Department of Environment, College of Environment, Karaj, Iran; Faculty of New Technologies Engineering, Zirab Campus, Shahid Beheshti University, Tehran, Iran.
Faculty of New Technologies Engineering, Zirab Campus, Shahid Beheshti University, Tehran, Iran.
Ecotoxicol Environ Saf. 2020 Dec 1;205:111103. doi: 10.1016/j.ecoenv.2020.111103. Epub 2020 Aug 17.
Oil pollution is a serious international concern due to its harmful effect on human health and the environment. This study aims to investigate the effective factors on the biodegradation of Iranian heavy crude oil by Bacillus licheniformis. For this purpose, oil removal from the artificial seawater was studied by response surface methodology (RSM). After the screening experiments, pH (4-10), NaCl concentration (0-10 g/L), and oil concentration (500-4500 ppm) were selected as influential factors. Moreover, to evaluate the bacterial capability in bioremediation of an actual polluted site, crude oil spill with a salinity of 35 g/L was experimentally simulated. The proposed model in this study clearly shows that both selected individual factors and their interactions are significantly effective on the crude oil biodegradation capacity. The results showed that Bacillus licheniformis was able to degrade crude oil at different concentrations of oil, especially at low concentrations, which are challenging in actual polluted sites. 15%-66% removal was achieved for 500-4500 ppm of crude oil after 14 days. Furthermore, according to the obtained results, this bacterium can tolerate the salinity up to 3.5%. At this salinity level, crude oil removal was 23.43 and 25.64% in neutral and alkaline conditions, respectively. Process factors were optimized, and 54.8% of crude oil was removed at optimum conditions i.e., 3500 ppm crude oil concentration, 2.5 g/L of NaCl and pH equal to 8.5. Finally, it can be concluded that the selected bacterium of this study can be more effective in harsh environments such as hypersaline and alkaline conditions.
石油污染是一个严重的国际问题，因为它对人类健康和环境都有有害影响。本研究旨在探讨地衣芽孢杆菌对伊朗重质原油生物降解的影响因素。为此，采用响应面法（RSM）研究了从人工海水中去除石油。在进行筛选实验后，选择 pH 值（4-10）、NaCl 浓度（0-10 g/L）和油浓度（500-4500 ppm）作为影响因素。此外，为了评估细菌在实际污染场地生物修复中的能力，实验模拟了盐度为 35 g/L 的原油泄漏。本研究提出的模型清楚地表明，所选的单个因素及其相互作用对原油生物降解能力有显著影响。结果表明，地衣芽孢杆菌能够在不同浓度的油中降解原油，特别是在低浓度下，这在实际污染场地中具有挑战性。在 14 天内，500-4500 ppm 的原油去除率达到 15%-66%。此外，根据获得的结果，该细菌可以耐受高达 3.5%的盐度。在该盐度水平下，中性和碱性条件下的原油去除率分别为 23.43%和 25.64%。优化了工艺参数，在最佳条件下（即 3500 ppm 原油浓度、2.5 g/L NaCl 和 pH 值为 8.5），去除了 54.8%的原油。最后，可以得出结论，本研究选择的细菌在高盐度和碱性等恶劣环境下可能更有效。
