Combined effects of temperature and pH on biohydrogen production by anaerobic digested sludge

A full factorial design was conducted to investigate the combined effects of temperatures and initial pH on fermentative hydrogen production by mixed cultures in batch tests. The experimental results showed that the modified Logistic model can be used to describe the progress of cumulative hydrogen production in the batch tests of this study. The modified Ratkowsky model can be used to describe the combined effects of the temperatures and initial pH on the substrate degradation efficiency, hydrogen yield and average hydrogen production rate. The temperatures and initial pH had interactive impact on fermentative hydrogen production. The maximum substrate degradation efficiency, the maximum hydrogen yield and the maximum average hydrogen production rate was predicted at the temperature of 37.8 °C and the initial pH of 7.1, 37.4 °C and 6.9, and 38.2 °C and 7.2, respectively. In general, the optimal temperature for the fermentative hydrogen production was around 37.8 °C and the optimal initial pH for the fermentative hydrogen production was around 7.1.