Cultivation of High Cell Density to Improve Degradation Efficiency of River-Water

Technology of bioaugmentation was used to degrade contaminants of river water. It was realized that degradation effectives was affected by the density of added microbes. Improving the density of microbes was necessary to reach satisfactory degradation effects on the contaminated river. Therefore a practical recycle cultivation method was studied. It was proved to be practical and effective, for easy to combine with air-lift bioreactor, and the process was easy to implement and take low cost. To achieve high cell density and keep them with high activity, three times cycle was the optimum. It was noticed that recycle cultivation was affected by centrifuge temperature and carbon concentration. More carbon source and higher centrifugal temperature were required to harvest high cell density. But for degradation ability of individual microbe, more carbon was not effective. Finally recycle culture was ended at low centrifugal temperature or higher, because a lot of gels were produced. The gels wrap to the cells so firmly that the cells can´t uptake the nutrient and their activities were limited.