Andrea Iris Schaefer

Andrea Iris Schaefer
Karlsruhe Institute of Technology | KIT · Institute for Advanced Membrane Technology (IAMT)

PhD

About

207
Publications
83,778
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Introduction
Our research is focused on the application of membranes for water applications with the vision ‘Safe Water for All Children’ (I) new membrane materials with higher efficiency & controllable contaminant and micropollutant removal (II) understanding of retention and fouling in complex and realistic water matrices that informs material development and process design (III) development of systems that operate long term in the most difficult circumstances such as rural area or developing countries
Additional affiliations
January 2020 - September 2020
Karlsruhe Institute of Technology
Position
  • Head of Department
March 2006 - February 2013
The University of Edinburgh
Position
  • Chair of Environmental Engineering
October 2002 - March 2006
University of Wollongong
Position
  • Professor (Associate)

Publications

Publications (207)
Article
Organic matter (OM) in surface and ground waters may cause membrane fouling that is laborious to clean once established. Spontaneous osmotic backwash (OB) induced by solar irradiance fluctuation has been demonstrated for early mineral scaling/organic fouling control in decentralised small-scale photovoltaic powered-nanofiltration/reverse osmosis (P...
Article
Full-text available
Micropollutants in the aquatic environment pose a high risk to both environmental and human health. The photocatalytic degradation of steroid hormones in a flow-through photocatalytic membrane reactor under UV light (365 nm) at environmentally relevant concentrations (50 ng l–1 to 1 mg l–1) was examined using a polyethersulfone–titanium dioxide (PE...
Cover Page
Full-text available
KIT researchers have been awarded one of the inaugural Undine Awards for 2022 for their long-standing contribution to R&D in the field of solar-powered water treatment, especially targetting small-scale distributed systems for the treatment of brackish groundwater in remote areas of Africa.
Article
Selenium (Se) is a dissolved oxyanion drinking water contaminant requiring appropriate removal technologies. The removal of selenite (SeIV) and selenite (SeVI) with nanofiltration (NF) was investigated with an emphasis on the role of Se speciation and membrane charge screening on the retention mechanisms. The pH (2 to 12) showed strong pH dependenc...
Article
Full-text available
Organic fouling is a major issue of nanofiltration/reverse osmosis (NF/RO) membranes because it causes severe and usually irreversible flux decline. Consequently, NF/RO requires frequent chemical cleaning and/or replacement. In directly coupled photovoltaic (PV) powered NF/RO systems for brackish water desalination, solar energy fluctuations can in...
Article
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In the field of ultrafiltration (UF) membranes for water treatment, fouling is a severe problem that limits the potential of the technology UF membranes and results in increased energy consumption. In this study, a small-scale photovoltaic-powered membrane system was employed to investigate the energy consumption of two UF backwashing configuration...
Article
Full-text available
Given the crucial role of noble metals in promoting singlet oxygen (¹O2) production, the feasibility of relying on cheaper and more abundant metals remains challenging. This work investigates the continuous-flow photocatalytic degradation of steroid hormone micropollutants, achieved with photocatalytic membranes based on noble-metal (Pd) and noble-...
Chapter
This chapter describes the relevance of nanofiltration (NF) as a reliable technology to remove trace contaminants from water. A variety of organic and inorganic trace contaminants, their occurrences in various water bodies, and their health effects are summarized. An overview of the current water guidelines for the most representative types of orga...
Chapter
Renewable energy-powered nanofiltration allows to (i) overcome the operational energy costs of nanofiltration and (ii) design decentralized treatment where advanced water treatment removal of dissolved contaminants is required and no reliable energy supply is available. Such decentralized treatment is a relatively a new paradigm that is required in...
Chapter
In this concluding chapter, the editor summarizes the contents of the three parts that make up the book and highlights key developments in each area that have happened since the publication of the previous edition. The contribution of nanofiltration to meeting challenges in the global water supply is outlined, and market and technology trends are r...
Chapter
The fouling chapter provides a comprehensive overview of fouling characteristics, common foulant types, fouling characterization methods, and membrane autopsy as well as a review of current models. A detailed description of the main fouling categories, namely organic fouling, scaling, colloidal and particulate fouling, and biofouling, is followed b...
Article
The removal of arsenic(III) (As(III)) with nanofiltration (NF) was investigated with emphasis on the role of salinity, pH and organic matter on retention mechanisms. While no measurable impact of salinity on As(III) retention with NF membranes (NF270 and NF90) was observed, a significant increase in As(III) retention occurred from pH 9 to pH 12. Th...
Article
A novel way of removing micropollutants – especially steroid hormones – from water has been developed in Germany at the Institute for Advanced Membrane Technology (IAMT) of the Karlsruhe Institute of Technology (KIT). As this article shows, it is based on the combination of a polymeric ultrafiltration (UF) membrane and activated carbon. The two res...
Article
Full-text available
The efficient degradation of steroid-hormone micropollutants is demonstrated in a single-pass, continuous operation of the photocatalytic membrane reactor (PMR) holding a visible-light excited Pd(II)-porphyrin-coated poly(vinylidene fluoride) microfiltration membrane. The PMR operated at a water flux of 600 L m⁻² h⁻¹ exhibited a residence time of 0...
