IWOX Premium

Viltra’s IWOX Premium is a 3-stage sewage treatment plant in a two-tank configuration 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 IWOX Premium sewage treatment plant is tested and certified to exceed the current Department of Agriculture, Environment and Rural Affairs (DAERA) standard of 97.5% BOD removal efficiency in Northern Ireland and meets all regulatory requirements in Scotland, England, and Wales, including SEPA, EA, and NRW, with 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

  • Certified for up to 8 people (1200 litres per day)

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

  • No complicated control panels within design of the system

How it works

The IWOX Premium sewage treatment plant is based on the activated sludge principle.

Primary Settlement Tank (PST)

The wastewater influent flows straight into the settlement tank. Larger and heavier pieces of waste in the flow will sink to the bottom of the compartment. At least once every year, the presence of these materials has to be checked (sludge judge test). If the water flow from the pre-settlement tank to the oxidation compartment is blocked, these materials have to be removed from the tank.

Biozone (BZ)

In the oxidation compartment, the purification of waste particles in the wastewater is carried out by bacteria in the activated sludge. Here, Chemical Oxidation Demand pollutants (COD) and Biological Oxidation Demand pollutants (BOD) are removed, and ammonia (NH4) is transformed into nitrate (NO3). The oxidation compartment also features a tube diffuser which provides the water with continuous airflow. The desired oxygen concentration (minimum of 1.5 mg O2/l) can be created with the adjustment of a valve.

Final Settlement Tank (FST)

Water and suspended solids are separated here. In the clarifier compartment, the activated sludge that has formed and settled on the bottom is returned to the aerobic compartment, thus achieving the removal of a more efficient pollutant. The circulation is performed by an airlift pump, which increases the system power efficiency. Once the pollution removal is achieved, the treated water (effluent) is discharged via the outlet pipe.

Key features

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

  • Strong and secure access covers

  • One-piece mould with no joints below water level

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

  • Features an external air compressor failure beacon – which can be fitted anywhere on the premises

  • 1 Year Warranty (Blower and small parts)

  • Removal efficiencies up to 99.2%

  • 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

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 IWOX Premium sewage treatment plant is tested and certified to exceed the current DAERA requirements of 97.5% with removal efficiencies up to 99.2%.

-5mg/l Biological Oxygen Demand (BOD)
-9.6mg/l Suspended Solids (SS)

Scotland, England and Wales

Viltra's IWOX Premium sewage treatment plant is tested and certified to EN12566-3 standards and meets all regulatory requirements including SEPA, EA and NRW.

-5mg/l Biological Oxygen Demand (BOD)
-9.6mg/l Suspended Solids (SS)

Why choose a Viltra sewage treatment plant?

  • Bespoke products that are created in the UK and Ireland

  • Premium products and services that are custom designed to meet client request

  • Recognised reputation in providing reasonably priced and competent sewage treatment plants in the wastewater industry across the UK and Ireland

  • Viltra’s domestic products are tested and certified to EN12566-3 European standards

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

  • Viltra organise and finalise the Consent to Discharge procedure for you, communicating with the regulatory bodies to safeguard compliance with any requirements imposed

  • At Viltra we have an esteemed team of enthusiastic and accomplished process, civil, electrical, mechanical and environmental engineers with over a decade of joint experience in the wastewater industry

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

  • Devoted after-sales package to give our clients clarity and assurance

  • Servicing and maintenance packages available at competitive rates to confirm your system is achieving anticipated functions continuously

  • Viltra have a respected internal civils team who can deliver an all-inclusive process when required. This service can implement a comprehensive installation pack from start to finish, saving you the trouble of implementing each part separately.

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 IWOX Premium 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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