High biodesulfurization efficiency of oil by aerobic (Burkholderia sp. and Serratia sp.) and anaerobic bacteria using various additives

Eleven oil-polluted environmental samples were collected from different contaminated sites in Cyprus. The solid and liquid samples were enriched after exposure to dibenzothiophene (DBT) or 2-hydroxybiphenyl (2-HBP) as the sole sulfur and carbon sources. The aerobic bacteria were isolated and tested for their ability to biodesulfurize (BDS) oil. After the growth of isolates and DNA extraction (PCR amplification), the results revealed two prominent bacteria, Serratia sp. and Burkholderia sp., which were able to decrease DBT concentrations by up to 90%. Furthermore, it was identified that adding zeolite as a carrier in the respective solution increased the removal efficiency of DBT; Burkholderia sp. was the most dominant species and suppressed Stenotrophomonas sp. Then, the selected bacteria were tested in real oil samples (heating oil) and managed to remove 70-80% of the sulfur content. Anaerobic BDS using various anaerobic inocula was also tested as a proof of concept. Specifically, anaerobic inocula from digester sludge, drill cuttings, and secondary sludge showed around 60% DBT removal after ten days. Anaerolineaceae, Clostridium sensu stricto 12, and Rummeliibacillus were identified in those inocula in relatively high abundance. The addition of ZVI to anaerobic inocula resulted in a further increase in DBT removal.