Aina Christalia Rinastiti, Dianita Ivana Permata, Bekti Palupi, Zuhriah Mumtazah, Meta Fitri Rizkiana, Atiqa Rahmawati

Effect of Time, pH, and Yeast Concentration on Bioethanol Levels in the Ulva sp. Fermentation Process

Introduction

Effect of time, ph, and yeast concentration on bioethanol levels in the ulva sp. Fermentation process. Optimize bioethanol production from Ulva sp. via fermentation. This study determined optimal conditions (7 days, pH 5.5, 1.5% yeast) yielding 7.55% bioethanol, showcasing its renewable energy potential.

Abstract

Bioethanol is a form of renewable energy that is used to reduce dependence on the use of fossil fuels which cause various negative impacts on the environment. Ulva sp. contains high carbohydrates so it has the potential as a raw material for bioethanol production. This study aims to determine the optimum conditions of the fermentation process with the variables used time, pH, and yeast concentration. This study used the results of hydrolysis of Ulva sp. with optimum operating conditions of 0.1 N HCl concentration, 80 mesh particle size, and 450 watt microwave power. Measurement of bioethanol levels was carried out using an alcoholmeter. The results showed that the optimal conditions for fermentation were 7 days of fermentation, pH 5.5, and yeast concentration of 1.5% which resulted in a bioethanol content of 7.55%.

Review

This study presents a timely and relevant investigation into optimizing bioethanol production from *Ulva sp.*, a promising non-food marine biomass with high carbohydrate content. The increasing global demand for renewable energy sources and the associated environmental concerns with fossil fuels underscore the importance of such research. The authors have set out to systematically determine the optimal fermentation conditions by varying key parameters: fermentation time, pH, and yeast concentration, building upon a previously optimized hydrolysis step for the *Ulva sp.* feedstock. This focused approach on refining the fermentation stage is a crucial step towards developing a viable and efficient bioethanol production pathway from this sustainable raw material. A significant strength of this work lies in its systematic approach to identifying the most favorable fermentation conditions. The abstract clearly highlights the experimental design, which methodically explores the impact of time, pH, and yeast concentration on bioethanol yield. The primary finding—that optimal conditions for fermentation were achieved at 7 days, pH 5.5, and a 1.5% yeast concentration, resulting in a bioethanol content of 7.55%—provides valuable empirical data. This result offers a concrete benchmark for subsequent research and process development, demonstrating the potential of *Ulva sp.* as a feedstock when coupled with carefully controlled fermentation parameters. The prior optimization of the hydrolysis process (0.1 N HCl, 80 mesh, 450 watt microwave) also indicates a comprehensive understanding of the overall conversion pathway. While the study provides valuable insights, a few aspects could be elaborated upon or considered for future work. The reliance on an alcoholmeter for bioethanol level measurement, while practical, might lack the precision and specificity of more advanced analytical techniques such as gas chromatography, which could also quantify other fermentation byproducts. Furthermore, the reported 7.55% bioethanol content, while a positive outcome, would benefit from being contextualized with comparative yields from other algal or lignocellulosic feedstocks in similar research, or discussed in terms of its theoretical maximum yield from the carbohydrate content. Future studies could explore the use of different yeast strains, investigate the impact of nutrient supplementation, or conduct a techno-economic analysis to assess the industrial feasibility and cost-effectiveness of this process at a larger scale. Despite these considerations, this paper lays a solid foundation for advancing the utilization of *Ulva sp.* in sustainable bioethanol production.

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