What is the difference between dispersants and bioremediation agents

In addition, the 3C-9 biosurfactant significantly enhanced the solubility of PAH substrates Peng et al. Halomonas is a ubiquitous genus of the order Altreromonadales. There organisms are found in diverse habitats of both marine Hassanshahian et al. Members of Halomonas are known to respond to hydrocarbon enrichment Calvo et al. A thermophilic H. The monosaccharide composition of the WB1's EPS was predominantly composed of glucose, mannose and galactose, and traces of uronic acids Chikkanna et al.

In addition to emulsifying activity, several species of halophilic Halomonas have been shown to produce highly sulphated exopolysaccharides Calvo et al. For example, halophilic H. EPS form H.

Alcanirorax is gram-negative genus of the Gammaproteobacteria order Oceanospirillales of strictly aerobic marine obligate hydrocarbonoclasic bacteria OHCB utilizing predominantly alkanes up to C 32 and branched aliphatics Head et al.

The best known species of the genera is Alcanivorax borkumensis which produces a low molecular weight anionic glycolipid biosurfactant when grown on hydrocarbons Schneiker et al. This particular glycolipid consists a glucose sugar linked to a tetrameric chain of fatty acids of C 6 -C 10 length and can be either cell-bound or extracellular Abraham et al.

Marine isolate A. However, the purification of the biosurfactant was easier when the culture was fed with heavy oil fraction as it remained on the surface at all times and consequently there were no substrate impurities Antoniou et al. Another species, A. These characteristics make the B-5 lipopeptide an attractive alternative for enhanced oil recovery and bioremediation applications. Pseudoalteromonas sp. The ecological role of the EPS was determined to improve the high-salinity and low-temperature tolerance of the strain Liu et al.

The carbohydrate content of EPS from P. The main biological activity of this strain was moisture retention and absorption of free radicals i. Marinobacter is a genus within the order Alteromonadales. Members of the genus, such as M. Although Marinobacter can use hydrocarbons as carbon source, various studies demonstrated that it can also grow and produce EPS on other carbon sources such as glucose.

Marinobacter species have been shown to produce exopolysaccharide polymers with excellent emulsifying activity against hydrocarbons that were superior to commercial synthetic surfactants like Tween 80 Caruso et al.

Marinobacter sp. W from Antarctic surface seawater produced EPS molecular weight of kDa with varying yields, strongly depending on the sugar substrate used to grow the strain and the incubation temperature. In addition, Marinobacter sp. Biosurfactant-producing bacteria can be found in a wide range of habitats, from aquatic fresh and sea water, and groundwater to terrestrial soil, sediment, and sludge environments.

Nicolaus et al. The environment can have a direct influence on the type of biosurfactants that microorganisms produce. With respect to cold-adapted bacteria, the monosaccharides in the EPS are usually characterized by the presence of mannose and galactosamine Nichols et al. Examples of extreme environments from which biosurfactant-producing microbes have been isolated and cultured under laboratory conditions include oil reservoirs Arora et al.

Moreover, the most obvious place to search for marine biosurfactant-producing microorganisms is in hydrocarbon-polluted areas since biosurfactants play an important part in the process of microbial biodegradation of hydrocarbons Chandankere et al.

Most biosurfactant-producing microorganisms can survive and even thrive in a wide range of temperatures, pH and salinity and therefore exhibit a wide range of metabolic processes. The majority of isolated and cultured microorganisms are aerobic because they are relatively easy to be sampled and handled in laboratory conditions.

However, the number of biosurfactant-producing microorganisms, largely comprising anaerobes, that are being discovered and successfully cultured in ex-situ conditions is steadily growing VanFossen et al. Anaerobic microorganisms are also able to produce biosurfactants and have typically been found in oil reservoirs where anaerobic hydrocarbon biodegradation processes occur through methanogenesis Head et al.

Biosurfactants are becoming important biotechnology products for many industrial applications including in food, cosmetics and cleaning products, pharmaceuticals and medicine, and oil and gas. The global market revenues generated by biosurfactants exceeded USD 1. Household detergents are the largest application market, followed by cosmetics and personal care, and the food industry Singh et al. Europe has over half of the market share followed by the United States and Asia Singh et al.

The increasing global interest in biosurfactants is due to their low toxicity, biodegradability, low environmental footprint and impact Desai and Banat, Adapted from Randhawa and Rahman Hydrocarbon soil contamination, such as from drilling, leaking pipelines, storage tanks, transportation etc. Being highly hydrophobic, particularly when adsorbed onto soil particles, hydrocarbons, and heavy metals are very resistant to removal.

Typically, a variety of physical and chemical treatments, such as removal, incineration, soil washing, and solvent extraction have been used successfully in the past. However, such techniques are deeply damaging to the soil structure and the autochthonous biodiversity, as well as cost-prohibitive.

