Filtration Principle

Three layers capture progressively finer particles. Coarse anthracite on top removes large particles. Medium sand captures smaller solids. Fine garnet at bottom polishes to target clarity. Graduated density prevents intermixing during backwash.

Filter Vessel

Vertical pressure vessel with raw water inlet distributor, anthracite layer 18-24 inches, sand layer 12-18 inches, garnet layer 6-12 inches, gravel support bed, underdrain system collecting filtered water and distributing backwash. Design per ASME Section VIII.

Media Specifications

Anthracite 1.0-2.0mm effective size, sand 0.5-0.8mm, garnet 0.3-0.5mm. Specific gravity differences prevent mixing. Total bed depth typically 36-54 inches. Media life 5-10 years before replacement.

Operating Pressure

Typical 50-100 psig service pressure. Pressure drop through clean bed 5-10 psi increasing to 15-20 psi at end of run. High differential pressure signals backwash requirement.

Backwash System

Reverses flow direction expanding bed removing trapped solids. Air scour loosens particles before water backwash. Backwash rate 15-20 gpm per square foot expands bed 30-50%. Waste routes to drain or recovery.

Material Construction

Carbon steel or FRP vessels for water service. Stainless steel internals and piping for corrosion resistance. Epoxy or coating protecting internal surfaces. External coating for atmospheric exposure.

Filtration Performance

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

Applications

Boiler feedwater pre-treatment, cooling tower makeup, process water clarification, wastewater tertiary treatment, irrigation water filtration, and any application requiring suspended solids removal.

Run Length

Time between backwashes depends on inlet solids loading typically 8-48 hours. Pressure drop or turbidity breakthrough triggers backwash. Automated systems optimize cycle based on conditions.

Automation

Control panel manages filtration, backwash, and rinse cycles. Pressure differential and turbidity monitoring trigger backwash. Sequential operation for multi-filter installations. Minimal operator intervention required.

Performance Benefits

Effective suspended solids removal protecting downstream equipment. Long run times reduce backwash frequency. Simple proven filtration technology. Minimal maintenance requirements.

Construction Standards

Pressure vessels per ASME Section VIII. Piping per applicable codes. Controls per manufacturer standards. Complete documentation with hydraulic design and performance specifications.

ERGIL multimedia filter packages provide reliable suspended solids removal in pre-treatment water filtration applications.