enhanced-oil-recovery-using-a-combination-of-biosurfactants

Enhanced Oil Recovery using a Combination of Biosurfactants

Biosurfactants are surface-active compounds capable of reducing the surface tension between two phases of different polarities. Biosurfactants have been ...

Indian Oil Corporation, Research and Development Faridabad

Petroleum produced water (PPW) is a waste-stream that entails huge cost on the petroleum industry. Along with other suspended and dissolved solids, it contains sulfate, which is a major hurdle for its alternative use intended toward enhanced oil recovery. This study proposes a two-step process for sulfate removal from PPW. A synthetic PPW was designed for the study using response surface methodology. During the first step, sulfate present in PPW was reduced to sulfide by anaerobic fermentation with 80% efficiency. In the second step, more than 70% of the accumulated sulfide was electrochemically oxidized. This integrated approach successfully removed sulfate from the synthetic wastewater indicating its applicability in the treatment of PPW and its subsequent applications in other oil field operations. 

Electrochemical removal of sulfate from petroleum produced water.

Refinery wastewater (RW) treatment in microbial fuel cell (MFC) was studied in batch mode operation followed by continuous mode operation with 8h and 16h hydraulic retention time (HRT). The MFC performance was evaluated in terms of power density, organics removal, specific contaminants (oil & grease, phenol and sulfide) removal and energy conversion efficiency with respect to operation mode. Higher power density of 225±1.4mW/m was observed during continuous mode operation with 16h HRT along with a substrate degradation of 84.4±0.8% including the 95±0.6 of oil content. The columbic efficiency during this operation was about 2±0.8% and the projected power yield was 340±20kWh/kg COD/day. Batch mode operation also showed good substrate degradation (81±1.8%) but took longer HRT which resulted in significantly low substrate degradation rate (0.036±0.002kgCOD/m-day) over continuous mode operation (1.05±0.01kgCOD/m-day). Overall, current study depicted the possibility of utilizing RW as substrate in MFC for power generation along with its treatment.

Electro-biocatalytic treatment of petroleum refinery wastewater using microbial fuel cell (MFC) in continuous mode operation.

Perturbations in various carbon pools like biological, geological, oceanic, and missing carbon sink affect its global data, which are generally neglected or ignored in routine calculations. These natural and anthropogenic events need to be considered before projecting a sustainable carbon management plan. These plans have both general and experimental aspects. General plans should focus on (a) minimizing emission; (b) maximizing environmentally sound reuse, reduce, and recycling; (c) effective treatment; and (d) converting carbon into valuable products with atom economy. Experimental carbon management plans involving various biological and chemical techniques with limitation in terms of research level and economic feasibility. Chemical options have benefits of higher productivity and wider product range, but it suffers from its higher-energy requirements and environmental unfriendliness. In contrast to this, biological options are more selective and less energy intensive, but their productivity is very low. Hence, there is a requirement of hybrid process where the benefits of both the options, i.e., biological and chemical, can be reaped. In view of above, the proposed review targets to highlight the various perturbations in the global carbon cycle and their effects; study the currently practiced options of carbon management, specifically in light of 3R principle; and propose various new hybrid methods by compatible combinations of chemical and biological processes to develop better and safer carbon management. These methods are hypothetical so they may require further research and validations but may provide a comprehensive base for developing such management methods.

Perturbations and 3R in carbon management.

Increasing oil prices and depletion of existing fossil fuel reserves, combined with the continuous rise in greenhouse gas emissions, have fostered the need to explore and develop new renewable bioenergy feedstocks that do not require arable land and freshwater resources. In this regard, prolific biomass growth of invasive aquatic weeds in wastewater has gained much attention in recent years in utilizing them as a potential feedstock for bioenergy production. Aquatic weeds have an exceptionally higher reproduction rates and are rich in cellulose and hemicellulose with a very low lignin content that makes them an efficient next generation biofuel crop. Considering their potential as an effective phytoremediators, this review presents a model of integrated aquatic biomass production, phytoremediation and bioenergy generation to reduce the land, fresh water and fertilizer usage for sustainable and economical bioenergy.

Aquatic weeds as the next generation feedstock for sustainable bioenergy production.

Impact of gas diffusion electrodes (GDEs) was evaluated in enhancing the CO bio-availability for its transformation to C4-organics, especially to alcohols using selective mixed culture. Observed current density was more stable (9-11 A/m) than submerged experiments reported and significantly varied with pH and respective CO solubility. Uncontrolled operating pH (starting with 8.0) showed its impact on shifting/triggering alternate metabolic pathways to increase the carbon length (butyric acid) as well as producing more reduced end products, i.e. alcohols. During the experiments, CO was transformed initially to a mixture of volatile fatty acids dominated with formic and acetic acids, and upon their accumulation, ethanol and butanol production was triggered. Overall, 21 g/l of alcohols and 13 g/l of organic acids were accumulated in 90 days with a coulombic efficiency (CE) of 49%. Ethanol and butanol occupied respectively about 45% and 16% of total products, indicating larger potential of this technology.

