Continuous anaerobic hydrogen and methane production using water hyacinth feedstock

Abstract

The water hyacinth, Eichhornia crassipes, impacts the environment in a number of ways. This study develops a continuous cultivation strategy and investigates the effect of these strategies for hydrogen production in anaerobic sequencing batch reactor (ASBR) and intermittent-continuous stirred tank reactor (I-CSTR) systems using the water hyacinth as feedstock. Glucose (10 g/L) was used as the feedstock to start-up the fermentor using pig slurry seed in a batch model. ASBR with increasing water hyacinth concentration was used as the start-up strategy for hydrogen production. However, the hydrogen performance decreased with increasing water hyacinth concentration. Finally, the metabolic pathway shifted to methane production with no hydrogen. A strategy for controlling the substrate and reaction pH and shortening the hydraulic retention time (HRT) in I-CSTR was used to enhance the hydrogen production. Low hydrogen production performance was achieved with a hydrogen production rate of 1.1 with 82.4mL/L-d methane production rate resulting from the I-CSTR operated using pH 4.0 feedstock and HRT 2days.