Performance of a Novel Monolith Biotrickling Filter Treating High Concentration of H2S from Mimic Biogas

Pre-treatment of hydrogen sulfide is required before the utilization of biogas to eliminate the detrimental effects of corrosive hydrogen sulfide to the following combustion engines and pipelines. Biotrickling filters as one of the biotechnological methods have been investigated in desulfurizing biogas in recent years. Although high removal efficiency has been achieved by conventional biotrickling filters, clogging of the biotrickling filter bed due to the accumulation of excess biomass and elemental sulfur, has been widely reported (Janssen et al. 1997, Fortuny et al. 2008). In this context, a novel biotrickling filter using a monolith as its filter bed has been proposed and studied in this work to investigate its performance in removing H2S and solving the bed-clogging problem through pigging, a common method used for pipeline and tubular reactor cleaning. The inlet H2S concentration was controlled around 1000 ppmv, corresponding to a loading rate of 122 g S--H 2S m-3 h-1, and the empty bed gas residence time (EBRT) was 41 s. The influence of different H 2S/O2 ratios on the removal performance was investigated at these conditions and results indicated that at H2S/O2 molar ratio of 1:2, an average removal efficiency of 95% was obtained. Under all conditions investigated, elemental sulfur and sulfate were measured to be the two dominant products and covered up to 93% of total end products. The monolith bed design also served to demonstrate that the risk of clogging was greatly reduced under this kind of design and bed-clogging problems could be resolved when bed pigging was implemented to remove excess biomass and elemental sulfur accumulated inside the bed. Based on the results reported here, the monolith filter bed can be an effective alternative to the conventional packing material with a high specific surface area and a comparable performance could also be achieved by this novel bioreactor.