Viltra’s OXTEC is a 3-stage biological process sewage treatment plant contained in a single tank structure. 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 OXTEC sewage treatment plant is tested and certified to exceed the current Department of Agriculture, Environment and Rural Affairs (DAERA) standard of 95% BOD removal efficiency in Northern Ireland and meets all regulatory requirements in Scotland, England, Wales and Republic of Ireland, including SEPA, EA, NRW and EPA (SR66 approved), with an overall average of 96.7% and removal efficiencies up to 99.2%.


  • Very small footprint

  • Can be tailored to suit individual sites

  • Manufactured in the UK and Ireland from robust, impact-resistant polyethylene

  • Easily installed due to lightweight material

  • Quiet in operation - there are no electrical or mechanical components within the tank. The only mechanical component is a small air compressor

  • Extremely low maintenance & running costs — (energy-efficient air pump —38-43W)

  • No complicated control panels within design of the system

How it works

Viltra's OXTEC is a 3-Stage biological process sewage treatment plant contained within a single tank structure.

Primary Settlement Tank (PST)

The primary settlement tank (PST) is a two-stage tank designed to maximize the removal of gross and suspended solids. The PST also incorporates a sludge storage volume depending on de-sludging 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, providing 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, 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 that is "unfixed" to the media, but treatment is achieved 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 a 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 to also ensure continuous flow during periods of low or no flow, thereby keeping the biomass in prime condition.

Key features

  • Single tank installation to minimise costs

  • Strong and secure access cover

  • Features an external air compressor failure beacon

  • No mechanical or electrical parts within the unit

  • Rotationally moulded in tough, durable polyethylene for easy and cost-effective installation

  • Sealed unit with no joints below water level

  • 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 OXTEC 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 OXTEC 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?

  • Custom designed products that are manufactured in the UK and Ireland

  • High-quality products and services that are tailor-made to our customer's requirements

  • Proven track record of supplying cost-effective and efficient sewage treatment plants within the wastewater market across the UK and Ireland

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

  • Fully comprehensive mechanical and electrical installation with technical support from design through to installation and final commissioning

  • We take care of 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 and environmental engineers with over 100 years of combined experience in the wastewater industry

  • 24-hour emergency breakdown service only a phone call away

  • Dedicated after-sales service to give our customers clarity and reassurance

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

  • Viltra have an esteemed internal civils team who can provide an all-encompassing end-to-end process when required. 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

Replacement of an existing septic tank and installation of a sewage treatment plant

The installation of a sewage treatment plant and removal of an existing septic tank

Start an OXTEC 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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