Toxicity and biodegradability of caffeic acid in anaerobic digesting sludge

Abstract

Caffeic acid in waste comes from a variety of industries, and its disposal is likely to increase due to emerging processes such as graphene production and use in healthcare products. The current sustainable option to treat waste caffeic acid and prevent its natural transformation in soil to greenhouse gases, is anaerobic digestion. However, little is known about the toxic and inhibitory effects of caffeic acid on biogas production as well as its ultimate anaerobic biodegradability; or about the reactiveadsorptive processes taking place with caffeic acid in sludge, metabolic intermediates, thermodynamic limitations and the effects on extracellular polymeric substances (EPS). Standard methods revealed that 80% of biogas production (EC 80) from a readily digestible biomass was inhibited at 389 mg caffeic acid·g-1 VSS. Up to 52% of caffeic acid was biodegraded. β-oxidation and reductive dehydroxylation were the initial activation reactions transforming caffeic acid into typical polyphenol structural units (protocatechuic acid and 4HBA).

Authors

Categories