Photobiological hydrogen production by using olive mill wastewater as a sole substrate source

In the present work olive mill wastewater (OMW) collected from West Anatolia—Turkey during 2001, containing 36.02 g carbon, 5.26 g hydrogen, and 0.96 g nitrogen in 100 g suspended solid was used as a sole substrate for the production of hydrogen gas by Rhodobacter sphaeroides O.U.001 in 400 ml glass, column-photobioreactors. Hydrogen production studies on diluted-OMW were investigated in the range of 20% (v/v) and 1% (v/v) OMW containing media. Below 5% OMW containing media, bacterial growth rate fitted well to the logistic model where hydrogen production was observed for the ones below 4% OMW. A maximum hydrogen production potential (HPP) of 13.9 lH2/lOMW was obtained at 2% OMW. During the biological hydrogen production process, chemical oxygen demand (COD) of the diluted wastewater decreased from 1100 to 720 mg/l; biochemical oxygen demand (BOD) decreased from 475 to 200 mg/l, and the total recoverable phenol content (ortho- and meta-substitutions) decreased from 2.32 to 0.93 mg/l. In addition, valuable by-products such as carotenoid (40 mg/lOMW) and polyhydroxybutyrate (PHB) (60 mg/lOMW) were obtained. According to these results, OMW was concluded to be a very promising substrate source for biohydrogen production process, with additional benefits of its utilization with regard to environmental and economical aspects.