Effects of cell density, carbon dioxide and molybdenum concentration on biohydrogen production by Anabaena variabilis ATCC 29413

Abstract

This paper aims to determine the effects of cell density, carbon dioxide, and molybdenum concentration towards hydrogen production rate. Batch cultures of Anabaenavariabilis sp. were incubated in anaerobic environment under continuous indoor illumination of 70μEm−2s−1 at 35°C. The optimal volumetric hydrogen production rate obtained was 44μmolH2mgchl a−1h−1 occurred at cells density of 110mgL−1, 5% carbon dioxide headspace concentration, and molybdenum concentration of 1.6mM. The effect of organic carbon source (glucose) was also evaluated in the present study and it was found that the additional carbon produced the highest hydrogen production rate in all conditions. An increased concentration of molybdenum significantly enhanced the hydrogen productivity rate almost to that of glucose-supplemented culture at 49μmolH2mgchl a−1h−1. However, further increase in molybdenum concentration beyond 1.6mM showed no further improvement in the amount of hydrogen produced.