Feast-famine biofilter operation as a robust and cost-effective strategy for methane mitigation

Packed bed clogging and channealing derived from the accumulation of biomass still represent technical challenges to be addressed in gas biofiltration in order to ensure a cost-effective performance under long-term operation. In the present study, multiple feast-famine strategies were assessed, for the first time, in two alternate biofilters and compared with a standard continuous biofilter using CH4 as the model C source. The robustness of the biofilters towards increasing famine periods, the decrease of the irrigation frequency and air deprivation was evaluated. The alternate biofilters, where the lowest average pressure drops were recorded, exhibited the maximum CH4 elimination capacities (27.8 g m-3 h-1) and mineralizations (171.4 %), along with the lowest recovery periods so far reported in biofiltration after pollutant supply resumption (1.5 h). Metagenomics analysis revealed an important shift in the structure of the microbial population induced by the feast-famine regimes, which favoured the occurrence of Planctomycetes and Proteobacteria phyla. Type I/II methanotroph ratios in the alternate units were 7.5 times higher than those found in the control unit, Methylomonas becoming the most resilient genus under feast/famine operation.