Feasibility analysis of anaerobic digestion of excess sludge enhanced by iron: A review

Jing Wei, Xiaodi Hao, Mark C.M. van Loosdrecht and Ji Li

Renewable and Sustainable Energy Reviews, 2018, vol. 89, issue C, 16-26

Abstract: The Paris Climate Treaty implies the coming of a new era towards carbon-neutral operation in wastewater treatment plants (WWTPs), and thus energy self-sufficiency from biosolids and/or heat in the form of wastewater temperature has to be considered. In this regard, anaerobic digestion (AD) of sludge should be paid renewed attention to resolve a low conversion efficiency of biosolids. As a potential way to energy positive operation, exogenous iron has been proposed to enhance methane production in recent years. In this review, the authors provided a deep insight into the feasibility of iron-enhanced AD system. Hydrogen evolution from iron corrosion and its effects on CH4 production is firstly reviewed; then the roles of iron in reducing ORP was illustrated with regard to its impact on fermentation type; serving as an essential element and potential electron donor, the stimulating effects of iron on microorganisms and enzyme activities were also elaborated, and thus the technical feasibility of iron-based AD could be evaluated. In regards of the environmental and economic impacts of iron-based AD, life cycle assessment (LCA) was employed to calculate its economic feasibility, and the results revealed that iron-based AD system could reduce both operational costs and carbon emissions. Conclusion was drawn that iron-based anaerobic digestion is promising on technical level as well as economic perspective, and is expected to contribute to carbon-neutral operation of WWTPs. Iron-based anaerobic digestion is such a promising and sustainable strategy towards circular economy that it could be applied to many cross-disciplinary fields.

Keywords: Anaerobic digestion (AD); Scrap iron; Oxidation-reduction potential (ORP); Enzyme activity; Life cycle assessment (LCA) (search for similar items in EconPapers)
Date: 2018
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Citations: View citations in EconPapers (10)

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DOI: 10.1016/j.rser.2018.02.042

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