Performance of a monolith biotrickling filter treating high concentrations of H₂S from mimic biogas and elemental...

A novel biotrickling filter using a 3D-printed honeycomb-monolith as its filter bed has been proposed and studied in this work and a solution to bed-clogging problems using pigging was demonstrated. The inlet H₂S concentration in the mimic biogas was controlled around 1000 ppm_v and the empty bed gas residence time (EBRT) was 41 s corresponding to a loading rate of 127 g S-H₂S m^-3 h^-1. The influence of different H₂S/O₂ ratios on the removal performance and fate of sulfur end-products was investigated. The results indicated that at a H₂S/O₂ molar ratio of 1:2, an average removal efficiency of 95% and an elimination capacity of 122 g H₂S m^-3 h^-1 was obtained. Under all conditions investigated, elemental sulfur (rather than sulfate) was the dominant end-product which mostly accumulated in the bed. However, the monolith bed design reduced the risk of clogging by elemental sulfur, while bed pigging was shown to be an effective means to remove excess biomass and elemental sulfur accumulated inside the bed and extend the life of the system indefinitely. Altogether, these findings could lead to significant process improvement for biological sweetening of biogas or for removing biomass in biotrickling filters at risk of plugging.