Cost-cutting strategies, production, and characterisation of microalgal-based biodiesel using a locally designed photobioreactor

Commercialisation of biodiesel is hampered by the high costs of the upstream and downstream production processes in microalgae-biodiesel refineries. Although closed photobioreactors are effective at producing biomass and lipids on a large scale, which are crucial for the amount and quality of biodiesel produced, the high cost of biodiesel commercialisation is exacerbated by the expenses associated with purchasing it and some of its components. The goal of this study is to solve the high expense of purchasing a photobioreactor by designing and constructing a 30-liter stirred tank stainless steel rectangle shaped photobioreactor (STSSRSP) for the production of biodiesel. The photobioreactor was constructed locally with premium, cost-effective materials. Lipid extraction, quantification, and biomass concentration were ascertained by filtering, solvent extraction, and gravimetric techniques. Sulphuric acid was utilised as a catalyst to transesterify lipids into biodiesel. For biodiesel characterisation, techniques from the American Society for Testing for Materials, Fourier Transform Infrared spectrometry (FTIR), gas chromatography-mass spectrometry (GC-MS), and predictive models based on fatty acid content were employed. Scenedesmus obliquus OSC and Chlorella vulgaris UIA showed the maximum biomass concentrations (21.85 ± 0.03 and 18.62 ± 0.02 g/L), lipid contents (89.30 ± 0.06 and 84.95 ± 0.08%), and optimal biodiesel yields (99.49 ± 0.01 and 96.46 ± 0.02%) after day four of cultivation. Biodiesel's physical and chemical characteristics met acceptable international criteria, and it’s saturated, monounsaturated, and polyunsaturated fatty acid composition and percentages are excellent. Chlorella vulgaris UIA and Scenedesmus obliquus OSC are highly promising and perfect for producing biodiesel, while the built STSSRSP is creative, affordable, and effective, as seen by the outcomes obtained.