Bioscrubbing

Bioscrubbing is a gas treatment technology that uses a biologically active liquid to scrub pollutants from gas streams. It combines physical gas-liquid contact with biological degradation, whereby contaminants dissolve in the scrubbing liquid and are metabolized by microorganisms.

Typical configurations include bioscrubbers, where contaminated gas is contacted with a circulating scrubber liquid in a wetted packing or spray zone, and biofilm-based systems such as biotrickling filters, where a thin liquid layer or trickle provides nutrients to a microbial community on packing material. Both rely on mass transfer of pollutants from gas to liquid, followed by biodegradation and mineralization to carbon dioxide, water, and biomass.

Important design and operating parameters include contact time (often described as empty bed contact time or gas residence time), liquid flow rate, pH, temperature, dissolved oxygen, and nutrient availability (nitrogen and phosphorus). The microbial community may be specialized for the target pollutants. The scrubber liquid should remain neutral to mildly alkaline and well oxygenated; foaming and biomass growth are common issues.

Applications include odor control and VOC removal in chemical plants, refineries, pulp and paper, food processing, wastewater treatment facilities, and mining operations. Bioscrubbers are especially suitable for pollutants with some water solubility and biodegradability, such as alcohols, aldehydes, sulfides, amines, and certain chlorinated VOCs.

Advantages include relatively low energy consumption compared with thermal incineration, compatibility with high-moisture emissions, and the possibility of treating the liquid phase. Limitations include sensitivity to shock loads, maintenance requirements for biofilms, potential biomass handling needs, and performance variability with environmental conditions and microbial health.