Transforming wastewater-derived algae biodiesel with ammonium hydroxide emulsion for enhanced energy efficiency and emission reduction

• Integrating wastewater treatment enhances microalgae biodiesel production • Chlorella vulgaris cultivated in human urine shows effective nutrient removal • Ammonium hydroxide emulsion boosts biodiesel's energy efficiency and emissions • CVAB blended with diesel exhibits promising fuel characteristics and efficiency • Sustainable biodiesel production leverages low-cost wastewater resources effectively The growing demand for sustainable energy has prompted a search for alternative fuels, with microalgae-based biodiesel emerging as a promising option. However, improving its energy efficiency and minimizing environmental impacts remain key challenges. This study presents a novel approach by integrating wastewater-derived algae cultivation with ammonium hydroxide emulsion to enhance biodiesel performance. Chlorella vulgaris microalgae were grown in a medium of diluted human urine, where nutrient removal efficiency was evaluated, and biooil was extracted via solvent extraction. The resulting biodiesel was analyzed for elemental, chemical, and physicochemical properties. A 30% blend of chlorella vulgaris algae biodiesel (CVAB) with normal diesel fuel (NDF) was prepared. To further boost energy efficiency and emissions performance, ammonium hydroxide emulsion was added at concentrations of 5% and 10%. Results confirmed that wastewater-sourced algae cultivation is a viable method for sustainable biodiesel production. While CVAB's combustion characteristics were similar to NDF's, it exhibited a 7% decrease in brake thermal efficiency and a 5% increase in nitrogen oxide emissions. The addition of ammonium hydroxide emulsion notably improved both energy efficiency and emission profiles. This study highlights a breakthrough in using ammonium hydroxide emulsion to enhance algae biodiesel, making it a more competitive alternative to fossil fuels. Economically, this approach offers a dual advantage: utilizing low-cost wastewater for biodiesel production while improving fuel performance and reducing emissions.