Abstract:Bioremediation of petroleum-contaminated saline soil was investigated via biostimulation (BS) and biostimulation-bioaugmentation (BS+BA)in a microscale simulation system. The removal of hydrocarbon and 16 PAHs, changes of soil pH, surface tension, dehydrogenase activity and microbial community structure were monitored during incubation. The results showed that soil properties were changed by the addition of humic acid, NovoGro and biological organic calcium. With the accumulation of acidic metabolites the soil pH decreased from 8.1~8.2 to 6.6~7.0 after remediation. Due to the microbial activities the surface tension of soil had decreased from 72.2 mN/m to 64.9 mN/m in BS+BA treatment and from 71.8 mN/m to 67.2 mN/m in BS treatment, respectively. Thus the bioavailability of petroleum hydrocarbons may be enhanced. The higher removal efficiency was obtained in BS+BA treatment in which 50.8 % of TPH and 69.2 % of total PAHs were degraded, whereas in BS treatment only 40.5% of petroleum hydrocarbon and 61.2% of total PAHs were degraded. Particularly, exotic microorganism showed high efficiency on removal of 5~6 ring PAHs. Different remediation strategies affected soil microbial activity notably, indicated by the dynamic changes of soil enzyme activity and bacterial community structure.