As such, bioremediation is the preferred soil treatment due to its efficiency, lower environmental impact, and cost-effectiveness. Bioremediation involves naturally occurring soil microorganisms which convert petroleum hydrocarbons into carbon dioxide, water, and cell biomass.

There are many factors that influence the rate and extent of hydrocarbon degradation in soils, such as moisture content, aeration, pH, temperature, the biological condition of the soil aged vs. The optimisation of these environmental factors is critical for the bioremediation success. Soil bioremediation can be conducted either in place i.

In-situ bioremediation involves, generally, the treating of only the top cm layer of the soil with fertilizers to stimulate indigenous soil microorganisms to break down the hydrocarbons Atlas and Hazen, This treatment is the preferred method of choice, but the risk of contaminating underlying aquifers with dissolved hydrocarbons must be considered.

Partially purified biosurfactants have been used in-situ to increase the solubility and bioavailability of hydrocarbons, and other hydrophobic contaminants, by increasing their surface area Ron and Rosenberg, ; Bustamante et al. However, the majority of bioremediation studies with biosurfactants are under laboratory conditions. A study from Argentina demonstrated that surfactin from B. The addition of rhamnolipid from P.

The effect was enhanced by adding nutrients to the treatments Cameotra and Singh, The authors compared different bioremediation techniques i. H and with MELs caused the highest total petroleum hydrocarbon degradation rate during the first 4 weeks of treatment. However, at the end of the experiment days the amount of residual hydrocarbons was similar for all treatments Baek et al. The idea behind MEOR is that when favorable conditions are present in the reservoir, the introduced microbes grow exponentially and their metabolic products would mobilize the residual oil Gao and Zekri, MEOR bares with it its advantages and limitations, and the various processes of its application have been described extensively in the literature and recently summarized by Nikolova and Gutierrez MEOR is based on two fundamental principles.

Firstly, oil movement through porous media rock formation is facilitated by altering the interfacial properties of the oil-water-minerals displacement efficiency i. The second principle constitutes the degradation but also the removal of sulfur and heavy metals from heavy oils, by microbial activity Shibulal et al. In the majority of MEOR field trials, injection of indigenous or other MEOR suitable pre-cultured bacteria or a consortium of bacteria along with nutrients e.

However, biosurfactants produced ex-situ can also be used to enhance the microbial growth in oil reservoirs. In addition, when poor oil recovery from an oil well is due to low permeability of the rock formation, or to the high viscosity of the crude oil, the ability of biosurfactants to reduce IFT between the flowing aqueous phase and the residual oil saturation can improve the recovery process Brown, Reduction of IFT by biosurfactants can also reduce the capillary forces that prevent the oil from moving through rock pores, however, the decrease in IFT must be at least two orders of magnitude to achieve mobilization of the oil.

To our knowledge such values have not yet been reported for known biosurfactants, and hence the effectiveness of IFT reduction may be limited in practice. Moreover, considering the type of oil reservoir sandstone, carbonates etc. In addition to reduction of IFT, biosurfactants can alter the wettability of rock formations, emulsify the crude oil, and contribute to the microbial metabolism of viscous oil Sen, Nevertheless, there are some promising results reported from different research groups that investigate biosurfactants for MEOR applications.

Of all known biosurfactants, lipopeptides were mostly used in laboratory-based MEOR studies due to their ability to reduce the IFT to below 0. Both bench-scale and in-situ lipopeptide production by stains of Bacillus spp. Surfactins have been shown to maintain activities under a wide range of temperature, pH, and salinity while able to recover sand trapped oil.

For example, B. Surfactin was recently shown to alter the wettability of CO 2 injected in a subsurface rock formation demonstrating its potential suitability in carbon capture and storage application Park et al. Addition of biosurfactants during chemical surfactant flooding can improve the flooding performance in general.

It has been suggested that rhamnolipids act as sacrificial agents by preferably adsorbing to the oil sands, making the surfactant more available for displacement activity and resulting in altering the wettability of porous media Perfumo et al. Recently, another biopolymer produced by Rhizobium viscosum CECT showed better efficiency than xanthan gum in the recovery of heavy oil Couto et al. Crude oil is highly hydrophobic and it is composed of thousands of hydrocarbon and non-hydrocarbon species and metals, each with their respective aqueous solubilities.

When an oil is introduced into a water phase, it will float on the surface of the water phase due to its lower density relative to water. Together with viscosity, surface tension is an indication of how rapidly and to what extent an oil spreads over the surface and, when dispersed, within the subsurface.

