Bioaugmentation with a thermophilic inoculum for enhanced bioconversion of sewage sludge and food waste into fertilizer

Abstract

Two indigenous thermophilic bacterial isolates, identified to be Bacillus stearothermophilus strain SD13 and Bacillus coagulans strain FW04 by partial 16S rRNA gene sequencing, were used to prepare an inoculum in order to bioaugment the bioconversion process from sewage sludge and food waste into fertilizer. Prior to the bioconversion process, a preliminary biodegradability test was performed by inoculating the mixed culture of these two isolates into a 2% sewage sludge and 2% food waste slurry medium and subsequently incubating at 60?C for 10 days. The results showed that the inoculum was effective in degrading sewage sludge and food waste, as indicated by the significantly higher levels of total solids weight loss, volatile solids reduction, CO2 evolution and the increase of pH in comparison with the control in which no inoculum was added.