Bio-processing of algal bio-refinery: a review on current advances and future perspectives

Microalgae biomass contains various useful bio-active components. Microalgae derived biodiesel has been researched for almost two decades. However, sole biodiesel extraction from microalgae is time-consuming and is not economically feasible due to competitive fossil fuel prices. Microalgae also contains proteins and carbohydrates in abundance. Microalgae are likewise utilized to extract high-value products such as pigments, anti-oxidants and long-chain polyunsaturated fatty acids which are useful in cosmetic, pharmaceutical and nutraceutical industry. These compounds can be extracted simultaneously or sequentially after biodiesel extraction to reduce the total expenditure involved in the process. This approach of bio-refinery is necessary to promote microalgae in the commercial market. Researchers have been keen on utilizing the bio-refinery approach to exploit the valuable components encased by microalgae. Apart from all the beneficial components housed by microalgae, they also help in reducing the anthropogenic CO2 levels of the atmosphere while utilizing saline or wastewater. These benefits enable microalgae as a potential source for bio-refinery approach. Although life-cycle analysis and economic assessment do not favor the use of microalgae biomass feedstock to produce biofuel and co-products with the existing techniques, this review still aims to highlight the beneficial components of microalgae and their importance to humans. In addition, this article also focuses on current and future aspects of improving the feasibility of bio-processing for microalgae bio-refinery

A system dynamics approach to pollution remediation and mitigation based on increasing the share of renewable resources.

This study explores the role of renewable energy (RE) penetration in Malaysia's energy security (ES) and its implications for the country's target of 20% capacity in the energy mix by 2025. Renewable energy (RE) is a critical driver of long-term energy security. In 2018, the share of renewable energy in Malaysia's energy mix was 9%, falling far short of the national target of 20% penetration by 2025. This study employs a system dynamics approach to investigate the relationship between RE penetration and correlated indicators from energy security (ES) dimensions: energy availability, environmental sustainability, and socio-economics. The causal relationships between the three-dimensional indicators of ES have been established using causal and stock and flow logic. Simulated results show that energy consumption has increased sharply, while energy efficiency and economic growth have only increased by a small margin with an increase in RE from 2015 to 2020. The energy intensity is expected to rise slightly by the end of the fifth year. As a result, the overall impact is positive for Malaysia's environmental sustainability while reducing its reliance on energy imports and meeting national economic growth demands

Conversion of the toxic and hazardous Zanthoxylum armatum seed oil into methyl ester using green and recyclable silver oxide nanoparticles

The cleaner and sustainable production of biodiesel from toxic and hazardous non-edible seed oils offer a remarkable opportunity to deal with energy crises and provide a renewable substitute to depleting fossil fuels. In the current study, the potential of the novel, toxic and non-edible seed oil of Zanthoxylum armatum was investigated for eco-friendly production of biodiesel catalysed by green nanoparticles of silver oxide. Silver oxide nanoparticles were synthesised with aqueous leaf extract of Silybum marianum. Heterogeneous green nanocatalysts were preferred due to their recyclable nature and easy recovery. The maximum yield of 95% of methyl ester was obtained at optimum reaction conditions of oil to methanol molar ratio 1:7, catalyst loading 0.5 (wt.%), reaction temperature 90 °C and reaction time 2 h. Characterisation of synthesised nanoparticles of silver oxide was carried out with X-Ray diffraction (XRD), scanning electron microscopy (SEM), and energy diffraction X-ray (EDX). Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) confirmed the formation of methyl esters. 5, 8-octadecenoic acid was found to be the major fatty acid methyl ester in the biodiesel sample. Fuel properties of biodiesel were investigated and found comparable to international standards of ASTM D-6571 and EN-14214. It was concluded from the current investigation that Zanthoxylum armatum is a potential biomass feedstock for the sustainable production of biodiesel using green nanoparticles of silver oxide

Food and High Value Products from Microalgae: Market Opportunities and Challenges

Microalgae are a potential source of molecules for a wide range of food and novel high-value products and have good market opportunities. They can be used in biofuels, health complements, feed, medicine and cosmetics. The development of innovative and sustainable technologies with minimum energy inputs is required for large-scale cultivation and downstream processing of lipids and hydrocarbons in order for the production to be economically viable. In addition, the viability of bioenergy production from microalgae biomass is contingent on the net energy gain of the overall process, with exhaustive utilization of algal biomass for biofuel and other co-products for feed, food, and chemicals. The energy output from the biomass as fuel has to be greater than the energy required to produce and process the algae. Microalgae produce a comprehensive variety of bioproducts such as enzymes, pigments, lipids, sugars, vitamins and sterols. Moreover, its capability to alter atmospheric CO2 into beneficial products such as lipids, carbohydrates, metabolites and proteins cannot be overstated. The key challenges appear to be high cost of operation, infrastructure and maintenance, selection of algal strains with high protein contents, dewatering and commercial scale harvesting. Optimizing the manufacture and commercialization of microalgae value products depend also on numerous factors (such as market and financial affairs). There is limitation of authentic and reliable data and statistics of microalgae market opportunities which make it difficult to assess their actual potential. Long-term research is needed to develop systems for the production of sustainable algal-based products, as sustainability is a key concern especially for food, feed and fuel