The Main Categories of Common Filtration Methods from Low to High Precision| Insights by AQUALITEK

1. Introduction

Water filtration is an essential process in ensuring clean and safe water for various uses. From household drinking water systems to industrial water treatment plants, different filtration technologies are applied depending on the level of impurities and the required water quality.
This guide outlines the main categories of filtration methods, organized from low to high precision, to help you understand how each method functions and when it should be used.

2. Sedimentation and Coarse Filtration (Low Precision)

Precision range: >50 microns
This is the first stage of most water treatment systems. It primarily removes large suspended solids, such as sand, silt, rust, and debris.

•Typical equipment: Sand filters, mesh strainers, and sediment cartridges.

•Applications: Pretreatment for domestic water filters, industrial cooling systems, and agricultural irrigation.

•Advantages: Low cost, easy maintenance, and high flow rates.

•Limitations: Cannot remove dissolved substances, bacteria, or fine particles.

3. Microfiltration (MF)

Precision range: 0.1–10 microns
Microfiltration provides higher clarity by removing small particles, bacteria, and some protozoa. It’s often used as a pretreatment step before ultrafiltration or reverse osmosis.

•Typical membrane material: Polypropylene (PP), PVDF, or PES.

•Applications: Food and beverage industries, pharmaceutical water systems, and municipal water purification.

•Advantages: Removes most microorganisms and turbidity.

•Limitations: Cannot remove dissolved salts or organic molecules.

4. Ultrafiltration (UF)

Precision range: 0.01–0.1 microns
Ultrafiltration uses a semi-permeable membrane that blocks bacteria, viruses, and macromolecules. It is widely used in wastewater treatment, industrial process water, and drinking water purification.

•Typical membrane materials: PVDF, PES, or PAN.

•Advantages: High recovery rate, stable performance, and chemical resistance.

•Limitations: Cannot remove dissolved ions or small organic molecules.

•Typical use case: Municipal wastewater recycling and pre-treatment for RO systems.

5. Nanofiltration (NF)

Precision range: 0.001–0.01 microns
Nanofiltration provides selective ion removal, allowing small molecules like calcium and magnesium to be reduced while retaining some beneficial minerals. It bridges the gap between ultrafiltration and reverse osmosis.

•Applications: Softening hard water, removing color and organic matter, and partial desalination.

•Advantages: Lower operating pressure than RO and selective permeability.

•Limitations: Cannot achieve full desalination.

6. Reverse Osmosis (RO) – High Precision Filtration

Precision range: <0.001 microns
Reverse osmosis is the most precise and effective filtration method. It removes 99% of dissolved salts, heavy metals, microorganisms, and organic contaminants.

•Applications: Desalination plants, semiconductor manufacturing, laboratory water, and household RO systems.

•Advantages: Produces pure water, suitable for any application requiring high purity.

•Limitations: Higher energy consumption, lower water recovery rate, and membrane fouling potential.

7. Conclusion

From simple sediment filtration to advanced reverse osmosis, each filtration category serves a specific role in water purification. Selecting the right filtration method depends on the water source, target contaminants, and required purity level.
A well-designed water treatment system often combines multiple filtration stages, ensuring comprehensive contaminant removal and consistent water quality.