Simultaneous Biodiesel Production Research Articles

Cohesive phycoremediation of pyrene by freshwater microalgae Selenastrum sp. and biodiesel production and its assessment.

In this study, the freshwater microalgae Selenastrum sp. was assessed for the effective degradation of pyrene and simultaneous production of biodiesel from pyrene-tolerant biomass. The growth of algae was determined based on the cell dry weight, cell density, chlorophyll content, and biomass productivity under different pyrene concentrations. Further, lipids from pyrene tolerant culture were converted into biodiesel by acid-catalyzed transesterification, which was characterized for the total fatty acid profile by gas chromatography. Increased pyrene concentration revealed less biomass yield and productivity after 20days of treatment, indicating potent pyrene biodegradation by Selenastrum sp. Biomass yield was unaffected till the 20mg/L pyrene. A 95% of pyrene bioremediation was observed at 20days of culturing. Lipid accumulation of 22.14%, as evident from the estimation of the total lipid content, indicated a marginal increase in corroborating pyrene stress in the culture. Fatty acid methyl esters yield of 63.06% (% per 100g lipids) was noticed from the pyrene tolerant culture. Moreover, fatty acid profile analysis of biodiesel produced under 10mg/L and 20mg/L pyrene conditionshowed escalated levels of desirable fatty acids in Selenastrum sp., compared to the control. Further, Selenastrum sp. and other freshwater microalgae are catalogued for sustainable development goals attainment by 2030, as per the UNSDG (United Nations Sustainable Development Goals) agenda. Critical applications for the Selenastrum sp. in bioremediation of pyrene, along with biodiesel production, are enumerated for sustainableand renewable energy production and resource management.

Detailed mechanistic investigation of stress-induced lipogenesis in oleaginous yeast for value-added metabolites

In the present study, a marine red yeast Rhodotorula glutinis ISO A1 cultivated under combinations of artificial seawater (ASW) and sewage wastewater (SWW) has been subjected to detailed mechanistic investigations via physiological and biochemical analysis to dissect the pathway of halotolerance behavior and carbon flux channelization towards enhanced lipid synthesis. Amid all tested groups (25–100% ASW), cells grown in 25% ASW yielded ∼ 1.4-fold higher lipid yield than glucose synthetic medium (GSM) and revealed metabolic rewiring of cells to channelize carbon pools for producing neutral lipids of vehicular quality. Detailed carbohydrate profiling showed enhanced glycerol, trehalose, mannose, and xylitol/arabitol under saline stress, suggesting the interplay of these metabolites to impart tolerance against osmotic imbalance. Further, the strengthened enzymatic activity (glutathione reductase, superoxide dismutase, ascorbate peroxidase) and non-enzymatic metabolites (betaine, proline) highlighted the active yeast defence network to counter altered redox state arise due to high salinity. The stress-induced responses also constituted substantial variations in membrane fluidity and production of biodiesel-quality lipids. Further findings like low thermal degradation temperature (at ∼ 265°C) and high chitin (can be converted into chitosan) entity in yeast de-oiled biomass primarily derived from yeast cells grown under contaminated environment; sea and sewage wastewater, signified its potential utilization for chitosan recovery, a commercially important product. Conclusively, this study elucidated a competent model of yeast-based biorefinery approach integrating seawater-wastewater utilization and simultaneous production of biodiesel and value-added products vital for a sustainable and circular bioeconomy.

Enzymatic esterification/transesterification of rice bran acid oil for subsequent γ-oryzanol recovery

This study recovered γ-oryzanol from rice bran acid oil (RBAO), following an initial enzymatic esterification/transesterification to selectively convert its glyceride impurities into fatty acid ethyl esters (FAEEs) or biodiesel. γ-oryzanol was then deprotonated and separated from the biodiesel into the resulting aqueous phase via acid-base extraction. Herein, we determine the effects of varying reaction conditions, i.e., ethanol:RBAO molar ratio, temperature, reaction time, enzyme loading, and agitation speed, on the degrees of glyceride removal, γ-oryzanol loss, free fatty acid (FFA) remaining, and biodiesel content. Up to 100% glyceride removal was achieved with a relatively high biodiesel yield (84%) and γ-oryzanol loss as low as 26% under our most suitable reaction conditions (5:1 ethanol:RBAO molar ratio, 40 °C, 24 h reaction time, 10%wt enzyme loading, 200 rpm agitation). Furthermore, of the remaining oryzanol, up to 94% was recovered by the acid-base extraction with 2-4 M ethanolic NaOH solution. Our results suggest that a combination of enzymatic esterification/transesterification with subsequent acid-base extraction offers an efficient alternative approach to the simultaneous production of biodiesel and γ-oryzanol recovery from low-cost RBAO. Based on our analysis of techno-economic and environmental sustainability, integration of the present method into a rice bran oil refinery would make the process profitable, with the minimum use of toxic chemicals and energy.

