Start-up of hydrogen bio-production reactor and ethanol-type fermentation

To find out the law of rapid start-up the natural response of an continuous stirred-tank reactor (CSTR) for hydrogen bio-production using molasses wastewater as substrate was investigated. Emphasis was placed on assessing organic loading rate (OLR) on the ethanol-type fermentation during the system's start-up process. It was found that at an initial biomass of 6.24 gVSS/L and an OLR of 7.0 kgCOD/m³ d, an equilibrial microbial community in the ethanol-type fermentation could be established within 30 days while the hydraulic retention time (HRT) was controlled at 6 h, pH and ORP were kept within the ranges of 4.0-4.3 and-440 - -470 mV, respectively. Following that, hydrogen production rates in the reactors were relatively stable and the rapid start-up of hydrogen bio-production reactor was finished. When the initial OLR were set at different levels (3.0, 7.0 and 10.0 kgCOD/ m³ d), the rates of hydrogen production after 30 days of start-up were quite different. Specifically, when OLR was achieved at 30 kgCOD/m³ d, the hydrogen production rate of ethanol-type fermentative bacteria initially acclimated with 7.0 kgCOD/m³ d loading was 56% higher than that acclimated with 3.0 kgCOD/m³ d.