BACKGROUND The present work explores the catalytic and electric performance of a microbial fuel cell (MFC) implemented with high chemical oxygen demand (COD) industrial wastewater from Spain. The polymer inclusion membrane based on 70% [MTOA][Cl] IL was used as separator and showed a good efficiency in power production and COD removal. RESULTS Outputs of 72% in COD conversion, 200 mV voltage and 32 mW m−3 power density were obtained, demonstrating that slaughterhouse wastewater is a good feedstock for the scale-up of this technology. Furthermore, the effect of the microbial fuel cell on the physical/chemical parameters of the slaughterhouse wastewater was analyzed. The concentration of nitrite, orthophosphate, sulfate and ammonium was reduced by more than half. CONCLUSIONS Air breathing cathode-microbial fuel cells based on polymer ionic liquids inclusion membranes allow the treatment of an industrial and high load slaughterhouse wastewater with good depuration and electrical performance efficiency. © 2016 Society of Chemical Industry