Ultrafiltration Membranes: A Vital Component in Wastewater Treatment and Reuse

Pore Size Range of Ultrafiltration Membranes

Ultrafiltration membranes typically have a pore size ranging from 0.001 to 0.1 micrometers. This size range endows them with the ability to effectively retain suspended solids, colloids, bacteria, viruses, and other impurities in water while permitting the passage of water molecules and small solutes, thereby achieving advanced purification of wastewater.

Applications of Ultrafiltration Membranes in Wastewater Treatment and Reuse

Advanced Wastewater Treatment

Removal of Suspended Solids and Colloids: Ultrafiltration membranes can efficiently intercept suspended particles and colloidal substances in wastewater, significantly reducing the turbidity of the effluent. For instance, after ultrafiltration treatment, the turbidity of the secondary effluent from a municipal wastewater treatment plant can be reduced from 1 - 2 NTU to below 0.1 NTU.

Removal of Microorganisms: With a pore size smaller than the dimensions of bacteria and viruses, ultrafiltration membranes can completely remove bacteria and E. coli from water and achieve a high removal rate of viruses, enhancing the sanitary safety of the water quality.

Reduction of Organic Matter Concentration: Although the removal of dissolved organic matter by ultrafiltration membranes is limited, they can retain some large molecular organic matter, thereby partially reducing the chemical oxygen demand (COD) and biochemical oxygen demand (BOD) in wastewater.

Water Reclamation and Reuse

Municipal Water Reclamation:

Landscape Watering: The reclaimed water after ultrafiltration treatment has a relatively high quality and can be directly used as a supplementary water source for urban parks, lakes, fountains, and other landscape water bodies. For example, the Changping Regenerated Water Plant in Beijing uses ultrafiltration membrane technology to treat the secondary effluent, and the effluent quality meets the "Standards for the Use of Reclaimed Water in Urban Landscape Environment," serving as a supplement to the upstream landscape water body.

Municipal Miscellaneous Water Use: It can be utilized for non-potable water purposes such as urban road sprinkling, green space irrigation, and car washing. The reclaimed water treated by ultrafiltration can meet the water quality requirements for these applications, reducing the reliance on fresh water resources.

Industrial Water Reclamation:

Cooling Water: In industrial production, the water quality requirements for cooling water are stringent, necessitating the removal of impurities and microorganisms to prevent equipment scaling and corrosion. The reclaimed water treated by ultrafiltration can serve as a supplementary water source for industrial circulating cooling water, conserving a significant amount of fresh water resources.

Process Water: For some industrial process water with relatively low water quality requirements, such as water for papermaking in the paper industry and water for dyeing in the printing and dyeing industry, the reclaimed water treated by ultrafiltration can be reused in the production process after appropriate treatment, reducing the water costs for enterprises.

Boiler Feedwater: The reclaimed water treated by ultrafiltration and further advanced treatment (such as reverse osmosis) can be used as boiler feedwater, enhancing the utilization rate of water resources.

Advantages of Ultrafiltration Membranes in Wastewater Treatment and Reuse

High Efficiency Separation Performance: Ultrafiltration membranes can achieve efficient separation of substances with different particle sizes in wastewater, providing stable removal effects and reliable effluent water quality.

Simple Operation: The ultrafiltration process is typically carried out at ambient temperature, with mild operating conditions, and does not require complex equipment or processes, facilitating automated control.

Low Energy Consumption: Compared to conventional water treatment technologies, ultrafiltration membrane technology has relatively low energy consumption and operating costs.

Small Footprint: The compact structure of ultrafiltration membrane components occupies a small area, making it suitable for application in wastewater treatment plants or reclamation facilities with limited space.

Application Cases of Ultrafiltration Membranes in Wastewater Treatment and Reuse

Changping Regenerated Water Plant in Beijing: This plant employs ultrafiltration membrane technology to treat the secondary effluent from a municipal wastewater treatment plant, with a treatment capacity of 20,000 cubic meters per day. After ultrafiltration treatment, the effluent quality meets the "Standards for the Use of Reclaimed Water in Urban Landscape Environment" and is used to supplement the upstream landscape water body. The modified ultrafiltration system operates stably, with a significant increase in water production and improved water quality.

A Major Steel Enterprise: The enterprise utilizes ultrafiltration water reclamation technology to treat and reuse production wastewater. After preliminary treatment such as grid filtration, sedimentation, and air flotation, the wastewater enters the ultrafiltration system. The ultrafiltration membrane effectively retains suspended solids, colloids, microorganisms, and other impurities in the water. The ultrafiltration permeate is then treated by reverse osmosis, and the water quality meets the standard for industrial circulating cooling water, enabling its reuse in the enterprise's production process. This results in substantial annual savings of fresh water resources, reduced production costs, and decreased environmental impact from wastewater discharge.

Ultrafiltration membrane technology holds a promising future in the field of wastewater treatment and reclamation. It can effectively achieve advanced treatment of wastewater and efficient reclamation of water, providing strong support for alleviating water resource shortages and protecting the aquatic environment.