The lower the interfacial tension with water, the greater is the extend of spreading Fingas, To increase the solubility of oil in water i. The natural fate of crude oil biodegradation biological oxidation by microorganisms in the marine environment has been extensively described Atlas and Hazen, ; Kostka et al.

The limitation of marine oil remediation when relying solely on indigenous microorganisms is that the concentrations of cells in oil-polluted open water systems is never high enough to effectively emulsify oil Ron and Rosenberg, Biosurfactants, have been shown to be effective in dispersing crude oil and enhancing the biodegradation process only under laboratory conditions due to logistical, financial and regulatory limitations of conducting large-scale field trials.

However, the overall removal efficiency of n -alkanes by the bacterial consortium and rhamnolipid was higher than the control. Similar trend was observed for PAH and biomarkers Chen et al. These results were more or less consistent with another study which also used rhamnolipids in combination with a pre-adapted bacterial consortium Nikolopoulou et al. The average specific degradation rate was reported to be 23, 20, and 10 times higher than the control for n C 15 , n C 20 , and n C 25 , respectively.

In addition, LMW PAHs and, notably, the biomarkers pristane and phytane were also significantly degraded in the presence of rhamnolipid Nikolopoulou et al. The origin of nutrients i. Bioemulsifiers can also be used in oil spill response with promising results. A bioemulsifier exopolysaccharide produced by Acinetobacter calcoaceticus , called EPS , was shown to be effective in enhancing crude oil biodegradation in natural seawater microcosms Cappello et al.

The addition of EPS to the microcosms not only enhanced hydrocarbon-degrading bacteria, including Alcanivorax, Marinobacter, Oceanospirillum , and Pseudomonas , but also caused a 2-fold faster biodegradation of the total oil compared to microcosms without the EPS Cappello et al.

All of these studies, however, focused entirely on the degradation rate of crude oil on a handful of selected oil-degrading bacteria without investigating the indigenous marine microbial community response as a whole. However, due to varying reasons, including current high costs of biosurfactants available on the market and logistics around field studies, there is a marked lack of reported studies investigating the effectiveness of biosurfactants as oil spill treating agents.

We are aware of only one study that compared a synthetic chemical dispersant and a biosurfactant. In that case, a surfactin produced by Bacillus sp. Surfactin enriched for hydrocarbonoclastic bacteria more so than the synthetic dispersant, but no difference in oil biodegradation between the two was observed.

In more recent work, rhamnolipid from P. The rhamnolipid promoted higher diversity in oil-degrading bacteria than the synthetic dispersant, however, the crude oil was ultimately more biodegraded when synthetic dispersant was added to the oil, with the exception of the aromatic fraction of the oil.

Notably, the synthetic dispersant resulted in a clear inhibition of Cycloclasticus —a genus comprising species of obligate oil-degrading bacteria which are recognized for using aromatic hydrocarbons as a preferred source of carbon and energy Head et al.

Although biosurfactants may have a positive effect on the oil-degrading microbial community, it is necessary to advance their performance in dispersing crude oil. Developing novel types of biogenic surface-active compounds and more environmentally friendly technologies to combat large offshore oil spills is fertile ground for ongoing and future exploration.

In this respect, research and development of biosurfactants for treating oil spills at sea has significantly intensified, particularly over the past 10 years due mainly to concerns over the enormous quantities of the synthetic chemical dispersant Corexit that were used during the Deepwater Horizon oil spill in the Gulf of Mexico.

Growing awareness among society regarding the environmental hazards associated with the use of chemical dispersants has led to increased interest toward the use of naturally-derived, biological dispersing products i. Over the past decades, numerous marine microorganisms, especially bacteria, have been identified that are able to degrade hydrocarbons by producing effective biosurfactants Al-Wahaibi et al.

However, the current knowledge on microbial biosurfactants has been limited to only a few compounds produced by a small number of bacteria and yeast species, such as Pseudomonas, Bacillus, Candida , and Acinetobacter Ruggeri et al. These organisms, and their produced biosurfactants, have potential promise for application in offshore oil spill response, enhanced oil recovery, and soil washing treatment of petroleum-contaminated sites Banat et al.

A highly promising source for discovering novel biosurfactant-producing microorganisms is the marine environment as it harbors an extensive and largely untapped microbial biodiversity, which has shown itself as a proven repository of powerful molecules currently used for pharmacological, food, and cosmetics applications Kennedy et al. The development of a new generation of dispersants that are as, or more, effective than commercial synthetic dispersants, cost efficient, and have minimal side effects when they come in contact with, or are ingested by, marine organisms and humans is a path that has gained traction since the Deepwater Horizon disaster.

Whilst some of these C-MEDS projects utilize non-biomaterials, below we summarize some that use materials from biological sources so in keeping with the context of this review. In particular EPS with a higher protein-to-polysaccharide ratio resulted in higher enzymatic action and marine-oil-snow sedimentation efficiency, higher microbial diversity and cell abundance, and in more extensive biodegradation compared to oil treatments with Corexit, although the latter maintained a more stable emulsion of the oil droplets.

