Viltra’s OXCRETE is a 3-stage sewage treatment plant in a single tank concrete structure that uses a biological process to effectively treat sewage. Designed specifically for domestic applications, it is a highly efficient, reliable and cost-effective way to dispose of domestic sewage where there is no access to a main sewer. The OXCRETE sewage treatment plant is tested and certified to exceed the current Department of Agriculture, Environment and Rural Affairs (DAERA) standards of 95% and 97.5% BOD removal efficiencies, with removal efficiencies up to 99.2%.


  • Created locally in the UK and Ireland from concrete and can be tailor-made to suit specific sites

  • Very small footprint

  • Easy to fit

  • Very low maintenance and running costs; only one mechanical part (energy efficient air pump – 38-43W)

  • No disruption in operation

  • No complicated control panels within design of the system

  • Certified from 5 to 50 PE (population equivalent)

  • Both 95% and 97.5% BOD removal options available

How it works

Viltra's OXCRETE is a 3-stage biological process sewage treatment system contained within a single tank structure

Primary Settlement Tank (PST)

The primary settlement tank (PST) is a two-stage tank designed to maximise the removal of gross and suspended solids. The PST also incorporates for a sludge storage volume depending on de-sludge periods.

Biozone (BZ)

The biological treatment phase incorporates two proven principles of biological process in the form of a fixed film reactor and a suspended floc dispersed growth system for high transfer rates and operational control, achieving a stable treatment process unaffected by shock loads.

The heart of the process is a submerged, high rate, plastic media on which a fixed film of biomass is grown. The film consumes incoming settled effluent and oxygen, which is provided by a small blower. The media is aerated through HDPE membrane diffusers that provide fine bubble aeration.

The fine bubble aeration is carefully controlled, providing optimum oxygen transfer rates and scouring to slough off excess biomass, while keeping the thickness of the fixed biological film at optimum levels.

The fact that the media remains submerged means that there will be biomass which is “unfixed” to the media but this is treated through suspended aeration.

Final Settlement Tank (FST)

The final settlement tank is designed to provide maximum settlement of any suspended solids prior to discharge. The system incorporates continuous sludge return airlift to return sludge from both the final settlement tank back to the primary settlement tank.

This system also provides for continuous recycling of treated effluent back to the PST to not only provide dilution of incoming settled effluent, but also to ensure continuous flow during periods of low or no flow, thereby keeping the biomass in prime condition.

Key features

  • Concrete outer

  • Only one mechanical part - (energy-efficient air pump – 38-43W)

  • Strong and secure access cover

  • Failure beacon system as standard and not at additional cost

  • Sealed unit with no joints below water level

  • Our unique flow buffering technology (ALF) ensures a constant steady flow 24 hours a day through your system with a gradual release to the natural environment

  • Removal efficiencies up to 99.2%

Environment Agency Standard

Northern Ireland

The Department of Agriculture, Environment and Rural Affairs (DAERA) currently require one of two minimum standards of 97.5% and 95% BOD removal efficiency depending on receiving watercourse and catchment size. Viltra's OXCRETE sewage treatment plant is tested and certified to exceed the current DAERA standard of 95% and treats wastewater to an overall average of 96.7%, with removal efficiencies up to 99.2%:

- 10mg/l Biological Oxygen Demand (BOD)
- 12mg/l Suspended Solids (SS)
- 5.8mg/l Ammoniacal Nitrogen (AMM-N)

Scotland, England, Wales and Ireland

Viltra's OXCRETE sewage treatment plant is tested and certified to EN12566-3 standards and meets all regulatory requirements including SEPA, EA, NRW and EPA (SR66 approved).

- 10mg/l Biological Oxygen Demand (BOD)
- 12mg/l Suspended Solids (SS)
- 5.8mg/l Ammoniacal Nitrogen (AMM-N)

Why choose a Viltra sewage treatment plant?

  • Manufactured in the UK and Ireland, Viltra custom design their products to suit the requirements of customers

  • Established reputation in providing affordable and effective sewage treatment plants within the wastewater market in the UK and Ireland

  • Our domestic products are tested and certified to EN12566-3 European standards

  • An inclusive mechanical and electrical fitting with technical support from design through to installation and final commissioning

  • We organise the Consent to Discharge process for you, liaising with the all-regulatory bodies to ensure compliance with any requirements enforced

  • At Viltra we have a team of dedicated and skilled process, civil, electrical, mechanical and environmental engineers with over a decade of mutual experience in the wastewater industry

  • 24-hour response if there is an unexpected breakdown

  • Enthusiastic after-sales package to ensure customer satisfaction

  • Servicing and maintenance packages available at good rates to ensure your system is accomplishing expected functions at all times

  • Viltra have a respected internal civils team who can deliver an all-inclusive end-to-end course when needed. This service can implement a complete installation pack from start to finish, saving you the disturbance of executing each element individually.

Our latest projects

A sewage treatment plant installation and civil works for a homeowner

Viltra provides a solution to help a local meat processing facility comply with environment agency regulations

Viltra keeps all National Trust sites compliant all year round

Start an OXCRETE sewage treatment plant project with us

At Viltra, we are specialists in separating waste and water. Whether you have an individual household, a business or a development, we all need and rely on water, we all create and dispose of waste and we all must keep these two worlds apart.

Viltra are a dedicated team who design, manufacture and install wastewater treatment solutions for a wide range of sectors across the UK and Ireland, including the commercial and industrial sector, education sector, conservation sector, domestic sector, agricultural sector and the tourism and hospitality industry. Offering an end-to-end service, the experienced team at Viltra ensure our customers receive a premium service and a robust solution to their wastewater management requirements.

To make an enquiry or to book a FREE site visit by our expert engineers who will find a solution for you, please get in touch with Viltra through the contact form provided.

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