Ashiwin Vadiveloo

The valorization of food and agro-industrial wastes into platform chemicals offers a sustainable solution to waste management and resource utilization, addressing both environmental and economic challenges. This review explores the latest advancements in bioconversion technologies for producing platform chemicals, such as bioethanol, lactic acid, succinic acid, and levulinic acid. It highlights the potential of utilizing agro-industrial residues, including crop residues, fruit and vegetable processing waste, and dairy by-products, as valuable feedstocks for chemical production. These residues, often discarded as waste, contain organic compounds that can be converted into essential platform chemicals, which are vital for biofuels, bioplastics, and specialty chemicals. The review examines both thermochemical and biochemical processes, such as pyrolysis, gasification, enzymatic hydrolysis, and fermentation, for converting food and agro-industrial wastes into valuable products. Case studies, including the enzymatic production of lactic acid from spoiled grains and anaerobic digestion of fruit wastes to produce volatile fatty acids, demonstrate the effectiveness of these technologies in waste valorization. Furthermore, the review discusses the environmental and economic benefits of waste-to-value processes, incorporating life cycle assessments and circular economy principles. Despite challenges such as feedstock variability, process scaling, and the need for regulatory standards, ongoing innovations in genetic engineering and integrated biorefineries present promising solutions for overcoming these barriers. The successful commercialization of these technologies requires collaboration among researchers, industries, and policymakers to foster sustainable production practices and reduce dependence on fossil-based resources, ultimately contributing to a circular bioeconomy.

Extremophile microalgae have been categorized into six main categories that include thermophiles (able to tolerate high temperatures up to the boiling point of water), psychrophiles (capable of living in cold environments below the freezing point of water), barophiles (able to tolerate pressure as high as 1,000 atm), halophiles (capable of growing at salinities up to saturation state), acidophiles (thriving well at pH close to zero), and alkaliphiles (capable of growing at high pH > 10.0). In addition, some microalgal strains have developed mechanisms to thrive in an environment with multiple stress conditions that are collectively known as polyextremophiles. Here, we examine several microalgae that grow in a wide range of extremophilic conditions. Descriptions of the potential products synthesized by these exceptional microorganisms applied biotechnology is discussed. Examples of genetic and metabolic engineering already adapted in some extremophilic microalgae are also presented. The future direction and exploitation of extremophilic microalgae cultivated on a large scale are suggested.

The shift toward the production of sustainable and green energies such as algal biofuels has necessitated prioritization of scale-up technologies to improve the overall techno-economics of the process. There is now a great emphasis on the development and adoption of digitization and automation technologies within the algae sector to meet the desired scale of production and for the optimization of operating parameters. The integration of advanced process control strategies, improvement in digitization, and data analytics are among the key elements required to meet the demand for low-cost microalgae commodities. Apart from the economics, real-time continuous monitoring and automated control of large-scale microalgae cultures are also essential to maximize the output of the system. In this chapter, we critically reviewed the growth and technical requirement of mass microalgae cultivation for biofuel production as well as various process control strategies, innovative physical equipment (e.g., proportional-integral-derivative and fuzzy logic controllers), and monitoring systems for the efficient automation of algae cultivation systems. We discussed the potential of novel and upcoming technologies (Industry 4.0 and 5.0) and tools (smart sensors and actuators) that can be potentially integrated within microalgae cultivation processes to enhance their continuous and remote monitoring, automation, and optimization. How upcoming technologies such as the application of Internet of Things (IoT) to automation and smart farming can contribute toward significant improvement in commercial algae production was also discussed. This chapter concludes with a brief discussion on the fundamental challenges that restrict the deployment of process control strategies and advanced equipment within microalgae cultivation processes, and future recommendations that can potentially be implemented to overcome these challenges and thus drive the establishment of the algae-based biofuel industry.

Naturally sourced colorants and dyes are currently gaining demand over synthetic alternatives due to an increase in consumer awareness brought forward by health and environmental issues. Microalgae are unicellular organisms which are microscopic in size and represent major photosynthesizers with the ability to efficiently convert available solar energy to chemical energy. Due to their distinct advantages over terrestrial plants such as faster growth rates, ability to grow on non-arable land, and diversity in the production of various natural bioactive compounds (e.g., lipids, proteins, carbohydrate, and pigments), microalgae are currently gaining promise as a sustainable source for the production of natural food-grade colorants. The versatility of microalgae to produce various pigments (e.g., chlorophylls, carotenoids, xanthophylls, and phycobiliproteins) that can be commercially exploited as a source of natural colorant is there to be explored. Various growth factors such as temperature, pH, salinity, and light in terms of both quality and quantity have been shown to significantly impact pigment production. In this chapter, we comprehensively review the characteristics of microalgal pigments and factors that affect pigment production in microalgae while evaluating the overall feasibility of exploiting them as a natural source of food colorants.

The increasing demand for food, energy and valuable bio-based products has necessitated the development of commodity end-products from unconventional, renewable and sustainable resources. Microalgae represent an attractive alternative for the production of food, energy, biomaterials and fine chemicals due to their environmentally friendly characteristics. Nonetheless, the commercial cultivation of microalgae for various end-products is currently restricted by high capital and operating cost. As such, the cultivation of microalgae in various wastewaters does not only improve the economics of this technology in terms of performance efficiency and production cost but also allows for the simultaneous treatment of the waste stream and the production of valuable biocommodities, such as biofuels, pigments, biofertilizers, proteins and other value-added biochemicals. This chapter focuses on the sustainable production and downstream processing options of various bio-based products produced from wastewater grown microalgae. This chapter also aims to provide an in-depth analysis and discussion of current trends on the dual potential of microalgae for wastewater treatment and its biotechnological application as novel sources of bioproducts.