Applications of Filtration Equipment and Consumables in the Water Treatment Field
With economic and social development, water pollution has intensified and water quality has deteriorated. Water treatment has become increasingly important for advancing industrial production, improving product quality, protecting the human environment, and maintaining ecological balance. Filtration, as a common unit operation for separation, has been widely and extensively applied in both potable water treatment and wastewater treatment.
The filtration equipment industry has expanded from the microfiltration (MF) sector into the fields of ultrafiltration (UF) and reverse osmosis (RO), developing a series of water treatment filtration products to improve water quality and meet the technical requirements for potable water treatment, industrial wastewater treatment, and industrial water treatment (including boiler feedwater treatment, makeup water treatment, main condensate treatment for steam turbines, and circulating water treatment).
I. Reverse Osmosis Systems
RO technology is commonly used in processes such as boiler feedwater, pure/ultrapure water, leachate treatment, and seawater desalination. RO membranes are sensitive to the pH, temperature, and certain chemical substances in the feedwater. Strict requirements are imposed on feedwater quality: a pH range of 4–10, a temperature <40°C, a silt density index (SDI) <5, free gas <0.1 mg/L, turbidity < 1 NTU, and iron content < 0.1 mg/L, among other parameters.
To meet the feedwater requirements for RO membranes, the raw water must first undergo security filtration before entering the RO membrane system. It is then pressurized by a booster pump and fed into the membrane modules, where, under pressure, the raw water passes through the RO membranes to become product water.
1. Pure Water/Ultrapure Water
Reverse osmosis membrane elements can achieve high water flux and desalination rates at relatively low operating pressures. Their operating pressure is approximately two-thirds that of conventional low-pressure brackish water membranes, enabling high desalination while meeting the system’s water production requirements under low-pressure conditions. Ultra-low-pressure reverse osmosis membrane elements are generally suitable for desalination treatment of water sources such as brackish water, surface water, groundwater, and tap water with a salinity of 2,000 ppm or less.
Test Conditions:
1. Operating pressure: 150 psi (1.03 MPa); 1,500 mg/L NaCl solution; temperature: 25°C; pH: 7.5 ± 0.5; recovery rate: 15%;
2. Operating pressure: 225 psi (1.55 MPa); 2,000 mg/L NaCl solution; temperature: 25°C; pH: 7.5 ± 0.5; recovery rate: 15%;
2. Security Filtration
High-flow filter cartridges enable the most minimal and cost-effective filter configuration, allowing high-flow media to pass through the filter media. They offer advantages such as high efficiency, low pressure drop, and long service life.
· Reinforced polypropylene (PP) skeleton ensures the cartridge resists deformation and withstands operating temperatures up to 85°C and a pressure differential of 0.25 MPa
· Precision filtration membranes with an efficiency of 99.5% or higher effectively intercept particulates in the feed water
· Seamless welding ensures excellent filter cartridge integrity
When used as a security filter, a single 40-inch (5-micron) high-flow filter cartridge achieves a maximum water flux of 60 m³/h. Under operating conditions of 2.4 bar at 20°C, the high-flow filter cartridge guarantees a maximum filtration lifespan of 180 days for the RO system.
II. Ultrafiltration Purification System
Traditional water treatment methods are effective only against general organic pollutants: they are ineffective at removing “two types of parasites” and algae, and disinfection often leads to the formation of byproducts. The ultrafiltration (UF) process emphasizes the elimination of toxic byproducts while improving treatment efficiency and optimizing results. It enhances resource and energy utilization, reduces pollution loads, and improves environmental quality.
1. Water Supply Purification
Column-type ultrafiltration membranes use the pressure difference across the membrane as the driving force, with the ultrafiltration membrane serving as the filtration medium. Under a certain pressure, when the feed solution flows over the membrane surface, the densely packed micropores on the membrane surface allow only water and small-molecule substances to pass through, forming the permeate. while suspended solids, colloids, and large-molecule organic compounds in the feed solution—whose sizes exceed the pore diameter of the membrane—are retained on the feed side of the membrane, forming the concentrate. This process achieves the objectives of purifying, separating, and concentrating the feed solution.
