Characteristics and operation of enhanced continuous bio-hydrogen production reactor using support carrier

A kind of granular activated carbon, whose granular size is no more than 2 mm and specific gravity is 1.54 g/cm³, was used as the support carrier to allow retention of activated sludge within a continuous stirred-tank reactor (CSTR) using molasses wastewater as substrate for bio-hydrogen production. Continuous operation characteristics and operational controlling strategy of the enhanced continuous bio-hydrogen production system were investigated. It was indicated that, support carriers could expand the activity scope of hydrogen production bacteria, make the system fairly stable in response to organic load impact and low pH value (pH < 3.8), and maintain high biomass concentration in the reactor at low HRT. The reactor with ethanol-type fermentation achieved an optimal hydrogen production rate of 0.37L/(g · d), while the pH value ranged from 3.8 to 4.4, and the hydrogen content was approximately 40%~57% of biogas. It is effective to inhibit the methanogens by reducing the pH value of the bio-hydrogen production system, consequently accelerate the start-up of the reactor.