In the absence of Corexit, however, protein-rich EPS is formed, and which is significantly more efficient in purging the water column from the oil. Following this, the researchers are exploring ways to trigger the production of protein-rich EPS by natural communities of microorganisms in seawater during the event of another large oil spill.

Scientists from the University of Maryland and Tulane University have investigated the use of food-grade emulsifiers as substitutes for synthetic chemical dispersants. By examining the stability of emulsions of crude oil in seawater when in the presence of various food-grade emulsifiers, they found that lecithin a cell membrane component from soybean in combination with Tween 80 emulsifier used in ice cream and other foods were found to effectively disperse and produce more stable emulsions of crude oil than Corexit Athas et al.

Using combinations of natural clay minerals and new carbon materials with synthetic polymer-based materials, new products are being evaluated to test for adhering strongly to the oil-water interface and stabilize oil droplets, which could prevent the formation of large slicks.

C-MEDS researchers from the University of South Florida published research showing cactus mucilage dispersed crude oil more efficiently than synthetic dispersants, and notably requiring lower concentrations Alcantar et al. In other work, biopolymers derived from cactus mucilage and chitosan show promise in synergistically working together with chemical dispersants, potentially helping to reduce the use of solvents that are typically intrinsic in synthetic chemical dispersant formulations.

Taking a different approach, C-MEDS researchers are also exploring new natural gelation agents in order to prevent oil slicks from spreading and, consequentially, reaching coastlines. Work led by Tulane University and collaborators used a gel-like matrix incorporated with Tween 80 and lecithin which resulted in improved stabilization of crude oil in seawater emulsions—more so over longer periods compared to traditional liquid dispersants Owoseni et al.

The gel-like formulation was designed to largely replace DOSS, the key surfactant component of synthetic chemical dispersants, with lecithin. The application of food-grade surfactants into a gel-like mesophase acts as a compact buoyant pod for improved delivery of the surfactants to sea surface oil slicks.

It does this by way of remaining afloat where the oil is largely confined and avoiding the use of polypropylene glycol and the generation of volatile solvents in the atmosphere through aerial or ship-based spraying. Researchers from the University of Texas at Austin investigated the potential use of nanoparticles as non-conventional dispersants and as tools to improve existing surfactant-based dispersants. Their work has led to the development of nanoparticles that are less toxic, more efficient oil spill treatments compared to synthetic chemical dispersants.

By mixing hydrophilic nanoparticles i. Caprylamidopropyl betaine CAPB is a surfactant that is formed using fatty acids from coconut or palm kernel oil and used in personal care products. The researchers recorded changes in the growth rate, lag time, and cell density of A. The food-grade surfactant, Tween 20, was found to work best by synergistically working with the organism, increased the surface area of oil droplets, and resulting in more bacterial growth and oil degradation.

Conversely, the other surfactants inhibited the adherence of the bacterial cells to oil, limiting its biodegradation capacity. In conclusion, the authors recommended further investigation into the use of different surfactants, in particular Tween 20, to replace the current stockpile of synthetic chemical dispersants to treat future oil spills.

In a similar study, researchers from the University of Houston compared the food-grade surfactant Tween 20 with several synthetic chemical dispersants to determine how they affect the adhesion of the hydrocarbon-degrading species Marinobacter hydrocarbonoclasticus to oil droplets 20—60 um , which is for some hydrocarbon-degrading bacteria an initial key step for biodegradation Dewangan and Conrad, They found that increasing concentrations of all surfactants tested resulted in reduced adhesion of the cells to oil droplets, though electrostatic charge associated with some of the surfactants tested appeared to influence adhesion.

Their results suggest that the choice of surfactant s in dispersant formulations should be accounted for with respect to how it affects bacterial adhesion to oil droplets and, hence, the biodegradation process. In a study led by Tulane University in collaboration with Lappeenranta University of Technology, Finland, the stability of carboxymethylated chitosan nanoparticles cross-linked with either magnesium, calcium or strontium ions were studied under different pH and salinity in an effort to determine which could be used in oil spill treatment Kalliola et al.

The nanoparticles cross-linked with calcium ions, as well as when cross-linked with dodecane, were found to be most stable, showing potential for oil-spill treatment. In one other study, scientists from different institutions in Canada conducted work on the design of a lipopeptide biosurfactant produced by Bacillus subtilis NP from fish waste-based peptone as a primary nutrient substrate for this bacterium Zhu et al.

