The use of enhanced anaerobic bioremediation for treatment of chlorinated solvents in groundwater has increased at a rapid rate within the past three years. Since there are a number of different hydrogen donors that can potentially be used, it is important that practitioners understand the cost implications of the hydrogen donor(s) selected for the project. A comparative economic analysis is presented which indicates that the donor source cost can be misleading unless converted to a cost per pound of hydrogen equivalents. Although we have not attempted to determine the minimum hydrogen donor dose that is necessary to achieve complete dechlorination, we have based the hydrogen requirements on stoichiometric demand. In addition to the donor cost, practitioners must also be cognizant of the cost associated with the required delivery system. A template site approach is used to compare remediation net present value costs for the following in situ bioremediation processes to treat chlorinated solvents: anaerobic bioremediation with a recirculation system using lactate, methanol, ethanol, and sodium benzoate; anaerobic bioremediation with periodic feeding of soluble substrates such as molasses or lactate; anaerobic bioremediation with long-lasting substrates such as Hydrogen Release Compound (HRC?) or edible oil emulsions; and natural attenuation. The analysis shows that the cost of hydrogen donors can vary significantly in addition to having a significant effect on the substrate delivery system cost.
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