In situ bioremediation mainly divided into biostimulation and
bioaugmentation. The former is performed by stimulating activity
of the intrinsic microorganisms to biodegrade the organic contaminants
through addition of exogenous oxygen and inorganic
nutrients [19]; the latter is performed by injecting competent
biodegrading microorganisms to accelerate biodegradation of
pollutants, in addition to the exogenous oxygen and inorganic
nutrients [5]. The biostimulation can effectively remediate the
low concentration BTEX-contaminated groundwater (no more than
5 mg l−1 for each pollutant) to meet the standard level of potable
water [9,20,21]; however, when the BTEX compounds present in
groundwater are at much high concentrations such as 25 mg l−1
for each pollutant or above, the biostimulation approach harvests
such low removal efficiencies that the remaining concentrations
of BTEX do not meet potable water standards [16]. Facing the
low performance of biostimulation in treating high concentration
BTEX-contaminated groundwater, bioaugmentation process poses
potential due to higher bioremediation efficiency [5]. However,
there were few reports about bioaugmentation remediation of high
concentration BTEX-contaminated groundwater.