LAUSR

Abstract Despite the numerous studies that have been carried out on electricity generation from biomaterials, there is no systematic information about the influence of operational conditions on the performance of these systems. In addition, the carried out researches in the different studies have been done in various conditions and systems, leading to a large variation in the parameters reported for each system. In this regard, the main goal of this study was to determine the operational conditions which the electricity generating systems are able to demonstrate the desirable performance. Therefore, a reactor has been designed with the aim of generating electrical energy, directly from municipal waste-activated sludge simultaneous with its aerobic digestion process and its performance has been successfully optimized using response surface methodology (RSM). The results of the optimization showed that the best performance of the reactor for the volatile suspended solid (VSS) removal could be obtained when the temperature and the pH values are about to 35 °C and 7.0, respectively. Under these conditions, the models estimated 42% VSS removal efficiency. Also, the generated electrical power density achieved its peak in 35 °C and 7.0 for the temperature and the pH. The value obtained for the generated electrical power under these conditions was 2.81 W/m 3 . The comparison of the results derived from the laboratory experiments and the optimization process proved the validity of the obtained models. Another noticeable point was that the determined optimized conditions for the stabilization and the electricity generation processes were conforming to each other.