Zero Valent Iron Significantly Enhances Methane Production from Waste Activated Sludge by Improving Biochemical Methane Potential Rather Than Hydrolysis Rate

Abstract

Anaerobic digestion has been widely applied for waste activated sludge (WAS) treatment. However, methane production from anaerobic digestion of WAS is usually limited by the slow hydrolysis rate and/or poor biochemical methane potential of WAS. This work systematically studied the effects of three different types of zero valent iron (i.e., iron powder, clean scrap and rusty scrap) on methane production from WAS in anaerobic digestion, by using both experimental and mathematical approaches. The results demonstrated that both the clean and the rusty iron scrap were more effective than the iron powder for improving methane production from WAS. Model-based analysis showed that ZVI addition significantly enhanced methane production from WAS through improving the biochemical methane potential of WAS rather than its hydrolysis rate. Economic analysis indicated that the ZVI-based technology for enhancing methane production from WAS is economically attractive, particularly considering that iron scrap can be freely acquired from industrial waste. Based on these results, the ZVI-based anaerobic digestion process of this work could be easily integrated with the conventional chemical phosphorus removal process in wastewater treatment plant to form a cost-effective and environment-friendly approach, enabling maximum resource recovery/reuse while achieving enhanced methane production in wastewater treatment system.

Simulated Dairy Wastewater Treatment in a Pilot Plant Scale Magneto-Active Hybrid Anaerobic Biofilm Reactor (Ma-Habr)

“…In a study of an UASB reactor filled with iron elements, Zhang et al (2011) achieved a 66.8% content of methane in biogas versus 47.9% in biogas generated in an UASB reactor without elements. An increase in the efficiency of methanogenesis in reactors filled with steel elements was also reported by other researchers (Shi et al, 2011;Liu et al, 2015).…”

Enhancement of Dairy Wastewater Treatment in a Combined Anaerobic Baffled and Biofilm Reactor with Magneto-Active Packing Media

“…According to the literature, the corrosion of metals intensified methanogenesis (Shi et al, 2011;Liu et al, 2015). During the study, the placement of the active packing media in methanogenic tanks significantly enhanced the biogas production and yield.…”

Metallic Iron for Environmental Remediation: Starting an Overdue Progress in Knowledge

“…Therefore, a better argumentation is still needed to convincingly explain the in-depth knowledge on the mechanisms causing contaminant removal in Fe 0 /H 2 O systems. Another important application of Fe 0 materials entails using Fe 0 to induce a pH shift and/or enhance microbial processes involved in methane production in anaerobic digesters [72][73][74][75]. This aspect is not considered herein as it is not focused on contaminant removal as discussed in Section 2.…”