The produced lipopeptide was evaluated as an ingredient together with DOSS, which is the key surfactant ingredient found in Corexit With respect to the Oil and Gas industry, the application of biosurfactants for MEOR and in dispersant formulations to treat oil spills are areas of significant interest, but not yet applied on an industrial scale.

This circumstance was taken into consideration and to avoid anaerobic conditions, contaminated sediments were placed in contact with permanently circulating seawater. Qualitative analyses of the various HC showed a significant degree of oil disappearance from sediments. Actygea and Madep partners worked together in order to achieve economically feasible bioaugmentation product based on Rhodococcus erythropolis HFO-S2B.

These partners paid particular attention to following aspects: i high producer variants in the population; ii short fermentation downtime; iii use of low cost materials as ingredients for the fermentation medium. Growth of R. Emulsifying products excreted by this microorganism was indirectly determined using the Emulsification Index on crude oil or on hexadecane.

For bioaugmentation purposes, R. Strain maintenance was performed through subsequent cycles of in-plate isolation of colonies with the typical morphology, replicated on slants or plates of TSA medium and tested in-flask for optimal emulsifying activity. Slants or plates with the highest emulsifying activity were used for the production of second-generation slants or plates. The colonies displaying expected morphology of R.

Plating of serial dilutions of this starting material was performed and selected colony re-suspended to re-inoculate slants of TSA medium 1st generation slants. When 1st generation slants or plates had the expected morphology, each selected colony was collected from slants to prepare glycerol stocks.

The strain was cultivated on an Actygea proprietary medium. Starter culture was carried out in three-litre bioreactors prior to a production stage performed in liter bioreactors. The strain was grown in aerobic, submerged, batch fermentation mode. Biosurfactants production was used as the indicator of the potential of the strain to degrade crude oil and was monitored using the emulsification test. Fermentation was stopped when the maximum emulsifying activity was observed about hours.

The biomass was harvested and stored. Three bioelectrochemical systems aiming to facilitate biodegradation of hydrocarbons in anoxic sediments and one capping technology based on the use of a cheap and renewable material for oil pollution containment were developed within WP5. The system consists of a single conductive material i.

The segment of the electrode that is buried within the sediment plays a role of anode, accepting the electrons deriving from the anaerobic oxidation of contaminants and other reduced species. Electrons flow through the conductive material up to the part exposed to the aerobic environment i. Microcosms containing 1 or 3 graphite snorkels and controls snorkel-free and autoclaved were monitored for over days.

The results of confirmed that the snorkels accelerate oxidative reactions taking place within the sediment, as documented by a significant 1. Accordingly, the initial rate of total petroleum hydrocarbons TPH degradation was also enhanced. Further research efforts are needed to clarify factors and conditions affecting the snorkel-driven biodegradation processes and to identify suitable configurations for field applications. Lab-scale bioelectrochemical experiments were carried using toluene, as a model contaminant.

The objectives of this study were to i investigate the biodegradability of toluene in bioelectrochemical systems inoculated with marine contaminated sediment, ii evaluate the effect of anode potential on toluene biodegradation, iii identify the most abundant microbial populations involved in bioelectrochemical toluene degradation process, and iv investigate the role of the sulfur cycle on toluene biodegradation in bio-electrochemical systems.

The most abundant microorganisms enriched both in the anodic and in the bulk communities were sulphate-reducing bacteria, some of which were phylogenetically related to known anaerobic hydrocarbon degraders.

This study demonstrated that a potentiostatically-controlled bioanode could be implemented as an effective strategy to remove toluene from marine oil contaminated sediments. Interestingly, results strongly indicated that sulphur metabolism was involved in toluene bioelectrodegradation.

Preliminary microbial characterization of the bulk anolyte and anode samples by 16S rRNA-based Illumina sequencing conducted at the end of the experiments confirmed this assumption since sulphate reducing microorganisms were the prevailing bacterial population. Results of this analysis confirm and stress the role of sulphur metabolism in hydrocarbons degradation.

The experiments were setup in approximately 1 L wide-mouth jars. The jars were filled with approximately g on a dry weight basis of sandy marine sediments from Messina Harbour Italy and seawater approximately mL from the site. A DSA electrode 44 cm2 geometric area; Ti mesh covered with mixed metal oxides, primarily consisting of Ir and Ru was placed at the bottom of the jars buried within the sediment whereas a stainless steel type 40 mesh woven cathode 44 cm2 geometric area was placed in the overlaying seawater.

For field applications, anodes have to be deployed underneath the contaminated sediment layer. A precise estimation of the radius of influence of the technology will, however, require conducting experiments with larger scale systems.

Such an estimate will ultimately allow determining the geometric size of electrode required to treat e. Intermittent application of electrolysis proved to be an effective strategy to minimize the energy requirements of the process, without adversely affecting degradation performance.

