Influence of packing material on the biofiltration of butyric acid: A comparative study from a physico-chemical, olfactometric and microbiological perspective

The influence of bed material on the odor removal performance of a biofilter was studied. A compost-wood biofilter and a wood biofilter were treated with a gaseous stream contaminated with butyric acid and comparatively evaluated at pilot scale using olfactometric, physico-chemical and microbiological approaches. The variables analyzed in both biofilters were correlated with specific families of their microbiota composition. In addition to a higher nutrients content (nitrogen and phosphorus), the compost-wood biofilter registered maximum values in number of aerobic microorganisms (3.6.108 CFU/g) and in aerobic microbiological activity (approximate to 40 mg O2/g VS of cumulative oxygen demand at 20 h). This may explain the higher performance of this biofilter compared to the wood biofilter, withstanding odor loads of up to 1450 ouE/m2.s with odor removal efficiencies close to 100%. The analysis of the microbial community showed that Actinobacteria, particularly the mostly aerobic Microbacteriaceae family, might play an important role in butyric acid degradation and hence reduce odor impact. The multidisciplinary analysis carried out in this work could be a very useful strategy for the optimal design of biofiltration operations.