Effects of several inocula on the biochemical hydrogen potential of sludge-vinasse co-digestion

Abstract

The influence of the inoculum on the Biochemical Hydrogen Potential test (BHP) was investigated. Thermophilic BHP from sludge-vinasses co-digestion (50:50) was studied employing three types of inocula: Acidogenic Inoculum, Sludge Inoculum and Thermal Sludge Inoculum. The maximum hydrogen yield was obtained with a sludge inoculum (177 mL H2/g VSadded). This yield was 21 and 36% higher than for acidogenic inoculum and thermal sludge inoculum, respectively. The results revealed that the choice of inoculum had significant impact on the hydrogen yield and the sludge inoculum is the most beneficial for BHP tests. The percentages between Eubacteria:Archaea increased from 59.2:40.8 to 92.0:9.0 during BHP tests using the sludge inoculum while it remained stablish in the others cases around 50:50. Furthermore, hydrogen production was accompanied by the generation of volatile fatty acids, mainly acetic, butyric and propionic acids. There were no differences in the rate of hydrogen production in any of the BHP.