Roles of magnetite and granular activated carbon in improvement of anaerobic sludge digestion

• Published in: Bioresource technology Vol. 249; pp. 666 - 672
• Main Authors: Peng, Hong, Zhang, Yaobin, Tan, Dongmei, Zhao, Zhiqiang, Zhao, Huimin, Quan, Xie
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2018
• Subjects: activated carbon; adsorption; anaerobic digesters; anaerobic digestion; Anaerobic sludge digestion; Anaerobiosis; Bioreactors; Charcoal; electrical conductivity; Ferrosoferric Oxide; Fourier transform infrared spectroscopy; Granular activated carbon; Hydrolysis; Magnetite; metabolism; Methane; Methane production; methanogens; nitrogen; Sewage; sludge; surface area; Hydrolysis; Granular activated carbon; Anaerobic sludge digestion; Magnetite; Methane production
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2017.10.047

[Display omitted] •Magnetite enriched iron-reducing bacteria.•Magnetite accelerated sludge hydrolysis via dissimilatory iron reduction.•GAC enhanced syntrophic metabolism between iron-reducing bacteria and methanogens.•Simultaneous addition of magnetite and GAC favored anaerobic sludge digestion. Granular activated carbon (GAC) or magnetite could promote methane production from organic wastes, but their roles in enhancing anaerobic sludge digestion have not been clarified. GAC, magnetite and their combination were complemented into sludge digesters, respectively. Experimental results showed that average methane production increased by 7.3% for magnetite, 13.1% for GAC, and 20% for the combination of magnetite and GAC, and the effluent TCOD of the control, magnetite, GAC and magnetite-GAC digesters on day 56 were 53.2, 49.6, 48.0 and 46.6 g/L, respectively. Scanning electron microscope (SEM), nitrogen adsorption, Fourier transform infrared spectroscopy (FTIR) and microbial analysis indicated that magnetite enriched iron-reducing bacteria responsible for sludge hydrolysis while GAC enhanced syntrophic metabolism between iron-reducing bacteria and methanogens due to its high electrical conductivity and large surface area. Supplementing magnetite and GAC together into an anaerobic digester simultaneously accelerated sludge hydrolysis and methane production, resulting in better sludge digestion performance.