Anaerobic Digestion of Chicken Manure Assisted by Carbon Nanotubes: Promotion of Volatile Fatty Acids Consumption and Methane Production

Abstract

In this study, the effect of different concentrations of carbon nanotubes (Taunit-M; 0.5–6.5 g L−1) on the efficiency of anaerobic digestion of chicken manure is investigated. The highest positive effect on the specific production of methane is obtained when 5.0 g L−1 of carbon nanotubes are added to the anaerobic reactors. In addition, carbon nanotubes at these concentrations stimulate the biodegradation of volatile fatty acids, mainly acetate, butyrate, and finally propionate. The maximum production rate of methane increases by 15–16% in the presence of carbon nanotubes (5.0–6.5 g L−1). Also, addition of carbon nanotubes at certain concentrations increases total methane production. Finally, the addition of carbon nanotubes to the anaerobic reactors is found to the favor consumption of volatile fatty acids and improve the methane production kinetics and productivity during the anaerobic digestion of chicken manure.