Showing papers by "Juliana Calábria de Araújo published in 2017"

Microbial communities in anammox reactors: a review

Abstract: The anammox (anaerobic ammonium oxidation) process has been used to remove nitrogen from wastewaters and is considered a promising approach due to its advantages over conventional processes (nitrification and denitrification). The development of molecular biology tools has allowed for great advances in describing the microbial communities in anammox reactors, which is important to understand the complex reactions and interactions that occur inside these systems. This study presents a review of the microbial diversity studies in anammox reactors. Several researchers have investigated the microbial community composition in anammox reactors, in order to elucidate the roles that the different microbial groups (besides the anammox bacteria) play in these systems. The microbial communities of anammox reactors appear to be affected by several factors, such as the configuration of the reactors, the biomass growth mode inside of the reactors, operational conditions and type of inoculum used for start-up. H...

Illumina sequencing-based analysis of a microbial community enriched under anaerobic methane oxidation condition coupled to denitrification revealed coexistence of aerobic and anaerobic methanotrophs

Abstract: Methane is produced in anaerobic environments, such as reactors used to treat wastewaters, and can be consumed by methanotrophs. The composition and structure of a microbial community enriched from anaerobic sewage sludge under methane-oxidation condition coupled to denitrification were investigated. Denaturing gradient gel electrophoresis (DGGE) analysis retrieved sequences of Methylocaldum and Chloroflexi. Deep sequencing analysis revealed a complex community that changed over time and was affected by methane concentration. Methylocaldum (8.2%), Methylosinus (2.3%), Methylomonas (0.02%), Methylacidiphilales (0.45%), Nitrospirales (0.18%), and Methanosarcinales (0.3%) were detected. Despite denitrifying conditions provided, Nitrospirales and Methanosarcinales, known to perform anaerobic methane oxidation coupled to denitrification (DAMO) process, were in very low abundance. Results demonstrated that aerobic and anaerobic methanotrophs coexisted in the reactor together with heterotrophic microorganisms, suggesting that a diverse microbial community was important to sustain methanotrophic activity. The methanogenic sludge was a good inoculum to enrich methanotrophs, and cultivation conditions play a selective role in determining community composition.

Metagenomic analysis and performance of a mesophilic anaerobic reactor treating food waste at various load rates

Abstract: The performance of a demonstration-scale anaerobic reactor treating food waste was evaluated with an emphasis on microbial response to increasing organic loading rates (OLRs) The reactor e

Studies of filter media for zero-discharge systems collecting light greywater

Abstract: Zero-discharge constructed wetland environments are more prone to the accumulation of pollutants. The relationship between filter media and microbial communities in this type of environment is still poorly known. We conducted bench-scale studies of different filter media (polyurethane foam, blast-furnace slag, and loofah) in these systems by simulating the batch operation with light greywater for 433 days. Physicochemical and microbiological analyses (scanning electron microscopy and polymerase chain reaction electrophoresis denaturing gradient gel) were used. In all systems, anoxic environments prevailed. These environments were crucial for methanogenesis and sulfidogenesis processes, which are primarily responsible for organic material conversion. The chemical oxygen demand/sulfate (COD/SO42−) ratio was the limiting factor in the competition of microorganisms involved in these processes. This condition, combined with the neutral-alkaline pH, also allowed Chloroflexi phylum bacteria to oxidize su...