Anoxic biodegradation of petroleum hydrocarbons in saline media using denitrifier biogranules

• TPH-biodegrading mesophilic denitrifiers were biogranulated in saline media.
• The biogranules composed of clustered Bacillus spp. bacteria was developed.
• Over 99% of 4 g/L TPH was biodegraded in saline media by anoxic biogranules.
• A maximum TPH biodegradation as high as 2.6gTPH/gbiomass.dgTPH/gbiomass.d was obtained.
• TPH biodegradation by anoxic biogranules was much faster than by other bioreactors.

The total petroleum hydrocarbons (TPH) biodegradation was examined using biogranules at different initial TPH concentration and contact time under anoxic condition in saline media. The circular compact biogranules having the average diameter between 2 and 3 mm were composed of a dense population of Bacillus spp. capable of biodegrading TPH under anoxic condition in saline media were formed in first step of the study. The biogranules could biodegrade over 99% of the TPH at initial concentration up to 2 g/L at the contact time of 22 h under anoxic condition in saline media. The maximum TPH biodegradation rate of 2.6 gTPH/gbiomass.dgTPH/gbiomass.d could be obtained at initial TPH concentration of 10 g/L. Accordingly, the anoxic biogranulation is a possible and promising technique for high-rate biodegradation of petroleum hydrocarbons in saline media.