Guidelines for optimal design of electron acceptor injection wells to enhance bioremediation of contaminated groundwater

The finite element model METABIOTRANS, which simulates the fate and transport of contaminants in the subsurface, is used to identify general guidelines for the optimal design of electron acceptor injection wells to enhance bioremediation of contaminated groundwater aquifers. Several scenarios were simulated to examine the sensitivity of remediation effectiveness to the number and locations of wells and injection rates of electron acceptors. Results show that an injection well placed near the plume core, where highest contaminant concentrations exist, is always desired. The nearest injection well to the source zone caused higher stimulation to bacterial growth than further downgradient injection wells. It also exhibited longer resident time for the electron acceptors in the aquifer; and therefore yielded higher biodegraded contaminant mass. Higher injection rates of electron acceptors are not always needed to increase bioremediation efficiency. This should be noticed in real practices of groundwater remediation design.