This study simulated in situ bioremediation for diesel-contaminated soil by a column operation. Several bioremediation approaches were conducted to examine the feasibility. Four lab-scale soil columns were operated specific to the following approaches: nutrients enhancement (NE). bioaugmentation (BA), biostimulation (BS), and sterilized soil (SS). Within 330 days of operation, the residual total petroleum hydrocarbon-diesel (TPH(d)) was degraded from 10,290 mg TPH(d)/dry soil to 3026, 1851, 4105, and 6506 mg TPH(d)/kg dry soil by Columns Ne, BA, BS, and SS, respectively. The diesel-degradation efficiency was, 67%, 80% 45%, and 24%, accordingly. Microbial diversity was monitored with molecular biotechnology DGGE. It was found that introduced bacteria CC-CF3 and CC-JG39 become undetectable after 90 days of operation, but another introduced bacteria, CC-RSI, evidently remained with small signals during the last time stage of operation. (c) 2008 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.