Removal of zinc by Selenastrum sp. and simultaneous biodiesel production from metal-resistant biomass for energy and environmental sustainability

In this study, the phycoremediation of zinc by the unicellular green alga, Selenastrum sp. and simultaneous biodiesel production from heavy metal resistant biomass was investigated. The microalga Selenastrum sp. was used to remove the zinc amended at 1, 3, 5, 7 ppm in the BG II medium. In all the tested zinc concentrations (1–7 ppm), there was no noticeable heavy metal stress on the microalga and the algal culture showed a steady and better growth pattern in zinc amended medium than that control (no zinc added). Furthermore, on the 24th day, the biomass concentration was 1.63 g/L for the 5 ppm and 7 ppm zinc dosed experiments, which was higher than the control. Atomic adsorption spectroscopic analysis showed that zinc concentration in the medium (5 and 7 ppm) was reduced to ~0.44 ppm, which is equivalent to 90 % heavy metal removal efficiency. The total lipid content and biodiesel yield from zinc-resistant Selenastrum biomass was 17.6 and 65.1 %, respectively. Finally, test microalga grown in zinc-added media produced beneficial fatty acids such as palmitic, palmitoleic, oleic, stearic, linoleic, and linolenic acid for high-quality biodiesel production.

Statistical optimization of microalgal biodiesel production and protein extraction from Chlorella sorokiniana cultivated in dairy effluent

In this study, Chlorella sorokiniana isolated from natural pond water, was evaluated for simultaneous production of biodiesel and protein C. sorokiniana was cultivated under non-sterile conditions in dairy wastewater using large scale outdoor ponds and the biomass was processed for lipid production. Response surface methodology was applied to optimize the transesterification reaction variables and the optimum conditions were found to be reaction time (144 min), temperature (58 °C), oil to methanol ratio (1:6.8) and H2SO4 as catalyst (3% w/v). A maximum yield of 95% (w/w) and 40% (w/w) of crude and decolorized algal biodiesel, was obtained under optimum conditions, respectively. Gas chromatography analysis of decolorized biodiesel confirmed the FAME yield of 88.3%. Amino acid profiling of algal protein revealed glycine (5%), glutamic acid (6%) and phenylalanine (3.3%) as some of the major amino acids.

Development of a low-cost cultivation medium for simultaneous production of biodiesel and bio-crude from the chlorophycean microalga Tetradesmus obliquus: A renewable energy prospective

Microalgal biodiesel production experiences hurdles in every step, beginning from cultivation of microalgal strains for biomass generation followed by harvesting, drying, oil extraction, and transesterification, leading to higher cost of production. In this study, an approach was adopted to minimize the cost of biomass production by utilizing the locally available agricultural fertilizers, viz. urea, NPK 10 26 26, diammonium phosphate, potash, superphosphate, etc. for cultivation of the green microalga Tetradesmusobliquus that can be subsequently used for biodiesel and bio-crude production. For this, an optimized urea medium (OUr) was developed, which reduced the cost of production by 47-fold as compared to the commonly used N 11 medium, formulated with the analytical grade inorganic salts. This optimized medium further enhanced the biomass yield by 32% while reducing the requirements of the major nutrients like potash, magnesium sulfate and superphosphate by 29, 25 and 25%, respectively. Urea requirement was, however, increased by 20%. Raceway pond cultivation of T. obliquus in the newly formulated medium depicted a biomass productivity of 12.6 g m−2 day−1 during winter season followed by 10. 9 g m−2 day−1 in summer and 4.8 g m−2 day−1 in rainy season at a culture depth of 30 cm, thus leading to an estimated biomass productivity of 30.04 ton hectare−1 year−1,and a biodiesel productivity of 2.07 ton hectare−1 year−1. The fuel characteristics of the biodiesel produced showed comparable characteristics with petro-diesel, and were also within the limits specified by the national and international standards. Bio-crude productivity of 10 ton hectare−1 year−1 was projected from the de-fatted biomass. This study was thus successful in utilizing >40% of the biomass for simultaneous production of biodiesel and bio-crude from the same biomass, eventually paving a path for the development of a microalgal refinery by exploring the spent biomass for further applications.

