Fate and toxic effects of nitrophenols on anaerobic treatment systems

Abstract

Modern industrial societies discharge vast quantities of chemicals into the environment. Removal of priority pollutants is a vital task of increasing importance. A literature search shows that more quantitative information about the effects and fates of these pollutants during anaerobic treatment is needed. The objective of this research was to study the fate and toxic effects of nitrophenols (2-nitrophenol, 3-nitrophenol, 4-nitrophenol and 2,4-dinitrophenol) on methanogenic bacteria. Both batch and continuous flow experiments were performed. Batch anaerobic toxicity assay (ATA) were performed in methanogenic enrichment cultures. The effects of 4-nitrophenol were also studied using chemostats at 15-day solids retention time. Stock acetate enrichment cultures were developed and used in this research. An inhibition coefficient model was used to quantify the effects of 4-nitrophenol. The competitive inhibition coefficient model can adequately describe the fate of the systems exposed to 4-nitrophenol. The results of this research showed that about 81% of 4-nitrophenol can be removed by biodegradation. Among the nitrophenols studied, 4-nitrophenol and 2,4-dinitrophenol were most toxic.