No abstract

h i g h l i g h t sThe treatment of sulfur odorous compounds in mixture, H 2 S, DMDS and EtSH by biofiltration was examined. Removal efficiencies of biofilters packed with pine bark and composted wood mulch were compared. The degradation of the three compounds decreased as follows: H 2 S > DMDS > EtSH. Contrarily to EtSH and DMDS, H 2 S removal was not affected by the lack of nutrients in the biofilter. pH decrease caused by H 2 SO 4 accumulation impacted EtSH and DMDS degradation contrarily to H 2 S removal. a b s t r a c tThe treatment of sulfur odorous compounds in mixture, hydrogen sulfide (H 2 S), dimethyl disulfide (DMDS) and ethanethiol (EtSH), by biofiltration was examined. A significant effort was focused on the impact of nutrients supply, without forgetting the effect of other parameters such as the pH, on the process performances. Removal efficiencies of three biofilters packed with pine bark and composted wood mulch and sprinkled by different nutritive solutions were compared.Owing to the biodegradability of H 2 S, its removal was not affected by the lack of nutrients in the biofilter. However, for EtSH and DMDS, considered as more recalcitrant, the influence of nutrients on biodegradation was clearly observed; it was enhanced when the supplementation in the watering solution was increased. Furthermore, EtSH removal yield increased from 80% in the absence of supplementation to an almost total removal in the presence of nutrients in the watering solution. The degradation of the three compounds decreased as follows: H 2 S > DMDS > EtSH. The impact of the pH of the packing materials was also underlined. The decrease in pH caused by the accumulation of sulfuric acid in the packing material, the most abundant product of the biological oxidation of sulfur compounds, led to a reduction of the elimination efficiencies of EtSH and DMDS; while the microorganisms involved in H 2 S degradation appeared active in a large pH range, from less than 3 to close to 9.

This research focuses on the identification and quantification of odorous components in rendering plant emissions by GC/MS and other analytical methods, as well as the description of phenomena occurring in biofilter in order to improve the removal efficiency of industrial biofilters. Among the 36 compounds quantified in the process air stream, methanethiol, isopentanal and hydrogen sulfide, presented the major odorous contributions according to their high concentrations, generally higher than 10 mg m(-3), and their low odorous detection thresholds. The elimination of such component mixtures by biofiltration (Peat packing material, EBRT: 113 s) was investigated and revealed that more than 83% of hydrogen sulfide and isopentanal were removed by biofilter. Nevertheless, the incomplete degradation of such easily degradable pollutants suggested inappropriate conditions as lack of nutrients and acidic pH. These inadequate conditions could explain the lack of performance, especially observed on methanethiol (53% of RE) and the production of oxygenated and sulfur by-products by the biofilter itself.