Screening of ionic liquids for PUFA extraction from microalgal biomass using COSMO-RS

Omega-3 Poly Unsaturated Fatty Acids (PUFA) particularly eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) have many health benefits including reducing the risk of cancer, cardiovascular disease, autoimmune, inflammatory disorders, cystic fibrosis, disrupted neurological function, bowel disease and mental illness. The EPA and DHA from microalgae are favorable due to algal is farmed in a controlled environment that avoids harmful contamination such as methyl mercury, copper from the sea. Moreover, microalgae oil do not have the problem to deficiency of vitamin E unlike fish oil. It has also the advantage of presenting neither an unpleasant odour nor a high amount of cholesterol, and contains squalene and phytosterols, which offer additional benefits to human health. However, the existing conventional methods of lipid extraction like soxhlet consume large amount of solvent and consider as high toxic and energy intensive methods. Ionic liquids (ILs) is one of the new classes of solvent that has potential in extracting the microalgae PUFA. It provides low vapor pressure, high thermal stability, non-toxicity and dissolve polar, non polar organic, inorganic and polymeric components. However, very limited research has been conducted on extracting microalgae PUFA using ILs. Therefore, this study aims to screen the potential ILs that can be used in the microalgae extraction process. The screening work was carried out using Continuum Solvation Models for Real Solvents (COSMO-RS). In this research use cosmo-rs to investigate the effect of hydrophilic and hydrophobic anions base ILs and also effect of the increase alkyl chain length from C2 to C8 on the EPA and DHA extraction. Cosmo-rs done this simulation by the calculation of activity coefficient (γ). It was found that the lowest activity coefficient has the best interaction between the solute and solvent. According to the results lowest activity coefficient for EPA and DHA extraction belong to [Cl] as anion for the imidazolium, pyridinium and pyrrolidinium with different alkyl chains. The effectiveness of those combinations will be further tested in the microalgae extraction

Preliminary study on supercritical fluid extraction of microalgae Nannochloropsis salina

Supercritical Fluid Extraction (SFE) is an emerging extraction method because it is clean, selective and efficient compared to the chemical extraction methods that use toxic solvent. Microalgae Nannochloropsis salina was selected as the feedstock in this study due to its high content of Polyunsaturated Fatty Acids (PUFA). The use of carbon dioxide (CO2) as a solvent in SFE makes the process as one of the green extraction technologies. This study aims to observe the effect of co-solvent (5% ethanol) and different types of microalgae holder (cotton and steam bun cloth) on the yield of lipid. The holder is required during the process due to the fine particle of microalgae that has potential to clog the instrument. The study was conducted for 4 hours at 60°C, 30 MPa and flow rate of 4 ml/min. The obtained lipid was then transesterified and analyzed for fatty acid methyl ester (FAME) profile. The results showed that high yield of lipid (16 wt.%) obtained when co-solvent was added during the SFE. The microalgae holder used in this study also affected the yield of lipid. The used of cotton cloth as microalgae holder for SFE with co-solvent gave high lipid yield compared to steam bun cloth. It was found that the yield of lipid from SFE was double the amount of lipid obtained using Soxhlet extraction. This preliminary findings can be further researched by optimizing the co-solvent concentration with suitable microalgae holder for high lipid yields

Lipid-extracted algae to value added products: a review

The squandering supplies of fossil fuels accompanied by the fractious burning of petrol, diesel, gasoline and coal are the major issues that the whole world is currently facing. Hence, the world is migrating towards greener and more sustainable energy sources to reduce the effects from fossil fuels burning, such as global warming, climate change, acid rain and greenhouse gases (GHG) emissions. Among the available alternatives are the exploration of renewable energy options, such as solar energy, wind energy, hydro energy, biomass and fuel cells. Biomass is one of the preferred options for biofuel generation, such as biodiesel and bioethanol. Among established methods explored for biofuel manufacturing is transesterification of algal oil extracted from algae after algal oil extraction technique. Algae are simple eukaryotes that are present in the size range from microalgae to large seaweeds, which can be further classified in groups according to their color, for instance, blue algae, green algae and red algae. They have similar properties to plants that enable them to store nutrients which can be processed into biofuel, health supplements, food and beverages as well as filter in waste water treatment. The algal oil extraction step creates algal residue which still contains proteins and carbohydrates and has wide potential to be transformed to value-added products to avoid dumping the useful leftover-extracted algae (LEA) into the environment. For instance, livestock feed and feedstock for bioethanol generation and biogas generation. Since the world is shifting towards third generation biofuel or algal fuel, more LEA downstream processing methods should be introduced in order to consume algae as the new source of fuel effectively. This paper presented the pathways of microalgae to biofuel generation and downstream processing of LEA to value added products via different approaches

