While biologically mediated reductive dechlorination continues to be a significant focus of chlorinated 
solvent remediation, there has been an increased interest in abiotic reductive processes for the 
remediation of chlorinated solvents. 

In situ chemical reduction (ISCR) uses zero-valent iron (ZVI)–based technologies, such as nanoscale 
iron and bimetallic ZVI, as well as naturally occurring reduced minerals incorporating dual-valent 
iron (DVI), such as magnetite, green rust, and iron sulfides that are capable of dechlorinating 
solvents. A more recent area of development in ISCR has been in combining biological and abiotic 
processes. There are several ways in which biological and abiotic processes can be combined. First, 
the interaction between the two may be “causative.” A second type of interaction between abiotic 
and biotic processes is “synergistic.” For example, biological processes can enhance the activity 
of reduced metals/minerals. This is the basis of the EHC® ISCR technologies, which combine ZVI with 
a (slowly) degradable carbon substrate. This combination rapidly creates buffered, strongly 
reducing conditions, which result in more complete solvent degradation (i.e., direct mineralization). 
The extent and level of reducing activity commonly observed are much greater when both the carbon 
substrate and the ZVI are present. When the carbon substrate is expended, the reducing activity 
due to ZVI alone is much less. The understanding of biogeochemical processes and their impact on 
abiotic processes is still developing. As that understanding develops, new and improved methods 
will be created to enhance volatile organic compound destruction.