Removal of hydrogen sulfide in air using cellular concrete waste: Biotic and abiotic filtrations

Abstract

The objective of this study was to investigate the removal of hydrogen sulfide (H2S) present in air using cellular concrete waste as the packing material. Air filtration was performed under biotic and abiotic conditions. Experiments were carried out in a laboratory-scale PVC column (internal diameter of 300mm) filled with a volume of 70L of cellular concrete (1m height). The polluted air flow was generated at 4m3h−1 corresponding to an Empty Bed Residence Time (EBRT) of 63s. In dry conditions without biomass (abiotic conditions), cellular concrete can be an effective medium for the treatment of H2S in air. For an H2S concentration of 100ppmv, the removal efficiency was around 70% (Elimination Capacity (EC) of 5.6gm−3h−1). This finding can be explained by the physicochemical reactions that can take place between H2S and the cellular concrete components (mainly CaO, CaCO3 and Fe2O3). However, interactions between cellular concrete and H2S are not yet fully understood. Used as a packing material for H2S biofiltration (biotic conditions), cellular concrete waste efficiently treated (Removal Efficiency=100%) high concentrations of H2S (up to 133ppmv corresponding to an EC of up to 10.5gm−3h−1). Physicochemical and biological mechanisms explaining H2S removal seem to occur simultaneously in the biofilter. At an EBRT of 63s, the maximal elimination capacity (ECmax) was 17.8gm−3h−1. A packed bed of cellular concrete also presents a satisfactory mechanical behavior with low pressure drops.