Migration and evolution of an in situ bioreactive zone formed with emulsified vegetable oil for the long-term remediation of nitrobenzene-contaminated groundwater

[Display omitted] •The one-time injection of emulsified vegetable oil formed a bioreactive zone.•The bioreactive zone can effectively intercept and remediate nitrobenzene plume.•The nitrobenzene remediation efficiency and permeability in aquifer were evaluated.•The formation and evolution process of the reactive zone was monitored and analyzed. The enhancement of in situ bioreactive zones by injecting emulsified vegetable oil is an effective method for the remediation of nitrobenzene-contaminated aquifers. The injection of emulsified vegetable oil can stimulate biogeochemical processes underground and effectively reduce nitrobenzene to aniline, but the nitrobenzene remediation efficiency and the evolution of the in situ reactive zone during the remediation process are still unclear at present. In this study, emulsified vegetable oil was used as the sole exogenous organic matter to construct an in situ reactive zone in a simulated tank; the formation and evolution of the reactive zone were analyzed, and the nitrobenzene remediation efficiency and permeability in the aquifer were evaluated. The results suggest that the one-time injection of emulsified vegetable oil can form an in situ bioreactive zone and exist stably for at least 164 days, the in situ bioreactive zone can effectively intercept and remediate 100 mg/L nitrobenzene plume in the long term. During the experiment, a total of 178,400 mg of nitrobenzene flowed into the simulated tank, of which 93.04% was degraded, and the main product was aniline.