Influence of light intensity on hydrogen production by Rhodobacter sphaeroides from swine manure wastewater

In this paper, the effects of light intensity on the hydrogen production of Rhodobacter sphaeroides 1.1737 using swine manure wastewater as substrate were investigated. The results show that the increase in light intensity increases both hydrogen production rate and total hydrogen evolved by Rhodobacter sphaeroides, and the activity of Rhodobacter sphaeroides is getting stronger. The rate of hydrogen production increases highly when light intensity is above 1000 lux than lower, and the activity of bacteria were improved drastically. As to 1200 lux, 1600 lux and 2000 lux, the increase of hydrogen production rate is not significant. The rate of hydrogen production reached maximum at approximately 1600 lux. These indicate that the influence on activity of hydrogen production of the bacteria will decline when light intensity increases to a certain degree, the effect of light intensity on rate and the amount of hydrogen production decreases gradually and further increase in light intensity does not have any effect while light intensity reaches a certain value.