The anaerobic fermentation of food waste: a comparison of two bioreactor systems

Here, two methods for the generation of biogas from organic waste materials produced by the food industry are compared. The resulting biogas can be further converted into heat and electricity. To efficiently convert food waste to biogas, it is necessary to choose the most appropriate process, reactor system and parameters. In this work, to define the most efficient method, fermentation experiments were carried out in two reactor types: a CSTR (Continuous Stirred Tank Reactor) and an FBR (Fluidized Bed Reactor). Fermentation yielded 670 NL biogas/kg volatile solids (VS) with the CSTR and 550 NL biogas/kg VS with the FBR. The productivities were 3.9 NL biogas/(L*d) with the CSTR and 3.4 NL biogas/(L*d) with the FBR. The average methane concentration was approximately 60% for both reactor systems. The results show that it was possible to efficiently produce biogas by the use of either reactor system; however, the stability of the process was greater in the FBR, indicating that the use of this system may be more advantageous.