Process Safety and Environmental Protection, Vol.88, No.6, 420-424, 2010
Hydrogen sulphide removal from landfill gas
Control of odours should be considered to be a fundamental issue in order to site, design and manage sanitary landfills. With regard to construction and demolition (C&D) debris, landfilling was the mainly adopted solution in many European Countries; in particular, gypsum drywalls can produce high concentrations of hydrogen sulphide (H(2)S) in landfill gas ranging from 7 ppm to 100 ppm. In some cases also dangerous concentrations until to 12,000 ppm were detected. In this paper H2S removal efficiency in a lab-scale vertical packed scrubber was investigated. Hydrogen sulphide abatement was evaluated for inlet H(2)S concentrations of 1000-100-10 ppm, adjusting scrubbing liquid pH in the range 9-12.5 by means of caustic soda (NaOH 2N solution). Moreover, best operating conditions for the system were defined as well as H(2)S abatement along the tower and liquid recirculation effectiveness in case of inlet H(2)S concentration of 10 ppm (typical odour concentration). Results showed that pH of 11.5 in scrubbing liquid could be considered the best value for removal of different inlet H(2)S concentrations, also taking into account parasitical consumption of NaOH due to CO(2) absorption. Moreover, in case of continuous working of the system at H(2)S concentration of 10 ppm, strong removal efficiency was already obtained with a packed bed height of about 70 cm. Significant performances were ensured after 1 h of constant activity, consuming about 3 ml of soda per cubic meter of polluted air. Subsequently liquid blowdown was necessary. (C) 2010 Published by Elsevier B.V. on behalf of The Institution of Chemical Engineers.