Strategies for energy conversion from sludge to methane through pretreatment coupled anaerobic digestion: Potential energy loss or gain. (15th March 2023)

• Record Type: Journal Article
• Authors: Wang, Xu; Jiang, Cancan; Wang, Huacai; Xu, Shengjun; Zhuang, Xuliang
• Is Part Of: Journal of environmental management. Volume 330(2023)
• Publication Date: 2023-03-15
• Subjects: Sludge pretreatment -- Anaerobic digestion -- Potential energy loss; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.117033
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Anaerobic digestion (AD) of wasted activated sludge from wastewater plants is recognized as an effective method to reclaim energy in the form of methane. AD performance has been enhanced by coupling various pretreatments that impact energy conversion from sludge. This paper mainly reviewed the development of pretreatments based on different technologies reported in recent years and evaluated their energy benefit. Significant increases in methane yield are generally obtained in AD with pretreatments demanding energy input, including thermal- and ultrasound-based methods. However, these energy-intense pretreatments usually gained negative energy benefit that the increase in methane yield consumed extra energy input. The unbalanced relationship counts against the goal of energy reclamation from sludge. Combined pretreatment consisting of multiple technologies normally outcompetes the single pretreatment, and the combination of energy-intense methods and chemicals potentially reduces energy input and simultaneously ensure high methane yield. For determining whether the energy reclamation from sludge via AD contribute to mitigating global warming, integrating greenhouse gas emission into the evaluation system of pretreated AD is further warranted. Graphical abstract: Image 1 Highlights: Combined pretreatment outcompetes the sole pretreatment in terms of methane yield. Massive methane yield demands energy-intense types of sludge pretreatments. Massive methane yield at the cost of extra energy input causes negative net energy consequences. Development of energy saving type of sludge pretreatment facilitates carbon neutralization.