Biodesalination and biodegradation of crude oil in aqueous solutions by Halobacillus halophilus

Abstract

Today, freshwater scarcity is one of the serious problems of human societies. Given the abundant reserves of saline water across the world, seawater desalination is one of the promising ways to supply freshwater. Another problem is the oil pollution of seawater caused by the extraction of petroleum from the seabed. Bacteria can be employed to desalinate seawater and to clean oil pollution. In this context, the effect of Halobacillus halophilus was assessed on the desalination and degradation of crude oil in aqueous solutions. The results indicated that maximum growth rate occurred within 6 d after culturing where the optimum temperature and pH for maximum growth of Halobacillus halophilus were 25°C and pH = 7.5. Under optimum temperature and pH, Halobacillus halophilus could desalinate seawater with 3%–15% of NaCl and degrade 1%–7.5% crude oil. A high absorption rate was observed in 5% NaCl (48% ± 2.3) and 5% crude oil (36 ± 1.2). In the final step, the simultaneous absorption of NaCl and oil degradation was measured. The total NaCl and crude oil removal rate were similar to the case where the bacterium performed each of these processes separately (NaCl: 42 ± 12.6, Oil degradation rate: 35.4 ± 3.5). Thus, the bacteria could desalinate water and remove oil pollution both separately and simultaneously.