Use of rare earth element (REE)-contaminated acidic water as Euglena gracilis growth stimulator: A strategy for bioremediation and simultaneous increase in biodiesel productivity

Rare earth elements (REEs) have emerged as contaminants in water systems because their use and disposal are on the rise in many industries. To achieve environmentally benign treatment of REE-contaminated acidic water, we examined a strategy that uses Euglena gracilis for the bioremediation of REEs and simultaneous biodiesel production from used biomass. The presence of lanthanum (La3+) in the medium (0–100 µM) stimulated the growth of E. gracilis. The removal efficiency of La3+ was 99.9%, indicating that bioremediation using E. gracilis is feasible. The La3+ treatment accelerated the endocytic activity of E. gracilis and enabled cells to take up more nutrients (glucose and macro/micro elements). Also, La3+ increased the paramylon yield of E. gracilis, with the fatty acid methyl ester (FAME) yield below 3 wt% in both the control and La3+-treated cells. To increase the FAME yield and productivity, wax ester fermentation was conducted under anaerobic conditions. After wax ester fermentation, the FAME yield and productivity of the La3+-treated sample were 9.49 wt% and 78.76 g/L/day, 1.4- and 1.6-fold higher than the yield and productivity of the control sample. Moreover, the series of La treatment and wax ester fermentation enhanced the quality of biodiesel by increasing its saturated fatty acid (SFA) content. We confirmed that other REE species (cerium, neodymium, and a mixture) also stimulated the growth and biodiesel production of E. gracilis. Taken together, our E. gracilis-based bioremediation of REE-contaminated water provides high removal efficiency and a chance to simultaneously improve biodiesel productivity and quality.

Study on the ethanol production from hydrolysate derived by ultrasonic pretreated defatted biomass of chlorella sorokiniana NITTS3

Abstract Microalgae biomass is considered by many as a most promising renewable source for future generation feedstock for simultaneous production of biodiesel and bioethanol due to the accumulation of considerable amounts of lipids and carbohydrates, respectively. In this work, defatted green microalga, Chlorella sorokiniana NITTS3 biomass was ultrasonic pretreated and effectively used as a culture medium for ethanol production through fermentation using Saccharomyces cerevisiae NITTS1. The ultrasonic pretreatment improved ethanol yield by 25.83 g/L than untreated defatted microalgal biomass. Carbohydrate content of hydrolysate of defatted microalgal biomass after ultrasonic pretreatment was analyzed and found that hydrolysate primarily possessed simple sugars, namely glucose and xylose. Maximally 52.10 ± 0.12 g/L (86.70 ± 0.52 mg bioethanol/g DMB) of ethanol was produced at optimum fermentation conditions of 30 ℃, pH 4 and 200 rpm. This study results show that pretreated microalgal biomass could be used as a cheap, sustainable feedstock for enhanced ethanol production.

Biodiesel production integrated with glycerol steam reforming process, solid oxide fuel cell (SOFC) power plant

Process of biodiesel production integrated with glycerol steam reforming process, solid oxide fuel cell power plant, and also the organic Rankine cycle for the simultaneous production of biodiesel and electricity is investigated. In the biodiesel production scenario, biodiesel is obtained from waste cooking oil using acid catalyst coupled with hexane extraction. The glycerol obtained from the above method is subjected to steam reforming process to produce hydrogen. The hydrogen produced is then used as fuel in the solid oxide fuel cell to provide thermal and electrical energy for biodiesel production and reforming processes. In addition, generating extra power will allow biodiesel production to be more economical by injecting it into the electricity network. It also provides the heat duty of organic Rankine cycle. Sensitivity analysis is accomplished on the proposed model to indicate the effects of several parameters on the biodiesel production, glycerol production, power generation, and process efficiency. This study showed that with increasing oil flow rate, total generated power in SOFC, SOFC cycle efficiency, input flow to fuel cell and cell number decreased. Also, with increasing the fuel utilization coefficient, electrical efficiency, cell number, total output power from SOFC and overall thermal efficiency increased. The effect of inlet heat to distillation towers on parameters such as overall thermal efficiency and electrical efficiency and total generated power was also investigated. As main results, solid oxide fuel cell efficiency, Electrical efficiency, and overall thermal efficiency based on LHV are 25.09%, 28.14%, and 85.16%, respectively. Overall, developing a biodiesel production plant by upgrading glycerol to hydrogen through steam reforming and using hydrogen produced in solid oxide fuel cell and employing organic Rankine cycle to generate power is an attractive strategy to make biodiesel production cycles more economical.

