Practical Considerations and Challenges Involved in Surfactant Enhanced Bioremediation of Oil

Abstract

Surfactant enhanced bioremediation (SEB) of oil is an approach adopted to overcome the bioavailability constraints encountered in biotransformation of nonaqueous phase liquid (NAPL) pollutants. Fuel oils contain n-alkanes and other aliphatic hydrocarbons, monoaromatics, and polynuclear aromatic hydrocarbons (PAHs). Although hydrocarbon degrading cultures are abundant in nature, complete biodegradation of oil is rarely achieved even under favorable environmental conditions due to the structural complexity of oil and culture specificities. Moreover, the interaction among cultures in a consortium, substrate interaction effects during the degradation and ability of specific cultures to alter the bioavailability of oil invariably affect the process. Although SEB has the potential to increase the degradation rate of oil and its constituents, there are numerous challenges in the successful application of this technology. Success is dependent on the choice of appropriate surfactant type and dose since the surfactant-hydrocarbon-microorganism interaction may be unique to each scenario. Surfactants not only enhance the uptake of constituents through micellar solubilization and emulsification but can also alter microbial cell surface characteristics. Moreover, hydrocarbons partitioned in micelles may not be readily bioavailable depending on the microorganism-surfactant interactions. Surfactant toxicity and inherent biodegradability of surfactants may pose additional challenges as discussed in this review.

Potential microbial drivers of biodegradation of polycyclic aromatic hydrocarbons in crude oil sludge using a composting technique

“…78 The surfactants (anionic and nonionic) involved in this study could not perhaps perform their vital role in bioremediation, which is reducing the binding capacity of PAHs by enhancing the mass transfer of PAHs from a solid/nonaqueous liquid phase to aqueous phase in order to improve bioavailability. 26…”

“…Furthermore, the ability of microbial isolates to produce suitable enzymes for the metabolism of HMW PAHs could be hindered by low bioavailability of PAHs . Bioavailability of HMW PAHs could be improved by the addition of surfactants impacting positively on biodegradation of hydrocarbons …”

“…Surfactants possess a hydrophilic head and a hydrophobic tail which often is a hydrocarbon chain . These surface‐active agents are classified as anionic, nonionic, cationic or zwitterionic surfactants based on the ionic charge of the hydrophilic head of the molecule . Addition of surfactants is believed to enhance solubilization and dissolution of hydrocarbons resulting in improved bioremediation process, by changing the binding effects of PAHs thereby increasing mass transfer of hydrocarbons into the aqueous phase .…”

“…24 Bioavailability of HMW PAHs could be improved by the addition of surfactants impacting positively on biodegradation of hydrocarbons. [25][26][27][28] Surfactants are amphiphilic surface-active agents that reduce the surface and interfacial tensions of the medium in which they are dissolved. Surfactants possess a hydrophilic head and a hydrophobic tail which often is a hydrocarbon chain.…”

Alkyl polyglucosides as cell surface modification factors: influence of the alkyl chain length

“…The addition of surfactants allows to increase biodegradation rate of persistent pollutants (Mohanty, Jasmine and Mukherji 2013). In this case, interactions between surfactant and cell surface play an key role (Ortega-Calvo et al 2013;Zhang and Zhu 2012).…”