Kit Wayne Chew

Microalgae biorefinery: High value products perspectives

Microalgae have received much interest as a biofuel feedstock in response to the uprising energy crisis, climate change and depletion of natural sources. Development of microalgal biofuels from microalgae does not satisfy the economic feasibility of overwhelming capital investments and operations. Hence, high-value co-products have been produced through the extraction of a fraction of algae to improve the economics of a microalgae biorefinery. Examples of these high-value products are pigments, proteins, lipids, carbohydrates, vitamins and anti-oxidants, with applications in cosmetics, nutritional and pharmaceuticals industries. To promote the sustainability of this process, an innovative microalgae biorefinery structure is implemented through the production of multiple products in the form of high value products and biofuel. This review presents the current challenges in the extraction of high value products from microalgae and its integration in the biorefinery. The economic potential assessment of microalgae biorefinery was evaluated to highlight the feasibility of the process.

Analysis of Economic and Environmental Aspects of Microalgae Biorefinery for Biofuels Production: A Review

Microalgae are considered promising feedstock for the production of biofuels and other bioactive compounds, yet there are still challenges on commercial applications of microalgae‐based products. This review focuses on the economic analysis, environmental impact, and industrial potential of biofuels production from microalgae. The cost of biofuels production remains higher compared to conventional fuel sources. However, integration of biorefinery pathways with biofuels production for the recovery of value‐added products (such as antioxidants, natural dyes, cosmetics, nutritional supplements, polyunsaturated fatty acids, and so forth) could substantially reduce the production costs. It also paves the way for sustainable energy resources by significantly reducing the emissions of CO2, NOx, SOx, and heavy metals. Large‐scale biofuels production has yet to be successfully commercialized with many roadblocks ahead and heavy competition with conventional fuel feedstock as well as technological aspects. One of the prominent challenges is to develop a cost‐effective method to achieve high‐density microalgal cultivation on an industrial scale. The biofuels industry should be boosted by Governments support in the form of subsidies and incentives, for addressing the pressing climate change issues, achieving sustainability, and energy security.

Recent Developments and Applications of Three-Phase Partitioning for the Recovery of Proteins

Three-phase partitioning (TPP) is rapidly developing as a novel bioseparation technique for the separation and purification of biomolecules. TPP has been applied in a wide range of applications including enzyme stability and enhancement of its catalytic activity. The partitioning into three phases is mainly dependent on the concentration of alcohol and salt used. TPP provides high enzyme recovery and can be utilized along with external techniques such as ultrasound, microwave assisted, microaffinity ligand-facilitated and also ionic-liquid based. This technique has attracted interest in the large scale recovery of proteins from crude feedstocks or fermentation broths. In this review, the basic principles, refolding of proteins using TPP, key design variables of TPP, types of TPP, applications of TPP in food industry as well as the challenge of TPP were analyzed. The work presented in this review will be beneficial for further researches in TPP or related separation techniques.

An overview on the development of conventional and alternative extractive methods for the purification of agarose from seaweed

ABSTRACT This overview describes the development of the classical and alternative methodologies used for the extraction of agarose from seaweed. The first mentioned methods for agarose extraction, including acetylation of agar, methylation and extraction using polyether compounds, do not show high yield or good quality of agarose extract-product. Besides that, they ceased to be eco-friendly. The low level of their environmental sustainability has led to the development of alternative technologies to produce agarose in a more purified, ecological and cost-effective manner. Examples of these methods include mainly ionic liquid (IL)-based or bio-IL-based extraction. This review is aimed at providing a survey on agarose extraction techniques and methods related to biomolecules separation.

Biofuels from Microbial Lipids

Various alternatives have been exploited to produce biofuels economically and to reduce the environmental impacts with sustainable biowaste management. Lipids are valuable energy rich compounds that has the potential to replace conventional fossil fuels through the production of biofuels. Oleaginous microorganisms contain significant amount of microbial lipids consisting of special fatty acids with varied applications as food additives and nutraceuticals. Biofuels produced from microbial lipids as a third generation feedstock are a promising substitute for fossil fuels and animal fats or vegetable oils. However, the development and scalable production of biofuels from microbial lipids is yet to be commercialized and intensive research is required to evaluate the lipid extraction approaches for optimum biofuel production. In this chapter, we describe the sources of microbial lipids, factors that affect the microbial lipids production, technologies for microbial lipids conversion into biofuels. Alternative and innovative techniques for biofuel production and the life cycle impact of biofuel production from microbial lipids are also discussed.

Sonication and grinding pre-treatments on Gelidium amansii seaweed for the extraction and characterization of Agarose

Various pretreatments methods including sonication and grinding were performed on red seaweed Gelidium amansii for the subsequent extraction of agarose. The agarose products are usually extracted from agar powder products from seaweeds. In this study, the agarose was extracted using a direct polyethylene glycol (PEG) method without the need to first process the agar from seaweed. The agar extract was frozen then thawed and mixed directly with PEG solution to precipitate the agarose. The quality of agarose obtained was evaluated through physico-chemical properties analysis which includes spectral technique (FTIR), melting and boiling point, gel strength and sulfate content. These properties were compared with a non-pretreated sample and it was found that the addition of pretreatment steps improved the quality of agarose but gave a slightly lower yield. The gel strength of pretreated samples was much higher and the sulfate content was lower compared to non-pretreated samples. The best pretreatment method was sonication which gave gel strength of 742 g cm-2 and sulfate content of 0.63%. The extraction of agarose can be further improved with the use of different neutralizing agents. Pretreating the seaweed shows potential in improving the quality of agarose from seaweed and can be applied for future extraction of the agarose.

Food waste compost as an organic nutrient source for the cultivation of Chlorella vulgaris

The present study investigates the prospective of substituting inorganic medium with organic food waste compost medium as a nutrient supplement for the cultivation of Chlorella vulgaris FSP-E. Various percentages of compost mixtures were replaced in the inorganic medium to compare the algal growth and biochemical composition. The use of 25% compost mixture combination was found to yield higher biomass concentration (11.1%) and better lipid (10.1%) and protein (2.0%) content compared with microalgae cultivation in fully inorganic medium. These results exhibited the potential of combining the inorganic medium with organic food waste compost medium as an effective way to reduce the cultivation cost of microalgae and to increase the biochemical content in the cultivated microalgae.