The automatic self-cleaning deep-bed filter for produced water polishing and industrial wastewater tertiary treatment.
KELIER's SFM Surface-Modified Filtration Media uses atomically-modified, super-hydrophilic silicate media to achieve ~1 µm filtration precision via three combined actions — hydrophilic coalescence/demulsification, physical interception, and sieve action — removing residual oil and fine solids to oil ≤5 ppm, SS ≤2 mg/L in a single polishing stage. Fully automatic hydraulic backwash (12–24 h interval, 5–10 min cycle) restores 100% performance without chemicals, manual intervention or media replacement. 15-year media service life. The final polishing stage for produced water reinjection and oily wastewater treatment trains.
Benchmark-setting numbers.
Deep-Bed Filtration, Reinvented for Unattended Operation
SFM is an activated media filter — not a commodity sand filter. Its silicate-based media undergoes atomic-deposition surface modification, creating a super-hydrophilic nano-structure with surface area approximately 300× that of quartz sand. The negatively-charged surface adsorbs positively-charged particles and impurities below 20 µm, adds electrostatic-desorption during backwash for 100% cleaning efficiency, and continuously generates free radicals that sterilise the bed — eliminating bio-fouling and media caking.
The result is ~1 µm filtration precision (oil <5 ppm, SS ≤2 mg/L), fully automatic 5–10 minute backwash cycles every 12–24 hours, and a 15-year media service life — without chemical cleaning, manual intervention, or consumable cartridges.
Conv = conventional cartridge or rapid-sand filter. All comparisons are indicative; performance depends on application stream characteristics.
Four Stages — From Inlet to Automatic Regeneration
SFM operates in a continuous filtration-and-regeneration cycle. Deep-bed filtration removes residual oil and suspended solids throughout the media depth; automatic backwash restores capacity without any manual intervention.
Inlet distribution & pre-classification
Pressurised feed enters from the top inlet and passes through a perforated-tube radial distributor that spreads flow uniformly across the full filter cross-section — eliminating localised jetting and channelling. Water then descends at a stable filter velocity of 8–12 m/h into the media bed, ensuring consistent loading across the entire depth. Inlet requirements: oil ≤50 ppm, SS ≤50 mg/L. When inlet oil or suspended solids exceed 50 ppm the backwash interval shortens; feeds containing colloids require upstream demulsification pre-treatment to prevent media agglomeration and caking.
Hydrophilic precision filtration
Water passes through the atomically-modified, super-hydrophilic silicate media layer. Three combined actions deliver ~1 µm precision: hydrophilic coalescence and demulsification (breaks and captures residual emulsified oil droplets), physical interception (pore-size-based capture of particles), and sieve action (size exclusion at sub-micron scale). Together these achieve oil ≤5 ppm, SS ≤2 mg/L at the outlet.
Continuous quality monitoring
Differential pressure sensors and optional inline turbidity or OIW monitors track filter performance in real time. As the media bed accumulates contaminants and ΔP rises toward the setpoint, the PLC initiates backwash automatically — without operator intervention. Typical run interval: 12–24 hours.
Full-fluidization regeneration
The backwash pump injects treated effluent bottom-to-top, fluidising the media bed to 20–35% expansion. The media's strong hydrophilic anti-fouling properties combined with complete bed fluidization produce more thorough contaminant removal each cycle than non-fluidized regeneration — preventing bio-fouling and particle adhesion without chemical agents. Backwash cycle: 5–10 minutes; 100% filtration performance restored. 70% less backwash water and 50% lower energy per ton versus conventional filters.
Filtration
Forward flow through graded-porosity media. Solids captured throughout bed depth.
ΔP monitoring
Differential pressure sensor tracks bed loading in real time.
Backwash trigger
PLC initiates backwash when ΔP reaches setpoint — no manual action needed.
Regeneration
Reversed flow fluidises bed to 20–35% expansion (5–10 min). Electrostatic desorption releases particles cleanly — 100% performance restored, no chemical flush. Typical run interval: 12–24 h.
Self-Cleaning.
Built to Last.
Zero cartridges · Zero chemicals · Zero downtime
SFM's superhydrophilic silica-based filter media removes oil and suspended solids through coalescence demulsification, material interception and sieve separation — then the exceptional anti-fouling properties of the media, combined with fully automatic fluidised high-efficiency backwashing, complete the backwash cycle in 5–10 minutes. No cartridges, no chemicals, no operator required. 15-year media service life and consistent reinjection-grade polishing across continuous, unattended operation.
