Seven different rockwool media were analyzed for their suitability for use in a compact biofilter for odorous gas treatment. The examined parameters included flow distribution and pressure drop, media characteristics, and aptness for immobilization of microorganisms. Three rockwool
media were used in a pilot-scale biofilter in three different applications with odor problems: at a restaurant (fryer), pulp mill, and wastewater pumping station. Rockwool fiber mats with pre-set structures were preferable to loose rockwool due to their easier handling, improved gas flow distribution,
and lower pressure drops. However, some of the hydrophobic mats had low mechanical and chemical stability. A linear relationship between pressure drop and surface loading was established, even at very high gas velocities. Enumeration of the biomass showed a wide range of bacteria able to immobilize
and grow in the media. A number of operational problems were identified, as well as possible biological or mass-transfer limitations.
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