Combining Chemical and Biological Oxidation for Sustainable Treatment of Chloronitrobenzene in Anoxic Groundwater. Issue 1 (28th January 2021)

• Record Type: Journal Article
• Authors: Amiri, Samia; Hanson, Andrea J.; Pica, Nasim E.; Mack, E. Erin; Blotevogel, Jens
• Is Part Of: Ground water monitoring & remediation. Volume 41:Issue 1(2021)
• Page Start: 106
• Page End: 115
• Publication Date: 2021-01-28
• Subjects: Groundwater -- Periodicals; Groundwater -- Purification -- Periodicals; Wellhead protection -- Periodicals; Hydrogeology -- Periodicals; 553.790286
• DOI: 10.1111/gwmr.12425
• Languages: English
• ISSNs: 1069-3629

Abstract

Abstract: Chloronitrobenzenes (CNBs) are important chemical intermediates that are resistant to natural degradation processes in anoxic environments. When receptors are threatened by CNB‐contaminated groundwater, advanced oxidation processes (AOPs) offer a rapid response to protect human health and the environment. While AOPs are effective for the transformation of persistent organic contaminants, driving chemical oxidation reactions to complete mineralization is often not energy‐ and cost‐efficient due to the formation of recalcitrant intermediates or competition by natural organic matter. In this study, we applied an electrochemical AOP to elucidate the degradation pathways and kinetics of CNB under varying treatment conditions and times. Nontargeted mass spectrometry revealed multiple ring hydroxylation and ring opening products such as dicarboxylic acids that became increasingly harder to chemically oxidize as treatment time progressed. To determine the universal biodegradability of the generated intermediates under anoxic conditions, AOP‐treated water samples collected at different stages of electrochemical oxidation were exposed to a microbial culture derived from generic rhizosphere soil. All ring opening products were completely biodegraded anaerobically within 28 days of microcosm incubation. While multiple oxygenated ring intermediates were substantially removed, CNB was stable in the absence of oxygen. Our findings demonstrate that the combination of limited and targeted chemical oxidation with subsequent biodegradation of incomplete oxidation products is a more sustainable approach than the exclusive application of AOPs for the treatment of groundwater contaminated with CNBs and likely other aromatic compounds. Abstract : Article impact statement : The application of resource‐intensive engineered approaches for the destruction of persistent organic pollutants may be reduced to a point at which more efficient natural degradation processes can ensue.