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<p>Hydrogen is a promising alternative energy source that can help meet future global energy demands while replacing fossil fuels. It offers eco-friendliness, enhanced energy security, economic benefits, and a pathway for decarbonization. Microalgae, particularly those with improved growth rates, are being explored for bio-hydrogen extraction, as their high water content can affect the stability of gasification processes. This investigation aims to enhance the growth rate of microalgae in grey wastewater by using varying concentrations of cerium oxide (CeO<sub>2</sub>) at 0.2, 0.4, and 0.6 vol%. These microalgae serve as biomass feedstock for bio-hydrogen production via potassium hydroxide (KOH) catalyzed supercritical water gasification (SCWG). The gasification process is carried out at temperatures between 300 and 500&#xa0;°C with a residence time of 30&#xa0;min at a pressure of 25&#xa0;bar. The study measures the impact of CeO<sub>2</sub> on the specific growth rate of microalgae and the harvesting efficiency. Results indicate that 0.6 vol% of CeO<sub>2</sub> achieves the highest specific growth rate of 0.81 µ/day and a harvesting efficiency of 87%. The presence of CeO<sub>2</sub> nanoparticles contributes to increased microalgae density, promoting higher biomass concentration and supporting enhanced hydrogen production. This feedstock undergoes a bio-conversion SCWG process, and the effects of gasification temperature and KOH catalyst concentration on various parameters such as molar fraction, hydrogen (H<sub>2</sub>) gas yield, hydrogen selectivity, and gasification efficiency are investigated. At a gasification temperature of 500&#xa0;°C, the KOH catalyst demonstrates excellent performance, yielding molar fractions of 57% hydrogen and 24% methane, along with a high H<sub>2</sub> yield of 24&#xa0;mol/kg, hydrogen selectivity of 17.8, and a gasification efficiency of 87%, which is better than lower gasification temperature. The hydrogen extracted from grey wastewater microalgae is suggested for use in energy sectors, such as the automotive and power generation industries.</p>

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Cerium oxide activated microalgae growth from grey wastewater for bio-hydrogen extraction via KOH catalyst adopted gasification route: performance evaluation

  • 期刊论文

  • 发表日期：

    2025年2月7日

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  • R. Venkatesh,
  • Aman Sharma,
  • Nagabhooshanam Nagarajan,
  • K. Karthik,
  • Apurv Verma,
  • Manzoore Elahi M. Soudagar,
  • Mohanavel Vinayagam,
  • Sami Al Obaid,
  • Sulaiman Ali Alharbi

摘要

Hydrogen is a promising alternative energy source that can help meet future global energy demands while replacing fossil fuels. It offers eco-friendliness, enhanced energy security, economic benefits, and a pathway for decarbonization. Microalgae, particularly those with improved growth rates, are being explored for bio-hydrogen extraction, as their high water content can affect the stability of gasification processes. This investigation aims to enhance the growth rate of microalgae in grey wastewater by using varying concentrations of cerium oxide (CeO2) at 0.2, 0.4, and 0.6 vol%. These microalgae serve as biomass feedstock for bio-hydrogen production via potassium hydroxide (KOH) catalyzed supercritical water gasification (SCWG). The gasification process is carried out at temperatures between 300 and 500 °C with a residence time of 30 min at a pressure of 25 bar. The study measures the impact of CeO2 on the specific growth rate of microalgae and the harvesting efficiency. Results indicate that 0.6 vol% of CeO2 achieves the highest specific growth rate of 0.81 µ/day and a harvesting efficiency of 87%. The presence of CeO2 nanoparticles contributes to increased microalgae density, promoting higher biomass concentration and supporting enhanced hydrogen production. This feedstock undergoes a bio-conversion SCWG process, and the effects of gasification temperature and KOH catalyst concentration on various parameters such as molar fraction, hydrogen (H2) gas yield, hydrogen selectivity, and gasification efficiency are investigated. At a gasification temperature of 500 °C, the KOH catalyst demonstrates excellent performance, yielding molar fractions of 57% hydrogen and 24% methane, along with a high H2 yield of 24 mol/kg, hydrogen selectivity of 17.8, and a gasification efficiency of 87%, which is better than lower gasification temperature. The hydrogen extracted from grey wastewater microalgae is suggested for use in energy sectors, such as the automotive and power generation industries.