Landfill site BIDOX® and Water Treatment Plant

Project Background:

Landfill sites are known to produce toxic environmental pollutants and GHG emissions. Aquest Colsen provided a BIDOX® (BIological biogas Desulphurization by OXidation) installation to efficiently reduce the H2S gas produced by a landfill in South Africa.

The BIDOX® installation is designed considering the latest technological advances made by Colsen International b.v., as well as practical operational results obtained at other, similar installations from around the world.

An additional requirement was the need for heated freshwater supply to the BIDOX® reactor. As a first of its kind, discharge water from the BIDOX® is treated and re-used with Top-up water from borehole and surface water sources. This treated water is then heated to the desired temperature with an energy efficient Heat Pump.

Technology used/Solution offered- BIDOX®

The raw biogas from the landfill is treated by aerobic bacteria in a wet biological scrubber system (i.e. BIDOX®). The general biochemical reaction that takes place in the BIDOX® system is shown below:

H2S + 2O2 → SO42- + 2H+

The bacteria convert H2S from the biogas under aerobic conditions and the generated sulphur compounds are washed out of the system by periodical refreshment of the scrubbing water. The scrubbing water is circulated over the system. A small amount of scrubbing water is periodically drained from the BIDOX®. This BIDOX® discharge water is treated by the onsite Water Treatment Plant.

Technology used/Solution offered – BIDOX® Water Treatment

  • Combined borehole and BIDOX discharge feedwater
  • Media Filtration
  • Ultra-Filtration
  • pH Correction
  • Reverse Osmosis
  • Telemetry
  • Heat Pump System

Performance targets

  Amount unit
Design biogas throughput 500 Nm3/h
H2S Inlet Concentration max 14500 ppm
H2S outlet ave <250 ppm
Water treatment plant treated water volume 4.7 m3/h
RO Recovery 85 %

Aquest’s added Value

  • Holistic, environmentally friendly engineering design
  • Turnkey project delivery and integration of all disciplines
  • Design, build and commission plant in short timeline
  • Full project integration into the existing premises
  • Tailor made solution/design

Project Initiation and project completion

The project was initiated in July 2019, construction began in October and the project was completed in April 2020.

Project outcome

  • Reduced water and air pollution
  • Improved biogas quality