Electro-biocatalytic conversion of carbon dioxide to alcohols using gas diffusion electrode.

Electro-biocatalytic reactor was operated using selectively enriched mixed culture biofilm for about 320 days with CO/bicarbonate as C-source. Biocathode consumed higher current (-16.2 ± 0.3 A/m) for bicarbonate transformation yielding high product synthesis (0.74 g/l/day) compared to CO (-9.5 ± 2.8 A/m; 0.41 g/l/day). Product slate includes butanol and butyric acid when CO gets transformed but propionic acid replaced both when bicarbonate gets transformed. Based on electroanalysis, the electron transfer might be H mediated along with direct transfer under bicarbonate turnover conditions, while it was restricted to direct under CO. Efficiency and stability of biofilm was tested by removing the planktonic cells, and also confirmed in terms of Coulombic (85-97%) and carbon conversion efficiencies (42-48%) along with production rate (1.2-1.7 kg/m electrode) using bicarbonate as substrate. Selective enrichment of microbes and their growth as biofilm along with soluble CO have helped in efficient transformation of CO up to C4 organic molecules.

Long-term operation of electro-biocatalytic reactor for carbon dioxide transformation into organic molecules.

Petroleum industry is one of the largest and fast growing industries due to the ever increasing global energy demands. Petroleum refinery produces huge quantities of wastes like oily sludge, wastewater, volatile organic compounds, waste catalyst, heavy metals, etc., because of its high capacity and continuous operation of many units. Major challenge to this industry is to manage the huge quantities of waste generated from different processes due to the complexity of waste as well as changing stringent environmental regulations. To decrease the energy loss for treatment and also to conserve the energy stored in the chemical bonds of these waste organics, bio-electrochemical system (BES) may be an efficient tool that reduce the economics of waste disposal by transforming the waste into energy pool. The present review discusses about the feasibility of using BES as a potential option for harnessing energy from different waste generated from petroleum refineries.

Bio-electrochemical system (BES) as an innovative approach for sustainable waste management in petroleum industry.

The aim of this work was to study the CO bio-sequestration application of indigenous Citrobacter species and its carbonic anhydrase (CA). Intracellular CA was purified from Citrobacter freundii (CF; accession no: MH283871) isolated from limestone rock site in Kumaun region of Indian Himalaya studied for the sequestration of carbon dioxide and the formation of calcite. CF showed maximum CA enzyme activity at 11.3 EU/ml at pH 7.0 and 37 °C. Hydration of CO into carbonate was characterized by calcite phase of calcium carbonate using absorption spectroscopy and imaging technique. Purified CA showed a significantly high CO sequestration capacity of 230 mg CaCO/mg of purified as compared to crude enzyme (50 mg CaCO/ml of enzyme).

Intracellular carbonic anhydrase from Citrobacter freundii and its role in bio-sequestration.

Tandem bio-inorganic platform by combining efficient light harvesting properties of nano-inorganic semiconductor cadmium sulfide (CdS) with biocatalytic ability of electro-active bacteria (EAB) towards carbon dioxide (CO) conversion is reported. Sulfur was obtained from either cysteine (EAB-Cys-CdS) or hydrogen sulfide (EAB-HS-CdS) and experiments were carried out under similar conditions. Anchoring of the nano CdS cluster on the microbe surface was confirmed using electronic microscope. Bio-inorganic hybrid system was able to produce single and multi-carbon compounds from CO in visible spectrum (λ > 400 nm). Though, acetic acid was dominant (EAB-Cys-CdS, 1.46 g/l and EAB-HS-CdS, 1.55 g/l) in both the microbe-CdS hybrids, its concentration as well as product slate varied significantly. EAB-HS-CdS produced hexanoic acid and less methanol fraction, while the EAB-Cys-CdS produced no hexanoic acid along with almost double the concentration of methanol. Due to easy harvesting process, this bio-inorganic hybrid represents unique sustainable approach for solar-to-chemical production via CO transformation.

Photosensitization of electro-active microbes for solar assisted carbon dioxide transformation.

Sustainable production of solar-based chemicals is possible by mimicking the natural photosynthetic mechanism. To realize the full potential of solar-to-chemical production, the artificial means of photosynthesis and the biological approach should complement each other. The recently developed hybrid microbe-metal interface combines an inorganic, semiconducting light-harvester material with efficient and simple microorganisms, resulting in a novel metal-microbe interface that helps the microbes to capture energy directly from sunlight. This solar energy is then used for sustainable biosynthesis of chemicals from CO. This review discusses various approaches to improve the electron uptake by microbes at the bioinorganic interface, especially self-photosensitized microbial systems and integrated water splitting biosynthetic systems, with emphasis on CO bioelectrosynthesis.

