Ultrafiltration Device High-Efficiency Pressure-Driven Membrane Separation Technology for Purification and Separation

The core principle of the ultrafiltration device is to use asymmetric microporous structure and semipermeable membrane media, and use the pressure difference on both sides of the membrane as a driving force to perform cross-flow filtration, so that solvents and small molecules pass through the membrane pores, while large molecules are retained.​

Definition and Principle:
Ultrafiltration (UF) equipment is a membrane separation device driven by pressure difference. Its core is the ultrafiltration membrane, which has an asymmetric microporous structure and can intercept substances with a large relative molecular mass. In the ultrafiltration process, when a solution containing impurities passes through the ultrafiltration membrane under a certain pressure, the membrane allows water and small molecular solutes (such as inorganic salts, small molecular organic matter, etc.) to pass through, while retaining large molecular substances (such as proteins, colloids, bacteria, viruses, etc.) on one side of the membrane, thereby achieving the purification, separation and concentration of the solution.

For example, in water treatment, when raw water passes through the ultrafiltration membrane, suspended matter, large molecular organic matter, etc. in the water are retained on the membrane surface, while small molecular substances such as water molecules and dissolved salts pass through the membrane to achieve the purpose of purifying water quality. The separation principle of ultrafiltration is mainly based on screening, that is, the pore size of the membrane determines the substances that can pass through. However, in addition to the screening effect, the interaction between the membrane surface and the solute (such as adsorption, charge repulsion, etc.) also has a certain influence on the separation effect.

Main components:
Ultrafiltration membrane assembly:
Hollow fiber membrane assembly:

This is the most common form. It consists of a large number of hollow fiber membrane filaments, the outer diameter of which is generally between 0.5 and 2.0 mm, and the inner diameter is between 0.2 and 1.0 mm. Water enters from the outside of the membrane filament. Under pressure, small molecules pass through the membrane wall and enter the inside of the membrane filament, while large molecules are retained on the outside of the membrane filament. This assembly has a high membrane packing density and can provide a large membrane area per unit volume, thereby improving the filtration efficiency.

Rolled membrane assembly:

The ultrafiltration membrane, guide net and central tube are wound together. During operation, the incoming water flows along one side of the membrane under pressure, and the liquid that passes through the membrane is collected in the central tube through the guide net, and the retained substances remain on the other side of the membrane. The advantage of the rolled membrane assembly is that it has a compact structure and is suitable for treating some relatively clean liquids.

Casing and support structure:
It is used to protect the ultrafiltration membrane assembly and provide it with necessary support. The shell is usually made of materials such as stainless steel, fiberglass or engineering plastics, which have good corrosion resistance and mechanical strength and can withstand a certain amount of pressure. The design of the shell should take into account the uniform distribution of inlet and outlet water to ensure that all parts of the membrane assembly can fully function.

Pump system:
Feed pump:

transports the raw water to be treated to the ultrafiltration equipment. The feed pump needs to select the appropriate type and specification according to the properties of the raw water (such as viscosity, solid content, etc.) and the treatment scale. Generally speaking, the feed pump should be able to provide sufficient pressure to overcome the resistance of the ultrafiltration membrane so that the raw water can pass through the membrane assembly smoothly.

Circulation pump (some equipment has):

In some ultrafiltration systems, in order to improve the filtration efficiency and the service life of the membrane, a circulation pump will be set. The circulation pump returns part of the concentrated water that has not passed through the membrane to the feed port, mixes it with the newly entered raw water, and then ultrafilters it again, which can increase the flow rate on the membrane surface and reduce the occurrence of membrane pollution.

Valve and piping system:
Used to control the flow direction, flow rate and pressure of the liquid. Valves include water inlet valves, water outlet valves, concentrated water discharge valves, etc. By reasonably adjusting the opening of the valves, the operating parameters of the ultrafiltration process can be controlled. The pipeline system must ensure the smooth transportation of liquid inside the equipment, and suitable pipes must be selected to prevent corrosion and leakage. Pipes are usually made of stainless steel pipes, UPVC pipes (rigid polyvinyl chloride pipes) or PE pipes (polyethylene pipes).

Cleaning system:
Since the ultrafiltration membrane will inevitably be contaminated during use, a cleaning system is essential. The cleaning system includes chemical cleaning devices and physical cleaning devices. Chemical cleaning is to remove dirt (such as organic matter, inorganic matter, microorganisms, etc.) on the membrane surface by injecting specific chemical cleaning agents (such as acids, alkalis, oxidants, surfactants, etc.) into the membrane assembly. Physical cleaning includes water washing, backwashing and sponge ball scrubbing to remove loose dirt on the membrane surface.

Workflow:
Pretreatment:

Before ultrafiltration, raw water usually needs to be pretreated, such as filtration, sedimentation, etc., to remove larger particulate impurities and suspended solids to prevent these substances from clogging the ultrafiltration membrane. The pretreated water enters the feed port of the ultrafiltration equipment.

Ultrafiltration process:

The feed pump delivers the pretreated water to the ultrafiltration membrane assembly. Under pressure, water passes through the ultrafiltration membrane, and small molecules (such as dissolved salts, small molecular organic matter, etc.) and water pass through the membrane together to form a permeate (also called produced water), while large molecules (such as proteins, colloids, bacteria, etc.) are retained on one side of the membrane to form concentrated water. The permeate can be output as product water after being collected through the pipeline, and the concentrated water is discharged or further processed according to the specific situation.

Cleaning and maintenance:

As the ultrafiltration process proceeds, the flux of the ultrafiltration membrane will gradually decrease, which is due to the contamination of the membrane surface. When the membrane flux drops to a certain extent, the ultrafiltration membrane needs to be cleaned. The cleaning process includes first rinsing with clean water to remove loose dirt on the membrane surface, and then selecting a suitable chemical cleaning agent for chemical cleaning according to the type of pollution. After cleaning, the ultrafiltration equipment can restore good filtration performance.

