The following points should be investigated :
*how to achieve the suitable operational conditions,
*how to control the bacterial population in the system,
*how to irradiate photosynthetic bacteria, or the design of a photobioreactor, and
*how to harvest the biomass.
This work is concerned with the first two points.
For the former, the growth characteristics of purple nonsulfur bacteria should be
discussed. Many researchers have been investigating PHA production by purple
nonsulfur bacteria under nitrogen-limited conditions [2,3,4,5]. Under such
conditions, PHA would be accumulated and would never be converted into other
cell materials. However, since some wastewater contains sufficient nitrogen
compounds, we must investigate PHA accumulation/consumption under nitrogenunlimited
conditions. In this study, batch experiments were carried out using purple
nonsulfur bacterium Rhodobacter sphaeroides to determine its growth rates and PHA
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accumulation performances under various conditions (substrate, temperature, light
intensity and sulfide concentration).