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    Advanced sewage treatment plant


    Marsh ENCO sewage treatment plant

    High performance, highly competitive sewage treatment plants for today’s cash-conscious market

    Marsh sewage treatment plants are widely regarded as the most efficient, reliable and economical systems on the market.

    Building upon the outstanding reputation of the Marsh:Ensign® range of sewage treatment plants, the Marsh:ENCO is a cost-effective alternative where competitive pricing is required.

    Outstanding performance

    Tested and approved to BSEN12566-3/A1:2009 all ENCO units provide treatment well within national consent requirements.

    Unrivalled choice

    Ranging in size from 6 to 16PE and with a wide range of ancillaries, almost all site, consent and budget requirements can be met by units from the ENCO range.

    Why choose the Marsh:ENCO?

    The Marsh:ENCO provides an economical alternative to standard and ultra sewage treatment plants. End users, merchants and installers alike recommend the Marsh range due to its ease of installation, reliability, and cost-effective operation and maintenance. All backed by technical support from local contacts.

    Operating principle

    In addition to anaerobic digestion taking place in the primary settlement chamber the Ensign:Ultra unit allows the clarified water to pass into a second ‘aeration’ chamber where it is treated to remove the dissolved constituents. Here aerobic bacteria, supported by diffused air and mobile media, ensures full treatment is achieved before the treated effluent and ‘sloughed off’ bacteria flows to a final settlement chamber . The final effluent is then discharged to the drainage field or watercourse.


    1. Inlet
    2. Primary settlement chamber
    3. Aeration chamber
    4. Low-energy compressor
    5. Compressor housing – internal or external options available
    6. PVC pressure pipe/diffuser(s)
    7. Securing mesh
    8. Final settlement chamber
    9. 32mm sludge return
    10. Outlet
    11. Standard impermeable lid
    12. Stabilising feet
    13. Unique ‘keying-in’ lip
    Marsh Enco cutaway illustration


    1 Inlet
    Optional risers to increase invert depth are available.

    2 Primary settlement chamber

    3 Aeration chamber

    4 Low-energy compressor
    Near silent compressor ensures minimal running, maintenance and servicing costs.

    5 Compressor housing – internal or external options available
    The compressor can be housed internally or externally with no difference in cost.
    External recommended to increase compressor life, and supplied as standard on 4PE, shallow and pumped outlet versions.

    6 PVC pressure pipe/diffuser(s)
    Provides a protective conduit for the air diffuser line. Can be easily removed for maintenance and cleaning.

    7 Securing mesh
    Retains media in aeration chamber during transportation and handling, and in the event of flooding.

    8 Final settlement chamber

    9 Sludge return (32mm)
    Larger diameter sludge return prevents the possibility of blockages and improves system circulation. Provides higher effluent quality whilst balancing flow over a 24 hour period or periods of intermittent use.

    10 Outlet
    Optional pumped outlets are available.

    11 Standard impermeable lid
    Impermeable lid improves strength and durability whilst blending into the surrounding environment.

    12 Stabilising feet
    Stabilising feet prevents the tank from rolling and allows safe and steady transportation and installation.

    13 Unique ‘keying-in’ lip
    Assists anchoring into granular or concrete surrounds.

    High specification bio-media (310m3 per m2) and membrane diffusers ensure even circulation to eliminate ‘dead spots’. The bio-media is contained by a securing mesh to ensure no migration during handling or potential flooding.

    Integral lifting eyes
    For safe and secure handling onsite.


    Specifications table
    Model (pop) Length Width +/-50mm Height +/-50mm Inlet invert +/-50mm Inlet dia Outlet invert Outlet dia
    ENCO 6 2602 1650 1935 550 110 625 110
    ENCO 8 2602 1650 1935 550 110 625 110
    ENCO 10 2602 1650 1935 550 110 625 110
    ENCO 12 2860 1912 2139 550 110 625 110
    ENCO 16 2860 1912 2139 720 110 800 110

    Larger population sewage treatment plants may be supplied as multiple tank configurations.
    For precise tank sizes and configurations, please contact Marsh Industries.
    All dimensions in mm.
    Due to production processes, dimensions of finished units are within a tolerance of +/-2.5%.

    Technical downloads for architects, engineers, consultants and specifiers including BIM files (RFA and IFC), DWG CAD files


    Marsh ENCO range


    Marsh product portfolio and specifications


    Installation/technical manual