Using microalgae for remediation of crude petroleum oil–water emulsions

Abstract

Crude petroleum oil spills are among the most important organic contaminations.While the separated oils accumulated on the surface water are relatively easily removed, the emulsified portions are more difficult to remove and pose significant threats to the environment. Bioremediation using bacteria has proven to be an effective method, but the biomass produced in this case does not have any significant remunerative value. In this work, microalgae were proposed to combine emulsified oil remediation process with the potential of microalgae as a biofuel feedstock, thus enhancing the economic and environmental benefits of the process. A freshwater strain of Chlorella vulgaris was grown in water containing different concentrations of emulsified crude oil at different temperatures. The specific growth rate (μ max ) of the microalgae for each initial oil concentration was determined and was found to increase with the increase in initial oil concentration. For example, at 30 C, the specific growth rate, μ increased from 0.477 to 0.784 per day as the oil concentration increased from 57 to 222 mg/L. At 30 C, the effect of substrate concentration agreed with that of the microalgae growth, whereas at 40 C, the drop in oil concentration decreased with the increase in concentration. The results were fitted to a modified Monod kinetics model that used specific interfacial area as the influential substrate instead of the actual concentration. The results of this study clearly show the potential of using microalgae for emulsified oil remediation at relatively high concentrations.

Bioremediation of Crude Oil by Haematococcus Pluvialis: A Preliminary Study

“…It has been reported that some species can significantly reduce aliphatic compounds, such as 3-methyl decane, heptadecane, and octadecane [16], and that the ability of Chlorella spp. to reduce emulsified oil reached 80 % [17]. Further studies have shown that Chlorella spp.…”

Bioremediation: Review on oil spill management using oil eating microorganisms, and spill effects on marine and terrestrial environment

“…Chlorella vulgaris was tested in a study and was grown at altered temperature and in different concentration of emulsified oil. Results shows an increase in specific growth rate and decrease in drop oil concentration (Kuttiyathil et al 2021).…”

Crude Oil Bioremediation: From Bacteria to Microalgae

“…but also how, in nature, the mechanical action of sea waves contributes to creating an emulsion of water and crude oil that could favour the removal of pollutants making them more available. Their results show that following an initial period of adaptation, the Total Organic Carbon (TOC) of the solution was drastically reduced and that, after 5 days, Chlorella removed 80% of the emulsified oil [35]. Water mixing and how it can alter bioremediation was also studied in 2014 by Özhan et al, which demonstrated how the bioavailability of crude oil is altered by physical mixing applied in the laboratory.…”

“…The hormesis hypothesis claims that an organism responds to small doses of stress adaptively to survive [50]. However, some studies show that the ability of microalgae to remove contaminants continues even after the cell is dead as the microalgae can adsorb micro-drops of crude oil on their surface and, consequently, TOC, removing it from the solution as demonstrated by Kuttiyathil et al [35].…”