CEST2025

Lakes and water reservoirs are considered hotspots of GHG emissions, mainly methane with a flux of 91.6 Tg CH4-C/year. Moreover, several studies have shown that lake eutrophication causes an increase in the amount of organic matter present in both the water column and sediments, increasing CH4 emissions from freshwater ecosystems to the atmosphere. Therefore, these freshwater ecosystems are an important site for biogeochemical processes that contribute significantly to the global GHG budget. For this reason, it is not only important to limit eutrophication to preserve fragile water supplies, but also to avoid accelerating climate change. The main objective of this research proposal was to evaluate the effect of a microbial fuel cell on the emission of CH4 from a eutrophicated urban lagoon. This bioelectrochemical system produces electricity through electrons derived from redox reactions catalyzed by bacteria that degrade the organic matter present in sediment, so that under anaerobic-anoxic conditions the organic matter will be degraded by the electrogenic pathway and not by the CH4 production pathway. To carry out this study, analyses of physicochemical parameters such as COD, N-NH4+, N-NO3- were performed on the water samples collected. In sediments, in situ parameters such as Oxide Reduction Potential (ORP) (mV), dissolved oxygen (mg/L), pH and organic matter (ignition method) were measured. Regarding the quantification of CH4 emissions from the systems under study, the static chamber method was used where 10 mL gas samples were taken from the reactors once a day twice a week after start-up and were analyzed by gas chromatograph (AOC 20i and flame ionization detector). Finally, the microbial fuel cell electrical performance was evaluated by measuring the voltage difference between anode and cathode (Ecelda) recorded through an external 100ohm electrical resistance using a multimeter with data acquisition system (Model 2700, Keithley Instruments Inc., Ohio, USA).