Agroindustrial Wastewater Treatment with Simultaneous Biodiesel Production in Attached Growth Systems Using a Mixed Microbial Culture

The use of cyanobacteria in biological wastewater treatment technologies can greatly reduce operation costs by combining wastewater bioremediation and production of lipid suitable as biodiesel feedstock. In this work, an attached growth system was employed to achieve the above-mentioned dual objective using a mixed microbial culture dominated by Leptolyngbya and Limnothrix species in diverse heterotrophic consortia. Kinetic experiments on different initial pollutant concentrations were carried out to determine the ability of the established culture to remove organic load (expressed by d-COD, dissolved-Chemical Oxygen Demand), N and P from agroindustrial wastewaters (dairy, winery and raisin). Biomass and oil productivity were determined. It was found that significant removal rates of nutrients were achieved in all the wastewaters examined, especially in that originated from winery in which the highest d-COD removal rate (up to 97.4%) was observed. The attached microbial biomass produced in winery wastewater contained 23.2% lipid/biomass, wt/wt, which was satisfying. The growth in the dairy wastewater yielded the highest attached biomass productivity (5.03 g m−2 day−1) followed by the mixed effluent of winery-raisin (4.12 g m−2 day−1) and the winery wastewater (3.08 g m−2 day−1). The produced microbial lipids contained high percentages of saturated and mono-unsaturated fatty acids (over 89% in total lipids) in all substrates examined. We conclude that the proposed attached growth photobioreactor system can be considered an effective wastewater treatment system that simultaneously produces microbial lipids suitable as biodiesel feedstock.

Novel Design for Simultaneous Production of Biodiesel and Glycerol Carbonate from Soybean Oil

Glycerol is the byproduct of biodiesel production plants. The rapid increase of biodiesel production and demand has resulted in excessive glycerol supply in the market. Converting the cheap glycerol into high-value glycerol carbonate (GC) is a potentially valuable solution to the current worldwide excessive glycerol supply. In this paper, a novel process for simultaneous production of biodiesel and GC (SBDG meanwhile, the byproduct of GC production, methanol, is recycled as the feedstock of the biodiesel production. Second, the optimization of the columns duties has been performed via thermal analysis analyzing the Column Grand Composite Curves (CGCC). In addition, a mathematic model for the heat integration of the SBD&...

Biodiesel production with the simultaneous removal of nitrogen, phosphorus and COD in microalgal-bacterial communities for the treatment of anaerobic digestion effluent in photobioreactors

The anaerobic digestion effluent (ADE) generated from biogas projects has raised increasing environmental concerns. In this study, the algal cells integrity, pollutants degradation and the community compositions shifts were evaluated during the ADE treatment with simultaneous biodiesel accumulation in photobioreactors (PBR). The operation of six PBRs was initiated with diluted ADE (625, 393, 272, 193, 178 and 167 mg/L SCOD). The results showed that the high concentration of ADE (625 mg/L SCOD) led to considerable inhibition of algal cells growth. By comparison, the PBR (272 mg/L SCOD) attained the maximum lipid productivity (59.13 mg/L·d), and complete nutrient (nitrogen and phosphorus) removal was observed in PBR (167 mg/L SCOD). Moreover, the highest viable algal cells (86.2%) was attained in PBR (272 mg/L SCOD). Therefore, this study provides a feasible technology for microalgal cultivation with simultaneous treatment of ADE in PBRs. In addition, the approach of excitation-emission matrices with parallel factor (EEMs-PARAFAC) was utilized to further understand the organics degradation. The removals of component 1 (humic-like) and component 2 (protein-like, biological production) were ascended by the increased algal and bacteria activity in the microalgal-bacterial consortium. Additionally, the community composition analysis illustrated that bacterial diversity was reduced by the inoculation with microalgae, which was attributed to the formation of stable function groups with satisfactory contaminant degradation abilities and good algal cell growth; and Chlorella species were dominant, which benefited biodiesel accumulation in PBRs. These findings demonstrated the potential of using a bacterial-microalgal consortium for ADE purification simultaneous biodiesel production.

