WPL Sand filter tertiary polishing plant

WPL Sand Filters are designed to remove excess Suspended Solids (SS) and Biological Oxygen Demand (BOD) from sewage and wastewater treatment plants. Our sand filters meet stringent discharge consent standards above what is normally expected from a biological process or an industry standard clarifier.

This low cost and low maintenance sand filter tertiary polishing plant is an ideal addition for new and existing (permanent or temporary) process units.  The WPL Sand Filters are ideally configured to be retrofitted where an existing system is failing discharge consent conditions, for both SS and BOD.

The WPL Sand Filters will remove typically a minimum of 60% SS and 40% BOD dependent on particle size distribution.

Manufactured in glass reinforced plastic (GRP), the units are available in a range of sizes.


Above ground application of a WPL Sand filter


Why you should choose the WPL Sand Filter:

Low cost solution

  • Enhances performance of existing treatment plants that are failing to meet current, new or more onerous consent standards.

 Low operating costs

  • In comparison to other technologies in the market which require replacement parts and or consumables, operating costs are low.
  • There is no requirement for replacement parts or chemical dosing consumables like other technologies in the market making the operating costs low.


  • Can be installed above or below ground


  • Tried and tested design can be incorporated into WPL’s successful range of HiPAF treatment plants as a post filtration stage
  • Minimal serviceable parts reduce planned and reactive maintenance risks

Simple Operation

  • Timed backwash sequence incorporates combined air scour and backwash, with backwash pump for sludge discharge; ensuring minimal manual intervention required


  • Units are sized to tackle various flow rates
  • Single units can cope with population equivalents up to 600 but can also be linked in parallel to treat higher populations

25 Year Tank Life

  • GRP is UV stabilised with an external gel coat finish which extends the asset life to 25 years.
  • Produced in a quality controlled environment at the WPL factory.

WPL Sand Filter final stage treatment process

System Design:

  • Influent can flow by gravity or be pumped into the filter unit
  • Backwash removes solids trapped in sand filter media and waste backwash water is returned to the plant for co-settlement and re-treatment
  • Units are sized to accommodate various flow rates
  • No need to inhibit inflow to filter during backwash cycle

Technical specification

For technical specification information (including indicative drawing), please download  the WPL Sand Filter datasheet (available on this page).

Examples of WPL Sand Filters installed as part of a sewage treatment solution:

  • Salthome Wildlife Reserve, visitor Centre, Cleveland
  • Bramshill Police Training college, Hampshire
  • Lasham Private Airport, Hampshire