bioventing

Bioventing is an in situ soil remediation technique that stimulates aerobic biodegradation of organic contaminants in the vadose (unsaturated) zone by delivering air to the subsurface. The method relies on indigenous microorganisms to break down hydrocarbons and other biodegradable compounds as they consume the supplied oxygen.

The process involves placing air delivery points, such as wells or perforated piping, in the contaminated soil and operating a blower or other air supply to inject air at controlled rates. The injected air supplies oxygen, enhances moisture conditions, and creates favorable redox environments for aerobic microbial activity. Properly designed bioventing maintains moisture content and avoids excessive volatilization of contaminants, emphasizing biological degradation over rapid mass removal by vapor extraction.

Bioventing is commonly used for hydrocarbon-contaminated soils, including petroleum products and related solvents, where contaminants are primarily biodegraded under aerobic conditions and are located in the vadose zone. It is generally most effective when contaminants are not highly volatile and when the soil has adequate porosity and microbial activity. The technique emphasizes slow, sustained air flow to promote in situ biodegradation rather than wholesale volatilization of contaminants.

Monitoring and performance assessment are integral to bioventing and typically involve soil gas monitoring (oxygen, carbon dioxide, hydrocarbon concentrations), moisture measurements, and sometimes groundwater monitoring to ensure that remedial goals are being met and that volatilization losses are minimized.

Advantages include low energy use, preservation of soil structure, and suitability for long-term remediation of biodegradable contaminants. Limitations encompass longer time frames, reduced effectiveness for highly volatile or recalcitrant compounds, and the need for careful moisture and oxygen management to prevent plume migration or suboptimal biodegradation. Bioventing can be used alone or in combination with other in situ bioremediation approaches.