Enhancing methane production of co-digested food waste with granular activated carbon coated with nano zero-valent iron in an anaerobic digester

Abstract

Anaerobic digestion (AD) possesses dual benefits of waste treatment and energy generation. The use of conductive additives in AD matrix has potential to improve process yield. Hence, the study aimed to investigate a thermophilic AD (TAD) inserted by granular activated carbon coated with nano zero-valent iron (GAC/nZVI) in the matrix and was operated for mono-digestion and co-digestion of cow manure with food wastes (rice and bread) to check the bioprocess improvement. The results were compared with the control TAD without conductive additives. Biogas production increased by 11 folds upon using GAC/nZVI addition compared to the control TAD. Moreover, the addition of GAC/nZVI increased the methane in biogas by 20.7 folds compared to control one. With GAC/nZVI, the maximum COD removal of 78.29% and 85.21% were noticed for co-digestion and mono digestion, respectively. Such improvement of TAD performance was due to easy bacterial communication and electron exchange through the conductive particles.