A significant fraction of the food produced worldwide is currently lost or wasted throughout the supply chain, squandering natural and economic resources. Food waste valorization will be an important necessity in the coming years. This work investigates the ability of food waste to serve as a viable nutritional substrate for the heterotrophic growth of Chlorella vulgaris. The impact of different pretreatments on the elemental composition and microbial contamination of seven retail food waste mixtures was evaluated. Among the pretreatment methods applied to the food waste formulations, autoclaving was able to eliminate all microbial contamination and increase the availability of reducing sugars by 30%. Ohmic heating was also able to eliminate most of the contaminations in the food wastes in shorter time periods than autoclave. However, it has reduced the availability of reducing sugars, making it less preferable for microalgae heterotrophic cultivation. The direct utilization of food waste containing essential nutrients from fruits, vegetables, dairy and bakery products, and meat on the heterotrophic growth of microalgae allowed a biomass concentration of 2.2 × 10⁸ cells·mL⁻¹, being the culture able to consume more than 42% of the reducing sugars present in the substrate, thus demonstrating the economic and environmental potential of these wastes.

This work investigated the biomasses (seeds, seed husks, oilseed grains, crude and purified oils, cakes by pressing and by hexane extraction and methyl biodiesel the oil) of Moringa oleifera Lamarck, starting with its seedpods (ripe and dry fruits) in energetic application. The oil obtained from the grains by mechanical pressing had an average yield of 11.36% and of 36.48% by hexane extraction. The moringa biomasses presented calorific values between 15.87 and 37.53 MJ/kg, being suitable as renewable biofuels. The mixed crude oil (1:4) was refined in four steps: degumming, neutralization, washing and drying. The crude and refined oils were characterised by acidity index, peroxide index, water content, turbidity, specific mass, kinematic viscosity, power calorific higher, calorific power below and ash content. The crude oils by pressing and by solvent extraction were characterised through of the saponification index and iodine value. The purified biodiesel presented specific mass of 889 kg/m3 (20 oC), kinematic viscosity of 5.5 m2/s (40 oC), content of ester of 86.2% and 98.23% (in microscale, ratifying the viability of the method), acidity index of 0.43 mg KOH/g and water content of 615.8 mg/kg. The solid moringa biomasses (seeds, cakes (or pies) and the seed husks) show high potential for the production of briquettes or ecological firewood due to its content energy expressed as lower calorific value (between 15.87 and 23.31 MJ/kg) and simple and accessible technological production. The results show that moringa is an easily exploitable plant in sustainable energy, especially from its seedpods and seeds.

The European Union's Methane Action Plan outlined policies and targets supporting the Global Methane Pledge to cut CH₄ emissions by 30% by 2030, yet urgent implementation is needed to treat medium and diluted CH₄ streams. Microalgae-based technologies offer a groundbreaking solution, merging CH₄ mitigation with biomass valorization to drive sustainable industrial practices. This review examines three key applications: photosynthetic biogas upgrading, a viable alternative to physical/chemical methods, producing biomethane and valuable algal biomass; microalgae-methanotroph co-cultivation, a promising but underdeveloped method for diluted CH₄ streams; and CH₄-producing microalgae, unveiling a novel route for biomethane production. Despite their potential, significant research gaps remain, particularly in reactor design, culture conditions, and large-scale viability. By addressing these challenges, microalgae could revamp CH₄ management, bridging environmental goals with bioeconomic progress. This review calls for policy updates, intensified research, and industrial engagement to unlock microalgae's full potential in CH₄ mitigation and valorization.