Eight Reasons SFM Outperforms
Hydrophilic anti-fouling media
The super-hydrophilic surface modification actively resists bio-fouling and particle adhesion — no biocide required. The strong anti-fouling properties combined with full bed fluidization during backwash produce more thorough contaminant removal each cycle than non-fluidized regeneration. Anti-caking properties maintain consistent bed porosity over the full 15-year service life.
100% backwash recovery, every cycle
Electrostatic desorption cleanly releases captured contaminants from the charged media surface during each backwash. 100% filtration performance is restored in 5–10 minutes — no chemical flush, no partial recovery, no gradual performance drift.
~1 µm precision — removes oil too
Grade II precision media achieves effluent oil ≤5 ppm and SS ≤2 mg/L (median particle ≤1 µm) via three combined actions: hydrophilic coalescence/demulsification, physical interception, and sieve action. SFM removes residual emulsified oil alongside fine solids — a single-stage polisher that replaces what used to require multiple treatment steps.
15-year media service life
The media's inherent mechanical strength (an intrinsic property of the base material, unrelated to surface modification) delivers a wear rate of <0.2% — far lower than anthracite or garnet. Annual top-up is only 1–5%.
No pre-filter required for oilfield feed
SFM tolerates inlet oil ≤50 ppm and SS ≤50 mg/L without a dedicated pre-filter stage. When inlet oil or suspended solids exceed 50 ppm the backwash interval shortens. Feeds containing colloids require upstream demulsification pre-treatment to prevent media agglomeration and caking.
Chemical-free, zero-waste operation
Backwash uses clean treated effluent — no acid, caustic or cleaning agents at any stage. No chemical waste stream, no hazardous handling. 70% less backwash water and 50% lower energy per ton versus conventional media filters.
PLC / DCS integration
Full PLC automation: ΔP setpoint control, cycle-count logging, real-time alarm outputs and SCADA / DCS integration. Backwash triggerable by ΔP, elapsed time or manual command. Designed for continuous, unattended remote operation.
Single stage replaces multi-stage
SFM's combined hydrophilic coalescence/demulsification, physical interception, and sieve action replaces what conventional systems deliver in two or three stages — reducing footprint by 20–30% and eliminating inter-stage pumping.
Technical Parameters
- · SFM precision: ≤1 µm vs nutshell ~5 µm
- · No chemical cleaning agents; no internal stirrer
- · No agitator damage to media; 1–5% vs 5%+ annual replenishment
- · >5-year service life vs progressive saturation and replacement
SFM vs Conventional Media
Where SFM Delivers
Produced water polishing for reinjection
Reinjection water quality targets (oil ≤5 ppm, SS ≤2 mg/L, median particle ≤1 µm) demand a final polishing stage after flotation. SFM — positioned downstream of CDFU or CDOF — removes residual emulsified oil and fine solids to reinjection grade, protecting reservoir permeability from plugging. Proven across Congo, Xinjiang, Changqing, and Huabei oilfields.
Oilfield solutions
Chemical-industry wastewater — lithium battery plant polishing
Lithium battery manufacturing and chemical-process plants generate effluent laden with lithium slurry fines, residual process oil, and fine particulates that must be removed before discharge or reuse. SFM's charged-media filtration removes emulsified oil and sub-micron solids in a single polishing stage — no coagulant addition, no manual media change — delivering oil ≤5 ppm and SS ≤2 mg/L to discharge grade.
Power plant oily wastewater — compliance polishing
Heavy-oil power plants generate oily wastewater that must meet environmental discharge standards before release. SFM's pure-physical, zero-chemical process delivers oil ≤5 mg/L from inlet oil of 2,000–3,000 mg/L (via CDFU+SFM train) — proven in operation at a Sierra Leone heavy-oil power plant since June 2025.
Power-plant solutionsFull Treatment Train
Three downstream schemes by reservoir permeability — single, dual, or combined SFM + modified membrane.
N₂ aeration on CDFU; ozone oxidation on CDOF; side streams to recovered oil tank and exhaust gas treatment.
Proven Results
Representative SFM deployments across energy and industrial applications. Specific project data available on request.