Role of phycoremediation for nutrient removal from wastewaters: a review

The presence of high concentrations of chemical oxygen demand (COD), biochemical oxygen demand (BOD) and nutrients in wastewater generated industrially or domestically has resulted in significant water pollution situations and subsequently is leading to adverse health problems. Algae have been used in various applications in environmental biotechnology especially for phycoremediation as a tertiary wastewater treatment strategy through assimilation of high concentration of nitrogen and phosphorus for their growth, thus reducing potential eutrophication problems. This article discusses the role of phycoremediation to remove COD, BOD and nutrients from wastewater. The mechanism for nutrient removal from wastewater, challenges to process development and current commercial-scale algae-based wastewater treatment are reviewed too. It appears that phycoremediation plays a vital role to treat wastewaters efficiently

Recovery of aqueous phase of sub-critical water extraction (SWE) from Nannochloropsis gaditana

Microalgae had been proven to be rich in valuable biochemical components such as antioxidants and omega-3. Sub-critical water extraction (SWE) is considered an excellent technology for extraction as the process involves shorter extraction period with high efficiency and it uses a green solvent which is only water. Additional benefit of SWE would be the potential to recover the aqueous extracts which is rich in compounds such as sugar and organic carbon. Sugar could be used in fermentation process for bioenergy production and total organic carbon (TOC) could be used for nutrient recycling for microalgal cultivation. In this experiment, the process conditions of SWE include temperature (156°C-274°C), biomass loading (33 g/L-117 g/L) and retention time (6.6 min-23.4 min) were investigated to quantitatively determined the yield of the aqueous products, focusing on sugars and TOC. The experiments were designed using Central Composite Design (CCD) and the statistical analysis was performed using Design-Expert 7.0. The responses and interactions of each parameter towards the content of the aqueous phase were discussed. A second order polynomial model was chosen for both carbohydrates and TOC content with R2 = 0.9835 and R2 = 0.9845 respectively. The statistical tool also generates predictive equations which could be used to predict future experiments

Batch process for bio-hydrogen production on small scale bioreactor from palm oil mill effluent (POME)

In this study, treatment of palm oil mill effluent (POME) was carried out under anaerobic fermentation process with the intention to produce bio-hydrogen by micro flora. Experiment was investigated in 500mL bioreactor under mesophilic operation at  and different pH value. Raw POME was collected from cooling pond which is final discharge of effluent from the mill and POME sludge was collected from the anaerobic pond of a POME treatment plant at same Labu palm oil mill respectively. Source of inoculum was used is POME sludge as hydrogen producing bacteria. A batch reactor was found producing higher hydrogen at optimum parameter of pH 5.5 and 10% POME sludge (w/v) with maximum hydrogen production yield of 5988.96 mL H2/ L-med and maximum hydrogen percentage in the biogas of 36% were obtained at pH 5.5. Throughout the study, there is no methane gas was observed in the evolved gas mixture. Keywords: Bio-hydrogen, POME sludge, Raw POME

One-step microalgal biodiesel production from Chlorella pyrenoidosa using subcritical methanol extraction (SCM) technology

In this work, we propose a one-step subcritical methanol extraction (SCM) process for biodiesel production from Chlorella pyrenoidosa. Therefore, the present study attempts to establish and determine the optimum operating conditions for maximum biodiesel yield from SCM of C. pyrenoidosa. A statistical approach, i.e. response surface methodology is employed in this study. The effects of three operational factors: reaction temperature (140–220 °C), reaction time (1–15 min) and methanol to algae ratio (1–9 wt.%) were investigated using a central composite design. A maximum yield of crude biodiesel of 7.1 wt.% was obtained at 160 °C, 3 min reaction time and 7 wt.% methanol to algae ratio. The analysis of variance revealed that methanol to algae ratio is the most significant factor for maximizing biodiesel yield. Regression analysis showed a good fit of the experimental data to the second-order polynomial model. With no requirement of catalyst nor any pretreatment step, SCM process is economically feasible to scale up the commercial biodiesel production from algae

Preliminary study on lipid extraction from Nannochloropsis salina using supercritical carbon dioxide method

The issues involved with conventional lipid extraction methods, such as the usage of toxic solvents and accumulation of chemical waste, has motivated researchers to find an alternative approach to the extraction technology. One of the alternatives is via the Supercritical Carbon Dioxide (SC-CO2) method. This extraction method is considered as green as it provides a clean, selective and efficient process. Although the SC-CO2 method has been successfully used to extract lipids from microalgae, there are still some issues related to sample preparation and process parameters that need to be resolved. Therefore, this study investigates the effect of adding a modifier (ethanol) and using different types of holders (cotton and steam bun cloth) has on the yield of lipid from Nannochloropsis salina. The usage of a holder is required during the process due to the fine particles of the microalgae which have the potential to clog the instrument used. The SC-CO2 extraction without the modifier was conducted for 4 hours at 60°C, 30 MPa and CO2 flow rate of 4 ml/min, while the extraction with the modifier was conducted using 3.8 ml/min CO2 and 0.2 ml/min ethanol. It was found that the highest lipid yield of 0.16 g lipid / g dried microalgae was achieved using cotton cloth as a holder with the addition of the modifier. Lower amount of lipids were obtained when using the Soxhlet method (0.08 g lipid / g dried microalgae) and SC-CO2 without modification (0.02 g lipid / g dried microalgae). These preliminary findings show that the SC-CO2 process requires modifications to enhance the lipids yield from microalgae