WPL HiPAF solution

Wastewater treatment for the water utility companies

WPL is a framework supplier to the UK water utilities with over 25 years experience creating custom-built package wastewater (sewage) treatment plants for:

  • Remote sites
  • Hard-to-access locations
  • Demanding individual local environmental standards

The standard modular WPL HiPAF packaged wastewater treatment range is a below ground asset serving a population equivalent (PE) of up to 5000.  A typical systems can consists of separate primary settlement, biological treatment (submerged aerated filter) and final settlement modules depending on the site requirement.

Image of WPL bespoke HiPAF solution for utilities

WPL also creates bespoke above ground WPL HiPAF designs (image below)  to meet your on-site wastewater treatment specification.


Our complete in-house design and specification service including a turnkey service of initial site survey, commissioning and project liaison if required.


Why you should choose the WPL HiPAF solution:

Low maintenance

  • No internal mechanical moving parts therefore it requires minimal annual maintenance
  • Emptying of the tank is also not required during maintenance as WPL’s design can isolate and remove sections of the air distribution system

Low running costs

  • Significant reduction in power consumption can be achieved using VSD’s, timers, instrumentation and control to deliver the lowest TOTEX solution

Low installation costs and flexibility on site

  • Only a small excavation is required due to its compact design allowing flexibility of positioning on site

Bespoke configurations

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

Minimal visual impact

  • Does not impede views due to the below ground installation

Variable flows and loads

  • During low flow conditions the level in the primary tank is reduced utilising forward feed air lift pumps. This creates a buffering volume that reduces the impact during high flows

Reliable operation

  • Underpinned by the supply chain partners that WPL uses

Robust operation

  • Proven WPL submerged aerated technology (SAF) technology based on 25 years empirical data

Easy access

  • Large access lids therefore no requirement for confined space entry reducing health and safety risks
  • Access also offers ease of maintenance and process optimisation

Simple tankering operation

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


  • BS1509001 CDM regulations and BIM maturity level 1 (working towards level 2) – promoting collaborative working methods

Tank 25 years life

  • The below ground solutionis manufactured in glass reinforced plastic (GRP) which is ultra violet (UV)  stabilised with an external gel coat finish to extend the asset life to 25 years.
  • Built in a quality controlled environment at the WPL factory (UK)

Design parameters

  • Design criteria is as per the water utility asset standard
  • Peak flow treatment – bespoke design but generally 3-6 dry weather flow or formula A flows
  • Discharge standards – As specified. The WPL HiPAF will attain typically: BOD 10mg/l: SS 10mg/l: Ammonia Nitrogen 2mg/l (with tertiary treatment), however higher standards are achievable


Each system comes as standard with a weatherproof, acoustically lined kiosk situated above ground. This houses WPL’s standard Form 2 or Form 4 control panel and various blower options. Bespoke kiosk options are available.

Bespoke design options can include:

  • Lid type, orientation and colour finish options are available
  • Single or three phase power supplies
  • Blower kiosk cooling fan
  • N-SAF tertiary treatment options
  • Inverts 0.5m as standard
  • Volt free telemetry contacts on control panel
  • Form  2 or form 4 control panel
  • Pumped inlet flow control
  • Duty/standby and duty standby assist blower upgrades
  • Blower and airline hose upgrades for long hours
  • Kiosk options including walk in kiosk
  • Below ground GRP or above ground steel construction for transportable plants
  • Permanent or temporary hire solutions


MK3 lids for the UK Water Utilities specification:

  • Anti-slip pads on the lids
  • All lids are lockable
  • Two lids per width of the tank – lids less than 25 kilo’s to lift
  • Lockable stainless steel stays
  • Grating held in position under the lid when in the down position allows ease of access to all air distribution pipework
  • Grating when in place prevents risk of fall
  • Raised air distribution pipework allows for ease of maintenance

Ease of access is also a key feature for the WPL HiPAF range.  The internal sections of the below ground plant are accessible from the top by opening the large access lids, allowing for easy service, maintenance and de-sludging.

Image of WPL MK3 lids showing grates to walk on, part of the bespoke wastewater treatment system