Abiotic degradation of PCE and TCE favors Reductive ß-elimination reactions through acetylene. Anaerobic biological reactions follow sequential hydrogenolysis [2].

Monitored natural attenuation (MNA) can be an effective and low cost approach for remediation of chlorinated volatile organic compound (cVOCs) sites. MNA includes physical, chemical and biological processes that reduce contaminant mass or concentration in soil or groundwater. The most common MNA mechanisms at cVOC contaminated sites are anaerobic biodegradation and abiotic/chemical reduction. Biodegradation involves key bacteria that are capable of degrading cVOCs to non-toxic end products. Abiotic degradation of cVOCs is mediated by naturally occurring reduced iron and sulfur minerals, and although often unrecognized, is now considered a key process in natural attenuation of these compounds [1,2].

In support of MNA remedies, SiREM is pleased to offer SiREMNA™, a comprehensive analytical package that can be customized to identify and quantify reactive minerals, dechlorinating bacteria and other indicator parameters for abiotic and biotic degradation of cVOCs. The analyses can be performed directly on aquifer materials or complement SiREM’s bench-scale treatability testing services, including batch microcosm and column testing to:

  • Characterize site conditions for MNA evaluation and remediation decision tools such as BioPIC [3].
  • Assess the effectiveness and sustainability of biotic degradation of cVOCs.
  • Determine the role of abiotic reductive dechlorination by biogenic reactive minerals that occur in naturally reducing aquifers, and include iron sulfides, green rusts, pyrite, magnetite, biotite and siderite.
  • Support design and monitor performance of enhanced in-situ chemical reduction (ISCR).
  • Assess the role of abiotic dechlorination by biogenic reactive minerals formed by iron and sulfate reducing bacteria (SRB) at enhanced reductive dechlorination (ERD) bioremediation applications.

SiREMNA™ Methods for Evaluation of Abiotic and Biotic Natural Attenuation Processes For Chlorinated Volatile Organic Compounds

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