It has been calculated that annually 1.5 × 108 MWh are wasted as municipal, industrial, and animal wastewater. The recovery of at least part of this energy it is of primary importance in order to approach circular economy. As AD, MFC is a biotechnology that uses microorganism into an anaerobic environment for energy conversion and recovery. Differently from AD, MFC belongs to the sub-division of Bio-Electrochemical Systems (BESs), having the advantage to achieve a direct electrical output. Exoelectrogens bacteria are employed, capable to close their respiratory electron chain on the surface of an electrode. Up to know, BESs were used to extract energy from a multitude of wastes, such as distillery, food, animal carcass, brewery, biodiesel, manure, cheese, urine, feces, bad wine, old juices and composite vegetable. In various cases, BES obtained relatively high energy conversion, but still their use is limited to the laboratory scale, since scale up seems to embed some major limitations. First of all, the ion-exchange membranes used for the separation of the two electrodic compartments are expensive and brittle, making their use economically unsustainable. Sustainability can be improved by the integration of energy production with wastewater abatement in both compartments. As exposed in this thesis, a water contaminated by acid orange 7, was first abiotically decolored in the cathodic compartment and, then, residual carboxylic acids were fed to the anodic bio-community. Economics figures show that another constrain to BESs scale-up is represented by the cost of the catalysts used to improve the Oxygen Reduction Reaction (ORR) on cathode surface. Many attempts to overcome these limitations were done; notable is the single chamber MFC implemented by Prof. Carlo Santoro and co-workers that showed how a membrane-free MFC without cathode catalyst can obtain the same results of an identical MFC operating with a Pt catalyst thanks to an efficient cathodic biofilm. In my opinion, a third constrain to BESs scale-up can be given by the utilization of air-cathodes which are gas-diffusion electrodes (GDEs) capable to enhance ORR, but increasing system complexity and cost. In order to overcome these disadvantages, various researchers have investigated the utilization of Single Chamber Membraneless (SCML) not equipped with air-cathodes and also developed without any physical delimitation between the two environments. This has also been the choice made at the Laboratory of Chemical and Electrochemical Technologies (LTCE) of the University of Palermo, where my PhD was carried on. In this dissertation my efforts in this field are summarized.
Vicari, F.Bio-electrochemical systems for energy gathering from wastewater.
|Titolo:||Bio-electrochemical systems for energy gathering from wastewater|
|Citazione:||Vicari, F.Bio-electrochemical systems for energy gathering from wastewater.|
|Appare nelle tipologie:||4.2 Tesi di dottorato|