Influência do agente quelante EDTA no tratamento de efluente sintético com lodo granular aeróbio

Abstract

The treatment of sewage with aerobic granular sludge uses a biomass in the form of granules to remove the organic matter present in the sewage through a process of biological oxidation. Biomass in granules has a high sedimentation rate and flake formation capacity, facilitating the removal of organic matter. Aerobic sludge is continuously withdrawn from the system, dewatered, and properly disposed of. It is an advanced, efficient, economical, and sustainable technology for sewage treatment in densely populated urban areas. In this sense, studies indicate that bivalent cations, such as Ca2+, Mg2+ and Fe2+, are essential for the formation of aerobic sludge granules, where they act as binding agents, promoting the adhesion of bacteria and other microorganisms present in the biomass, in addition to helping in the formation of granule structure. On the other hand, some chelating agents, such as ethylenediaminetetraacetic acid (EDTA), can negatively affect the process of formation and stability of aerobic sludge granules, because EDTA is capable of binding to divalent cations, such as Ca2+ and Mg2+, essential for the formation of granules, forming stable complexes that prevent the formation of ionic bonds between bacteria and other microorganisms present in the biomass. This can lead to a weakening of the structure of the granules, making them more susceptible to rupture. Thus, the main objective of this study is to evaluate the formation of aerobic granular sludge (AGS) in the presence of synthetic chelating agents and the addition of divalent cations to promote granulation. To this end, two batch reactors will be operated in series process on a bench scale, in parallel. Both reactors will be initially fed with the same effluent, and after the AGS sedimentation in 1 (one) minute, the first reactor will receive incremental addition of EDTA until the granules rupture. Batch reactor cycles will last 12 (twelve) hours. It is hoped that this research will contribute to the development of industrial effluent treatments that contain excess EDTA, using AGS as an effective alternative to optimize the formation of granules and correct management of industrial waste, considerably reducing EDTA levels in the wastewater network effluents.