Chemical Bio-Gas scrubbers are particularly effective on sites with a medium to high flow. The single stage, counter current, process uses Sodium Hydroxide, also known as caustic soda, to reduce the content of Hydrogen Sulphide to an acceptable level for the CHP engine to operate efficiently. The raw Bio-Gas flows upwards through the media packed vertical tower. Simultaneously, the re circulated sodium hydroxide solution is sprayed downwards through the media absorbing the hydrogen sulphide (H2S) from the Bio-Gas.