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    Advanced sewage treatment plant

    Marsh:Marator™ oil separator

    High performance full retention oil separators for sites where the 'industry standard' is just not good enough

    Marsh:Marator oil separator – an innovative separator system that breaks the constraints of the current standards.

    The Marator oil separator takes advantage of nanofiltration technology to produce discharge that is 50 times better than any current separator available on the market today; that is less than 0.1mg/ltr – the standard only requires less than 5mg/ltr for a ‘class 1 discharge’.

    Testing was analysed for hydrocarbon content using infrared spectroscopy at GEOTAIX UMWELTTECHNOLOGIE GmbHA.

    During the sampling period, five samples of 500ml were taken via the sampling point. The quality of discharge from the Marator exceeded the measureable level of the test equipment not to mention the current EN standard:

    SampleResult GC in mg/litre (Industry standard <5mg/litre)
    NS 6-1<0.1
    NS 6-2<0.1
    NS 6-3<0.1
    NS 6-4<0.1
    NS 6-5<0.1
    NS 6-6<0.1

    Are outmoded EN standards an environmental concern?

    Current EN standard
    The European Standard, BS EN 858 parts 1&2, was introduced in 2002 to normalise design and regulate testing of products across Europe. This standard settled on a two-tier quality level – class 1 and class 2.

    Class 1 – designed to achieve a discharge concentration of less than 5mg/ltr of oil in the discharge
    Class 2 – designed to achieve a discharge concentration of less than 100mg/ltr of oil in the discharge

    Once testing is complete and approval achieved, manufacturers are free to bring their products to market.

    The effects of current standards
    A good starting point for any product is to set out relevant standards and levels of quality, both in oil separator build and performance. However, since the introduction of BS EN 858 in 2002, product development in gravity oil/liquid separation has remained static.

    Manufacturers are only required to meet the testing standards to sell product. There has been no natural drive to improve product performance.

    The current class 1 standard of less than 5mg/ltr of light liquid is only determined by test conditions. Our experience in this field tells us that this standard is rarely met once a product is installed.

    The reality of current standards
    With the current level of 5mg/ltr for a Class 1 discharge – we ask “Are Class 1 oil separators the very best that manufacturers can offer?”

    Studies have shown that the majority of hydrocarbon pollutants entering the water system stems from urban developments. Figure 2 shows the toxic effects of particular contaminants on humans and aquatic life.

    Leaving aside the toxic effects of contaminants on human and aquatic life, when a hydrocarbon molecule spreads to one molecule thick and given enough surface area to spread, five litres of oil would be more than enough to contaminate five football pitches.

    In addition, most hydrocarbon molecules are attached to silt particles; where Stokes law proves that these particles will sink rather than float as conventional separators require.

    When mixed with other elements in real life scenarios, such as glycol, standard gravity separators become less efficient at contaminate removal.

    In our view, the current testing standards covering products within the gravity oil separator market are outmoded and failing to protect the environment as they should. They do not reflect or address any ‘real-life’ scenario where hydrocarbon pollution is prevalent.

    The solution = the Marsh:Marator

    Typical applications

    • Car parks
    • Roadways
    • Industrial estates
    • Vehicle workshops
    • Refuel facilities
    • Fuel storage sites

    Operating principle

    Marsh Hydroil full-retention separators treat the full flow that is delivered by the drainage system, which is normally equivalent to the flow generated by a rainfall intensity of 65mm/hr.


    1. Inlet
    2. Oil retention chamber
    3. Coalescing filter
    4. Nanofiltration technology
    5. Outlet
    6. Breather pipe

    7. Surge balance tank

    8. Anti-flood valve

    9. Stormwater overflow control

    10. High level alarm

    11. Access turrets


    • Designed and tested to meet latest UK and European standards
    • Corrosion resistant
    • Tank shells guaranteed for 25 years with a design life of 50 years
    • Heavy duty shells enable installation in all ground conditions
    • Easy access turrets for maintenance and servicing (Turret guards optional)
    • Various alarm types available (Required by EN858-1)
    • Variable invert depths and inlet/outlet configurations ­­­to suit individual site conditions
    • Vented turrets can dissipate excessive fumes and vapours


    Specifications table
    Model Max flow
    area (m2)
    Silt storage
    Oil storage
    Marator 6 6 340 600 60 1250 3040 1862 200 900 1100
    Marator 10 10 566 1000 100 1250 4040 1862 200 900 1100
    Marator 15 15 851 1500 150 1812 4240 2360 315 900 1100
    Marator 20 20 1137 2000 200 1812 4240 2360 315 900 1100

    > The dimensions given on this page are for guidance only.
    > For precise tank sizes and configurations, please contact Marsh Industries.
    > Number of access shafts will be built to suit site specifications and to maintain safe access for emptying.
    > All dimensions in mm.
    > Due to production processes, dimensions of finished units are within a tolerance of +/-2.5%.


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