Optimization of photosynthetic hydrogen gas production by green alga in sulfur deprived condition

Abstract

Objective: To study the effects of nutrient concentrations, pH, sodium carbonate concentration and microwave irradiation on the growth and the hydrogen production rate of the algae Chlamydomonas reinhardtii. Method/Analysis: In this study the factors affecting the growth rate and hydrogen production by C. reinhardtii were evaluated using Response Surface Methodology (RSM). For maximum specific growth rate of the algae changes of ammonium, phosphate and sulfate concentration in the culture medium were studied. Findings: The optimum conditions determined were 7.2 mM of ammonium concentration, 1.81 mM of phosphate concentration and 1.89 mM of sulfate concentration with a maximum specific growth rate of 0.01662/h. Likewise, for hydrogen production rate, changes of ammonium and phosphate concentration as well as pH of the medium were investigated. The optimum condition were 7 mM of ammonium concentration, 1.94 mM of phosphate concentration and pH value of 8 with maximum hydrogen yield of 2784.73 ppm. Moreover it was determined that the microalgae grows best with 0.25% (v/v) of sodium carbonate added into the growth medium as additional carbon source. Novelty/Improvements: Optimization of the process of algae growth and hydrogen production with different levels was achieved using the RSM Box-Behnken design experiment.