Expand wastewater treatment site capacity with the Hybrid-SAF™

WCS Environmental Engineering patented Hybrid-SAF process technology employs a submerged moving-bed, fixed-film reactor which can treat wastewater with greater energy efficiency compared to traditional submerged aerated filters (SAFs), in a tighter site footprint whilst meeting environmental compliance.

Adaptable technology

A key advantage, the Hybrid-SAF modular technology cells can be retrofitted into any onsite vessel, regardless of shape or size. This reduces the high cost of rebuilding infrastructure, minimises onsite disruption, reduces waste and optimises site footprint.

Flexible containment vessel options

The Hybrid-SAF consists of a containment vessel made in either GRP, GRP with a steel exoskeleton, steel, stainless steel or concrete.

The Hybrid-SAF is available as follows:

  •  Standardised modular packaged plant
  •  Custom-built cells
  •  Above or below ground

The modular cells can either operate as individual treatment plants or connected in series to form larger plants

Key benefits

  • Enhanced hydraulics for high-rate processing
  • Optimising new or existing vessels of any shape and size
  • Site footprint 30% smaller than comparable technologies
  • Energy consumption reduced in line with site footprint
  • Achieving <0.4mg/l ammonia discharge
  • Modular off-site build
  • Low maintenance
  •  Technology can be retrofitted in to existing on-site tanks

Images clockwise: (1) custom build in to an existing onsite vessel (2) standardised modular Hybrid-16 units (3) five transportable units installed to meet the 5Ml/day flow (4) custom build to overcome tight site access


  • Utilities and municipal
  • Industrial (trade effluent) sites
  • Commercial sites
  • Ideal for environmentally-sensitive areas

Hire and Trial

Fast and flexible hire of WCS Environmental Engineering wastewater treatment units ensures that sites undergoing emergency reactive work, or planned refurbishment, can remain fully operational and within environmental consent. Whilst our full-scale operational trials provide a fast and effective solution, offering immediate enhancement to onsite industrial trade effluent treatment. This means full compliance is achieved as soon as possible, with no capital risk, putting your mind at ease while a permanent option is found.

Quick links – full features and benefits:

Why choose a Hybrid-SAF:

Low Maintenance

  • Fully optimised plant – maximum of one visual check a week
  • No mechanical or electrical moving parts within the cells
  • No need to drain tanks or remove the media during maintenance
  • No need to desludge process technology cells
  • Does not require additional equipment or adaptation to scour within the biological reactor
  • Cells can be removed, repaired and reinstalled individually without impacting on the process and discharge standard
  • No need for high-level access for internal maintenance

Installation and commissioning

  • Technology installed within days
  • Modular cells overcome site access restrictions
  • Off-site build significantly reduces installation time
  • Health and safety risk minimised
  • Can be delivered by Hiab loader crane
  • Reduced commissioning times

Design and off-site build

  • UK manufacture in a quality-controlled environment
  • 25-year design-life
  • Technology is patent pending
  • Interlocking modular units for larger capacities

Above ground standardised option

  • Scalable to accommodate growing populations
  • Cells can operate individually or connected in series to form a larger plant
  • Can redeploy elsewhere if existing installation becomes redundant before end-of-life

Repurpose of onsite vessels

  • CFD modelling carried out
  • Vessel scanned to ensure precision fit

Treatment standards

  • The technology meets high treatment standards for biochemical oxygen demand (BOD), ammonia, and soluble chemical oxygen demand (COD)
  • Additional equipment can be added to remove phosphorus (P)
  • The process can also be configured to provide anoxic conditions for nitrate (NO3) removal

Hydraulic design and control

  • Higher process treatment capacity achieved within each vessel, reducing the physical footprint, which in turn optimises energy per m³ treated
  • Hydraulic design ensures even and constant flows of nutrients and oxygen over the high specific surface area media, even during peak and low flow situations, providing ideal conditions for biological growth and treatment
  • The slow-moving media bed and hydraulic design ensure that the suspended solids that normally settle out are carried up and through the process to be captured in the final clarification stage


  • Secondary and tertiary treatment process
  • Standardised or repurpose options
  • Telemetry control system for the blowers
  • Variable speed drive blowers can deliver 50-100% of design requirements, allowing greater headroom for power optimisation
  • Control kiosks with blowers, panels and optional telemetry equipment are also factory built to reduce onsite installation time

Fully compliant

  • WIMES specification
  • British Standards
  • European Norms
  • Designed to meet individual UK water utility specifications
  • Designed to BS12255 – parts 1 to 15

Standard technical specification

The standardised above ground modular Hybrid-16 option (containment vessel made in GRP with a steel exoskeleton) is within the Assets section on this page. For a containment vessel made in either GRP, steel, stainless steel or concrete, please contact WPL.

  • UK water utility and industrial site references

Ebbsfleet video (below) – The modular configuration of WPL packaged plant designed to be highly flexible – serving the town as it expands