Wastewater streams contain organic molecules that need to be removal before disposal which requires an energy input on average of 6 kWh ton^-1. ⁽¹⁾ The fermentation of biomass to produce biogas employs living organisms and permits the valorization of the waste with generation of electricity. However, this technology present limitations in terms of capital cost (ranging USD0.06 and USD0.30 as a function of the size of the digester) and large volume footprint. ⁽²⁾ Microbial fuel cells (MFCs) offer the ability significantly reducing the Chemical Oxygen Demand (COD) contamination is waste water effluents while produce moderate amounts of power. ⁽³⁾

In this contribution, we present the first abiotic waste water fuel cell, a system that directly converts organic materials found in waste sources from different industries into electrical energy. The implementation of inorganic catalysts permits a so-called zero gap design which contributes to minimize the distance between the anode and cathode which is normally large for MFCs to minimize oxygen crossover. This configuration was combined with a commercial PtRu oxidation catalysts produced an unprecedented high power density when using real waste water streams (2.6 mW cm^-2). Moreover, when operated in a continuous loop COD removals as high as 50% has been achieved. This abiotic system significantly reduces processing time associated to incubation periods which are necessary for bio-processes such as biogas generation. ⁽⁴⁾

References:

(1) United States Environmental Protection Agency, Local Government Climate and Energy Strategy Series (2008).

(2) Weiland et al., Applied Microbiology and Biotechnology 85, 849-860 (2010).

(3) Liu et al., Environmental Science & Technology 38, 4040-4046 (2004).

(4) Mao et al., Renewable & Sustainable Energy Reviews 45, 540-555 (2015).