Treatment of reduced sulphur compounds and SO2 by Gas Phase Advanced Oxidation

Abstract Reduced sulphur compounds (RSCs) emitted from pig farms are a major problem for agriculture, due to their health and environmental impacts and foul odour. This study investigates the removal of RSCs, including H 2 S, and their oxidation product SO 2 using Gas Phase Advanced Oxidation (GPAO). GPAO is a novel air cleaning technique which utilises accelerated atmospheric chemistry to oxidise pollutants before removing their oxidation products as particles. Removal efficiencies of 24.5% and 3.9% were found for 461 ppb of H 2 S and 714 ppb of SO 2 in a laboratory system (volumetric flow Q  = 75 m 3 /h). A numerical model of the reactor system was developed to explore the basic features of the system; its output was in fair agreement with the experiment. The model verified the role of OH radicals in initiating the oxidation chemistry. All sulphur removed from the gas phase was detected as particulate matter, assuming the observed particles were made of sulphuric acid. In a second set of experiments a range of RSCs at mixing ratios typically found in pig farms were treated using a larger industry-scale system ( Q  = 600–1200 m 3 /h) that included a wet scrubber. Removal efficiencies >90% were found for all compounds. The study demonstrates the ability of GPAO to control RSC emissions with a low energy input relative to many currently available techniques.