Bilge water treatment with ceramic membranes

Bilge wastewater treatment on ships by filtration with ceramic membranes: enormous potential for savings

Filtration of bilge water on ships with ceramic membranes: reduction of wastewater volume, cost reduction, generation of filtrate suitable for discharge into the sea, compliance with discharge requirements.

Key technology for the treatment of emulsions

One of the most important environmental problems on ships is the uncontrolled overboard discharge of liquid waste. Among other things, oily wastewater (bilge water) accumulates in the lowest points of ships, called bilges.   Above all such large quantities accumulate on larger, older ships, which are too large for long-term storage.

Bilge water is a highly variable mixture of potable water and seawater with impurities from various sources such as fuels, oils and hydraulic fluids, cleaning agents, etc. 

Advantages of ceramic atech membranes in bilge wastewater treatment

  • Save discharge of treated water < 15 ppm oil
  • Maximum volume reduction gives minimum waste volume
  • Cost saving for harbor
  • Insensitive to seagoing movements
  • Polishing of the effluent from the OWS (oil- water – separator)

atech membranes meet the high requirements

The use of ultrafiltration plants at the Royal NL Navy and many other ship owners in the Netherlands Norway, UK and Germany from PROMAC with ceramic membranes from atech finally ensures that the specifications for the discharge of the permeate are met.

Onboard test and operational results confirm that any bilgewater mixture, even under emulsified conditions, is typically treated to a residual oil content of 2-5 ppm, but always below 15 ppm. Due to maximum volume reduction, the concentrated oily residual usually contains less than 2 -5% water (or 95-98% oil). The entire UF system line is IMO MEPC 60/33 certified and specifically designed for emulsified mixtures. The systems have been selected for advanced new construction and extensive retrofit programs.

Membranes suitable for filtration of bilge water emulsions

Channel- diameter (mm) Pore size Permeate performance (l/m²h) Temperatur TMP Velocity in channel
3 - 4 UF approx. 60 - 80 (depending on pollution level) 20 - 50 °C 140 - 176 °F approx. 1,5 – 3 bar approx. 21,7 - 43,5 PSI 4 – 6 m/s 13-19 ft/s
omparison of water quality before and after filtration

Comparison of water quality: raw bilge- water on the right, permeate on the left

Advantages and added value for the customer:

  • The ceramic membranes are capable of treating bilge water in a stable long-term operation and the membranes were successfully regenerated.
  • Cleaning intervals were able to keep the FLUX value constant over a long period of time.
  • The ceramic membranes are chemical resistance – ready for use in a range between 0 – 14.