Surface Modification of Various Substrates for Microbial Adsorption Optimization

Conversion of biomass to useful bio-products is a lengthy and often inefficient process. In our research, we have looked at the conversion of cellulose to ethanol by means of termite bacterial consortium in a fluidized bed bioreactor, where the bacteria are attached as bio-film to an activated carbon or cellulose support. Fairly high conversion rates were achieved in this reactor and the process was fairly robust and flexible.  However establishing the bio-film on the activated carbon was  a lengthy  and  fairly chaotic process in terms of the  time it took the bacteria to attach to the various substrates (Activated Carbon and Cellulose) and form flocculants. The formation of such flocculants substantially increases the reaction surface and hence should optimize the production of ethanol. Bacteria carry a negative surface charge and hence for increased attraction, the surface charge of the substrate should be modified to be positive. This research, performed initially as batch processes, has shown that with the correct surface charge modifications of the substrate the electrostatic attraction forces between the surface and the bacteria are maximized. As a result of the strong electrostatic attraction forces between the two surfaces the bacteria adsorbs and attaches to the substrate quicker and creates a thicker lining on the surface than seen previously. With these results optimization of flock creation in a fluidized bed bioreactor and its effect on the production of ethanol will be further investigated.