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    Advanced sewage treatment plant


    ensign sewage treatment plants

    Ensign sewage treatment plants

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

    The Ensign:Standard is a robust unit with no internal moving parts meaning simple installation and commissioning and minimal long-term maintenance and cleaning.

    Class leading performance

    CE ApprovedTested and approved to BSEN12566-3/A1:2009 all Ensign units provide treatment well within national consent requirements. Published test results of 11.5:19.2:8.4mg/ltr (BOD:suspended solids:ammonia), with influent concentrations on test higher than those chosen by most competitor plants, effectively equates to 97% pollutant removal.

    Unrivalled choice

    Ranging in size from 4 to 50 PE in Ultra, Standard and Shallow versions of each, and with a wide range of ancillaries, almost all site, consent and budget requirements can be met by units from the range.

    Why choose the Marsh Ensign?

    End users, merchants and installers alike recommend the Ensign 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 [2] the Ensign unit allows the clarified water to pass into a second ‘aeration’ chamber [3] 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 [10]. The final effluent is then discharged to the drainage field or watercourse via a Polylok filter.


    1. Inlet
    2. Primary settlement chamber
    3. Aeration chamber
    4. Compressor with
    5. Compressor housing (External or internal options)
    6. RCD / Electrical connection
    7. PVC pressure pipe for diffuser(s)
    8. Bio-media
    9. Stainless steel mesh

    10. Final settlement
    11. Sludge return
    12. Unique Polylok tertiary filter (Only on Ensign:Ultra units)
    13. Outlet
    14. Access lid
    15. Integral lifting eyes
    16. Stabilising feet
    17. Unique ‘keying-in’ lip


    1. Inlet with ‘Forsheda seal’

    Forsheda seal provides flexibility in the joint for easier installation.Optional risers to increase invert depth are available.

    2. Primary settlement chamber

    3. Aeration chamber

    4. Advanced compressor with alarm (Ensign:Ultra units only)

    Near silent compressor ensures minimal running, maintenance and servicing costs. Integral alarm detects low pressure in air line. (Regular Low-energy compressor on Ensign:Standard models).

    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. RCD/Electrical connection (Ensign:Ultra units only)

    The RCD box provides easier installation and proveds a higher degree of safety. (Regular plug/socket connection on Ensign:Standard models).

    7. PVC pressure pipe/diffuser(s)

    Provides a protective conduit for the air diffuser line. Can be easily removed for maintenance and cleaning.

    8. Bio-media

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

    9. Stainless steel mesh

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

    10. Final settlement chamber

    11. 32mm sludge return

    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.

    12. Unique Polylok tertiary filter (Ensign:Ultra units only)

    The Polylok tertiary filter reduces suspended solids and BOD by a further 40% helping to extend drainage field life.

    13. Outlet with ‘Forsheda seal’

    Forsheda seal provides flexibility in the joint for easier installation. Optional pumped outlets are available.

    14. Impermeable lid

    Heavy duty lid/frame improves strength and durability whilst blending into the surrounding environment. (Regular lid on Ensign:Standard models).

    15. Integral lifting eyes

    For safe and secure on-site handling.

    16. Stabilising feet

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

    17. Unique ‘keying-in’ lip

    Assists anchoring into granular or concrete surrounds.

    Specifications table
    Model (pop) Length Width +/-50mm Height +/-50mm Inlet invert +/-50mm Inlet dia Outlet invert Outlet dia
    4 1620 1352 1575 540 110 600 110
    6 2602 1650 1935 550 110 625 110
    8 2602 1650 1935 550 110 625 110
    10 2602 1650 1935 550 110 625 110
    12 2860 1912 2139 550 110 625 110
    16 2860 1912 2284 720 110 800 110
    20 3650 1912 2284 720 160 800 160
    25 3650 1912 2284 770 160 850 160
    30 4200 1912 2284 770 160 850 160
    35 4200 1912 2284 770 160 850 160
    40 5200 1912 2284 770 160 850 160
    45 5200 1912 2284 770 160 850 160
    50 5200 1912 2284 770 160 850 160

    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%.

    Optional extras


    Marsh Ensign range


    Marsh product portfolio and specifications


    Installation/technical manual


    Ensign™ CE Certificate