The effect of fermentation modes on the efficiency of organic waste treatment in batch bioreactors

Abstract

The amount of solid organic waste is constantly growing. This is caused by the growth of industrial and agricultural capacities, and the inefficiency of existing waste processing technologies. Biotechnologies can provide effective environmentally friendly solutions for waste treatment. Therefore, the goal of our work was to compare the efficiency of strictly anaerobic fermentation of multi-component solid organic waste with hydrogen synthesis and waste treatment with pulsed air access in batch bioreactors.During fermentation, the following parameters were controlled: pH, redox potential (Eh), concentration of dissolved organics, and the content of H2, O2, and CO2 in the gas phase. The efficiency was evaluated via the process duration, calculation of the ratio of the initial and final weight of waste (Кd), and the yield of molecular hydrogen. Obtained results revealed high efficiency of organic waste degradation in both variants. The weight of waste 83-fold and 86-fold decreased, respectively. The time required for fermentation in strictly anaerobic conditions was 4 days, whereas 7 days were required for the mode with pulsed air access. The first variant provided a 2.8-fold higher hydrogen yield (54±4,1 L/kg of waste), and the second one provided a decrease in the concentration of dissolved organic compounds in the fermentation fluid. Fermentation is the effective approach for accelerated degradation of solid organic waste. Strictly anaerobic fermentation appeared to be useful in the need to accelerate the process. The mode with the pulsed air access can provide not only degradation of solid waste but also purification of the fermentation fluid.