Where odorous air needs to be collected and treated before release, biological odour control systems offer a sustainable and cost-effective solution. These systems pass exhaust air from enclosed areas, wet wells, or covered treatment tanks through a bed of media colonised by naturally occurring microorganisms. The bacteria break down odour-causing compounds in the air stream, converting them into harmless byproducts through biological degradation.

The biological process is particularly effective against hydrogen sulfide and ammonia, which are the primary odour compounds in wastewater treatment environments. Under the right conditions, biological systems can achieve high removal efficiencies for these compounds, producing a treated air stream suitable for discharge without the need for ongoing chemical consumption.

The main operational requirements are maintaining moisture levels in the media bed and ensuring the microbial population remains active. Biological odour control systems have significantly lower operating costs than chemical scrubbers because they do not consume reagent chemicals. Once established, the microbial population self-sustains as long as the incoming air stream provides the compounds they use as an energy source.

System sizing is based on the air volume to be treated and the concentration of odour compounds in the inlet air. Undersized systems result in incomplete treatment and odour breakthrough, so accurate characterisation of the odour load is an important input to the design process.

These systems are used at sewage treatment plants, pumping stations, sludge processing facilities, and industrial wastewater plants where enclosed areas generate odorous exhaust air that needs to be treated before discharge. Their low operating cost and minimal environmental footprint make them a preferred long-term odour management solution for many facilities.