A two-stage desulfurization process including an abiotic filtration using cellular concrete waste (first stage) and anoxic biotrickling filter filling with inoculated expanded schist material (second was investigated to remove H2S in mimic biogas limited O2 amount (ranged from 0.5 0.8%). The able satisfactorily for all experimental conditions (RE > 97%; concentration = 1500 mg m−3; total Emp...