Low-cost biodiesel production using waste oil and catalyst

Advancing the bioconversion process of food waste into methane: A systematic review

With the continuous rise of food waste (FW) throughout the world, a research effort to reveal its potential for bioenergy production is surging. There is a lack of harmonized information and publications available that evaluate the state-of-advance for FW-derived methane production process, particularly from an engineering and sustainability point of view. Anaerobic digestion (AD) has shown remarkable efficiency in the bioconversion of FW to methane. This paper reviews the current research progress, gaps, and prospects in pre-AD, AD, and post-AD processes of FW-derived methane production. Briefly, the review highlights innovative FW collection and optimization routes such as AI that enable efficient FW valorization processes. As weather changes and the FW sources may affect the AD efficiency, it is important to assess the spatio-seasonal variations and microphysical properties of the FW to be valorized. In that case, developing weather-resistant bioreactors and cost-effective mechanisms to modify the raw substrate morphology is necessary. An AI-guided reactor could have high performance when the internal environment of the centralized operation is monitored in real-time and not susceptible to changes in FW variety. Monitoring solvent degradation and fugitive gases during biogas purification is a challenging task, especially for large-scale plants. Furthermore, this review links scientific evidence in the field with full-scale case studies from different countries. It also highlights the potential contribution of ADFW to carbon neutrality efforts. Regarding future research needs, in addition to the smart collection scheme, attention should be paid to the management and utilization of FW impurities, to ensure sustainable AD operations.

The Role of Bioeconomy in the Future Energy Scenario: A State-of-the-Art Review

The bioeconomy aims at decreasing reliance on fossil fuels, preventing or reducing climate change, eliminating insecurity, and efficiently using resources; however, fierce controversy exists on conceivable pathways to accomplish these objectives. The transport sector alone, which encompasses all other industrial sectors, has grown with regard to its energy demand by 50% over the past 30 years. The aim of this paper is to promote a dialogue as to whether an economy based on biomass can be more sustainable than today’s existing economies, considering that the economy needs to expand and be boosted, while creating a cascading and recycling system. This semi-systematic review paper discusses four research questions based on findings from the last 20 years: (i) What are the crucial issues in the ongoing debate on the development of a sustainable bioeconomy concept? (ii) Where are the major conflicting points and focuses? (iii) How does the bioeconomy follow current urbanization and land-abandonment trends? (iv) How will the crisis linked to the COVID-19 pandemic change these previous scenarios? As it is not easy to currently predict which pathway will be the most effective, whether it be the one taken as of now or a specific novel pathway, this article recommends following a strategy that is diverse regarding its approaches to shaping the bioeconomy and further funding of renewable energy sources, along with the involvement of urban planning. In addition, conclusions are validated through a questionnaire completed by 51 experts in the field.

A Valuable Product of Microbial Cell Factories: Microbial Lipase

As a powerful factory, microbial cells produce a variety of enzymes, such as lipase. Lipase has a wide range of actions and participates in multiple reactions, and they can catalyze the hydrolysis of triacylglycerol into its component free fatty acids and glycerol backbone. Lipase exists widely in nature, most prominently in plants, animals and microorganisms, among which microorganisms are the most important source of lipase. Microbial lipases have been adapted for numerous industrial applications due to their substrate specificity, heterogeneous patterns of expression and versatility (i.e., capacity to catalyze reactions at the extremes of pH and temperature as well as in the presence of metal ions and organic solvents). Now they have been introduced into applications involving the production and processing of food, pharmaceutics, paper making, detergents, biodiesel fuels, and so on. In this mini-review, we will focus on the most up-to-date research on microbial lipases and their commercial and industrial applications. We will also discuss and predict future applications of these important technologies.

Biodiesel Production From Lignocellulosic Biomass Using Oleaginous Microbes: Prospects for Integrated Biofuel Production

Biodiesel is an eco-friendly, renewable, and potential liquid biofuel mitigating greenhouse gas emissions. Biodiesel has been produced initially from vegetable oils, non-edible oils, and waste oils. However, these feedstocks have several disadvantages such as requirement of land and labor and remain expensive. Similarly, in reference to waste oils, the feedstock content is succinct in supply and unable to meet the demand. Recent studies demonstrated utilization of lignocellulosic substrates for biodiesel production using oleaginous microorganisms. These microbes accumulate higher lipid content under stress conditions, whose lipid composition is similar to vegetable oils. In this paper, feedstocks used for biodiesel production such as vegetable oils, non-edible oils, oleaginous microalgae, fungi, yeast, and bacteria have been illustrated. Thereafter, steps enumerated in biodiesel production from lignocellulosic substrates through pretreatment, saccharification and oleaginous microbe-mediated fermentation, lipid extraction, transesterification, and purification of biodiesel are discussed. Besides, the importance of metabolic engineering in ensuring biofuels and biorefinery and a brief note on integration of liquid biofuels have been included that have significant importance in terms of circular economy aspects.