LAUSR

Abstract This study introduces a new strategy to determine the maximum Elimination Capacity (ECmax) of a biofilter within a 10% error from a single experiment of 2 h. The procedure requires several ports for H2S measurement along the length of the biofilter in order to establish accurately the relative concentration profile versus the residence time of the gas. The ECmax value was directly deduced from the derivative of the curve at the y-intercept assuming that three kinetic regimes occur along the packing material, i.e. zero-order kinetics with reaction limitation in the lower part; zero-order kinetics with diffusion limitation in the upper part; and first-order kinetics at the outlet of the biofilter. The procedure was successfully applied to a laboratory-scale biofilter filled with expanded schist as the packing material for the treatment of H2S. At an Empty Bed Residence Time (EBRT) of 19.3 s, ECmax values were determined for 6 experiments corresponding to loading rates from 25.4 to 57.4 g m3 h−1 (inlet concentration up to 300 mg m−3) and compared with the value previously calculated from the classic technique based on the modified Michaelis-Menten model. The results showed that ECmax values calculated from both the rapid and classic procedures were in agreement. Moreover, the coexistence of both zero-order regimes in a large middle part of the biofilter was also evidenced for each of the six experiments carried out. However, the critical concentration separating both regimes could not be accurately assessed and, consequently, the Thiele modulus could not be used to characterize the limiting factor influencing the biodegradation.