KFM active filter media: a fine filtration stage for reinjection water at 1.5 μm cut-off
Most filtration problems in oily service are blamed on the wrong thing. The bed is not too shallow or the flow too fast; the medium simply prefers oil to water, and once it prefers oil it holds it, blinds, and demands backwash water that the plant would rather keep. The SINOKLE KFM active filter media filter takes the opposite starting position by changing the surface chemistry of the bed itself.
The mechanism in one paragraph
After superhydrophilic modification the active filter media has an extremely strong affinity for water. Water spreads rapidly across its surface and passes smoothly through the media pores, forming a stable hydrophilic coating film. When oily wastewater flows through the filter bed, the aqueous phase preferentially passes through the media while hydrophobic emulsified oil droplets are intercepted and adsorbed on the media surface and continuously enriched. Under hydraulic driving force they undergo collision coalescence and gradually form large droplets that float upward, separating from the oil phase.
The modified surface typically carries abundant micro-nano pore structures. These increase the stability of the hydrophilic film and the contact area between ultrafine emulsified oil droplets and the media, so droplets are intercepted, coalesced and merged into large ones instead of sliding through.
What the unit is specified to do
The KFM active filter media filter is built around this modified media and combines physical interception with surface adsorption. It suits advanced treatment of oily, polymer-bearing and suspended-solids wastewater, and is a preferred choice for oilfield reinjection water, power plant oily wastewater and similar duties.
- Treatment capacity: ~100m3/h
- Working temperature: up to 135 degrees C
- System pressure drop: 0.05~0.1 MPa
- Backwash interval: 8~12 h, with 5~10 min per cycle
- Influent limits: oil content 50 ppm or less, SS 50mg/l or less
- Effluent quality: oil content 6 ppm or less, SS 2mg/l or less, median particle size 1.5 μm or less
- Service: media replacement interval is long, and O&M work is limited to periodic inspection of the bed and the backwash valves
Two numbers deserve attention beyond the table. Service life of the filter media is 15 years, and the skid-mounted design reduces footprint by about 30%. In a brownfield retrofit those two figures often decide the project before the effluent numbers do.
The effluent specifications carry most of the procurement discussion, so state them precisely. Oil content is held at 6 ppm or less, equivalent to 6 mg/L in the units some operators use. Suspended solids stay at 2mg/l or less, and the median particle size of the particles that do pass is 1.5 μm or less. Taken together, those three numbers are what makes the outlet suitable for a reinjection well rather than merely acceptable for discharge.
Why quartz chemistry decides the operating envelope
The core active media is made from high-purity quartz with SiO2 content of 99.9% or more, which is almost completely inert to acids and alkalis, far superior to conventional media such as quartz sand, silicate media, emery and anthracite. Quartz also has a covalent bond network structure and is not attacked by chloride ions, so there is no risk of pitting or stress corrosion cracking in high-chloride service.
High-purity quartz releases no ions into solution, so the media cannot suffer pitting caused by its own insufficient chemical stability. Sand is acid-washed before leaving the factory until no ions leach out. Mechanically, the media has high hardness (Mohs 7) and shows no aging at 80 degrees C. These properties underwrite long-term operation at pH 1-12 and make the unit suitable for the corrosive, high-salinity conditions common in refining and oilfield service.
Filtration precision and the flexibility it buys
The micro-nano structure on the surface forms a superhydrophilic water film that greatly improves filtration precision, with removal efficiency above 99% at 1 μm. Fine oil droplets and suspended particles are intercepted, raising precision to the micron or even sub-micron level. That matters for applications with demanding water quality requirements, such as extract phase separation in the new energy industry and emulsified oil separation in oilfield and refining operations.
In a full train the KFM unit performs final fine filtration to ensure effluent oil content of 5 mg/L or less and meet stringent reinjection standards. Body construction uses carbon steel with internal anti-corrosion treatment, while core equipment and wetted parts use 316L or better.
Limits worth stating up front
Because separation is purely physical, the recovered waste oil has low moisture content and high quality and can be reused directly, and the system is highly automated with low energy and maintenance costs. The integrated skid-mounted structure is easy to transport and install, which shortens the construction cycle at oilfield sites where space is limited.
What the unit will not do is remove dissolved organics or salinity, and it needs a workable backwash supply at 8~12 h intervals. Treat it as the polishing stage that protects a reservoir from oil and fines, not as a substitute for upstream separation or downstream oxidation.
In practice the operating discipline that keeps the numbers above is unglamorous: hold the backwash interval rather than stretching it during a busy week, check differential pressure trends rather than alarms, and inspect the media surface once a year for fouling that the gauges have not yet registered. Units that lose their effluent quality usually lost it months before anyone noticed, and the cause is almost always a backwash sequence that was quietly shortened to save water.