Leading the biotech revolution
in wastewater and biogas

Three-in-one aerobic treatment system

The CIRCOX® bioreactor is a very aerobic treatment system for anaerobic effluents. It uses biofilm on a carrier material in an airlift reactor for simultaneous BOD removal, ammonia nitrification and nitrogen removal from wastewater. This compact, full-enclosed aerobic treatment system has outstanding purification performance, as the purified effluent can be directly discharged to surface water.

Advantages of CIRCOX®

  • Removal of organic compounds (COD), ammonia and sulfides
  • Compact design as volumetric loading rates are five times higher than conventional systems
  • High conversion rates (over 5 kg of COD/m3 per reactor per day)
  • Odorless off-gas and effluent
  • Good oxygen transfer rates
  • Low biological sludge production

Suitability and feasibility

If deep COD removal is required, CIRCOX® is a fully closed aerobic system with outstanding performance. It is very suitable for aerobic polishing of anaerobic effluent in urban areas because the bioreactors are relatively small and require little space, whilst the technology has a high volumetric conversion.

The mixing of water, gas and biomass is very good which leads to high conversion rates.

Characteristic Influent specification
Ammonia conversion rate up to 1.2 kg ammonia/m3/day
Biomass concentration 20 - 40 g/l VSS

How aerobic treatment system CIRCOX® works

CIRCOX® uses biofilm on a carrier material, so high concentrations of bacteria can eat the compounds, and the biological sludge slowly grows. This granular sludge is kept in suspension by means of airlifts. They have a high density and excellent settling properties. The granules are retained by a tilted plate settler on top of the reactor.

In addition to COD removal, CIRCOX® nitrifies ammonia and fully removes nitrogen with the special extension of an anoxic zone. In combination with a DAF - this is necessary as solids wash through the system - CIRCOX® results in high quality water.


At Paques, we believe in a cleaner, more sustainable world where innovation in biotechnology plays a crucial role in managing our planet's resources wisely.

If you have any questions or wish to explore what Paques technologies can do for your operations, we encourage you to connect with our team of experts. Our knowledgeable professionals are ready to assist you, offering insights and guidance tailored to your specific needs.

Leading the biotech revolution in wastewater and biogas

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Thank you for reaching out to Paques

Your inquiry is important to us, and we are eager to assist you in exploring our innovative solutions for biological wastewater and gas treatment.

A member of our expert team will be in touch shortly to discuss your specific needs and how Paques can help you achieve your environmental and operational goals.

We look forward to collaborating with you and hope to build a cleaner, more sustainable world together.

Warm regards,
The Paques Team