Microbial fuel cells (MFCs) are devices that use microorganisms to produce electricity from organic matter. In this study, the bacterium Delftia acidovorans spp was used to evaluate energy generation in a single-chamber MFC. In this evaluation, six MFCs were assembled with different exchange membranes: two with carbon fiber composite membrane, two with maghemite membrane and two with heat-treated maghemite. Synthetic maghemite was characterized using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FTIR) measurements. Bioelectricity monitoring in the MFCs was conducted for 15 days, with data collected every 60 seconds. The cell that achieved the highest bioelectricity production was the one with heat-treated maghemite, reaching a production of 286.50mV. It used 100% leachate from fruit and vegetable waste as a substrate, starting with values of 365 mg/L of N-NH₄, 96000 mg/L of biochemical oxygen demand (BOD₅₎, 101500 mg/L of chemical oxygen demand (COD) and a pH of 4.11. In the results, the carbon fiber treatment had a higher removal efficiency percentage of up to 63.38% for BOD₅ and 69.67% for COD. For ammonium nitrogen removal, all cells showed good removal efficiency of up to 92.49%. The pH value increased in all treatments due to the degradation of organic matter, reaching a value of up to 5.96. Thus, the efficiency of Delftia acidovorans spp. and carbon fiber are a good alternative as an exchange membrane in purifying leachate contaminants within an MFC.

Ecuador is a developing country that relies on mining as a significant source of economic income every year; however, there needs to be more studies on the soil pollution caused by mining over time. Biological remediation as an alternative to the use of physical and chemical methods offers a more cost-effective and environmentally friendly means to counteract the negative impacts that the presence of heavy metals in mining tailings soils can cause. This study focused on soil sampling from the mining tailings of the San Carlos de las Minas sector, in the Zamora Chinchipe province in Ecuador, to find potential bacterial strains that can degrade two specific contaminants, mercury (Hg) and cyanide (CN^-). For this purpose, 68 soil subsamples were collected. pH, electrical conductivity, moisture, and the concentration of the contaminants were analyzed and measured. The initial concentration of CN^- was 0.14 mg/kg, and of Hg was 88.76 mg/kg. From the soil samples, eight bacterial strains were isolated, characterized at macroscopic and microscopic levels, and identified at the molecular level. The bacteria were then subjected to degradability tests for CN^- and Hg, obtaining interesting results. The degradation capacity of CN^- stood out for the strains Micrococcus aloeverae and Pseudomonas alcaliphila, and for the degradation of Hg, the strains Hydrogenophaga laconesensis and Micrococcus aloeverae were highlighted, achieving degradation percentages of up to 98.80%. These results emphasize the discovery of these bacterial species with potential use in cyanide and mercury remediation processes.