Industrial water filtration systems are essential for removing suspended solids and impurities from liquids to ensure equipment protection, process stability, and product quality. Based on filtration principles, media type, and application scenarios, industrial filters can be divided into several core categories. The following provides a detailed, data-driven overview of their design, performance, and use cases.
1. Classification by Filtration Driving Force and Operation Mode
1.1 Gravity Filters
Sand Filter Tanks
Technical Parameters: Filtration rate 40–60 m/h; precision 0.1–0.5 mm; effluent turbidity <5 NTU.
Design Features: Multi-media layers (quartz sand, anthracite) capture suspended solids via gravity settling. Backwash water consumption is only 0.08%–0.6% of total flow.
Applications: Surface water pretreatment (e.g., Yellow River desalination projects), cooling water side-stream filtration, removing over 90% of large particles.
1.2 Vacuum Filters
Rotary Drum Vacuum Filter
Capacity: 5–50 m³/h; ideal for high-solids chemical slurries (>30% solids).
Filter Cake: Moisture content 15%–25%. Commonly used in mining tailings dewatering to minimize sludge volume.
1.3 Pressure Filters
Plate and Frame Filter Press
Operating Pressure: 0.6–1.0 MPa; reduces filter cake moisture to <60% with diaphragm squeezing.
Applications: Municipal sludge dewatering (reduces moisture from 95% to 60%), catalyst recovery in chemical processing; filtrate SS ≤100 mg/L.
2. Classification by Filtration Media and Structure
2.1 Cartridge Filters
Metal Filter Elements
Material Properties: Stainless steel mesh withstands –200°C to 800°C; sintered powder cartridges achieve 0.5–100 μm precision.
Applications: Petrochemical high-temperature gas/liquid filtration; intercepting FCC catalyst particles (5–20 μm).
Ceramic Filter Elements
Filtration Range: 0.1–80 μm; resistant to strong acids and alkalis (pH 1–14); over 500 backwash cycles.
Applications: Beverage and food sterilization (total bacteria ≤1 CFU/mL), industrial wastewater reuse (e.g., coking wastewater).
2.2 Membrane Filtration Systems
Microfiltration (MF):
Pore Size: 0.1–10 μm; bacteria removal >95%; used in pharmaceutical final filtration for injectables.
Case: Phosphate iron battery-grade material production — microfiltration membrane backwashing recovers valuable solids and reduces water treatment load.
Ultrafiltration (UF):
Molecular Weight Cutoff: 10⁴–10⁶ Da; separates proteins and viruses. Ceramic UF membranes remove <10 μm particles from grinding wastewater.
Combined Process: UF + RO for chip-cleaning ultrapure water; product water resistivity >18 MΩ·cm.
Nanofiltration (NF):
Desalination Capability: Divalent ion rejection 90%–98%; softens drinking water (reducing hardness by 80%), applied in coal chemical brine separation.
Energy Efficiency: 1.2–2.5 kWh/m³, only 50–70% of RO energy use.
Reverse Osmosis (RO):
Desalination Rate: >99.7% in seawater desalination; product water TDS <500 mg/L, meeting WHO standards.
Case Study: Shandong 44,000 m³/day Yellow River desalination project using “high-speed filtration + RO” for local water reuse.
3. Classification by Function and Automation Level
3.1 Self-Cleaning Filters
Working Principle: When ΔP >0.03 MPa, a hydraulic motor drives suction scanning for backwash. Backwash water use is only 0.08%–0.6% of total flow.
Performance: Filtration precision 10–3000 μm; single-unit flow 4–4160 m³/h.
Applications: Metallurgy circulating water (suspended solids ≤30 mg/L).
3.2 Fully Automated Filtration Systems
Control Logic: PLC controls filtration, backwash, and discharge cycles; automatic backwash every 8 hours in pharmaceutical mixing systems.
Advantages: Reduces manual intervention, prevents contamination, meets GMP standards.
