemical fermentation broth separation and refining, enzyme concentration and refining, sugar and xylitol clarification and filtration.

3.Ultrafiltration membranes can effectively filter most of the bacteria in the water, and can achieve the effect of sterilization and disinfection.

4.In the field of medicine, ultrafiltration membranes can filter impurities such as enzymes, viruses, nucleic acids, and special proteins.

5.In biochemical production, drugs (such as alkaloids, hormones, etc.) can be extracted from animals and plants

6.Impurities such as colloids, rust, suspended solids, sediment, and macromolecular organic matter can also be removed by ultrafiltration membranes.

7.Electrophoretic paints in industry can also be retained, and ultrafiltration membranes with excellent anti-fouling properties can also be used for electrophoretic paints**.

What impurities can't be filtered by ultrafiltration membranes?

Although ultrafiltration membranes can filter many impurities, some impurities smaller than the pore size of ultrafiltration membranes cannot be filtered, such as water alkali, odor, heavy metals, calcium, magnesium ions and trace elements, which usually need to be treated with reverse osmosis membranes, nanofiltration membranes or ion exchange resins to remove.

OK. The ultrafiltration membrane is in operation for a long period of time, under the influence of concentration polarization, the gel layer and the pollutant deposit layer are gradually formed, and under the action of the pressure difference, the fluid resistance is significantly increased, the permeable flux decreases sharply, and when the flux cannot be restored by physical methods, it must be cleaned with chemical cleaning agents.

When cleaning membranes, it should be noted that the composition and nature of the contaminants must be clarified in advance. In this way, an effective cleaning method can be adopted. If you can rinse with clean water, you should try to rinse with clean water as much as possible. Chemical cleaning methods should only be considered when rinsing with water does not achieve the desired effect.

No. The single-stage ultrafiltration membrane can remove most of the impurities in the water, but it cannot effectively remove the bleaching powder (residual chlorine) and heavy metals in the water.

A simple ultrafiltration membrane cannot filter out heavy metals at all, which is determined by the filter pore size of the membrane, because the filter pore size of the ultrafiltration membrane is microns), and heavy metals such as lead Pb2+ ions are completely able to pass through the pore size of the ultrafiltration membrane, and the filter pore size of the RO reverse osmosis membrane is not clear microns, that is, nanometers, all the heavy metal ions can be filtered out before drying.

Ultrafiltration membrane is a membrane separation technology widely used in the field of water treatment, and its main role is to purify and improve water quality by effectively filtering microorganisms, suspended solids, organic matter, particulate matter and other impurities in water, and ensuring the safety and stability of water quality. Specifically, it can effectively remove microorganisms such as colloidal substances, bacteria and viruses in the water to meet the requirements of the effluent standard, and at the same time ensure the stability of water quality, making the water more clear and transparent, better tasting and healthier. Therefore, in the fields of drinking water, pharmaceutical production, chemical industry, etc., ultrafiltration membranes are more and more widely used, bringing great convenience and benefits to people's daily life and production activities.

The whole house** water purification can solve the water quality problem in the cave beam of the home in one step, which can not only ensure the safety and health of the daily drinking water of the people who make me tremble, but also protect the wading appliances at home from the harm of water quality problems. From then on, drinking directly at home, washing vegetables and cooking, brushing teeth and washing face, bathing and laundry, and even flushing the toilet are purified water, which feels very cool!

The top ten famous brands of water purifier Lisheng water purification for family users provide the whole house ** water purification scheme is mainly composed of Lisheng pre-filter + ** ultrafiltration water purifier mountain preparation + ultrafiltration companion + water softener + instant hot water dispenser. Lisheng** ultrafiltration water purifier is the core of the water purification system, with an accuracy of up to micron PVC ultrafiltration membrane element, which can efficiently filter out harmful impurities such as sediment, rust, colloids and bacteria and microorganisms in tap water, while retaining beneficial minerals and trace elements in the water, providing sufficient healthy drinking water for the whole house.

In the Lisheng whole-house water purification system, the tap water will be centrally purified at the main pipe through the Lisheng ultrafiltration membrane water purifier, and then flow to different water places, and according to the water needs and water quality characteristics of different water places, different terminal ultrafiltration partners are installed. For example, the end of the kitchen is equipped with a deodorization partner to absorb the residual discoloration and odor in the water, so that the drinking water tastes more sweet and refreshing; Install a terminal water softener in the bathroom to soften the water quality and avoid the damage caused by mineral ions in the clean water; You can also install a pre-filter at the front end of the ultrafiltration water purifier to coarsely filter the drinking water in the whole house, reduce the purification pressure of the ultrafiltration water purifier, and effectively extend the service life of the water purifier.

Hello <> ultrafiltration membrane can filter foam 1, although ultrafiltration membrane can filter many impurities, but some impurities smaller than the pore size of ultrafiltration membrane can not be filtered, such as water alkali, odor, heavy metals, calcium, magnesium ions and trace elements and other substances, these substances usually need to be treated with reverse osmosis membrane high-state, nanofiltration membrane or ion exchange resin to remove the bird. 2. Ultrafiltration membrane is mainly used in industrial Qijian source water for separating bacteria, heat sources, colloids, suspended impurities and macromolecular organic compounds; purification of drinking water and mineral water in the food and beverage industry; concentration, purification and clarification of fermentation, enzyme preparation industry, pharmaceutical industry; fruit juice concentration and separation; separation, concentration and clarification of soybeans, dairy, sugar industry, wine, tea, vinegar, etc.; purification of industrial wastewater and domestic sewage; Electrophoretic paint ** and other items. Pro-<>

UF ultrafiltration can no longer be used when the membrane is dry. The ultrafiltration membrane is generally immersed in the protective solution for sealing and storage before use, so as to prevent the shrinkage of the wet membrane after dehydration, and the membrane pores become smaller, so that the membrane structure is damaged and the water flux is reduced. Therefore, please do not let it out of the protective solution before use.

The wet membrane will shrink and deform due to dehydration, which will greatly reduce the membrane pores, or destroy the membrane structure, and at the same time make the texture of the membrane brittle, and even make the filtration of the membrane completely invalid. The natural dehydration and drying of the ultrafiltration membrane will lead to the collapse of the membrane pores, which will seriously affect the permeability and mechanical strength of the membrane. Therefore, the membrane needs to be treated in a dry state.