Removal of Micropollutants from Wastewater in Aerobic Granular Sludge and Activated Sludge Systems

The presence of organic substances in the aquatic environment, such as pharmaceutically active compounds, antibiotics, and personal care products, has become a worldwide issue of increasing environmental concern. As they are present at nano- to microgram per liter concentrations, they are defined as organic micropollutants (OMPs). Understanding the removal of micropollutants mediated by biological processes in wastewater treatment plants is the key to developing and deploying strategies to efficiently reduce environmental exposure to such contaminants. The biomass configurations (suspended growth systems or biofilms) can affect the removal of OMPs, and the underpinning mechanisms need to be substantiated. Aerobic granular sludge (AGS) is a form of free-floating biofilm technology for the simultaneous removal of organic carbon, nitrogen, and phosphorus in a single process step. The features of AGS make this technology very attractive for the removal of OMPs, but an in-depth understanding of the fate of OMPs in such systems under different operational conditions is still required.The present work investigated the removal mechanisms of OMPs in biological treatment processes with a focus on AGS. Removal performances were evaluated by measuring the presence of OMPs in the water phase at both full-scale treatment plants and laboratory-scale reactors. The kinetics of transformation and sorption behavior were assessed in batch experiments with different biomass types. The microbial communities and antimicrobial resistance genes of the activated sludge and granular sludge systems were compared. The spatial distributions of a few pharmaceuticals inside the biological matrix of AGS were imaged and analyzed together with the endogenous biofilm molecules by secondary ion mass spectrometry.A higher transformation capacity for most of the investigated OMPs was observed for the activated sludge compared to the granular sludge system, both at the full-scale treatment plant and in the batch experiments. Despite the differences in microbial composition and diversity, the two systems shared similar antimicrobial resistance gene profiles. Micropollutant exposure to the biomass or mass transfer limitations in the dense matrix of AGS likely played an important role and could explain the observed differences in OMP removal. Oxic conditions seemed to support the microbial transformation of several micropollutants with a faster and/or comparable rate compared to anoxic conditions. Sorption of OMPs to the biomass was observed to be an important removal mechanism for a few compounds. Partitioning of the pharmaceuticals to AGS occurred quickly and increased over time for most pharmaceuticals, suggesting that the compounds can penetrate the deeper biofilm matrix. This observation was also confirmed by the chemical analysis of the biofilm matrix of AGS. The spatial distributions of the pharmaceuticals inside the biological matrix of AGS revealed that the interactions between the OMPs and the biomass happen at specific receptor sites distributed across the biofilm

Removal of Organic Micropollutants from Wastewater in Biofilm Systems

The presence of organic hazardous substances in the aquatic environment, such as pharmaceutically active compounds and personal care products, has become a worldwide issue of increasing environmental concern. Present at concentration of nano- to milligram per liter, they are defined as organic micropollutants (OMPs). \ua0Wastewater treatment plants (WWTPs) have been recognized as the main route of emission of OMPs into the environment and as hotspot for antibiotic resistance. Not being designed for the elimination of micropollutants, the removal is often incomplete, resulting in continuous discharge. Therefore, research currently focuses on the enhancement of conventional WWTPs via physical-chemical and biological treatment processes. Among biological processes, biofilm-based treatment technologies have been found more efficient in the biotransformation of OMPs than conventional activated sludge treatment processes. Aerobic granular sludge (AGS) is a form of free-floating biofilm technique for simultaneous removal of organic carbon, nitrogen, and phosphorus in a single process step. The longer solid retention time, the higher concentration and microbial diversity and the presence of micro-niches of different redox conditions are features of AGS that make this system very attractive for the removal of OMPs. An in-depth understanding of the fate of OMPs in such systems under different operational conditions is still required. The present work investigates the degradation mechanisms of OMPs in biomass from both full-scale treatment plants and laboratory reactors. Specifically, it focuses on the impact of different conformations of AGS on the sorption of selected pharmaceuticals and the potential of different biofilm systems at the full scale WWTP to eliminate OMPs

Aerodynamics and ballistics

Ballistics is a science hundreds of years old and this report is an attempt to show how these older principles can be used in the newer science of aerodynamics

Background

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The second normalization theorem between pairs

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Bibliography

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Bibliography

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The first normalization theorem

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The third normalization theorem

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