Abstract
The removal of high concentrations of H~2~S from waste gases containing mixtures of H~2~S and NH~3~ was studied using the pilotβscale biofilter. Granular activated carbon (GAC), selected as support material in this study, demonstrated its high adsorption capacity for H~2~S and good gas distribution. Extensive tests to determine removal characteristics, removal efficiency, and removal capacity of high H~2~S levels and coexisting NH~3~ in the system were performed. In seeking the appropriate operating conditions, the response surface methodology (RSM) was employed. H~2~S removal capacities were evaluated by the inoculated bacteria (biological conversion) and BDST (Bed Depth Service Time) methods (physical adsorption). An average 98% removal efficiency for 0.083β0.167 mg dm^β3^ of H~2~S and 0.004β0.021 mg dm^β3^ of NH~3~ gases was achieved during the operational period because of rapid physical adsorption by GAC and subsequently an effective biological regeneration of GAC by inoculated Pseudomonas putida CH11 and Arthrobacter oxydans CH8. The results showed that H~2~S removal efficiency for the system was not affected by inlet NH~3~ concentrations. In addition, no acidification was observed in the BAC biofilter. High buffer capacity and low moisture demand were also advantages of this system. The maximal inlet loading and critical loading for the system were 18.9 and 7.7 gβH~2~S m^β3^ h^β1^, respectively. The results of this study could be used as a guide for the further design and operation of industrialβscale systems. Copyright Β© 2004 Society of Chemical Industry