Enhancing bioregeneration of TCE-sorbed Biological Powdered Activated Carbon by dosing toluene as primary substrate and competitive adsorbate.

Removal of TCE by Biological Powdered Activated Carbon (BPAC), inoculated with Burkholderia vietnamiensis G4 and fed with toluene as the growth substrate, was investigated in fed-batch mode reactors, focusing on the regeneration of Powdered Activated Carbon (PAC). Cell-only and PAC-only reactors were operated in parallel for comparison. BPAC, once acclimated, removed toluene and TCE faster than cell-only or PAC-only reactors, leaving the lowest residuals in the liquid. This was amplified when the substrate dose was elevated. Toluene competitively adsorbed into the BPAC, resulting in TCE desorption, which accelerated bioregeneration of the TCE-sorbed BPAC. The regenerated BPAC exerted a similar adsorption capacity to PAC and a similar biodegradation capability to virgin BPAC under the experimental conditions. An acclimation of cells on TCE was necessary before its degradation, which indicated that TCE cometabolism may not be a fortuitous reaction. When a bioactive zone is constructed with BPAC, it is expected that TCE in the groundwater will be adsorbed to the BPAC; then, the adsorbed TCE will be desorbed and cometabolized upon pulse injections of toluene. A portion of left-over toluene will be stored in the BPAC and utilized for later TCE cometabolization. [ABSTRACT FROM AUTHOR]