Pre-Filter: The Foundation of Water Quality for Your Industry

Before water can be used for various purposes—whether it be drinking water, industrial process water, or feed for advanced systems such as Reverse Osmosis and Cooling Towers—it often has to go through a Pre-Filter stage. A pre-filter is an initial filtration system that serves to remove large contaminants and particles that can damage downstream equipment and interfere with further water treatment processes.

Understanding the types of filter media and their functions is key to designing an effective pre-filter system. At PT Jaya Sakti Internusa, we provide customised pre-filter solutions for various water quality issues.

Common Filter Media and Their Functions:

Each filter media is designed to address specific water issues. Here are some of the most commonly used filter media:

1. Silica Sand

• Contents: Hard and durable silica sand grains of varying sizes (e.g., 0.4−0.8 mm, 0.8−1.6 mm).

• Uses: This media is the first line of defence for removing Total Suspended Solids (TSS) such as mud, sand, sediment, and other solid particles that cause turbidity in water. Water is mechanically filtered as it passes through the sand layer.

• How it works: Contaminant particles larger than the pores between sand grains will be trapped. The smaller the sand size, the finer the particles that can be filtered.

2. Activated Carbon

• Contents: Made from organic materials (coconut shells, coal) that are activated through a high-temperature process without oxygen, creating millions of microscopic pores.

• Uses: Very effective for removing:

  • Free Chlorine: Chlorine is used as a disinfectant, but it can cause unpleasant odours and tastes, as well as damage RO membranes.

  • Organic Compounds: Cause unwanted odours, tastes, and colours in water.

• How it Works: Through the process of adsorption, where contaminants attach (are absorbed) to the surface of the activated carbon's extensive pores.

• Chemical Reaction (Simplified for Chlorine): C (carbon) + Cl₂ (chlorine) + H₂O → C-O (bonded) + 2HCl (hydrochloric acid) Chlorine is reduced and adheres to carbon.

3. Manganese Greensand / Birm

• Contents: Filter media coated with manganese oxide. Birm (BIRM - Brand Name) is another manganese oxide-based catalytic media.

• Uses: Specially designed to remove dissolved iron (Fe) and manganese (Mn) from water. The presence of iron and manganese can cause brown/black stains, metallic taste, and fouling in downstream systems.

• How it works: This media acts as a catalyst. Dissolved oxygen in water oxidises dissolved iron/manganese into insoluble solid forms, which are then filtered out by the media layer.

• Chemical Reaction (Simplified for Iron): 4 Fe²⁺ (dissolved iron) + O₂ (oxygen) + 10H₂O → 4 Fe(OH)₃ (solid precipitate) + 8H⁺ The iron precipitate is then filtered out.

• Note: This media requires regular backwashing and sometimes regeneration with potassium permanganate (for Manganese Greensand).

4. Ferrolite

• Contents: Filter media with a high manganese dioxide content. Similar to Manganese Greensand or Birm.

• Uses: Equally effective in removing dissolved iron (Fe) and manganese (Mn) from water, and can reduce hydrogen sulphide (H₂S), which causes a rotten egg smell.

• How it works: Ferrolite catalyses the oxidation of dissolved iron and manganese into insoluble forms, which are then trapped in the filter media.

• Chemical Reaction (Simple for Iron, similar to Manganese Greensand)

5. Anthracite

• Contents: Filter media made from ground hard coal (anthracite).

• Uses: Used to filter TSS (total suspended solids), often in combination with silica sand in a multimedia filter system. Due to its lower density than sand, it is often placed on top of sand for multi-stage filtration.

• How it works: Mechanical filtration, capturing suspended particles.

6. Ion Exchange Resin

• Contents: Synthetic polymer beads with functional groups that can exchange ions in water.

• Usage:

  • Softener Resin: Removes hardness-causing ions (Calcium Ca²⁺ and Magnesium Mg²⁺).

  • Demineralisation Resin: Removes all ions (cations and anions) to produce ultra-pure water.

• How it works: Undesirable ions in water are exchanged with harmless ions (e.g. Na⁺ for softeners or H⁺ and OH⁻ for demineralisation) bound to the resin.

• Chemical Reaction (Simplified for Softener Resin - exchanging Ca²⁺ with Na⁺): Ca²⁺ + 2 Resin-Na⁺ → Resin²⁺ - Ca²⁺ + 2 Na⁺ Saturated resin is then regenerated with a salt solution.

Why is a Pre-Filter Important?

A pre-filter is not just for producing water that looks clean. It is an important investment because:

• Protects Downstream Equipment: Prevents clogging and damage to pumps, valves, RO membranes, cooling tower fillers, and other components.

• Improves System Efficiency: Ensures that the subsequent water treatment system operates at optimal performance.

• Reduces Maintenance Costs: Reduces the frequency of cleaning and replacement of expensive components.

• Improves Final Product Quality: For industrial applications that require high-quality water.

PT Jaya Sakti Internusa is ready to assist you in designing and implementing the right pre-filter system with the appropriate filter media, ensuring a clean and protected water supply for all your needs. Contact us for a consultation.