Multi-layer pressure filtration systems for superior suspended solids removal and extended run times.
Treating a borehole or groundwater supply? See our full approach — aeration and catalytic multimedia filtration for iron and manganese, ultrafiltration for SDI and RO pre-treatment, and disinfection for potable supply — with example arrangements by application.
Borehole TreatmentOur multimedia filters use a graded bed of anthracite, silica sand and garnet. The lighter anthracite (SG 1.5) settles slowest after backwash and forms the coarse top layer; denser sand (SG 2.65) re-settles in the middle; the heaviest garnet (SG 4.1) drops to the bottom. The result is a bed that captures coarse solids near the surface and progressively finer particles deeper down, delivering depth filtration rather than surface straining.
Compared to single-media sand, the graded stack holds 3–5× more solids before head loss triggers a backwash, so run lengths are longer and the backwash water consumption per m³ filtered is lower. Effective filtration cut is 10–15 µm for plain TSS removal; with upstream coagulation we reliably hit SDI15 of 2–3 for RO pretreatment.
Standard build is a packaged pressure vessel skid in SS316L or rubber-lined carbon steel, with motorised valve set, dedicated backwash blower and pump, PLC, and remote-monitoring telemetry. Vessel design to PED 2014/68/EU module H for UK and EU duty, or ASME VIII Div 1 U-stamped for export.
Five focused subpages for the engineering detail behind the product
Anthracite, sand and garnet specifications — effective size, uniformity coefficient, specific gravity, depths. How the bed re-stratifies after backwash and why the standard stack works.
Read MoreHydraulic loading rate, bed depth, freeboard, distributor selection, nozzle-plate underdrain, pressure-code (PED / ASME). Pressure vs gravity filter selection.
Read MoreThe six-step air-scour-then-rinse sequence, fluidisation hydraulics, temperature correction, valve interlocks and SCADA logic that runs the cycle unattended.
Read MoreEight train positions where MMF earns its place — RO pretreatment, tertiary polishing, cooling, boiler feed, Fe/Mn removal, reuse. Plus honest limits of the technology.
Read MoreField diagnoses for the seven recurring MMF problems — mudballs, channelling, breakthrough, media loss, biofouling, greensand failures — plus the annual inspection checklist.
Read MoreHow multimedia filters compare to sand filters, GAC, cartridge filters, UF and self-cleaning filters.
Read MoreStandard Media Layers
The multi-layer design provides progressive filtration for optimal solids removal.
0.8-1.2 mm particle size. Captures larger suspended solids and provides depth filtration.
0.4-0.6 mm particle size. Primary filtration layer for fine suspended solids.
0.2-0.4 mm particle size. Polishing layer for finest particle removal.
This treatment stage is engineered to achieve specific contaminant removal targets while providing stable, predictable performance across variable inlet conditions. Design parameters are calculated from wastewater characterisation data, regulatory requirements, and site-specific constraints including footprint, energy availability, and operator capability.
Design validated by CFD modelling and pilot testing to confirm performance guarantees.
Equipment selected for 20-year design life with minimal wearing parts and easy access.
Automated dosing and feedback control minimise reagent consumption and sludge production.
Online monitoring and data logging demonstrate continuous consent compliance.
Real numbers for industrial pressure vessels — full sizing detail
| Service flow per vessel | 10–500 m³/h (single vessel), > 500 m³/h split across parallel filters |
| Service loading rate | 12–18 m/h (5–7 gpm/ft²) typical; up to 25 m/h on benign water |
| Bed depth | 850–1,000 mm total (300–500 anthracite / 250–350 sand / 75–150 garnet / 200–300 support gravel) |
| Filtration cut-off | 10–15 µm for plain TSS; SDI15 2–3 with upstream coagulation |
| Design pressure | 6–10 barg, PED 2014/68/EU module H or ASME VIII Div 1 |
| Clean-bed head loss | 0.2–0.4 bar; backwash trigger 1.0–1.5 bar |
| Run length | 20–36 h between backwashes on RO pretreatment duty |
| Backwash rate | 35–45 m/h (water), 50–80 Nm³/h·m² (air scour) — cycle detail |
| Backwash water use | 1.5–3 % of throughput (industrial), 3–5 % (municipal/DWTP) |
| Vessel shell material | SS304L / SS316L / CS-rubber lined / GRP (selected on chloride and disinfectant residual) |
| Internals | Hub-and-radial inlet distributor, nozzle-plate underdrain, optional surface wash |
| Controls | PLC with 8 motorised valves per vessel, SCADA integration, head-loss/turbidity/timer backwash triggers |
Multimedia filters do not appear in isolation — they sit between a clarification stage that removes the bulk solids and a sensitive downstream process that cannot tolerate residual particulate. The four most common positions are RO pretreatment, tertiary polishing of biological effluent, cooling-tower make-up, and boiler-feed pretreatment.
After secondary biology and clarification. Brings TSS < 5 mg/L for UV disinfection or water reuse.
Before softening or demin. Greensand variant adds Fe/Mn removal.
Greensand / pyrolusite cap turns the filter into a catalytic reactor. Borehole water before potable or process use.
No treatment stage operates in isolation. This process is designed to receive conditioned influent from upstream stages and deliver effluent quality suitable for downstream processes. Hydraulic and organic loading rates are balanced across the complete treatment train to prevent bottlenecking and ensure overall plant efficiency. Our engineers model the complete flowsheet to optimise Capital expenditure and Operating expenditure across the plant lifecycle.
Screening, equalisation, and pre-treatment protect this stage from damage and overload.
Effluent quality ensures downstream biology, filtration, or disinfection performs optimally.
Reject streams, filtrate, and centrate are routed back to appropriate upstream points.
Contact Our Engineers to discuss your filtration requirements and get a customised quotation.
Our expertise spans multiple industries with sector-specific water treatment solutions.