Resistance and resilience of removal efficiency and bacterial community structure of gas biofilters exposed to repeated shock loads

► Four biofilters were exposed to repeated substrate pulses of increasing intensity. ► New quantitative indices of resistance and resilience capacity were proposed. ► We highlighted different robustness levels according to the contaminants. ► There was an impact of the perturbation regime at the community level (DGGE). ► Bacterial community structure partially coupled to removal efficiency robustness. Since full-scale biofilters are often operated under fluctuating conditions, it is critical to understand their response to transient states. Four pilot-scale biofilters treating a composting gas mixture and undergoing repeated substrate pulses of increasing intensity were studied. A systematic approach was proposed to quantify the resistance and resilience capacity of their removal efficiency, which enabled to distinguish between recalcitrant (ammonia, DMDS, ketones) and easily degradable (esters and aldehyde) compounds. The threshold of disturbing shock intensity and the influence of disturbance history depended on the contaminant considered. The spatial and temporal distribution of the bacterial community structure in response to the perturbation regime was analysed by Denaturing Gradient Gel Electrophoresis (DGGE). Even if the substrate-pulses acted as a driving force for some community characteristics (community stratification), the structure-function relationships were trickier to evidence: the distributions of resistance and composition were only partially coupled, with contradictory results depending on the contaminant considered.