Iron Release in Microelectrolysis Treatment for Arsenic Removal from Landfill Gas Condensate and Its Use to Predict Arsenic Removal Efficiency

Abstract

Arsenic poses a significant threat as a highly hazardous contaminant. Its concentrations are particularly high in landfill gas (LFG) condensate, a byproduct of landfill gas purification, and landfill leachate generated at sites with combined LFG and renewable natural gas (RNG) production. This thesis addresses several aspects of the utilization of micro-electrolysis (ME) techniques for arsenic removal from LFG-derived condensate, specifically focusing on the release of iron solutes and colloidal particles from zero-valent iron (ZVI), a key component of ME treatment. The study encompasses multiple experiments aimed at quantifying and optimizing the ME process, with the objective of exploring alternative options for arsenic removal monitoring, and maximizing resource utilization. Another aspect of this study is that ME treatment is accompanied by release of high concentrations of iron whose presence may lead to challenges in post-treatment scenarios such as the formation of voluminous solids and contamination due to the presence of excessively high iron levels. To tackle this issue, a thorough analysis was conducted to characterize iron content, particle sizes, ZVI weight loss, and other parameters relevant to ME treatment and its effluent properties.Experiments reported in this thesis further explored the kinetics of iron release during the ME treatment process and compared the results using different analytical methods. The findings from this study suggest that field-enabled spectrophotometric (or color) measurements of iron concentrations can be used as a sufficiently reliable surrogate parameter with which to predict the removal of arsenic and co-occurring elements such as antimony in ME treatment under most circumstances. While the performance of this parameter needs to be explored for a wider range of ME treatment conditions (i.e., varying doses of ZVI and GAC, different types of the active media), this approach to monitor the efficiency of As removal by ME treatment can be employed when ME technology is deployed in pilot or full-scale applications.