Bioremediation strategies for petroleum removal and bacterial communities in loess under 10°c

Selecting a remediation technology is an emergency task for drought and infertile loess with serious dispersal of petroleum pollution in the region of Yanchang Oilfield, Yan'an, China. Batch experiments were performed to study natural attenuation (NA), bioaugmentation (BA), and biostimulation combined with bioaugmentation (BSBA) effect on the degradation of petroleum hydrocarbons and indigenous microbial communities under low temperature (10°C). Results showed that compared to NA, BA with JY (mixed strains cultured in laboratory) inoculation led to symplastic growth of specific low temperature tolerant oil degraders Variovorax, Methanobrevibacter, and Comamonas and thus a higher degradation efficiency of aromatics (62.34%) and polar components (63.64%). BSBA showed negligible community shift since the indigenous microbe competing ability was enhanced by NH₄Cl addition, which contributes to an adding effect of JY and indigenous petroleum degraders for best performance in total petroleum hydrocarbon (34.76%), saturate (27.62%), and aromatic (70.13%) removal. BSBA had the best removal efficiency and BA was more suitable for purpose of some special fraction removal.