CIRCOX - aerobic COD removal by Paques - 1

If deep COD removal is required, then anaerobic treatment is usually followed by aerobic treatment.

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.

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. Biological sludge slowly grows in high concentrations on biofilms on a carrier. The mixing of water, gas and biomass is very good which leads to high conversation rates.

Advantages of CIRCOX®

  • Removal of organic compounds (COD), ammonia and sulphides
  • 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)
  • Odourless off-gas and effluent
  • Good oxygen transfer rates
  • Low biological sludge production

Typical characteristics

Characteristic Capacity
COD conversion rate up to 8 kg COD/m3/day
Ammonia conversion rate up to 1.2 kg ammonia/m3/day
Biomass concentration 20 - 40 g/l VSS

Working principle

CIRCOX® uses biofilm on a carrier material. 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.

CIRCOX® cases