Congo Oilfield — Produced Water Reinjection
System inlet: oil 3,825 mg/L, SS 972 mg/L
Sierra Leone Heavy-Oil Power Plant
System inlet: oil 2,000–3,000 mg/L, SS 100 mg/L — pure-physical, zero additives
China Oilfield Track Record
Xinjiang 2016 (360 m³/d) · Yanchang 2017 (240 m³/d) · Changqing 2017 (350 m³/d) · Xinjiang 2018 (4,800 m³/d) · Huabei 2019 (300 m³/d)
Common Questions About Surface-Modified Filtration Media
SFM — Surface-Modified Filtration Media — is an activated, surface-modified silicate media filter that combines ultra-high filtration precision (~1 µm) with fully automatic hydraulic backwash. Unlike cartridge filters that require manual element replacement or conventional sand filters that need chemical cleaning, SFM's super-hydrophilic anti-fouling media releases captured contaminants during each backwash cycle, restoring 100% filtration performance in 5–10 minutes without operator intervention or chemical addition.
SFM's self-cleaning capability is driven primarily by its super-hydrophilic anti-fouling surface modification, which actively resists bio-fouling and particle adhesion throughout the filtration cycle. During backwash, treated effluent is pumped bottom-to-top, fully fluidising the media bed to 20–35% expansion. The strong anti-fouling surface properties combined with complete bed fluidisation ensure captured contaminants release cleanly each cycle — without chemical agents — yielding more thorough regeneration than non-fluidised systems. Electrostatic desorption from the negatively-charged media surface provides additional contaminant release during fluidisation. Backwash cycle: 5–10 minutes; 100% filtration performance restored. Result: 70% less backwash water and 50% lower energy per ton versus conventional media filters.
SFM achieves ~1 µm filtration precision (>95% interception of 1 µm particles; median effluent particle size ≤1 µm). Grade II precision media delivers effluent oil ≤5 ppm and SS ≤2 mg/L — sufficient for produced water reinjection in both high- and low-permeability reservoirs. Grade III coarse media gives effluent oil ≤15 mg/L, SS ≤5 mg/L for less demanding streams. KELIER engineers select the grade based on inlet particle distribution and the target effluent specification.
Yes. SFM removes residual emulsified oil alongside fine suspended solids through three combined actions: hydrophilic coalescence and demulsification (breaks and captures residual emulsified oil droplets), physical interception, and sieve action. Confirmed effluent performance is oil ≤5 ppm (Grade II) — meeting reinjection and environmental discharge quality targets for produced water and oily power-plant wastewater. This dual oil+solids removal in a single polishing stage replaces what conventional systems deliver in two or three steps.
SFM is designed to accept inlet oil ≤50 ppm and SS ≤50 mg/L without a dedicated pre-filter stage — typically the effluent quality already achieved after an upstream CDFU or CDOF flotation unit. When inlet oil or suspended solids exceed 50 ppm, the backwash interval shortens to maintain effluent quality. Feeds containing colloidal impurities require upstream demulsification pre-treatment to prevent media agglomeration and caking. SFM is not suited as a primary separator for high-oil feeds.
SFM is the final polishing stage in a KELIER oily-wastewater treatment train, positioned downstream of a primary gravity separator and a secondary flotation unit (CDFU or CDOF). The two-stage CDFU + SFM configuration is the standard train for produced water reinjection — CDFU removes bulk and emulsified oil, SFM polishes the remaining fine solids and residual oil to reinjection grade. SFM can also serve as a standalone tertiary polisher where upstream separation is already effective.
SFM has been deployed across multiple oilfield and industrial projects. In Africa, a 200 m³/h CDFU + SFM train at a Congo oilfield (2023) polishes produced water to oil 4.1 mg/L and SS 4.6 mg/L for reinjection; a CDFU + SFM system at a Sierra Leone heavy-oil power plant (operational June 2025) delivers oil ≤5 mg/L for environmental discharge compliance. In China, five oilfield projects for PetroChina and Yanchang Group (2016–2019) — spanning Xinjiang, Yanchang, Changqing, and Huabei oilfields — established the CDFU + SFM train as the standard produced-water reinjection configuration, with installed capacities from 240 m³/d to 4,800 m³/d.
Ready for Continuous, Unattended Filtration?
Our engineers can size an SFM system for your flow rate, inlet solids loading and target effluent — and integrate it with upstream CDFU or CDOF flotation for a complete treatment train. Pilot tests available for high-solids or variable-load streams.