WPL HiPAF Compact Plant (1 to 60 PE)

For more high stringent standards stipulated by the Environmental Agency


The WPL HiPAF Compact (HPC) offers sewage and wastewater treatment for properties of 1 – 60 people equivalent where mains drainage is unavailable. The compact sewage and wastewater system (installed above or below ground) treats wastewater using no chemicals to a high standard for more stringent standards stipulated by the Environmental Agency.

Renowned for its high quality effluent treatment the HiPAF compact sewage treatment plant  will safely discharge wastewater in to the local environment where extra consideration is needed for locations such as a burn, site of Special Scientific Interest (SSI), nature reserve, fisheries, Salmon River or close proximity to water extraction (well).

The HiPAF compact plant has the primary tank, submerged aerated filter (SAF) and final settlement as one unit, it is made in glass reinforced plastic (GRP) and can be installed above or below ground.

Our cutting-edge, ‘off-the-shelf’ HiPAF package sewage plants are tailored to your requirements to offer environmentally-friendly, legislation-compliant solutions that are simple to install, easy to live with and economical to maintain.

The HPC is an EU compliant wastewater treatment system as per the statutory requirements. Designed and manufactured in the UK, they are easily transported to the continent.


Typical uses for the HiPAF Compact sewage treatment plant include:

  • Domestic housing
  • Commercial buildings and offices
  • Stately homes and country estates
  • Small hotels and bed and breakfasts
  • Small retail such as farm shops
  • Small villages, rural communities and housing associations
  • Water Utilities


Features and benefits of the HiPAF Compact sewage treatment plant (HPC):

Low running cost and maintenance

  • The unique design of the HiPAF has no internal mechanical moving parts which means the plant requires minimal annual maintenance making it economical to run
  • Emptying of the tank is also not required during maintenance of air distribution system

 Discrete and low cost installation

  • Only a small excavation is required due to its compact design

Tailored applications

  • Energy saving options and chemical dosing packages can be tailored to the design for site specific requirements

Minimal visual impact

  • The HiPAF does not impede views when installed below ground

 Variable flows and loads

  • The unique design of the flow balancing in the primary tank means it can cope with variable flows and loads making it ideal for caravan sites and other seasonal venues


  • Robust operation and stand-by facility

Easy access

  • Safe, clean, accessible air diffuser system with large access lids for easy maintenance

No odours

  • Most other treatment plants have a separate primary tank which store settled solids and can emit odours; however our HiPAF Compact design has no separate primary tank and is therefore odour-free

 Simple tankering operation

  • Humus and primary sludge are stored in one place for simple tankering operation


The WPL HiPAF Compact Standard

The WPL HiPAF Compact range meets the following industry standards:

  • CE marked, fully type tested and certificated in accordance with the mandatory European standard BS EN12566-3, and meets all current legislation under the Environmental Permitting Programme
  • Fully compliant with UK Building Regulations and Environment Agency recommendations
  • The WPL HPC is designed using the British Water Code of Practice Flows and Loads, to ensure correct sized tanks

WPL’s in-house Engineering Expertise

WPL’s in-house engineering expertise is highly valued by all our customers including highly regulated UK water utilities, industrial and commercial users and right through to individual home owners.

WPL is diligent in ensuring our customers’ sites are environmentally compliant and that the right level of protection is in place.

Technical Specification of the WPL HiPAF Compact Sewage Treatment Plant (HPC)


wpl-hipaf-compact-technical-table-sewage-treatment-not-connected -to-mains-drainage

The table is an indicative guide only; all applications are specified to comply with the British Water Code of Practice for Flows and Loads.  For further advice please contact our experienced technical sales team.

WPL HiPAF Diagram Showing Treatment Process

1.  Primary settlement tank

2.  Settled solids at the bottom

3. Biological treatment unit (biozone)

4. Air diffusers at the bottom of each chamber

5. Filter media

6. Settled sludge air lift back to primary

7. Final (humus) settlement tank


Image of HiPAF Compact process showing sewage and wastewater treatment process


The HiPAF Treatment Process

  • Primary – Primary settlement is in accordance with EN12255-4, giving the required hydraulic retention time and ensuring that 30% of the BOD will settle out in the primary tank.  WPL HiPAF plants below 500 persons will have sludge storage integral to the primary tank. The primary settlement tank is equipped with baffles to prevent floating scum entering the biological phase of the treatment process. It also incorporates WPL Limited’s unique forward feed system which lowers the level in the tank, during periods of low flow, to provide a buffering capacity for possible surges in the influent.
  • Biological – After primary settlement, the settled liquor flows to the biological treatment unit by displacement and via the air lift forward feed. The biozone is fully segmented internally to eliminate the risk of process short cuts. Each biozone segment is filled with high voidage plastic filter media, where both carbonaceous and nitrifying processes take place, mitigating process risks associated with variable loads. Air to oxygenate the influent and to scour excess biomass from the filter media is introduced continuously below each chamber by a series of diffusers.
  • Final – Following biological treatment the effluent flows into the final (humus) settlement tank where the excess biomass settles out. The humus tank is equipped with air lifts which are arranged to automatically transfer settled humus sludge to the primary tank for co-settlement. The treated effluent flows under gravity to the works outfall.

WPL HiPAF Compact Plant installed below ground

Image of WPL HiPAF Midi compact sewage treatment plant at a campsite for off mains drainage