Coupled microscale zero valent iron-autotrophic hydrogen bacteriadechlorination system is not always superior to its standalone counterparts:A sustainable remediation perspective br

The coupling of microscale zero-valent iron with autotrophic hydrogen bacteria (mZVI-AHB) are often believed toshow greater potential than the single abiotic or biotic systems in remediating chlorinated aliphatic hydrocarbon-contaminated groundwater. However, our understanding of the remediation performance of this system under realfield conditions, especially by incorporating the concept of sustainable remediation, remains limited. In this study,the performances of the mZVI, H2-AHB, and mZVI-AHB systems in dechlorinating groundwater containing complexelectron acceptors were compared by evaluating their removal efficiency (RE), reaction products, and electron effi-ciency(EE), using trichloroethylene (TCE) as the target contaminant and NO3-and SO42-as the coexisting natural elec-tron acceptors. Ultimately, which of these systems had TCE removal superiority was dependent on the coexistingelectron acceptor. mZVI-AHB and mZVI resulted in more complete dechlorination, whereas H2-AHB exhibited higherN2selectivity in reducing NO3-. Regardless of the coexisting electron acceptor, the mZVI-alone system showed thehighest EE. Finally, the sustainability concerns and applicability of the three systems were evaluated on the basis oftheir TCE RE, complete dechlorination ratio, N2selectivity, EE, and cost, which were integrated into a comparisonof overall benefits. Ourfindings provide comprehensive and insightful information on the factors that determine reme-diation scheme selection in real practice

Automated summary

This study compared the performance of microscale zero-valent iron, autotrophic hydrogen bacteria, and their coupling system in remediating chlorinated aliphatic hydrocarbon-contaminated groundwater. The results showed that the mZVI-AHB and mZVI systems were more efficient in dechlorination, while the H2-AHB system exhibited higher selectivity in reducing nitrate. After considering factors such as degradation efficiency, reaction products, electron efficiency, and cost, the mZVI-AHB system showed higher potential in sustainable remediation.