Contaminantes comunes de la membrana de ósmosis inversa y su método de eliminación

Reverse osmosis (RO) systems are widely used in industrial, municipal, and commercial water treatment. However, membrane fouling is inevitable during long-term operation and can severely impact performance, leading to reduced water flux, lower salt rejection, higher pressure requirements, and shortened membrane life.

Understanding common pollutants of reverse osmosis membranes and using the right cleaning strategy is essential for restoring membrane performance, reducing operating costs, and preventing irreversible damage.

This article provides a detailed overview of common RO membrane foulants and their effective removal methods, along with a step-by-step guide for proper RO cleaning.

Calcium carbonate scaling occurs when:

• Scale inhibitor dosing fails
• Acid dosing is interrupted
• Feedwater pH increases abnormally

Early removal method:

• Lower feedwater pH to 3.0–5.0 and circulate for 1–2 hours

Long-term or heavy scaling:

• Use RT-818A or equivalent acidic cleaners
• Apply cyclic cleaning or overnight soaking

Important notes:

• Cleaning solution pH must not drop below 2.0 to avoid membrane damage
• Maximum allowed cleaning pH is 11.0
• Use HCl or H₂SO₄ to decrease pH; use ammonia to increase pH

Calcium sulfate scale is harder and less soluble than calcium carbonate.
Removal method:

• Use specialized calcium sulfate scale cleaning agents
• Avoid acid cleaning alone, as it may worsen precipitation

This includes:

• Ferric hydroxide
• Aluminum hydroxide
• Manganese oxide

Removal method:

• Use the same acidic cleaning method used for calcium carbonate
• Typically easy to dissolve when treated early

Silica fouling is one of the most difficult RO pollutants to remove.

Silica scale types:

• Colloidal silica
• Polymerized silica
• Silica mixed with metal oxides or organics

Removal method:

• Requires specialized silica cleaning chemistry
• Standard acidic or alkaline cleaners are often ineffective

Recommendation: Contact membrane suppliers for advanced silica-cleaning procedures.

Includes:

• Biological slime
• Biofilms
• Proteins and organic compounds
• Humic acids
• Mold stains

Removal method:

• Use alkaline cleaning agents formulated for organics
• If biological activity exists, use:
  • Sterilizing solution
  • Selected biocides
  • Long soaking time (often several hours)

Important: Only use biocides compatible with RO membranes.

Effective cleaning requires:

• Proper foulant identification
• Selection of correct cleaners
• Correct cleaning pH and temperature
• Correct flow velocity and soaking time

Cleaning notes:

• Use RO permeate (chlorine-free) to prepare solutions
• Cleaning can be performed at ≤ 40°C, up to 60 minutes
• Record every cleaning cycle for future optimization

The method of removing calcium carbonate scale described above can be used to easily remove the deposited hydroxide (such as ferric hydroxide).

Pump clean, chlorine-free RO product water into the pressure vessel and flush for several minutes.

Mix cleaning chemicals in a clean tank using RO permeate.
Ensure complete dissolution and uniform mixing.

• Circulate inside pressure vessels at low pressure, high flow
• Typical flow rates:
  • 8″/8.5″ vessel: 35–40 GPM (133–151 L/min)
  • 6″ vessel: 15–20 GPM (57–76 L/min)
  • 4″ vessel: 9–10 GPM (34–38 L/min)
• Circulation time: ~1 hour

Remove remaining cleaning solution and rinse thoroughly.
Refill with clean RO permeate.

Pump clean permeate through the membrane to flush residual cleaner.
Drain after a few minutes.

Operate the RO unit with the product valve open until product water is:

• Clear
• Free of foam
• Free of chemical smell
  Typically requires 15–30 minutes.

RO membrane fouling is inevitable but manageable when proper cleaning and preventive strategies are in place. Understanding the common pollutants of reverse osmosis membranes—including calcium carbonate, calcium sulfate, metal oxides, silica, and organic fouling—helps operators select the right cleaning chemistry and procedures.

Consistent monitoring, early detection, and correct cleaning practices will:

• Extend RO membrane life
• Maintain high permeate quality
• Reduce operational pressure and energy costs
• Minimize downtime

Following standardized cleaning procedures ensures long-term stable performance of the RO system.

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Calcium carbonate scaling and organic fouling are the most frequently observed in industrial and municipal RO systems.

Clean when normalized permeate flow drops 10–15%, or feed pressure increases 10–15%.

No. Silica fouling requires specialized cleaning agents and is often the most difficult to remove.

Chlorine can permanently damage polyamide RO membranes and reduce salt rejection.

Crystals can grow and physically damage membrane surfaces, causing irreversible performance loss.

Xian CHIWATEC Water Treatment Technology es una empresa de alta tecnología especializada en varios dispositivos de procesamiento de agua. Aparte de estos productos individuales, que cubren una serie de tipos y series, también podemos ayudar con proyectos de ingeniería integrales relacionados. Gracias a nuestro arduo trabajo y dedicación desde nuestra fundación, ahora somos uno de los fabricantes de equipos de tratamiento de agua de más rápido desarrollo en el oeste de China.

Otras lecturas:

• Principles of Removing Inorganic Compounds Using Reverse Osmosis Membrane Separation Technology
• Optimized Reverse Osmosis Membrane Cleaning Process Flow
• Introducción de materiales de membrana de ósmosis inversa.
• Introducción a la ósmosis inversa: introducción a las características de la membrana de ósmosis inversa y la membrana de ultrafiltración