Hydrogen and Methane Production from Biodiesel Wastewater with Added Glycerine by Using Two-Stage Anaerobic Sequencing Batch Reactor (ASBR)

In this work, a simultaneous production of hydrogen and methane from biodiesel wastewater with added glycerine was investigated by using a two-stage anaerobic sequencing batch reactor (ASBR) system. The hydrogen and methane reactors with 4 and 24 L of working volumes, respectively were operated under mesophilic temperature (37 °C) and 6 cycles per day while the pH in the hydrogen reactor was controlled at 5.5. The glycerine was added to the biodiesel wastewater at 3.5 %w/v to obtain a constant feed COD of 45,000 mg/L. A recycle ratio of 1:1 was used to minimize an NaOH addition in the hydrogen reactor for pHadjustment. The two-stage ASBR system was operated at different COD loading rates (ranging from 33.75 to 84.38 kg/m3d based on the hydrogen ASBR system or 5.63 to 14.06 kg/m3d based on methane ASBR system ) in order to study the effect of organic loading rate on both hydrogen and methane production. Thehighest hydrogen and methane production performance was found at a COD loading rate of 67.50 kg/m3 d and 11.25 kg/m3 d based on hydrogen and methane reactors, respectively.