Fermentative hydrogen production from food waste without inocula

The kind of seed microorganisms and its growth conditions are important factors for the hydrogen fermentation. However, there are many kinds of bacteria in food waste, and it is necessary to know their behavior if it is used as a substrate. Therefore, hydrogen fermentation of food waste was investigated in the absence of inocula with an initial pH varying from 5 to 9 and in a temperature range between 22 to 50°C. Hydrogen production occurred when the initial pH of the solution containing the food waste was adjusted to 7-9 and the temperature was adjusted to 22 or 35°C (maximum production was 40ml-H ₂/g-TS at an initial pH of 9 and a temperature of 35°C). However, the hydrogen production stopped when the pH decreased due to the accumulation of organic acids. In the next step, the pH was controlled by the addition of a NaOH solution between 5.0 and 9.0. When the pH was controlled between 5.0-6.0, the hydrogen production increased to a maximum of 90ml-H₂/g-TS at a pH of 5.5 and a temperature of 35°C; more than 4 times more than for the sample without pH adjustment, due to the acceleration of butyrate fermentation.