Background: Bio-ethanol is a renewable, clean-burning liquid fuel with minimal environmental impact compared to petroleum-based alternatives. It can be produced from various organic wastes using either chemical or biological methods. While ethene from fossil sources can be hydrated to form ethanol, fermentation of sugar-rich feedstocks remains a viable alternative. Purpose: This study aims to produce bio-ethanol from agricultural residues and organic wastes, specifically rice husk, biochar, Spirogyra, and seaweed using acid and base hydrolysis. Methods: Rice husks were sourced from Effium Rice Mill, Ohaukwu (Ebonyi State, Nigeria), with a portion converted into biochar via pyrolysis at the Alex Ekwueme Federal University Ndufu-Aliki Ikwo Biotechnology Laboratory. Spirogyra and seaweed were collected from Okpuitumo Dam, Ikwo (Ebonyi State), thoroughly washed, oven-dried, pulverized, and sieved to uniform particle size (250 mm). Samples were characterized to determine lignin, cellulose, hemicellulose, and lignocellulose content. Pretreatment, hydrolysis, saccharification, and fermentation processes were conducted to evaluate ethanol yield. Results: Acid hydrolysis using 1 mol/dm³ hydrochloric acid yielded the highest ethanol output (59.53%) compared to 1 mol/dm³ sodium hydroxide. Among the substrates, seaweed and Spirogyra showed the highest bio-ethanol yields at 59.53% and 41.88%, respectively. Conclusion: Algal biomass, particularly seaweed and Spirogyra, represents a high-potential, underutilized resource for bio-ethanol production. Acid-mediated hydrolysis is especially effective and should be further explored for sustainable biofuel generation.
Nwankwo Samuel Chiemerie (2026) studied this question.