· Retention pore size of 0.03 microns, high separation precision, with purified water turbidity ≤ 0.2 NTU and suspended solids (SS) < 1 mg/L
· Excellent hydrophilicity and strong resistance to fouling; pure water flux (at 25°C and 0.1 MPa) reaches 150 L/(m²·h)
· Made of PVDF (specifically designed for replacement in older systems); operates within a pH range of 2–10 and can withstand residual chlorine concentrations of up to 5,000 ppm
· External pressure operation with a proprietary casting process that protects the membrane fiber roots; average service life of 3–5 years
2. Membrane Bioreactor
The MBR (Membrane Bioreactor) organically integrates membrane separation technology with traditional biological treatment technology. By separating the sludge retention time from the hydraulic retention time, it significantly improves solid-liquid separation efficiency. Furthermore, the increased concentration of activated sludge in the aeration tank and the emergence of specific bacteria (particularly dominant bacterial communities) in the sludge enhance the rate of biochemical reactions.
MBR membranes effectively remove suspended solids from wastewater and reduce organic matter and ammonia nitrogen, while simultaneously reducing the production of excess sludge (even to zero) by lowering the F/M ratio, thereby fundamentally resolving many of the prominent issues associated with the traditional activated sludge process.
· Hydrophilic PVDF material is resistant to fouling and offers high chemical resistance; it operates within a pH range of 2–10 and can withstand residual chlorine concentrations of up to 5,000 ppm
· High filtration precision of 0.04 µm; water production rate of 10–25 L/h; stable effluent turbidity ≤ 1 NTU; suspended solids (SS) < 3 mg/L
· The outer layer exhibits high peel strength exceeding 5 bar, while the reinforced inner membrane filaments have a tensile strength of up to 300 N (approximately 30 kg)
· Integrated design featuring a membrane frame with built-in piping; compact internal layout of the membrane housing; easy to disassemble and reassemble
III. Wastewater Recycling and Reuse System
According to surveys, industrial water consumption accounts for approximately 25% of total water use across all sectors, indicating significant potential for water conservation. Water quality requirements for industrial water vary greatly depending on its intended use; the higher the quality requirements, the higher the water treatment costs. When considering whether a particular process can utilize recycled wastewater, the water must meet the required quality standards, and the costs of reusing the wastewater and treating it must be calculated to achieve maximum economic benefits.
1. Zero-Discharge Treatment of High-Concentration Wastewater
High-pressure anti-fouling products utilize a new membrane surface treatment process that significantly increases the hydrophilicity of the membrane surface. This effectively reduces fouling caused by colloidal organic matter and other contaminants, thereby improving the membrane’s cleaning and recovery performance. At the same time, a specially designed feed channel structure further enhances the membrane element’s resistance to fouling and its cleaning and recovery performance. The membrane modules operate at pressures up to 90 bar, making them suitable for the concentration treatment of high-salinity industrial wastewater.
These high-pressure, anti-fouling products are applied in RO concentrate reuse, near-zero discharge of high-salinity wastewater, material concentration, and desalination of brackish water. They are particularly suitable for treating industrial wastewater containing small amounts of organic pollutants and slightly contaminated water sources, as well as for their (near) zero-discharge treatment.
Operating pressure is reduced by approximately 15%–25%, and energy consumption is 4.7% lower than that of comparable products
· Features the industry’s highest desalination rate of 99.89%, with treated water quality improved by 30% compared to similar products. Test conditions: operating pressure 800 psi (5.52 MPa), 32,000 mg/L NaCl solution, temperature 25°C, pH 7.5 ± 0.5, recovery rate 15%.
2. Process Water Recirculation
Condensate, cooling water, and low-quality process water (used for washing, ash flushing, dust removal, direct cooling, etc.) generated during industrial production can be treated via microfiltration (MF) to remove impurities and be reused.
A combination of iron removal filters and precision filters can effectively remove more than 90% of solid particulate metal contaminants and colloidal flocs ranging from 6 to 15 μm in size. For systems with a solids content exceeding 1%, candle filters or backwash filters can be selected for pre-filtration and interception. CIP cleaning frequency is reduced by 50%.
