Multi-Layer Principle

Three layers capture progressively finer particles optimizing filtration depth. Coarse anthracite top layer removes large particles without rapid plugging. Medium sand middle layer captures smaller solids. Fine garnet bottom layer provides final polishing. Graduated density prevents intermixing during backwash.

Filter Vessel Construction

Vertical pressure vessel with raw water inlet distributor ensuring uniform flow, anthracite layer 18-24 inches, sand layer 12-18 inches, garnet layer 6-12 inches, gravel support bed 12-18 inches, underdrain system collecting filtered water and distributing backwash.

Media Specifications

Anthracite effective size 1.0-2.0mm with uniformity coefficient under 1.5. Sand effective size 0.5-0.8mm. Garnet effective size 0.3-0.5mm. Specific gravity differences prevent mixing - anthracite 1.4-1.7, sand 2.6, garnet 4.2. Total bed depth 36-54 inches.

Operating Pressure

Typical 50-100 psig service pressure. Clean bed pressure drop 5-10 psi increasing to 15-20 psi at end of filtration run signaling backwash requirement. Design per ASME Section VIII.

Filtration Performance

Removes suspended solids to 5-10 microns. Turbidity reduction from 10-50 NTU inlet to under 1 NTU outlet meeting drinking water standards. Efficiency depends on loading rate typically 5-10 gpm per square foot.

Material Construction

Carbon steel vessels with internal epoxy lining for municipal water. Stainless steel for high-purity or corrosive applications. FRP construction for specialty waters. Internal distribution systems corrosion-resistant. External coating protects atmospheric exposure.

Backwash Operation

Upflow water at 15-20 gpm per square foot expands bed 30-50% washing trapped solids to waste. Air scour optional before water backwash improving cleaning for heavily loaded applications. Backwash duration 10-15 minutes.

Run Length

Time between backwashes 8-48 hours depending on inlet turbidity and solids loading. Pressure drop or turbidity breakthrough triggers backwash. Automated controls optimize cycles based on conditions.

Applications

Municipal water treatment for drinking water production, industrial process water clarification, cooling tower makeup pre-treatment, boiler feedwater filtration, wastewater tertiary treatment, irrigation water cleanup.

Chemical Pretreatment

Coagulation with alum or ferric chloride plus polymer flocculation improves removal efficiency. Chemical conditioning forms larger flocs captured more effectively. pH adjustment optimizes coagulation.

Control Systems

Automated backwash initiation based on differential pressure, turbidity breakthrough, or time. Sequential operation for multiple filter installations prevents production interruption. PLC controls manage complete cycles.

Capacity Sizing

Filter area based on design flow rate and loading rate. Multiple filters provide redundancy during backwash. Proper sizing ensures continuous water production meeting demand.

Media Replacement

Media life 5-10 years with proper operation and backwash. Gradual degradation from abrasion and chemical exposure. Complete replacement restores performance. Simple media removal and reloading procedures.

Performance Benefits

Effective suspended solids and turbidity removal. Superior to single media through depth filtration. Long run times reduce backwash frequency. Proven municipal and industrial technology.

Construction Standards

Pressure vessels per ASME Section VIII. Piping per applicable codes. Materials for water service. Underdrain design preventing media loss. Complete documentation with hydraulic calculations and performance specifications.

ERGIL multimedia filters provide reliable multi-layer water purification removing suspended solids and turbidity in municipal and industrial water treatment applications.