Remediation performance of different enhanced Fe(II)-based advanced oxidation processes on groundwater contaminated by multiple mixed chlorinated hydrocarbons: Removal efficiencies, costs, and optimal systems.

[Display omitted] • The removal performance of various types of CHCs was systematically examined. • The predominant reactive species were identified in different enhanced systems. • The removal efficiencies, costs, and toxicity of the enhancers were evaluated. • The most applicable techniques for the single CHC were elucidated. • A complete set of remediation strategies for multiple mixed CHCs were formed. Conventional Fe(II)-based advanced oxidation processes required enhancement to achieve desired contaminant removal. In this study, the introduced enhancers were divided into four categories: organic acids-based enhancers, inorganic reductants, slow-release iron substances, and short-chain alcohols or acids. Chlorinated hydrocarbons (CHCs) were chosen as the targets and classified into three groups: chlorinated olefins, non-perchlorinated alkanes, and perchlorinated alkanes. The remediation effects of different enhanced systems (oxidant/Fe(II)/enhancer) on different types of CHCs were systematically examined. The predominant reactive species were identified and elucidated to provide the most applicable technique for the remediation of each type of chlorinated hydrocarbon. Their dechlorination and mineralization degree were investigated as well. Meanwhile, a complete set of remediation strategies for multiple mixed CHCs in contaminated groundwater were formed by combining the remediation efficiencies, costs, and toxicity of the enhancers, which could provide far-reaching implications for the systemic governance of CHCs in practical applications. [ABSTRACT FROM AUTHOR]