Use of bag-filter gas dust in anaerobic digestion of cattle manure for boosting the methane yield and digestate utilization.

[Display omitted] • BGD from the iron-making process was first utilized as an accelerant in AD. • BGD accelerant (0.5–2.5 wt.%) can increase methane yield by 22.6%–51.3%. • Digestate with 2 wt.% BGD showed optimal stability (57.9%) and fertility (4.86%). • The electron transfer ability of the AD system was enhanced with BGD. • A strategy for understanding BGD added to boost AD performance was proposed. Plenty of refractory and environmentally hazardous bag-filter gas dust (BGD) is produced in the iron-making process. The effects of untreated BGD on anaerobic digestion (AD) with cattle manure were investigated. The BGD had the potential to boost the methane yield and digestate utilization considerably. The digester with 2.0 wt% BGD gained the highest methane yield (256.3 mL/g VS) and chemical oxygen demand removal rate (56.8%), 51.3% and 20.1% higher than that (169.4 mL/g VS, 47.3%) of the control group, respectively. The digestates with BGD possessed a utilization potential with the stability of 49.5–57.9% and fertility of 4.65–4.86%. Electrochemical measurements demonstrated that 2.0 wt% BGD improved the electron transport capacity of the AD system and increased the limiting current and redox peak current by 40.3% and 12.9%, respectively. A strategy for understanding the BGD reinforcing methanogenesis was proposed. This work also provides a technical support for recycling the BGD. [ABSTRACT FROM AUTHOR]