Article
A breakthrough curve in nanofiltration (NF) is observed when micropollutants adsorption and subsequent diffusion through the membrane occur at environmentally relevant low concentrations. The role of hydrodynamics and operative conditions to characterize the curve shape is unknown. In this study, the impact of mass transport and residence time on t...
Article
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The potential for lithium-ion (Li-ion) batteries and supercapacitors (SCs) to overcome long-term (one day) and short-term (a few minutes) solar irradiance fluctuations with high-temporal-resolution (one s) on a photovoltaic-powered reverse osmosis membrane (PV-membrane) system was investigated. Experiments were conducted using synthetic brackish wa...
Presentation
Mineral scaling is common in brackish water treatment and causes higher energy consumption and cleaning frequency [1, 2]. In photovoltaic-powered nanofiltration/reverse osmosis (PV-NF/RO) membrane system application energy fluctuations cause discontinuous operation and impacts on scaling are unclear. Osmotic backwash (OB) occurs naturally during fl...
Article
Full-text available
Removal of naturally occurring strontium (Sr) from groundwater is vital as excessive exposure may lead to bone growth problems in children. Nanofiltration/reverse osmosis (NF/RO) is commonly used in groundwater treatment due to the high effectiveness and simple maintenance of these pressure driven membrane processes. In this research, a pilot-scale...
Article
Full-text available
Mineral scaling is a key limiting factor for membrane desalination and results in increased operation and maintenance costs. In directly coupled battery-less photovoltaic-powered nanofiltration/reverse osmosis (PV–NF/RO) membrane systems, solar energy fluctuations cause intermittent operation and direct osmotic backwash (OB) spontaneously. This pot...
Article
Full-text available
Climate change will affect water quality through a change in salinity, pH and organic matter (OM) content due to seawater intrusion, temperature change and subsurface biological processes. Therefore, a systematic evaluation of the impact of water quality variations is of particular importance to maintain the performance of a treatment process desig...
Article
Full-text available
The occurrence of steroid hormones in water and their serious impact on human and ecosystem demand high performance materials for efficient removal of such micropollutants. Here, an affinity membrane is developed for hormone removal with regenerable binding sites. By using photodynamic disulfides as a linker, UV induced detachment of β‐CD ligands f...
Article
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Directly-powered photovoltaic membrane filtration (PV-membrane) systems possess no energy storage components, hence operate under energy fluctuations that result in variations in the membrane performance. Here, the resilience of a PV-membrane system under such conditions as a function of membrane type and feedwater quality is investigated. Five Tan...
Article
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The European Union has proposed the value of 1 ng L⁻¹ as a drinking water quality standard for estradiol. With conventional technologies only partially removing estradiol, the investigation of novel alternatives is more than ever required. Tagliavini and Schäfer proposed that the use of a thin activated carbon layer combined with a membrane is wort...
Article
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Photocatalytic membrane reactors with different configurations (design, flow modes and light sources) have been widely applied for pollutant removal. A thorough understanding of the contribution of reactor design to performance is required to be able to compare photocatalytic materials. Reactors with different flow designs are implemented for proce...
Article
Cyclodextrin loaded composite nanofibers have been widely applied in water treatment. Electrospun polyethersulfone (PES) nanofibers with β-cyclodextrin-epichlorohydrin (βCDP) deposited on PES ultrafiltration (UF) membranes were prepared. Steroid hormone micropollutants (MP) were removed from the water over a broad concentration range (0.01–100 μg/L...
Article
The occurrence of micropollutants (MPs) including steroid hormones is a global environmental and health challenge. Carbon-based nanoparticles can be incorporated with water treatment processes to allow MP removal by adsorption. The aim was to compare the suitability of such nanoparticles (graphene, graphene oxide, carbon nanotubes and C60) to adsor...
Article
Full-text available
Detection of micropollutants such as steroid hormones occurring in the aquatic environment at concentrations between ng/L and µg/L remains a major challenge, in particular when treatment efficiency is to be evaluated. Steroid hormones are typically analysed using mass-spectrometry methods, requiring pre-concentration and/or derivatisation procedure...
Article
An effective way to remove micropollutants is desirable for water purification. In this work, a dual-functional ultrafiltration (DFUF) membrane was fabricated by loading hollow mesoporous carbon nanospheres (HMCNs) into the finger-like support layer pores of the polymeric ultrafiltration (UF) membrane. The designed DFUF membrane combines the high s...
Article
Direct osmotic backwash (OB) during solar energy fluctuations is an important observation in directly coupled, battery-less solar energy powered nanofiltration/reverse osmosis (NF/RO) membrane systems. OB occurs spontaneously and has the potential to induce membrane self-cleaning. The impact of controlled solar irradiance fluctuation conditions, fe...
Article
Full-text available
Photocatalytic membranes operating under flow-through conditions are promising for continuous single-pass water treatment, while factors influencing pollutant removal require further understanding. In this work, anodized aluminium oxide membranes with pore sizes of 20 nm and 200 nm were coated with a titanium dioxide (TiO2) photocatalyst via atomic...
