Power Plant Wastewater Treatment
Oil in the wrong place doesn't need to be there. Removing it doesn't have to mean chemicals.
Compact, chemical-free treatment systems for heavy and light fuel oil tank drainage and coal washing effluent at thermal power stations. CDFU and KHC remove emulsified fuel oil without generating oily sludge — proven at power stations from Shaanxi to Sierra Leone.
Four reasons conventional systems fail at power stations.
Power station oily wastewater presents a specific combination of constraints that conventional gravity separators and coagulant-DAF systems cannot meet economically or reliably.
Low-volume economics, full-quality requirement
Power station oily wastewater volumes are typically 120–1,200 m³/d — too small for the regenerative processes that large refineries use. Yet discharge standards are the same. Conventional equipment cannot solve the economics of small-volume, high-quality treatment.
Gravity separation fails on emulsified fuel oil
Heavy and light fuel oil tank drainage contains emulsified oil where droplets are too small for gravity-only oil-water separators. Density near-parity between the oil phase and process water makes gravity ineffective — the oil simply does not rise fast enough to be separated.
Conventional DAF generates oily sludge classified as hazardous waste
Traditional DAF units require coagulant dosing to break fuel oil emulsions. The resulting oily chemical sludge is classified as hazardous waste under most environmental regulations — creating recurring disposal cost and compliance risk.
Heavy oil and light oil cannot share the same treatment train
Heavy fuel oil and light fuel oil drainage have different viscosities, emulsion characteristics, and separation requirements. A single combined system optimised for one fails the other. The correct approach is separate treatment paths for each fuel type.
KELIER vs. conventional separation systems.
Adapted from the technical comparison table in the KELIER power plant application document (2026).
| Aspect | Conventional gravity / coagulant DAF | KELIER CDFU / KHC system |
|---|---|---|
| Separation principle | Gravity / centrifuge only | Coalescence + cyclonic separation + 3-phase flotation |
| Emulsified oil removal | Not possible — emulsified droplets too small for gravity | Resolved physically — down to 2 µm (CDFU) or 0.1 µm (KHC) |
| Oily sludge output | Large volume — classified as hazardous waste | Zero sludge — recovered oil returned to the fuel system |
| Shock-load resistance | Poor — performance degrades sharply with concentration spikes | Good — no internal media to clog, tolerates variable inlet quality |
| Automation | Low — manual skimming, cleaning, and chemical dosing | Full PLC / SCADA — remote unmanned operation |
| Fouling / cleaning | Manual cleaning required — scheduled downtime | Self-cleaning (CDFU) / automatic backwash (SFM) — no periodic shutdown |
Three process trains for three source streams.
Each source stream at a thermal power station has different oil type, emulsification characteristics, and volume. The treatment sequence is matched to the source, not averaged across streams.
Heavy fuel oil tank area drainageTank cleaning water, pump and pipe leakage, tank farm drainage. Contains heavy oil fractions and emulsified oil that gravity separators cannot resolve.
For direct discharge where organic polishing is also required.
Light fuel oil tank area drainageLight fuel and lubricant oil tank drainage. Lower viscosity but often forms stable emulsions with water.
Coal conveyor and coal washing effluent carries lubricant oil from conveyor systems. Even low oil content (hundreds of mg/L) causes severe shock loads on downstream treatment plants and prevents stable discharge.
Compact, chemical-free. Built for power generation constraints.
CDFU — Cyclonic Dissolved-Gas Flotation
Primary separation for heavy oil tank and coal washing streams
Physical cyclonic flotation removes emulsified oil in 1–5 minutes without chemicals. Handles shock loads without internal media to blind. Proven at heavy-oil power stations in Bangladesh, Sierra Leone, and Guinea.
Full technical specificationsKHC — High-Efficiency Coalescer
Separation for light oil tank drainage
Super-oleophilic coalescing fiber resolves emulsified light fuel oil down to 0.1 µm through physical coalescence. No chemical dosing. Applied as the primary separator on light fuel oil and lubricant tank drainage.
Full technical specifications
CDOFCDOF — Cyclonic Dissolved Ozone Flotation
Advanced oxidation for direct-discharge treatment trains
Applied after CDFU when direct discharge requires organic polishing. Catalytic ozonation removes COD and residual organics at pH 3–10 without Fenton-type sludge. Proven at the Guinea Simandou heavy-oil power station (2025).
Full technical specificationsPower station case record.
Five verified installations across Asia, West Africa, and South Asia. All cases drawn from project documentation.
| Client / Project | Location | Application | Configuration | Capacity | Year |
|---|---|---|---|---|---|
| Heavy Oil Power Station | Bangladesh | Heavy oil power station oily wastewater | 2-stage CDFU + KFM | 120 m³/d | 2021 |
| Regional Cogeneration Plant | Shaanxi, China | Backpressure cogeneration power plant | KHC coalescing deoiler | 120 m³/d | 2022 |
| State Power Construction Corp. | Sierra Leone | Heavy fuel oil power station — tank area wastewater | 2-stage CDFU + KFM | 120 m³/d (5 m³/h) | 2025 |
| Mining Industry Power Station | Guinea | Heavy fuel oil power station — tank area wastewater | CDFU + CDOF | 240 m³/d (10 m³/h) | 2025 |
Questions from power plant engineers.
Thermal power stations generate oily wastewater from several distinct sources: heavy fuel oil tank area drainage (tank cleaning, pump and pipe leakage, tank farm storm water); light fuel oil and lubricant oil tank drainage; coal washing and conveyor lubrication effluent; and turbine lubricant oil contamination in cooling circuits. Each source has different oil concentrations, oil types, and emulsion characteristics — requiring different treatment approaches.
Conventional gravity oil-water separators rely on buoyancy — Stokes' law settling velocity — to separate oil from water. For this to work, oil droplets must be large enough (typically ≥100 µm) and the density difference must be significant. Fuel oil tank drainage often contains emulsified oil where droplets are below 5 µm and oil-water density near-parity is created by surfactants and thermal history. Under these conditions Stokes' velocity approaches zero and the gravity separator passes oil-contaminated effluent unchanged.
No. CDFU and KHC are pure-physical processes with no chemical coagulants dosed at any stage. The separated oil exits as recovered fuel oil that can be returned to the heavy oil storage tank or recycle system — not as an oily sludge requiring hazardous-waste classification and disposal. This eliminates the largest recurring OPEX and compliance risk of conventional coagulant-based DAF at power stations.
The same technology modules — CDFU and KHC — handle both, but in different configurations. Heavy oil tank drainage, with its higher viscosity and emulsification severity, goes through a conventional oil-water separator followed by CDFU. Light oil and lubricant tank drainage, where coalescence is more effective, goes directly through KHC. Combining both streams into a single train would require designing to the worst-case heavy oil conditions and would over-engineer the light oil treatment.
Yes — this is where the KELIER system has a specific advantage. CDFU and KHC are pressure-vessel units that tolerate intermittent and batch flows. The typical power station installation is 120 m³/d (5 m³/h), which is well within the operating envelope of a single compact skid-mounted CDFU or KHC unit. The units restart cleanly after idle periods without coagulant dosing re-calibration or media maintenance that would be required in conventional systems.
Tell us your power station's fuel type and wastewater volume.
Heavy oil or light oil, coal washing or turbine drainage — specify the stream and KELIER will size the right compact treatment unit.