Factory Water Purification Choose RO or UF?

Core Choices In Factory Water Purification Technology

 In the manufacturing industry, water quality has a direct impact on product quality, equipment longevity, and operating costs. According to the U.S. Environmental Protection Agency (EPA) statistics, 63% of industrial water problems stem from the incorrect choice of filtration technology. Reverse osmosis (RO) and ultrafiltration (UF) as the two mainstream technologies, how to accurately match the needs of factories? This paper provides a decision-making framework from the technical principle, cost, maintenance and other dimensions.

A comparison of technical principles: molecular filtration vs. pore size retention

1. Reverse osmosis (RO): high-pressure-driven molecular purification

Principle: through a semi-permeable membrane under high pressure (usually 150-1200 psi) to retain dissolved salts, organic matter, bacteria and viruses, the desalination rate of up to 95% -99%.

Applicable Scenarios:

Ultrapure water for electronics industry (resistivity >18 MΩ-cm)

Boiler feed water (to prevent scaling)

Food and beverage industry (to remove microorganisms and dissolved solids)

Example: A semiconductor factory adopted RO system to improve product yield by 22%, and the wafer defect rate decreased due to the reduction of ions in the water.

2. Ultrafiltration (UF): a low-cost solution for physical screening

Principle: Use of hollow fiber membranes (pore size 0.01-0.1 μm) to retain suspended solids, colloids, macromolecular organic matter, and a low removal rate (<10%) of dissolved substances.

Applicable Scenarios:

Cooling tower circulating water (removing suspended solids to extend equipment life)

Food processing pre-treatment (protecting subsequent RO membranes)

Municipal wastewater reuse (lowering COD/BOD)

Example: After replacing sand filtration with UF in an automotive painting plant, the frequency of nozzle clogging was reduced by 80%, saving $120,000 in annual maintenance costs.

Second, 5 core parameters comparison: to help factories calculate the “economic accounts”.

Decision Tip:

If the influent TDS (Total Dissolved Solids) is >1000ppm, prioritize RO (UF cannot remove dissolved salts).

If the main pollutants are suspended solids and need high recovery rate, UF is more cost-effective.

Third, the industry fit guide: different factories “technical formula”

1. Electronics manufacturing: RO + EDI (electrodeionization) golden combination

Demand: ultra-pure water (SiO₂ <5ppb, particles > 0.1μm).

Solution:

Pre-multi-media filter + activated carbon adsorption (removes large particles and residual chlorine)

RO system (desalination rate of 98%)

EDI module (further removes ions, no need for chemical regeneration)

Effect: After adopting this solution in an LCD panel factory, the water-related downtime was reduced from 120 hours/year to 8 hours.

2. Food & Beverage: UF+RO Dual Stage Guarantee

Requirement: FDA-compliant sterile water while retaining minerals.

Solution:

UF system (removes turbidity, E. coli)

RO system (selectively removes heavy metals and retains beneficial ions such as potassium and calcium)

UV sterilization (ensures sterility at the end)

Case: A brewery improved the stability of the taste of beer by 15% through the process, and the change in flavor was lowered due to the reduction of impurities in the water.

3. Chemical industry: UF pretreatment + RO concentration

Requirements: Treatment of high concentration organic wastewater (COD>5000mg/L) and water recovery.

Solution:

UF system (retain large organic molecules, reduce the risk of RO membrane contamination)

RO system (concentrate wastewater to 20% by volume, realize zero discharge)

Data: after the implementation of a dyestuff factory, the cost of wastewater treatment was reduced from 8//m³  to 2.5/m³.

Fourth, common misconceptions and solutions

Misconception 1: “RO is a universal technology, all factories are applicable”

Risks: High TDS wastewater may face environmental penalties if discharged directly (such as China's “Comprehensive Wastewater Discharge Standards” GB 8978-1996).

Countermeasures:

Low TDS scenarios (e.g. cooling tower make-up water) are prioritized with UF + chemical softening.

Match with concentrated water recycling system (e.g. MBR+RO) to achieve resourcefulness.

Myth 2: “The smaller the pore size of the UF membrane, the better”

Risk: Too small a pore size (e.g. <0.01μm) is easy to clog, resulting in a 300% increase in differential pressure across the membrane.

Countermeasure:

Select the pore size according to the concentration of suspended solids in the influent water (e.g. 0.03μm membrane for SDI<3).

Perform air-water backwash regularly (frequency depends on water quality, usually every 2-4 hours).

Conclusion: Technology fit is more important than “sophistication”

When choosing a water purification technology, factories need to answer three questions:

Inlet water quality (TDS, suspended solids, organic concentration)?

Produced water requirements (use, standard, flow rate)?

Budget constraints (initial investment + whole life costs)?

Recommendations for action:

Contact us for a customized technology roadmap covering the entire process of pre-treatment, main system, and post-treatment.