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This study explores the potential of converting food waste (FW) in South Africa to biogas via anaerobic digestion (AD) using the Aspen Plus Simulator version 11. The simulation modeled the AD process, focusing on hydrolysis, acidogenesis, acetogenesis, and methanogenesis stages, with unconverted substrate recycling at the acetogenesis stage, employing a Non-Random Two-Liquid (NRTL) model for the polar mixture components. The FW used contained 49.86 % volatile solids (VS) of carbohydrates, 39.31 % VS of proteins, and 10.83 % VS of lipids. The results revealed that biogas yield at mesophilic temperature (37 °C) was 50 % higher than at thermophilic temperature (55 °C) with a residence time of 35 days, and methane composition was 45.98 % higher. Methane and carbon dioxide percentage compositions increased with hydraulic retention time (HRT), varying between 37.5–45.5 % and 34.3–39.9 % at mesophilic conditions. Economic analysis indicated a profitable outlook, with a payout period of 3 years, 5 months, and a 15-year positive revenue forecast. The project exhibited an internal rate of return (IRR) of 59.6629 %, suggesting strong economic viability and potential for investment. This study underscores the potential for optimized AD processes to enhance biogas production from FW in South Africa, presenting a viable, eco-friendly waste management solution.

In the search for an eco-friendly fuel, bio-oil is a promising alternative to fossil fuels due to its potential to reduce environmental impacts and its versatility in various applications. According to the International Energy Agency, biofuel demand will increase by 41 billion liters, or 28%, between 2021 and 2026. About 5% of the primary energy in the United States in 2021 came from biomass resources, producing nearly 5,000 trillion BTU. However, a major challenge facing bio-oil production is the limited lignocellulosic biomass resources as feedstock and the costly supply chain. Non-edible plant seeds are abundant as fruity plants and yield bio-oil with good heating values, but they are yet to get the required attention. They are usually discarded after consuming their mesocarp, contributing to environmental waste. Also, bio-oil requires improvement due to various issues like strong corrosive effects, high acidity, and a high water content. This review, therefore, provides an overview of the bio-oil from waste plant seeds as lignocellulosic biomass feedstocks for producing biofuel using pyrolysis. The findings reveal an average 47.85% bio-oil yield from plant seeds with more bioenergy value than that from other tree parts' biomass resources; it can be upgraded using catalytic, co-pyrolysis, and distillation improvement approaches for its potential usage as an energy source. This highlight also provides the future and challenges of using this bio-oil as an alternative energy source, presenting a clean and affordable biofuel production feedstock that can mitigate climate change through a cleaner environment, plus new ways of recycling waste.