Control strategies for hydrogen production through co-culture of Ethanoligenens harbinense B49 and immobilized Rhodopseudomonas faecalis RLD-53

The role of pH control on biohydrogen production by single stage hybrid dark- and photo-fermentation

“…Other control approaches proposed in literature are: high initial pH, high concentration of buffering agent (usually phosphate buffer), as well as an appropriate light/dark bacteria ratio in the inoculum (Ding et al, 2009;Kargi and Ozmihci, 2010;Liu et al, 2010a;Xie et al, 2010). Xie et al (2010) showed that high initial pH prevented pH decrease during process but further increase in initial pH to 8.0 and 9.0 resulted in a significant decrease of hydrogen production. Indeed, application of elevated initial pH may limit the activity of dark fermentation bacteria, which should be the first step in the co-culture processes.…”

“…Nevertheless, high levels of buffering agents is not preferable for real-life applications since it greatly increases the operation costs. Moreover, some bacteria are sensitive to high phosphate concentration (Xie et al, 2010;Zagrodnik, 2014). Application of variable light/dark bacteria ratios is not the optimal solution either.…”

“…The optimum pH for photo-hydrogen production is around 7.0 (Kim et al, 2012). Previous studied have shown that the major barrier for high hydrogen yields was pH fell to about 4.5-5.5 when substrate was consumed excessively in dark fermentation process (Ding et al, 2009;Liu et al, 2010a;Xie et al, 2010). The reason for this is the fact that production rate of VFAs by dark fermentation was much higher than their consumption by photofermentation.…”

“…Combined dark-light fermentations for bio-hydrogen production may have advantages over sequential fermentation by reducing fermentation time and increasing the hydrogen productivity . However, there are limited number of studies for such processes and there is little known about control strategies of co-culture systems (Xie et al, 2010).…”

Feasibility studies on continuous hydrogen production using photo-fermentative sequencing batch reactor

“…Among various hydrogen production processes, biological hydrogen production stands out as an environmentally harmless process carried out under mild operating conditions, using renewable resources [2]. Photo-fermentative hydrogen production offers distinct advantages for hydrogen production such as high theoretical hydrogen yield [3], ability to convert wide spectrum of light in to hydrogen gas [4], none oxygen evolution and utilization metabolites from dark fermentation [5,6]. However, the reported rates and yields of fermentative hydrogen production are not high enough to make the process economically viable [7].…”