The Potential for Uncoupling and Subsequent Augmentation or Disruption of Methanogenesis by Nonylphenol and Triclosan

Anaerobic digestion is a critical biosolids stabilization process for wastewater treatment. While digesters are often robust, they can also be susceptible to upsets and foaming. Classical problems for digesters include variations in temperature or organic loading rates, but more recently digesters have had to deal with an influx of contaminants that accumulate in solids. Little work has been performed to determine how these contaminants impact the anaerobic digestion process. This work focuses on two chemicals found at high levels in digesters: triclosan and nonylphenol. These two chemicals are of greater concern because they could act as uncouplers, i.e., chemicals that cause microbes to respire more without additional growth. In the case of methanogenesis, uncoupling could lead to an increase in methane production, but also to the death of important microbes. Triclosan elicited signs of uncoupling at 10 μM while nonylphenol was toxic to pure culture methanogens at 10 μM.