Enhancement of Stability and Biogas Production From Anaerobic Digestion of Food Waste and Its Mixture With Raw Sludge

Abstract

Anaerobic digestion (AD) is a widely used technology applied globally for managing food waste (FW). However, biogas production has  an issue with low yield due to the inhibition of microbial activities, consequently resulting in AD instability. In this study, sludge is used as  an additive during AD of (FW) to investigate the enhancement of AD’s biogas production and stability. This work aims to critically analyse  the sludge’s ability to produce biogas with and without sludge in AD of (FW) at 26°C. AD batch tests were performed at the laboratory  scale operating three sets of digestors (500 ml glass bottle with 350 ml operating volume). The first set of digestors operated without  sludge for (7, 14, 21 and 28 days), whereas the second set of digestors had different amounts of sludge dosage (1 g, 2 g, 3 g, and 4 g) for   14 days. The last set operated with a fixed sludge dosage of 4 g for (7, 14, 21 and 28 days). It was observed that biogas production increased  when sludge was added to the AD. Furthermore, the characterisation analysis of sludge identified the -OH, C-H, C-C and C-O functions by  Fourier-transform infrared (FTIR) spectroscopy and the elemental composition of Si, Al, and O observed by scanning electron microscope  equipped with energy-dispersive x-ray spectroscopy (SEM-EDX) which enhanced the biogas production and the stability of AD.