Biogas is a fuel gas produced by the anaerobic decomposition of organic compounds. Biogas is mainly composed of methane (70%), carbon dioxide (25%), small amounts of hydrogen sulphide, etc. The biogas in the Phil-Commerce & HydroThane facilities is produced by the ECSB and CSTR reactors.

Depending on the specific effluent and if required, the biogas produced is fed into a scrubber for removing hydrogen sulphate. This process is carried out by dewatering with a sodium base solution in countercurrent.

The biogas is stored in a gas holder, which is equipped with two types of overload protection - a hydraulic shutter and a flare for forced combustion.