These low energy requirements make the technology fully compatible with the use of solar panels photovoltaic modules as power supply systems. Taken as a whole, this study suggests that electrolysis-driven bioremediation could be a sustainable technology for the management of contaminated sediments. Active capping of oil-contaminated sediments with Biochar Partner UNIRM developed an in-situ pollution management solution using capping to confine hydrocarbon spreading in oil-contaminated sediment.

The material used for capping was biochar, a carbonaceous waste material usually obtained by the pyrolysis of biomass. First, the sorbent materials were initially tested in aqueous phase with several organic contaminants, such as toluene low hydrophobicity HC and a mixture of polycyclic aromatic hydrocarbons PAHs target compounds of the oil spill contamination in the sediment.

Batch tests were carried out to investigate adsorption kinetics and to obtain experimental isotherms for all the materials with all the contaminants. Kinetic tests have shown BC is the sorbent material that faster achieves the equilibrium. In addition, equilibrium tests adsorption isotherms were carried out using different contaminant concentrations.

From these experiments it can be concluded that the adsorption onto BC is comparable with the target materials, such as AC and OC.

Similar observations were made with more hydrophobic contaminants, such as the PAHs. Capping batch experiments have been started in box models using marine sediment from Messina Sicily contaminated with Dansk Blend crude oil and a mixture of PAHs in seawater.

The capping efficiency of a 2-cm layer of the material to be tested was experimentally monitored after 1, 2 and 6 months. The profiles through the sediment and the capping layer of the porewater concentration of the total PAHs acenaphtylene, fluorene, anthracene, fluoranthene and the comparison between AC, OC and BC, after 1 month monitoring could be achieved. The long-term modelling has shown capping performances of biochar after 12 month are still higher than AC and OC.

Four novel products were developed in the frame of this workpackage: two biostimulation systems for slow release of nitrogen and phosphorous combining either sorptive or bioaugmenting properties, one biostimulating and emulsifying formulation, and one sorbent boom with bioaugmenting, emulsifying and bioaugmenting capacities.

The limitation concerning the C:N:P availability for microbial oil degraders and the quick dilution of biostimulants in open sea environment can be circumvented with this product. Homemade and commercially available mesoporous silica particles were used as carrier material. The mesoporous structure allowed for the easy loading of the desired nitrogen and phosphorus nutrients into the pores.

Functionalization of the surface of the particles is carried out by grafting hydrophilic molecules at the surface of silica in order to procure hydrophobic properties to the particles and enable them to target specifically oil phase. This step is a 2-in-1 process where not only the particles are functionalised and becomes hydrophobic but also where "smart gates" are created. In fact, the pores are surrounded by alkyl chains that are collapsing, when transferred in a aqueous phase, creating a hydrophobic barrier maintaining the pores closed thus preventing the release of the nutrients and there rapid dilution in seawater.

The efficiency of N and P release was tested with a oil degrading model microorganism Marinobacter hydrocarbonoclasticus KS-ANU5 in artificial seawater contaminated with crude oil at a final concentration of 0. The performance of the SmartGate product was compared to a commercially available oleophilic fertilizer, namely S and controls abiotic and biotic containing basal concentration of N and P of seawater.

C12 to C15 were entirely degraded in S and SmartGate treatments. Interestingly, the addition of SmartGate compared to S treatment enabled a faster and complete degradation of long chain alkanes, i.

This fact might be attributed to the oleic acid contained in the formulation of S, which may slow down the degradation of C18 and longer chain hydrocarbons. Biotic controls demonstrated that basal concentration of N and P in seawater are not sufficient to support rapid and relevant biodegradation of oil components. In these systems inoculated with Marinobacter, benzene and naphthalene were markedly degraded when external source of N and P was added, the SmartGate giving better elimination. The efficiency of SmartGate particles was compared to the one of S in Aegean Sea in Keratsini Piraeus, Greece in pools formed by booms on the removal of heavy oil.

The product SmartGate gave satisfactory visual results removing heavy oil from the cleaning the surface of seawater. The oil removal performances of the SmartGate particles were at least as good as those obtained with S In addition to potential biodegradation impossible to demonstrate in open sea , two different dissipation phenomena occurred, i. Ecotoxicological tests with Vibrio fischeri have shown that the SmartGate product actually decreases the toxicity of heavy oil IFO to this microorganism and no ecotoxicity of the SmartGate product itself could be demonstrated using various organisms.

The SmartGate product is commercially available. Dry alginate beads DABs Another product was developed in order to intensify oil biodegradation by implementing a biostimulation and bioaugmentation approach. The primary goal was to develop a material that can slowly release bacteria that can degrade hydrocarbons HC together with nutrients to adjust C:N:P ratio and biosurfactants, which can increase the bioavailability of oil to the HC degraders. DABs microparticles performances in terms of oil biodegradation were tested in seawater contaminated with 0.

