Background: As a kind of hydrocarbon mixtures, diesel oil is mainly consisted of linear
chain alkanes as a medium distillate of petroleum. The removal of diesel oil depends on several technologies
not merely chemical or physical, but also biological methods, especially biodegradation.
Method: Five microorganisms considered as the potential diesel oil-degrading bacteria were chosen
for biodegradation experiment. Among these five microorganisms, D2 and D4 showed better removal
efficiency of diesel oil with removal rate reached to 75.16% and 69.09%, respectively.
Result: According to the test of 16S rDNA sequence, strain D2 and D4 were identified as Bacillus
subtilis strain ATCC 13952 and Bacillus cereus AH676, respectively. After optimizing biodegradation
condition of D2&D4 mixed strains by using response surface methodology (RSM), the removal
efficiency was promoted to 83.06%, with the optimal condition calculated as rotate speed 124
rpm, pH 7.1, temperature 37.0℃, and inoculum size 5.1% (v/v). Furthermore, immobilization technique
was applied for improving the removal efficiency sequentially.
Conclusion: Compared with free strains, the immobilized D2&D4 mixed strains, embedded by the
mixture of 4% (w/v) sodium alginate and 4% (w/v) polyvinyl alcohol (PVA), obtained a higher removal
rate reached to 95.95% with no breakage and well permeability.