Biofuel production and phycoremediation by Chlorella sp. ISTLA1 isolated from landfill site

The present study aims to investigate the biofuel production ability and potential of heavy metal remediation of Chlorella sp. ISTLA1 isolated from a landfill site. The strain was cultured in Bold’s Basal medium at different concentration of NaHCO3 and pH. Response surface methodology was employed for the optimization of nutrient sources for higher lipid production. Under the optimized conditions, the yield of lipid and biomass was 365.42 and 833.14 mg L−1 respectively. GC–MS analysis of lipid indicated the presence of C8 to C31 organic compounds consisting mainly of palmitic acid (C16:0), stearic acid (C18:0) and oleic acid (C18:1). Additionally, remediation of heavy metals like Zn, Cu, Mn and Fe from waste water was observed by AAS and EDX. The removal efficiency was 82.6% for Zn, 56.5% for Cu, 79.8% for Mn and 40% for Fe. The study revealed simultaneous biodiesel production and waste water treatment by Chlorella sp. ISTLA1.

Transesterification of soybean oil by PAAc catalytic membrane: Sorption properties and reactive performance for biodiesel production

Abstract A catalytic performance study for biodiesel production by a novel catalytically active membrane from polyacrylic acid (PAAc) crosslinked with 4,4′-diamino-2,2′-biphenyl sulfonic acid (PAAc-BDSA) was performed. Evaluation of oil and methanol sorption capacity as well as heterogeneous acid catalyzed transesterification of soybean oil by PAAc-BDSA was compared to polyvinyl alcohol, PVA (88% and 99% hydrolysed) catalytically active membranes crosslinked with sulfosuccinic acid (PVA-88-SSA and PVA-99-SSA). PAAc-BDSA membranes with similar ion exchange capacity ( IEC ) presented at least twice the swelling degree ( Q ) for soybean oil and methanol than PVA-88-SSA and PVA-99-SSA membranes. Effective diffusion coefficients of PAAc-BDSA for methanol and a mixture of methanol-glycerol determined by sorption method show that in this membrane the diffusion was at least 4 to 6 times faster than in PVA-88-SSA and PVA-99-SSA. Soybean oil transesterification reaction rate fits pseudo-first order kinetics and methyl ester yield follows the order 90, 92 and 73% for PVA-88-SSA, PVA-99-SSA and PAAc-BDSA, respectively. Higher diffusion coefficients and sorption of methanol and glycerol by PAAc-BDSA membrane make it a candidate for application in membrane reactors for simultaneous biodiesel production and glycerol separation.

Insight into a catalytic process for simultaneous production of biodiesel and glycerol carbonate from triglycerides

Biodiesel, a renewable liquid fuel derived from triglycerides, is a promising alternative to compensate for the increasing demand of petro-diesel. However, 10% w/w glycerol is co-produced in the biodiesel production process which reduces the efficiency. The present work deals with the one-pot simultaneous co-production of biodiesel and glycerol carbonate from in-situ coproduced glycerol using hydrotalcite as a catalyst. Uncalcined hydrotalcite, calcined hydrotalcite and rehydrated hydrotalcite were screened for their activity towards the reaction in terms of conversion of soybean oil triglycerides and selectivity of glycerol carbonate. Uncalcined hydrotalcite served best for this purpose. At oil to methanol mole ratio of 1:90 and oil to DMC mole ratio of 1:30, the reaction gave 97.3% conversion of triglycerides and 93.2% selectivity of glycerol carbonate at 150°C in 3h at a catalyst loading of 0.0125g/cm3. The virgin and reused catalysts were well characterized using various analytical techniques which reveals the presence of basic as well as acidic sites with high surface area and ordered pore-size distribution. Effects of various experimental parameters on the conversion of triglycerides and selectivity to glycerol carbonate were studied to interpret the reaction kinetics. The kinetic rate constants and the activation energies were calculated. Reusability study of the catalyst was done up to two cycles and the catalyst was found to be robust and reusable.

Efficient simultaneous production of biodiesel and glycerol carbonate via statistical optimization

Abstract The purpose of this study was to simultaneously produce biodiesel and glycerol carbonate. Glycerol carbonate is a high-value material that could be obtained from glycerol. Response surface methodology was used to perform optimization of simultaneous enzymatic production of biodiesel and glycerol carbonate. Independent factors for optimization of simultaneous enzymatic production included enzyme concentration, a molar ratio of dimethyl carbonate to soybean oil, and reaction temperature. The levels of satisfaction with the production reaction model for biodiesel and glycerol carbonate were high, 0.994 and 1, respectively. The optimum condition for simultaneous production was 116.76 g/L enzyme concentration, 9.27:1 molar ratio, and 52.56 °C reaction temperature. Under the optimum condition, biodiesel 96.3% and glycerol carbonate 99.7% were produced at the same time.