Material-Microbe Interfaces for Solar-Driven CO Bioelectrosynthesis.

Biomethanation potential of lignin rich residue (LRR) obtained from lignocellulosic ethanol fermentation was evaluated after subjecting to microbe assisted pretreatment using selectively enriched lignin depolymerizing consortia (LDC). The efficiency of LDC in lignin depolymerization was established using alkali and dealkali lignins (AL and DL) along with LRR as feedstocks. Microbial growth on media having lignin as sole carbon source, activity of lignin depolymerizing enzymes, viz., lignin peroxidase and laccase, ability of culture to decolorize the lignin mimicking dyes like methylene blue and ramezol brilliant blue, were considered to confirm the efficiency of enriched mixed culture. Microbial treatment using LDC showed significant positive impact on lignin breakdown irrespective of the substrate (LRR, 46.33%; AL, 31.37%; DL, 34.20%). The hydrolysate of LRR obtained from microbial pretreatment showed higher biogas yield (424 ml/g VS) owing to the efficiency of lignin depolymerization and availability of readily available biodegradable components in residual lignin from previous processing. Depolymerization of commercial lignins also produced a good amount of biogas (302-324 ml/g VS) after pretreatment with LDC. Overall, an additional energy conversion efficiency of about 11.75 kJ/g VS was obtained by valorizing the residual lignin through integrating biomethanation technology to ethanol fermentation. Outcome of this study indicated the feasibility of using lignin rich residue generated from the second generation cellulosic bioethanol plants as a potential feedstock to meet the current gaseous fuel demands. This integration also helps in closing the biomass based biorefinery loop and also promotes the circular economy.

Microbe assisted depolymerization of lignin rich waste and its conversion to gaseous biofuel.

Repurposed used cooking oil is a sustainable alternative to other feedstocks for biodiesel production offering enviro-economic benefits. Residual crude glycerol (RCG) from such biodiesel production plants is difficult to utilize due to presence of numerous toxic impurities with various inhibitory effects on biological fermentative reforming process. However, it is a new industrial feedstock for bio-based production of 1,3-propanediol. In this work, a new Clostridium butyricum strain L4 was isolated from biogas reactor leachate after rigorous adaption and 35 subcultures under increasing stress conditions and studied for green production of 1,3-propanediol (PDO) from RCG and further process development. Evaluation of fermentative reforming kinetics was performed and the optimal reaction conditions are pH 7.0, temperature 30 °C, 2 g yeast extract/L and 15 g ammonium sulphate/L. Glycerol-glucose co-fermentation (10:1) enhanced cell growth and thus, PDO output by 11.6 g/L. In comparison to batch fermentation (24.8 g PDO/L; 0.58 mol PDO/mol glycerol) there was 2.8-fold improvement with fed-batch process resulting in accumulation of 70.1 g PDO/L (Yield = 0.65 mol PDO/mol glycerol) using the studied biocatalyst in 150 h. In order to predict yields under different operational conditions a multiple linear regression model was developed (r = 0.783) with six independent variables (p < 0.05), where biomass (g/L) and temperature (C) were forecasted as top contributors to PDO yield. Finally, this biocatalyst appears as a potential candidate for industrial use due to its non-pathogenic nature, ability to grow in wide pH and temperature conditions, tolerance to high substrate and product concentration, insignificant generation of by-products and Coenzyme B12 independent biotransformation. The study can add value to bio-utilization of RCG to produce green 1,3-propanediol.

Fermentative reforming of crude glycerol to 1,3-propanediol using Clostridium butyricum strain L4.

Biosurfactants are amphipathic molecules produced from microorganisms. There are relatively few species known where the detailed chemical characterization of biosurfactant has been reported. Here, we report isolation and chemical characterization of the biosurfactant produced by a biodesulfurizing bacterium Gordonia sp. IITR100. Biosurfactant production was determined by performing oil spreading, drop-collapse, Emulsion index (E24), and Bacterial adhesion to hydrocarbons (BATH) assay. The biosurfactant was identified as a glycolipid by LCMS and GCMS analysis. The chemical structure was further confirmed by performing FTIR and NMR of the extracted biosurfactant. The emulsion formed by the biosurfactant was found to be stable between temperatures of 4°C to 30°C, pH of 6 to 10 and salt concentrations up to 2%. It was successful in reducing the surface tension of the aqueous media from 61.06 mN/m to 36.82 mN/m. The biosurfactant produced can be used in petroleum, detergents, soaps, the food and beverage industry and the healthcare industry.

Manoj Kumar

Indian Oil Corporation, Research and Development Faridabad

Enhanced Oil Recovery using a Combination of Biosurfactants