Alkaline fermentation and elutriation of waste activated sludge for short chain fatty acids abstraction

Abstract

BACKGROUND: Alkaline fermentation of waste activated sludge (WAS) is feasible to recover carbon for biological nutrients removal. However, it is difficult to abstract the soluble organics from the fermented mixture since sludge dewaterability is deteriorated after fermentation. In this study, a novel system consisting of complete mixing fermentation, water elutriation and settling reactor was developed to produce and abstract short chain fatty acids (SCFAs) from waste activated sludge through an alkaline fermentation process.

Synergistic effect and microbial community structure of waste-activated sludge and kitchen waste solids residue mesophilic anaerobic co-digestion

“…Anaerobic digestion technology is widely used in the treatment and disposal of KW, waste-activated sludge (WAS) and agricultural waste around the world due to its advantages of high treatment efficiency (Zahan et al 2016;Pan et al 2019;Shafiul et al 2022), low carbon emissions, low secondary pollution, low operating costs and suitability for centralized large-scale treatment (Morales-Polo et al 2018). Sludge, a byproduct of wastewater treatment, has a complex composition containing a large amount of organic matter and bacteria (Li et al 2018), KW is also complex in composition and contains a large number of organic compounds such as proteins, polysaccharides and fats (Pan et al 2019). Volatile solids (VS) removal and gas production were low in anaerobic digestion of WAS alone (Huang et al 2019), which was attributed to the low content of readily degradable organic matter in WAS, the lack of cell wall disruption, the difficulty of solubilizing biodegradable substances, and its low carbon to nitrogen ratio (C/N) and methane yield (Awe et al 2018;Kumar & Samadder 2020).…”