Estimating the Carbon Footprint of Microbial Electrolysis Cells in Wastewater Treatment Plants: Case Study

Microbial electrolysis cells are devices capable of converting the organic fraction present in the wastewaters into hydrogen. Integrating this relatively new technology into wastewater treatment plants can improve the energy balance and result in significant savings in greenhouse gases emissions. However, there are not many studies available in the scientific literature on the carbon footprint of these systems. This paper compares carbon footprint of a wastewater treatment plant located in South Spain, to the carbon footprint of this same plant in which the aerobic treatment is partially replaced by a microbial electrolysis cell. The carbon footprint attributed to the construction of the plants was similar in both cases. However, the wastewater treatment plant with the microbial electrolysis cell system would allow mitigating up to 2,700 t CO2-equivalents, which represents a 42% saving in greenhouse gas emissions compared to the existing wastewater treatment plants.