Performance characteristics:
High separation accuracy:

It can effectively intercept substances with a relative molecular mass greater than the membrane cut-off molecular weight, and the molecular weight cut-off range is generally between 1000-1000000Da. For example, for proteins with a relative molecular mass greater than 100000Da, the ultrafiltration equipment can intercept most of them on one side of the membrane, thereby achieving the separation of macromolecular substances in the solution.

Large filtration flux:

Under appropriate pressure and temperature conditions, the filtration flux of ultrafiltration equipment is relatively high. The flux is generally between 30-300L/(m²・h), which means that more liquid can be processed per unit time. However, the flux will be affected by many factors, such as the material of the membrane, the quality of the inlet water, the operating pressure and temperature, etc.

Strong anti-pollution ability:

Compared with some other membrane separation equipment, the anti-pollution ability of ultrafiltration equipment is relatively good. This is because the surface of the ultrafiltration membrane is relatively smooth, and some ultrafiltration membranes also have anti-pollution coatings or modified structures, which can reduce the adhesion of dirt on the membrane surface. At the same time, through reasonable operation (such as controlling the quality of the inlet water, appropriate flow rate, etc.) and regular cleaning, the anti-pollution ability of the equipment can be further improved.

Simple equipment and easy operation:

The structure of the ultrafiltration equipment is relatively simple, mainly composed of membrane components, pumps, valves and pipes. The equipment has a high degree of automation, and the control of the feeding, filtration, cleaning and other processes can be achieved through the automatic control system. The operator only needs to perform simple parameter settings and monitoring to ensure the normal operation of the equipment.

Wide range of applications:

It can be used in water treatment, food processing, pharmaceuticals, chemicals and other fields. In the field of water treatment, it is used for the purification of drinking water, pretreatment of industrial wastewater, etc.; in food processing, it is used for the clarification and sterilization of juice, milk, etc.; in the pharmaceutical industry, it is used for the refining and sterilization of drug extracts, etc.

Application field:
Water treatment field:
Drinking water purification:

As a means of deep treatment of drinking water, it can effectively remove impurities such as bacteria, viruses, colloids, and macromolecular organic matter in water, and improve the quality and safety of drinking water. For example, in some small water supply systems in rural areas, ultrafiltration equipment can treat groundwater or surface water, remove pollutants, and make the water quality meet the drinking water standard.

Industrial wastewater pretreatment:

For industrial wastewater containing macromolecular organic matter, colloids, suspended solids, etc., ultrafiltration equipment can be used as a pretreatment unit to remove these impurities and reduce the load of subsequent treatment units (such as reverse osmosis, biochemical treatment, etc.). For example, in the treatment of printing and dyeing wastewater, ultrafiltration equipment can remove dye macromolecules and fiber impurities in wastewater, creating good conditions for subsequent biological treatment or deep treatment.

Food industry:
Juice clarification and sterilization:

During the juice processing process, ultrafiltration equipment can remove impurities such as pectin, protein, bacteria, etc. in the juice, making the juice clear and transparent, while extending the shelf life of the juice. For example, in apple juice processing, after ultrafiltration treatment, the turbidity of the juice can be significantly reduced, and the flavor and nutrients of the juice can be retained.

Milk sterilization and concentration:

used for sterilization and partial concentration of milk. Ultrafiltration can remove bacteria, somatic cells and other impurities in milk, while retaining nutrients such as protein and lactose in milk. When producing dairy products such as cheese, ultrafiltration equipment can also be used for pre-concentration of milk to improve production efficiency.

Pharmaceutical industry:
Drug extract refining:

During the drug extraction process, ultrafiltration equipment can remove macromolecular impurities (such as polysaccharides, proteins, etc.) in the extract to improve the purity of the drug. For example, in the refining process of Chinese medicine extracts, ultrafiltration can effectively separate the active ingredients of the drug from impurities and improve the quality of Chinese medicine preparations.

Injection sterilization filtration:

As a sterilization filtration link in the production process of injections, ultrafiltration equipment can effectively remove pathogens such as bacteria and viruses to ensure the sterility of injections. Compared with traditional sterilization filtration methods, ultrafiltration has higher safety and reliability.

Jiangsu Gena Environmental Engineering Co., Ltd. is a high-tech environmental engineering equipment company focusing on water treatment and chemical liquid separation, focusing on environmental protection and resource recycling. It focuses on the production and manufacturing of complete sets of landfill leachate treatment equipment, MVR evaporator equipment, complete sets of wastewater zero discharge equipment, complete sets of reclaimed water reuse equipment, complete sets of seawater desalination equipment, nanofiltration equipment and STRO/DTRO complete sets of equipment.

The company's management team has been devoted to the application of membranes and product technology development, environmental water treatment technology and equipment development, and new process development in the fields of industrial liquid purification, refining and separation in the field of landfill leachate and chemical industry for many years. It provides complete integrated solutions for more than 50 large industrial customers across the country, and has invested in more than 500 water treatment production equipment and industrial filtration production equipment. Customers are spread across multiple industries such as landfill leachate, chlor-alkali, polyvinyl chloride, coking, pesticides, smelting, and steel.

The company has obtained 27 intellectual property rights through its own development. The research and development projects include: reverse osmosis concentrated water treatment device for landfill leachate, energy-saving microfiltration membrane wastewater treatment device, landfill leachate treatment device for garbage transfer station, ultrasonic landfill leachate integrated GNSB anaerobic device, spiral water treatment activated carbon filtration device, groundwater treatment and prevention equipment, etc.