The release and viability M. Hydrocarbonoclasticus was studied in these lab-scale microcosms using flow cytometry. The toxicity of the whole preparation has not been tested yet. DABs are still far from commercialization but the technology can be easily scaled up industrially. To bring these tools closer to the markets, future efforts will be directed to find a large-scale industrial producer and distributor.

Procedures followed the EPA bioremediation agent effectiveness test protocol with weathered crude oil over a period of 28 or 56 days with sampling every week for microbiological as well as chemical analysis.

Source of phosphorus: inorganic nutrient - K2HPO4, Lecithin Bolec native lecithin, derived from crude soybean oil, is a mixture of phospholipids, glycolipids and carbohydrates dissolved in triglycerides, 1. The biostimulation-emulsification efficiency of the various formulations was evaluated by determining the Most Probable Number microbial count , GC-MS analyses of the HC, and calculating biodegradation kinetics.

Special emphasis was given on the development of sorbent booms characterized by very high adsorption capacity which enabled the concomitant degradation of adsorbed oil by petroleum-degrading microbial consortia loaded into the sorbent boom cylinder.

Efficient and non-toxic oil-absorbing external part of Bio-Boom: oil-absorbing, water-repelling, nonwoven fabric Oilguard produced by partner HeiQ. Bacterial and fungal petroleum-degraders immobilized either in chitosan beads see part above or in other carriers see dry alginate beads.

Optimized bio-surfactant characterizing by both high efficacy of emulsification and low toxicity. We offer two products: homogenized sophorolipids and homogenized rhamnolipids. Optimized slow-released nutrients see the benchmark products developed by FHNW. The sterile HeiQ OilGuard sorbent was used as the control. However, in 2 other bacteria which are related to Pseudomonas spp and Bacillus genus 7-P and 8-E , the highest growth rate is when Pars 1 and Pars 2 are the only sources of carbon in the environment.

In 7-P bacterium the highest growth rate was observed in the presence of Pars 1 dispersant after one week. Moreover, 5-C and 1-E showed the highest growth rate after four weeks in the presence of Pars 2 dispersant. These findings confirm that Pars 1 dispersant has more adaptability to both province ecosystems, and also they have more ability in biodegradation of crude oil compared with the other two dispersants.

There was no significant differences in the effect of microorganisms on each dispersant and also on their combination with crude oil after 28 days. However, since the entered material to the ecosystem needs to be degraded fast, Pars 1 dispersant which shows more degradability in the first 24 hours comparing other dispersants, is more adaptable to the environment. In Siri province, The growth diagrams of Pseudomonas spp.

The growth peak was seen on day 14 in the presence of combination of Pars 1 dispersant and crude oil. The growth curve of Aureobasidium spp. However, the microorganisms had also enhanced growth in the presence of Pars 1 dispersant. The optical density of microorganism cultures containing dispersants is indicating the usage of these components as the sole carbon source which leads to microorganism growth and catabolism of the carbohydrate [ 11 , 25 ].

Therefore, the result of the OD reading and the Well method experiments show that Pars 1 and Pars 2 are more effective in biodegradation of crude oil of both provinces, also they are more biodegradable than Gamlen dispersant. Overall, these findings suggest that Pars 1 and Pars 2 are more bio-adaptable for both province offshores.

In agreement with results obtained from optical density reading and the Well method experiment, microorganism culture containing Pars 1 showed the highest level of BOD and COD.

BOD is an indicator of biodegradation of organic components in water. BOD is measured by the amount of required oxygen for bacteria to metabolize organic components. The BOD test identifies the approximate amount of required oxygen for biological oxidation of contaminated water, surplus water, and sewages. This is the only experiments determining the amount of required oxygen for bacteria in order to catabolize the organic components. Therefore, the higher BOD shows the increased amount of consumed oxygen which is consequently indicating the enhanced bacterial activity [ 24 ].

The COD value indicates the amount of oxygen needed to chemically oxidize organic compounds present in wastewater and adjacent to oxidizing material. In fact, chemical oxygen demand determines the amount of organic compound present in the sample which has the ability to be oxidized by a strong chemical oxidizing agent [ 24 ]. BOD and COD tests are well-known methods for assessment of biodegradability of organic materials such as surfactants; for instance, in a study in , the percentage of biodegradation of organic compounds was assayed [ 23 ].

Previous studies showed that none of the bacterial species are able to catabolize all the components of crude oil, and its complete biodegradation depends on the presence of various bacterial species and microorganisms. Even microorganisms which are consumers of non-hydrocarbonate compounds can play important role in biodegradation of crude oil [ 7 ]. Thus, in the present study, we measured the BOD and the COD of all microorganism cultures, which were originally isolated from sampling stations in the Persian Gulf in the presence of three dispersants and their mixtures with crude oil and also crude oil alone.

