Sewage treatment plants for ships

Sewage treatment plants (STPs) from Wärtsilä are the most cost-effective and safe answer for every ship or offshore platform to dispose of wastewater at sea. No tempering with the quality of our oceans.

Wärtsilä sewage treatment units - also known as 'Wartsila Hamworthy Super Trident' - are certified to meet IMO MEPC 227(64) guidelines. These have been in place for all new-build ships from 1 January 2016 onward.

Each Super Trident sewage treatment unit has been optimised to process all onboard black and grey wastewater streams. The plants are compatible with both conventional gravity and vacuum fed collection systems. On top of that, each STP is fully automatic, allowing for unattended operation. This greatly reduces maintenance requirements and lower long-term operating costs.

Finally, Wärtsilä sewage treatment plants for ships are compact and modular in design, suitable for between-deck installations and adaptable to customer new-build specifications.


    Benefits of Wärtsilä sewage treatment plants

    • Cost-effective, environmental friendly & safe answer for every ship to dispose of waste water at sea
    • Proven effluent quality: clean and safe effluent, suitable for discharging overboard
    • Low operational costs with:
      • minimal maintenance & spare parts required
      • minimal human intervention during operation
    • Simple & robust construction
    • Compatible with gravity & vacuum collection systems
    • Collecting tank integral part of STP


    Main features

    • IMO 227(64) & MED certified
    • Single power supply input point
    • Solids handling centrifugal discharge pump
    • Chemical disinfection and de-chlorination
    • Automatic control
    • Compact design


    STC 13 line

    System IMO certified
    (LxWxH in mm)
    Weight full
    STC-01-13 1740 1890 1400 1181 1550
    STC-02-13 3120 2518 1863 1336 3030
    STC-03-13 4660 2622 1863 1681 3959
    STC-04-13 6010 2722 2080 1821 5027
    STC-06-13 9360 3072 2280 1971 7367

    STC 14 line

    System IMO certified
    (LxWxH in mm)
    Weight full
    STC-08-14 11840 3000 2670 2000 9294
    STC-10-14 15810 3400 2750 2000 11314
    STC-13-14 20830 4400 2750 2000 15036
    STC-15-14 25704 3700 3215 2300 17836
    STC-20-14 33974 4620 3215 2300 22422
    STC-25-14 40778 4620 3490 2500 27446
    STC-30-14 47422 5012 3470 2700 30898
    STC-40-14 64150 6012 3915 2680 43614
    STC-50-14 80182 7000 4145 2900 55526
    STC-60-14 100800 7000 4180 3500 69754

    STC0-23 line

    SystemIMO certified
    (LxWxH in mm)
    Weight full


    As standard

    • Main tank
    • Air compressor
    • Discharge pump
    • Electrical control panel
    • Chlorination & dechlorination systems


    • Fitted vacuum sewage collection equipment
    • Conditioning water flow meter
    • Standby compressor (mounted)
    • Standby discharge pump (mounted)
    • Maceration
    • Separate sewage feed system
    • Retrofit options available to aid installation

    Process flow of a Wärtsilä sewage treatment plant

    Process Flow Wärtsilä sewage treatment plant




    • Leonidas

      Delivered in 2009, the 318,000 dwt Leonidas features a machinery installation incorporating a Wärtsilä 7RT-flex82T. The vessel is also equipped with the Super Trident Sewage Treatment Plant ST2A, certified to meet IMO MEPC 159(55) guidelines.

      Read more
    • HMS Daring

      The HMS Daring, commissioned in 2009, is the first of six vessels of the new Type 45 class. Each Type 45 Destroyer has an IEP (Integrated Electric Propulsion) system consisting of two gas turbine alternators and two Wärtsilä 12V200 diesel alternators. (photo courtesy of BVT). The vessel is also fitted with a MBR50N membrane bioreactor for advanced wastewater processing.

      Read more
      HMS Daring Courtesy BAE Systems

    Contact us

    Please fill in the form, we aim to respond within 1-2 business days depending on the enquiry. For an existing installation, provide all necessary details to identify the installation and the equipment. Fields indicated with an asterisk (*) are required.

    For NEWBUILD & RETROFITS, please contact +44 1202 662 600 or

    For spare parts, please e-mail us with the Equipment Serial Number or the name of the vessel at For urgent support, contact +44 1202 662 634.

    For technical support & service, please email us with the Equipment Serial Number or the name of the vessel at For urgent support, contact +44 1202 662 616.

    Equipment Serial Number is taken from the equipment nameplate and includes all letters and numbers as given on the equipment nameplate.