3.3 Intelligent Filtration Equipment
IoT Integration: Real-time monitoring of differential pressure and flow; cloud-based diagnostics with 72-hour predictive alerts for filter replacement.
Predictive Maintenance: Data-driven filter life estimation minimizes downtime and improves Industry 4.0 reliability.
4. Classification by Industrial Application
4.1 Hydraulic and Lubrication Systems
High-Pressure Line Filters: 3–10 μm precision; ISO 23369-compliant performance to protect servo valves from wear.
Return Line Filters: 5–25 μm precision; large contaminant capacity; ISO 16889 certified.
4.2 Petrochemical Industry
Bag Filters: Remove crude oil impurities (sand ≤0.01%); filter bag life 3–6 months; reduce downstream clogging.
Membrane Separation: Recover organic solvents (acetone, methanol) with >95% recovery rate, enabling closed-loop recycling.
4.3 Food and Pharmaceutical
PES Ultrafiltration Membranes: MWCO 300,000 Da; for recombinant protein separation; FDA- and GMP-compliant.
Ceramic Sterilization Filters: 0.2 μm pores; post-filtration colony count ≤1 CFU/mL; ensures food safety.
4.4 Water Treatment
Multi-Media Filters: Quartz sand + anthracite combination removes surface water turbidity (<5 NTU); backwash every 24–48 hours.
RO Systems: Product resistivity >18 MΩ·cm; particle count ≤100/mL @≥0.1 μm; ideal for semiconductor cleaning water.
4.5 Environmental Protection and Energy
Vacuum Filters: Tailings dewatering (moisture ≤20%) to reduce landfill footprint.
Activated Carbon Filters: Iodine value ≥800 mg/g; remove >90% VOCs in printing and coating industries.
5. Special Filtration Types
5.1 Magnetic Filters
Magnetic Strength: 0.3–1.2 T; flow 1–100 m³/h; captures ferromagnetic particles like rust.
Applications: Metalworking fluid filtration (iron ≤0.01%), bearing lubrication protection.
5.2 Centrifugal Filters
Separation Principle: 500–2000g centrifugal force; >90% removal of particles >50 μm.
Advantages: No filter media required, low maintenance, ideal for high-viscosity fluids like syrup or ink.
Key Technical Parameters and Selection Criteria
| Filtration Type | Precision Range | Typical Application | Key Performance Indicators |
|---|---|---|---|
| Sand Filter | 20–50 μm | Surface water pretreatment | Filtration rate 40–60 m/h; backwash water <3 m³ |
| Microfiltration (MF) | 0.1–10 μm | Pharmaceutical sterilization, electrolyte purification | >95% bacteria removal; turbidity <0.1 NTU |
| Ultrafiltration (UF) | 0.002–0.1 μm | Bioproduct separation, wastewater reuse | MWCO >90%; recovery rate 90% |
| Nanofiltration (NF) | 1 nm (200–400 Da) | Water softening, coal chemical desalination | Divalent ion rejection 90%–98%; energy 1.2–2.5 kWh/m³ |
| Reverse Osmosis (RO) | <0.1 nm | Seawater desalination, ultrapure water | Desalination >99.7%; recovery 75% |
| Self-Cleaning Filter | 10–3000 μm | Cooling water, irrigation | Backwash 0.08%–0.6% of total flow; continuous operation |
| Filter Press | 1–50 μm | Sludge dewatering, catalyst recovery | Cake moisture 30%–70%; SS ≤100 mg/L |
Filtration System Selection and Optimization
Selecting an industrial water filtration system requires balancing fluid characteristics (viscosity, corrosiveness), flow rate (5–10,000 m³/h), filtration precision (0.1–1000 μm), and lifecycle cost (CAPEX + OPEX).
Reverse Osmosis is optimal for high-salinity wastewater and deep purification.
Self-cleaning filters suit recirculating systems with coarse suspended solids.
A hybrid process — such as “Multi-media + Ultrafiltration + RO” — maximizes water recovery and supports industrial sustainability and green manufacturing.