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

Climate-Smart Stormwater Management

Increased precipitation and risk of flooding are major effects due to climate change that Swedish municipalities need to consider, while facing an ongoing growth in population and densification of urban areas. In this context, urban stormwater management represents a growing challenge. The vulnerability of the society towards climate change depends on the capability of the city to responds to environmental issues.This report presents the challenges and the needs for the implementation of sustainable stormwater solutions encountered in the urban planning process for the city of Gothenburg. The decision making process can be facilitated by the adoption of a stormwater toolbox, which functionalities are designed to support the stakeholders at each step of the planning process. The modules of the toolbox should be designed around a collaboration platform that assists with transparent information flows and allocation of responsibilities. The specific modules (e.g. hydrology, cost-benefit analysis, experience database) should support the needs along the different phases in the process.This study was financially supported by Climate KIC. The Knowledge and Innovation Communities (KICs) are partnerships set up by the European Institute of Innovation and Technology, EIT, that bring together businesses, research centers and universities with the purpose of developing innovative products and services, starting new companies and training a new generation of entrepreneurs. EIT Climate-KIC\u27s mission is to bring together, inspire and empower a dynamic community to build a zero carbon economy and climate resilient society and to enable Europe to lead the global transformation towards sustainability

Chemical Imaging of Pharmaceuticals in Biofilms for Wastewater Treatment Using Secondary Ion Mass Spectrometry

The occurrence of pharmaceuticals in the aquatic environment is a global water quality challenge for several reasons, such as deleterious effects on ecological and human health, antibiotic resistance development, and endocrine-disrupting effects on aquatic organisms. To optimize their removal from the water cycle, understanding the processes during biological wastewater treatment is crucial. Time-of-flight secondary ion mass spectrometry imaging was successfully applied to investigate and analyze the distribution of pharmaceuticals as well as endogenous molecules in the complex biological matrix of biofilms for wastewater treatment. Several compounds and their localization were identified in the biofilm section, including citalopram, ketoconazole, ketoconazole transformation products, and sertraline. The images revealed the pharmaceuticals gathered in distinct sites of the biofilm matrix. While citalopram penetrated the biofilm deeply, sertraline remained confined in its outer layer. Both pharmaceuticals seemed to mainly colocalize with phosphocholine lipids. Ketoconazole concentrated in small areas with high signal intensity. The approach outlined here presents a powerful strategy for visualizing the chemical composition of biofilms for wastewater treatment and demonstrates its promising utility for elucidating the mechanisms behind pharmaceutical and antimicrobial removal in biological wastewater treatment

Removal of organic micropollutants in the biological units of a Swedish wastewater treatment plant

The present study investigates the presence and removal of target organic micropollutants in a large Swedish wastewater treatment plant designed for nutrient removal including activated sludge, trickling filters, nitrifying moving bed biofilm reactors (MBBRs) and post-denitrifying MBBRs. A total of 28 organic micropollutants were analysed, at concentrations ranging from few ng/L to \ub5g/L, in the influent and effluent of the different biological reactors in two sampling campaigns. The observed micropollutant removal efficiencies of the wastewater treatment plant varied from insignificant (< 20%) to high (> 90%) between compounds. The activated sludge reactor, being the first in line, contributed to most of the removal from the water phase. Additional removal of a few compounds was observed in the biofilm units, but most of the persistent compounds remained stable through all biological treatments

Removal of organic micropollutants from municipal wastewater by aerobic granular sludge and conventional activated sludge

Removal performances of organic micropollutants by conventional activated sludge (CAS) and aerobic granular sludge (AGS) were investigated at a full-scale wastewater treatment plant. Lab-scale kinetic experiments were performed to assess the micropollutant transformation rates under oxic and anoxic conditions. Transformation rates were used to model the micropollutant removal in the full-scale processes. Metagenomic sequencing was used to compare the microbial communities and antimicrobial resistance genes of the CAS and AGS systems. Higher transformation ability was observed for CAS compared to AGS for most compounds, both at the full-scale plant and in the complementary batch experiments. Oxic conditions supported the transformation of several micropollutants with faster and/or comparable rates compared to anoxic conditions. The estimated transformation rates from batch experiments adequately predicted the removal for most micropollutants in the full-scale processes. While the compositions in microbial communities differed between AGS and CAS, the full-scale biological reactors shared similar resistome profiles. Even though granular biomass showed lower potential for micropollutant transformation, AGS systems had somewhat higher gene cluster diversity compared to CAS, which could be related to a higher functional diversity. Micropollutant exposure to biomass or mass transfer limitations, therefore played more important roles in the observed differences in OMP removal

PAC dosing to an MBBR – Effects on adsorption of micropollutants, nitrification and microbial community

Two nitrifying MBBR reactors were operated in parallel, one with PAC dosing and one without, to determine the effects of PAC dosing on nitrification and micropollutant adsorption in municipal wastewater. The removal of micropollutants was evaluated for several doses of PAC and batch experiments were performed to measure adsorption kinetics and nitrification rates. The influence of PAC on the nitrifying microbial community was examined by high-throughput amplicon sequencing. Long-term operation of the pilot reactors showed that nitrification could be maintained while supplying PAC at increasing doses, as confirmed by high nitrification rates and significant abundance of nitrifying bacteria. The adsorption of organic micropollutants could be controlled by the PAC dose, and increased dosing resulted in corresponding improvements in removal efficiency. Biomass, suspended or attached to carriers, did not interfere with the adsorption of organic micropollutants. Freundlich isotherms obtained from the batch experiments were used to predict removal of organic micropollutants in the pilot reactors, suggesting that batch adsorption experiments can be used to predict micropollutant removal on a full scale. Collectively, the results show that nitrification and adsorption of organic micropollutants can be performed simultaneously in an MBBR