Impact of bio-reduced graphene oxide on the anaerobic transformation of emerging pollutants

ENG- Human society has developed around a central pillar that enhances our well-being, increases life expectancy, and improves health. However, while medicines have been instrumental in solving many health issues, they also pose an environmental problem. Simply by living, we generate waste substances that must be expelled from our bodies, and the drugs we consume are no exception. Eventually, these drugs are released into the environment. To mitigate this, we have constructed a network of wastewater treatment plants designed to manage the waste we produce daily. These plants encourage bacterial growth by providing large amounts of oxygen for them to "breathe”. However, these facilities were primarily designed to remove organic matter and some nutrients, not to address the challenges posed by so-called emerging contaminants. Emerging contaminants are pollutants that, until recently, were difficult to detect, but advances in detection methods have revealed their significant environmental impact. The research conducted for this thesis investigated the addition of a nanomaterial derived from graphene (graphene oxide) to enhance the growth of microorganisms that do not use oxygen for respiration. The advantage of using these microorganisms is that they can convert organic matter in wastewater into methane, thus allowing energy recovery from wastewater. However, these microorganisms are slow to act. Graphene oxide serves as a support structure for these microorganisms, allowing them to grow more effectively and exchange energy (electrons) through its matrix. The conclusion of this doctoral research reveals an ambivalent effect from adding graphene oxide. During the adaptation phase, microorganisms were able to degrade even the most persistent drugs in wastewater more efficiently, but methane production decreased. Nevertheless, once microorganisms had adapted to the new material, drug elimination was no longer enhanced, but methane production increased significantly. This finding is crucial because it opens the door to exploring new conditions that might favor the removal of pharmaceutical contaminants from wastewater