Abordagem funcional no estudo da comunidade de ciliados em uma estação de tratamento de esgoto combinada UASB-lodo ativado

Abstract

Studies using a functional approach have been growing in the past years, however, there are no studies in this scope utilizing the ciliated microeukaryotes community located in biological wastewater treatment plants. This research is focused on applying a functional approach to the study of the ciliated protists community located in a wastewater treatment plant that operated in a combined Upflow Anaerobic Sludge Blanket (UASB)-activeted sludge system, with the following purposes: 1 investigate the composition and the taxonomic and functional diversity of the ciliated community, as well as presenting data of its time dynamics; 2 investigate the correlation between the indices used in taxonomic and functional diversity; 3 assess the connection between composition and the functional traits of the ciliated community and the environmental conditions; and 4 investigate which traits of the functional diversity could be used as indicators of the wastewater treatment plants' efficiency. 21 ciliated species were registered from 37 samples collected, a lower number when compared to other plants, although expected considering that it is a combined system of anaerobic followed by aerobic (UASB + activated sludge). Due to this, it is identified the occurrence of a phenomenon similar to an environmental filter, creating a temporary functional composition more homogenous than the taxonomic composition, considering that several species have the same functional trait. The relations between the indexes were significant between the functional and taxonomic diversities, indicating that the community is functionally redundant and therefore presents a niche complementarity. This redundancy indicates a stable system, confirmed by the plant's constant high efficiency in removing pollutant components. The community's functional profile was the expected for the wastewater treatment plants, represented by flake-forming and bacterivores species. The flake-forming trait is a specific and important trait in wastewater treatment plants with an innovative philosophy and with the possibility of being an important characteristic in understanding the system's efficiency. Future studies will broaden the knowledge on wastewater treatment systems and on the functional diversity in biological wastewater treatment systems, this being the first step towards the unprecedented application of this methodology in artificial ecosystems.