The Effect of the Monosubstituted Benzenes Functional Groups on the Inhibition of Methane Gas Biosynthesis

Aromatic compounds are inhibitors of methane biosynthesis in anaerobic treatment of solid wastes and industrial efflu-ents. Anaerobic treatment of solid wastes and industrial effluents may be limited by the methanogenic bacteria inhibi-tion exerted by these types of compounds, the production of biogas is not possible and the organic matter contained in the effluent is not reduced. These effluents poured in the nature can be the basis of the pollution. The objective of this study is to evaluate the effect of monosubstituted aromatic compounds functional groups on the methanogenic inhibi-tion. The toxicity to acetoclastic methanogenic bacteria has performed in serum flasks, utilizing digested pig manure as inoculums, by measuring methane production. The nature of aromatic functional groups was observed to have a pro-found effect on the toxicity of the monosubstituted aromatics. Among the monosubstituted aromatic, the chlorobenzene was the most toxic with 50 % of inhibition occurring at the concentration of 30.08 mg/l. In contrast, benzoic acid is the least inhibitory with IC50 of 2515.20 mg/l. The partition coefficient octanol/water (logPoct), an indicator of hydropho-bicity, had a significant correlation with the methanogenic toxicity