Assistant Professor UAE University, United Arab Emirates
Abstract Description: This study investigates hydrogen (H₂) production in a batch reactor using a co-culture of Chlamydomonas reinhardtii and activated sludge bacteria, with a focus on the impact of different glucose-to-ethanol ratios. Three conditions were tested: daily addition of 2.5 g/L glucose for 4 days, 7.5 g/L glucose with 2.5 g/L (3.167 mL) ethanol, and 5 g/L glucose with 5 g/L (6.334 mL) ethanol. The first condition produced 411.7 mL/L of total gas, with H₂ comprising 24% and the pH decreasing from 8.14 to 3.93 over 4 days. The second condition resulted in 701.87 mL/L of total gas, with H₂ accounting for 34.98% and the pH dropping from 9.31 to 4.01 over 5 days. The third condition yielded the highest gas volume, 858.93 mL/L, with H₂ making up 36.13%, and the pH decreasing from 9.47 to 4.67, maintaining the highest final pH of all conditions. Notably, the third condition extended the experiment duration to 6 days, compared to 4 and 5 days for the other conditions. The observed pH decline in all conditions was attributed to the accumulation of volatile fatty acids, which influenced gas production trends. These findings highlight the importance of glucose-to-ethanol ratios in optimizing H₂ production, with the highest glucose-to-ethanol ratio resulting in greater gas yield, longer reaction times, and a more favorable final pH. This contributes to sustained hydrogen production, emphasizing the potential for continuous gas generation in future biotechnological applications. Furthermore, the results underscore the efficiency of the co-culture system, particularly with the inclusion of activated sludge bacteria, in enhancing bio-hydrogen output.
