**Paweł P. Włodarczyk \* and Barbara Włodarczyk**

Institute of Technical Sciences, Faculty of Natural Sciences and Technology, University of Opole, Dmowskiego Str. 7-9, 45-365 Opole, Poland

**\*** Correspondence: pawel.wlodarczyk@uni.opole.pl; Tel.: +48-077-401-6717

Received: 5 May 2019; Accepted: 25 June 2019; Published: 28 June 2019

**Abstract:** The possibility of wastewater treatment and electricity production using a microbial fuel cell with Cu–B alloy as the cathode catalyst is presented in this paper. Our research covered the catalyst preparation; measurements of the electroless potential of electrodes with the Cu–B catalyst, measurements of the influence of anodic charge on the catalytic activity of the Cu–B alloy, electricity production in a microbial fuel cell (with a Cu–B cathode), and a comparison of changes in the concentration of chemical oxygen demand (COD), NH4 <sup>+</sup>, and NO3 – in three reactors: one excluding aeration, one with aeration, and during microbial fuel cell operation (with a Cu–B cathode). During the experiments, electricity production equal to 0.21–0.35 mA·cm−<sup>2</sup> was obtained. The use of a microbial fuel cell (MFC) with Cu–B offers a similar reduction time for COD to that resulting from the application of aeration. The measured reduction of NH4 <sup>+</sup> was unchanged when compared with cases employing MFCs, and it was found that effectiveness of about 90% can be achieved for NO3 – reduction. From the results of this study, we conclude that Cu–B can be employed to play the role of a cathode catalyst in applications of microbial fuel cells employed for wastewater treatment and the production of electricity.

**Keywords:** non-precious metal catalysts; Cu–B alloy; microbial fuel cell; cathode; environmental engineering; oxygen electrode; renewable energy sources
