Combined sulphur cycle based system of hydrogen production and biological treatment of wastewater.

The experiment was conducted to investigate continuous hydrogen production with lower cost and sulphate-rich wastewater treatment. In this paper, both anaerobic bio-treatment of sulphate-rich wastewater and hydrogen production were applied to construct a laboratory-scale combined sulphur cycle based system. The system consisted of two reactors, which were a photocatalytic reactor and an anaerobic bioreactor, respectively. In the anaerobic bioreactor, sulphate-reducing bacteria (SRB) converted SO4(2-) to S(2-). The produced S(2-) yielded by SRB was further used as a sacrificial reagent to produce H2 in the photocatalytic reactor. Then, S(2-) was changed into SO4(2-), which returned to the anaerobic bioreactor for treatment again. The present study highlighted an advantage compared with the conventional method, in that no extra S(2-) was added to the photocatalytic reactor, which reduced the total cost and realized continuous hydrogen production. The average COD removal efficiency was 79.6%.