Biotreatment of raisin and winery wastewaters and simultaneous biodiesel production using a Leptolyngbya-based microbial consortium

Combining wastewater treatment with biodiesel production can greatly reduce the cost of environmentally friendly technologies. In this work wastewaters of high environmental importance originating from raisin and wine industries were employed as substrates for a mixed cyanobacterial/algal cultivation system dominated by the filamentous cyanobacterium Leptolyngbya sp. The mixotrophic microalga Ochromonas contributed to less than 5% of the total photosynthetic population and grazed on broken Leptolyngbya trichomes. Satisfactory lipid yields and removal of nutrients and chemical oxygen demand (COD) were observed when raisin or winery wastewaters were used separately as substrates. However, exceptional removal rates were recorded in blends of the above-mentioned wastewaters (i.e., 92.8%, 78.1% and 99% for COD, total nitrogen and phosphate, respectively), while the biomass produced contained around 13% lipids (w/w) on a dry weight basis. The ratio of saturated/mono-unsaturated fatty acids in this lipid reached 85%, making this system suitable for biodiesel production. The proposed system can effectively approach a technology that integrates wastewater treatment with simultaneous biodiesel production.

Exergetic evaluation of incorporation of hydrogen production in a biodiesel plant

Over the last century, the consumption of fossil fuels has increased significantly, which led to a depletion of their reserves. Hence, the search for new alternative sources as biodiesel and hydrogen has become an attractive endeavor to meet world energy demand. In the production process of biodiesel, a proper choice of feedstock and catalyst has been the subject of studies in order to analyze the technical and economic viability of biodiesel production. Nowadays, studies are also directed to an energy-efficient use of glycerin. In this context, the present study aims to assess the simultaneous production of biodiesel and hydrogen. An exergetic analysis methodology is use to identify irreversibilities in each component of the plant, as well as quantify which ones present higher and lower efficiencies. As a result, it is found that the highest irreversibility is associated with the transesterification process and the largest exergetic efficiencies are promoted by the washing processes, the methanol recovery and the catalyst removal. Finally, it is possible to conclude that the simultaneous production of Biodiesel and Hydrogen is a technology which offers technical viability and leaves a room for thermoeconomic and ecological studies to be carried out in the future looking for the complementation of the results obtained in this paper.

Optimal Simultaneous Production of Biodiesel (FAEE) and Bioethanol from Switchgrass

In this work, we optimize the simultaneous production of biodiesel (fatty acid ethyl esters, FAEE) and ethanol from switchgrass. Two technologies are considered for switchgrass pretreatment: dilute acid and ammonia fiber explosion (AFEX). Next, enzymatic hydrolysis follows any of the pretreaments to obtain fermentable sugars, mainly xylose and glucose. We separate the lignin, and, with the sugars, we consider the production of bioethanol and/or FAEE. Based on a superstructure of alternatives, the problem is formulated as an mixed-integer nonlinear program (MINLP) with simultaneous optimization and heat integration. An economic evaluation is performed and water consumption is calculated. The simultaneous production of bioethanol and FAEE from switchgrass is shown not to be competitive at the current development of the conversion of sugars to FAEE, but it can become promising if the conversion from sugar exceeds 0.5. The optimal solution indicates bioethanol to be the preferred product because of its higher...

Design of an optimal process for enhanced production of bioethanol and biodiesel from algae oil via glycerol fermentation

In this paper, we optimize a process that integrates the use of glycerol to produce ethanol via fermentation within the simultaneous production of biodiesel and bioethanol from algae. The process consists of growing the algae, determining the optimal fraction of oil vs. starch, followed by oil extraction, starch liquefaction and saccharification, to sugars, oil transesterification, for which we consider two transesterification technologies (enzymes and alkali) and the fermentation of sugars and glycerol. The advantage of this process is that the dehydration technologies are common for the products of the glucose and glycerol fermentation. Simultaneous optimization and heat integration is performed using Duran and Grossmann’s model. The fermentation of glycerol to ethanol increases the production of bioethanol by at least 50%. The energy and water consumptions are competitive with other processes that either sell the glycerol or use it to obtain methanol. However, the price for the biofuels is only competitive if glycerol cannot be sold to the market.