Response surface analysis and modeling of n-alkanes removal through bioremediation of weathered crude oil

Abstract

Central composite design (CCD) and response surface methodology (RSM) were employed to optimize four important variables, i.e. amounts of oil, bacterial inoculum, nitrogen and phosphorus, for the removal of selected n-alkanes during bioremediation of weathered crude oil in coastal sediments using laboratory bioreactors over a 60 day experimentation period. The reactors contained 1 kg soil with different oil, microorganisms and nutrients concentrations. The F Value of 26.89 and the probability value (P < 0.0001) demonstrated significance of the regression model. For crude oil concentration of 2, 16 and 30 g per kg sediments and under optimized conditions, n-alkanes removal was 97.38, 93.14 and 90.21% respectively. Natural attenuation removed 30.07, 25.92 and 23.09% n-alkanes from 2, 16 and 30 g oil/kg sediments respectively. Excessive nutrients addition was found to inhibit bioremediation.

Biodegration of Tapis Crude Oil Using Consortium of Bacteria and Fungi: Optimization of Crude Oil Concentration and Duration of Incubation by Response Surface Methodology

“…According to Changyi et al (2009), when crude oil in the environment reached a definite concentration it would have toxic effect on microorganisms, because the strain could not tolerate the high concentration of crude oil, which would inhibit the normal microbial growth to dramatically reduce the hydrocarbon degradation rate. The inhibitory concentration varies with oil composition (Mohajeri et al 2011). Alkanes of intermediates chain length (C 10 -C 24 ) are often degraded immediately, while long chain alkanes are resistant to microbial degradation (Ijaha & Antaib 2003).…”

“…Study by Mohajeri et al (2011) using central composite design and RSM to optimize four variables which include amount of oil, bacterial inoculum, nitrogen and phosphorus for the removal of n-alkanes of weathered crude oil in coastal sediments showed an increase in oil concentration will decrease n-alkanes removal. The maximum n-alkanes removal was achieved at 4.8 × 10 6 cells of bacterial consortium.…”

Bioremediation of Total Petroleum Hydrocarbons (TPH) by Bioaugmentation and Biostimulation in Water with Floating Oil Spill Containment Booms as Bioreactor Basin

“…Some researchers have used other methods by applying N:P:K nutrient ratios [18,19], food wastes [20]. Some researchers have applied it in the field [12,15,18,19,[21][22][23][24]. A comprehensive and practical collection of guidelines for the application of this technology to seawater oil spill responders is urgently required to address questions such as when to use bioremediation, what bioremediation agents should be used, how to apply them, and how to track and evaluate the outcomes [25].…”

“…A comprehensive and practical collection of guidelines for the application of this technology to seawater oil spill responders is urgently required to address questions such as when to use bioremediation, what bioremediation agents should be used, how to apply them, and how to track and evaluate the outcomes [25]. The application of micro-organisms for the bioremediation of petroleum hydrocarbon pollutants in this day and age is a priority in the effort to establish green technology [22][23][24][25][26]. The lack of guidelines as to how and when to use this technology is now one of the biggest obstacles for the implementation of oil bioremediation in marine water.…”

Application of reduced graphene oxide/ natural rubber composite for petroleum removal in sea water

“…Biostimulaion is the addition of nutrients or other co-substrates for stimulation native organisms to degrade petroleum pollutants. While bioaugmentation enhances oil degradation by the addition of oil-degrading organisms to supplement the existing microbial populations (Al-Majed et al, 2012;Mohajeri, Aziz, Zahed, & Isa, 2008;Tewari & Sirvaiya, 2015). Bioremediation was shown to be effective in highly porous shorelines where nutrients and oxygenated seawater could reach the surface and sub-surface oil residue (Al-Majed et al, 2012;Ivshina et al, 2015).…”