Utilization of microbial fuel cells for the treatment of wastewater from a pig farm

Pig farms generate wastewaters, which are difficult to treat since they contain high concentrations of organic matter, nutrients, and pathogens. The organic matter contained in the wastewaters works as an electron provider for the bacteria to generate energy. The possibility of generating electricity was studied using a single-chamber microbial fuel cells (MFC) fed, having swine wastewater as electron donors, and simultaneously reducing the organic load during the wastewater treatment. The results showed that the pig wastewater can be used to produce electricity using a MFC single-chamber, generating simultaneously removals of organic matter, nitrogen, and phosphorus (chemical oxygen demand 71.9%, ammoniacal nitrogen 29.2% and total phosphorus 15.1%). The maximum voltages reached in the MFC were between 63 mV and 218 mV. The higher power density was 256 mW/m² for a current density of 4, 000 A/m² (10 Ω). For an external resistance of 10 Ω, 100 Ω, and 1, 200 Ω, the coulombic efficiency was 39 %, 5.5%, and 0.9%, respectively. The sscanning electron microscope image and the elemental analysis showed a biofilm bacterial developed on the carbon fiber (anode), as well as inorganic salts precipitated during the treatment of pig farm wastewater by MFC.