Effect of Co-Solvents on Transesterification of Refined Palm Oil in Supercritical Methanol

This study examined the non-catalytic transesterification of refined palm oil, using supercritical methanol as a solvent with and without the presence of co-solvent, i.e. toluene, benzene, or hexane. Without the presence of a co-solvent, methyl esters can be produced via the non-catalytic transesterification of palm oil at 300oC, using a methanol to oil molar ratio of 45:1, with 89.4% conversion achieved after 50 min. The reaction performance could be improved by adding either benzene or toluene (with 10% v/v solvent to oil) as co-solvent to 92.1 and 95.1%, respectively, while reducing the required amount of excess methanol from 45:1 to 25:1. Under most conditions, the conversion of palm oil decreased with the addition of hexane due to its antisolvent properties

Microalgal Lipid Extraction and Evaluation of Single-Step Biodiesel Production

This work examined solvent extraction of lipid from microalgae for production of renewable biofuels, thereby allowing appropriate selection of solvent and extraction methods. The results of this study revealed that the mixture of chloroform and methanol (C/M) at the ratio of 2:1 (v/v) could extract the highest amount of total lipid from algae, while hexane was found to be a good solvent, concerning the selectivity for nonpolar targeted lipids such as mono-, di- and tri-glycerides. As far as the extraction methods are concerned, applying ultrasound could accelerate the rate of lipid extraction from algae with tough cell walls such as Chlorella vulgaris. On the other hand, ultrasound and microwave assisted extraction techniques added no benefits to the extraction of lipid from powder of Haematococcus pluvialis whose cell wall was previously damaged. Other than lipid extraction, this paper concerns with the development of transesterification process for algal lipid using C. vulgaris as a model system. Here, the effects of the amount of catalyst, alcohol to biomass ratio and reaction time on biodiesel yield were investigated. We also studied a single-step biodiesel production where extraction and transesterification simultaneously take place, and made comparison between this method and the conventional two-step biodiesel production process

An overview of the utilisation of microalgae biomass derived from nutrient recycling of wet market wastewater and slaughterhouse wastewater

Microalgae have high nutritional values for aquatic organisms compared to fish meal, because microalgae cells are rich in proteins, lipids, and carbohydrates. However, the high cost for the commercial production of microalgae biomass using fresh water or artificial media limits its use as fish feed. Few studies have investigated the potential of wet market wastewater and slaughterhouse wastewater for the production of microalgae biomass. Hence, this study aims to highlight the potential of these types of wastewater as an alternative superior medium for microalgae biomass as they contain high levels of nutrients required for microalgae growth. This paper focuses on the benefits of microalgae biomass produced during the phycore-mediation of wet market wastewater and slaughterhouse wastewater as fish feed. The extraction techniques for lipids and proteins as well as the studies conducted on the use of microalgae biomass as fish feed were reviewed. The results showed that microalgae biomass can be used as fish feed due to feed utilisation efficiency, physiological activity, increased resistance for several diseases, improved stress response, and improved protein retention

Enhanced Energy Recovery from Food Waste by Co-Production of Bioethanol and Biomethane Process

The primary objective of this research is to study ways to increase the potential of energy production from food waste by co-production of bioethanol and biomethane. In the first step, the food waste was hydrolysed with an enzyme at different concentrations. By increasing the concentration of enzyme, the amount of reducing sugar produced increased, reaching a maximum amount of 0.49 g/g food waste. After 120 h of fermentation with Saccharomyces cerevisiae, nearly all reducing sugars in the hydrolysate were converted to ethanol, yielding 0.43–0.50 g ethanol/g reducing sugar, or 84.3–99.6% of theoretical yield. The solid residue from fermentation was subsequently subjected to anaerobic digestion, allowing the production of biomethane, which reached a maximum yield of 264.53 ± 2.3 mL/g VS. This results in a gross energy output of 9.57 GJ, which is considered a nearly 58% increase in total energy obtained, compared to ethanol production alone. This study shows that food waste is a raw material with high energy production potential that could be further developed into a promising energy source. Not only does this benefit energy production, but it also lowers the cost of food waste disposal, reduces greenhouse gas emissions, and is a sustainable energy production approach

Effect of mixed light emitting diode spectrum on antioxidants content and antioxidant activity of red lettuce grown in a closed soilless system

Abstract Background Light spectra have been demonstrated to result in different levels of comfort or stress, which affect plant growth and the availability of health-promoting compounds in ways that sometimes contradict one another. To determine the optimal light conditions, it is necessary to weigh the vegetable’s mass against the amount of nutrients it contains, as vegetables tend to grow poorly in environments where nutrient synthesis is optimal. This study investigates the effects of varying light conditions on the growth of red lettuce and its occurring nutrients in terms of productivities, which were determined by multiplying the total weight of the harvested vegetables by their nutrient content, particularly phenolics. Three different light-emitting diode (LED) spectral mixes, including blue, green, and red, which were all supplemented by white, denoted as BW, GW, and RW, respectively, as well as the standard white as the control, were equipped in grow tents with soilless cultivation systems for such purposes. Results Results demonstrated that the biomass and fiber content did not differ substantially across treatments. This could be due to the use of a modest amount of broad-spectrum white LEDs, which could help retain the lettuce’s core qualities. However, the concentrations of total phenolics and antioxidant capacity in lettuce grown with the BW treatment were the highest (1.3 and 1.4-fold higher than those obtained from the control, respectively), with chlorogenic acid accumulation (8.4 ± 1.5 mg g− 1 DW) being particularly notable. Meanwhile, the study observed a high glutathione reductase (GR) activity in the plant achieved from the RW treatment, which in this study was deemed the poorest treatment in terms of phenolics accumulation. Conclusion In this study, the BW treatment provided the most efficient mixed light spectrum to stimulate phenolics productivity in red lettuce without a significant detrimental effect on other key properties

A Novel Lipid Extraction Method from Wet Microalga Picochlorum sp. at Room Temperature

A novel method using ethanol was proposed for extracting lipids from wet microalga Picochlorum sp. at room temperature and pressure. In this study, Central Composite design (CCD) was applied to investigate the optimum conditions of lipid extraction. The results revealed that the solvent to biomass ratio had the largest effect on lipid extraction efficiency, followed by extraction time and temperature. A high lipid extraction yield (33.04% of the dry weight) was obtained under the following extraction conditions: 5 mL solvents per gram of wet biomass for 37 min with gentle stirring at room temperature. The extraction yield was comparable to that obtained by the widely used Bligh-Dyer method. Furthermore, no significant differences in the distribution of lipid classes and fatty acid composition were observed according to different extraction methods. In conclusion, these results indicated that the proposed procedure using ethanol could extract lipids from wet biomass efficiently and had giant potential for lipid extraction at large scale