Agro-industrial wastewater purification as source of cheap electricity and biohydrogen. Towards Microbial Fuel/Electrolysis Cells scaling-up and field application

Microbial fuel cells (MFC) and Microbial electrolysis cells (MEC) are an innovative biotechnological application that combines complex bio-electrochemical processes that allow to contemporarily treat wastewater and produce electric current (MFC) and/or bio-hydrogen (MEC). Both organic and inorganic contaminants in water can be degraded by particular bacterial species known as exo-electrogens that are able to exchange electrons with conductors and thereby to create electric fields. MFC/MEC are energy-producing wastewater treatment technologies and, for this reason, they have the potential to replace energy-consuming processes such as active-sludge, nitrification-denitrification, etc. However, this biotechnology has been systematically investigated in the last 15 years at laboratory scale, but really few applications at pilot-scale or commercial scale have been developed till today. Different bioreactor designs, different materials and different types of bio-chemical conditions have been tested by a relatively consistent number of research groups worldwide and basic research already indicated that the up-scaling of some applications of both MFCs and MECs would be possible in the next future. Important agro-industrial sectors by-produce huge amounts of wastewaters that in many cases are cause of environmental concerns and/or imply expensive and energy-consuming purification processes, using traditional technologies. Only in Italy, food-production sectors such as winery, olive oil, dairy and farming, by-produce nearly 200 million cubic meters per year of polluted wastewaters. Nowadays, due to the high management costs related to proper disposal and treatment, this amount of polluted water is mainly spread to agricultural land as-it-is and/or, after inefficient purification processes, discharged to superficial/groundwater bodies. A future scenario in which MFC/MEC technologies could be applied at various scales to treat all these effluents must be taken into consideration. Considering only these 4 main sectors of agro-industry in Italy, nearly 50 MW electric power could be produced, while treating effluents. The same estimation might be done for household wastewater and other industrial sectors. The present project aims at elaborating a research strategy for enhancing the application of MFC/MEC on full-scale, in 4 relevant sectors of agro-industrial production (olive oil, winery, dairy, farming). An interdisciplinary approach will be adopted, as the nature of this biotechnology itself requires. The first year of research will focus on reactor design/architecture optimization, in adaptation to each particular application and on the optimal choices for the structural materials (in particular conductors and membranes for cathodes and anodes). The acceptability of both material cost and efficiency will be the challenge. New designs of electrode shape will be also investigated. This step will be driven at laboratory scale and the new prototypes will be tested to optimize the process parameters, their production yields, the chemical and bio-chemical process pathways involved and the microbiological communities growth. In the second year, the best solution will be optimized on wastewater type at lab scale under long-term process conditions, to verify the stability of both the bio-chemical system, the microbial communities and the materials durability. During the third year, a pilot prototype will be built and tested on the field in at least 2 case studies of particular interest, with the goal of developing one or more patents on the new application, that could be subsequently engineered and further scaled up. All project will be carried out at DISAA-University of Milan and at NAST-University of Tor Vergata, with external collaboration of Bruce Logan, Director of Dept. Civil & Environmental Engineering ¿ Pennsylvania State University, USA.