In this study, the highest BOD and COD in Siri province were related to culture containing Pars 1 in comparison with the two other dispersants studied. Likewise, BOD-COD test performed on different combinations of dispersants and crude oil showed highest score for the combination of Pars 1 and crude oil and secondly to the mixture of Pars 2 and crude oil. These findings suggest that microorganisms with the presence of these compounds require the highest amount of oxygen for their activities including the biodegradation of such components.

Furthermore, in oxidation and degradation reactions, in presence of oxidizing agents, the highest amount of chemical oxygen is demanded; therefore; Pars 1, mixture of Pars 2 and crude oil, and also mixture of Pars 1 and crude oil hold more degradability properties compared to the mixture of Gamlen and crude oil.

In fact, Pars 1 and Pars 2 increased biodegradability of crude oil more than that of Gamlen dispersant. Since Pars 1 showed more degradability compared with the other two dispersants, the bioadaptability of this dispersant is high enough, so that it does not get accumulated in the region and does not make the environment contaminated.

This study revealed that Pars 1 and Pars 2 dispersants are more biodegradable than Gamlen and have more effectiveness in biodegradation of crude oil. These findings suggest that, in each region, the most suitable compound for removing oil spill from offshores with least secondary contamination should be investigated.

The authors are grateful to the director of the Research and Development Department of this company for his assistance and cooperation. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Article of the Year Award: Outstanding research contributions of , as selected by our Chief Editors. Read the winning articles. Journal overview. Special Issues. Academic Editor: Kelishadi Roya. Received 27 Sep Accepted 10 Oct Published 26 Jan Abstract Objective. Introduction The main causes of oil pollution in the oceans are extraction of oil, transportation with ballast water release and tanker accidents, and also war-related incidents [ 1 ].

Methods and Materials We selected two provinces in Persian Gulf because of their location in one of the biggest offshore oil drilling rig and high traffic density of oil vessels in the sea lanes of Persian Gulf; Siri and Bahregan provinces were studied because of their numerous shorelines contaminated by oil spills. Statistical Analysis The obtained data was analyzed by the Statistical Package for Social Sciences software version For example, Wolfe et al.

Studies on the effect of dispersants on the fate of dispersed oil has often been conflicting with some workers proposal that dispersants had little effect on oil biodegradation, some suggested a positive effect and others noted a negative effect [ 7 ]. It has been suggested that dispersants tend to increase oil biodegradation by increasing the surface area for microbial attack and encouraging migration of the droplets through the water column making oxygen and nutrients more readily available [ 8 ].

Dispersants also may enhance biodegradation of bulk crude oil by increasing the bioavailable fraction of hydrocarbon. This is accomplished through mobilization of adsorbed hydrocarbon or by increasing its effective aqueous solubility [ 9 ].

However, studies on the effect of dispersants used in Nigeria and under Nigerian conditions on the natural biological remediation process initiated by microorganisms hydrocarbon-utilizing on crude oil has received little attention. A sealed test flask made of glass was designed with stopcocks placed both in the applicator top and near the base of the flask for subsurface sampling according to Blondina et al.

It was stored in a sealed plastic vessel in the laboratory at room temperature and used within a period of 30 days. Dispersant IV Biosolve : This is a water-based, biodegradable hydrocarbon mitigation agent approved for oil spill control in Nigeria.

Into the flask was measured ml of fresh water. After swirling, a settling time of 10 minutes was allowed before extracting the sample to be analyzed [ 11 ]. From each sample mixture was obtained ml by pouring through the top of the flask into a ml bottle.

This was stored in the refrigerator until analysis. For each mixture, the proportion of each constituent compound dictated by the ratio was computed and measured out. Crude oil was applied to the substrate before transferring the dispersant at the desired concentration into the bioassay tank.

There were Two 2 replicates per mixture and these were exposed over a period of Thirty 30 days. Minimal Salt Medium MSM was prepared using the concentrations stated above and to which was added Agar solidifying agent. The Agar was allowed to cool and then poured into sterile petri dishes. For isolation, 1 ml of sample mixture was taken with the aid of a syringe and transferred into a test tube containing 9 ml of distilled water after cooling.

Ten-fold serial dilution was done up to 7 times that is, 10 7 and then 0. The sample was spread on the surface with the aid of a glass spreader for even distribution of colonies or cells. A sterile filter paper to which crude oil had been added and spread evenly was placed on the inside top cover of the petri dish before covering. These plates were stored in an incubator at room temperature for 5 to 10 days optimal growth time for hydrocarbon utilizing Bacteria.