Article
Short activated carbon fibers (ACF) with high surface area were fabricated via carbonization in N2 and activation in CO2 at high temperatures, with cellulose fibers as the raw materials. The obtained ACF were subsequently deposited into the support layer of a polyethersulfone (PES) ultrafiltration membrane by a facile filtration process to obtain t...
Article
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Energy management is required to enable autonomous photovoltaic-powered membrane (PV-membrane) desalination systems to make the optimal use of solar energy. In this paper, a novel charge controller based on pre-set voltage sensing thresholds was designed to optimise the energy from PV panels and supercapacitors (SCs). The control algorithms were es...
Article
Photovoltaic-powered membrane filtration (PV-membrane) systems are of interest for the provision of clean drinking water in small communities, especially in remote areas. In order to deliver clean water at the lowest cost over the lifetime of the system, a reliable and robust design is paramount. This paper provides a comprehensive review of the op...
Article
A novel combination of a poly(vinylidene fluoride) (PVDF) membrane with pore size 0.2 μm and a photosensitizer 5,10,15,20-tetrakis (pentafluorophenyl)-21H,23H-porphine palladium(II) (PdTFPP) makes a promising hybrid material for the generation of singlet oxygen (¹O2) and, thus, water treatment applications. The fabricated photocatalytic membrane ex...
Article
Full-text available
The present study investigated ultrafiltration (UF) membranes in a combination with a polymer-based spherical activated carbon (PBSAC) thin layer on the permeate side (UF-PBSAC) to remove the steroid hormone micropollutant (MP) estradiol (E2) from water. The impact of dissolved organic matter on the process was assessed using two types of water: on...
Presentation
Osmotic backwash (OB) of dense membranes has been developed as a novel cleaning method to control membrane fouling (Qin et al. 2009, Kim 2014, Liberman 2018). OB is based on permeate backflow to the feed side due to a negative driving force between the operating and osmotic pressure of feed solution across nanofiltration/reverse osmosis (NF/RO) mem...
Article
Comparison of nanofiltration characterization data from literature is challenging due to different hydrodynamics and system designs, which affect membrane retention. In this study, stirred cell (SC), micro and macro cross flow systems (micro and macro CF) with different configuration were used to measure salt and organic tracer retention. Minimal c...
Article
Integration of renewable energy and membrane filtration technologies such as nanofiltration (NF) and reverse osmosis (RO) can provide drinking water in places where freshwater is scarce and grid electrical connections are unavailable. This study investigated a directly-connected photovoltaic-powered membrane system under fluctuating solar condition...
Article
Renewable energy powered membrane systems operate with fluctuating energy. Such fluctuations affect pressure and feed flow and as such the hydrodynamic conditions in a membrane system. Hydrodynamic variations alter the membrane surface concentration and boundary layer thickness which in turn determines permeate water quality. In this work this is c...
Article
Environmental contextContamination of surface water by micropollutants is a major environmental concern because of their high persistence and toxicity. Micropollutants are only partially removed in nanofiltration water treatment systems, encouraging the investigation of more complex systems involving partitioning with membrane materials, organic ma...
Article
Full-text available
Membranes: solar-powered filtration in rural communities A solar-powered portable filtration unit is capable of treating ground and surface water to drinking standards in rural communities in Tanzania. Water treatment in remote communities is extremely challenging because establishing permanent infrastructure is often not viable. Instead, decentral...
Article
Full-text available
The Maji ya Chai River in Northern Tanzania, a fluoride-rich tropical area, shows a seasonal variation of natural organic matter (NOM) and fluoride concentration. Water samples collected monthly during one year from two locations of the River were characterized. High levels of precipitation in the rainy seasons increased the total organic carbon (T...
Article
In the context of decentralised brackish water treatment in development applications, the influence of water quality on membrane separation was investigated with real waters. High ionic strength (low net driving pressure) on fluoride (F) retention by nanofiltration (NF) and reverse osmosis (RO) was investigated over a wide pH range (2–12). Further,...
Article
Full-text available
Effective micropollutant removal requires energy intensive advanced treatment processes. A novel hybrid membrane configuration – consisting of both ultrafiltration (UF) and nanofiltration (NF) – with permeate-side polymer-based activated carbon (PBSAC) was developed and investigated for the removal of natural hormones with a particular focus on est...
Chapter
Remote areas face particular infrastructure challenges relating to the provision of clean drinking water and electricity. The installation of classical centralized water and electricity systems in such areas is economically unfavorable because of low population densities. This situation provides unique opportunities for the implementation of autono...
Chapter
This chapter presents an overview of the manufacture, physicochemical properties, and effective application of carbon nanotube (CNT) membranes in desalination technologies. A comprehensive discussion on the current knowledge pertinent to CNT exploitation in desalination is made. It is demonstrated that considerable efforts have been made in the pas...
Article
Full-text available
Cyclodextrin-polymer-composite electrospun nanofibers were developed for micropollutant removal from water. Fibers were fabricated by electrospinning of mixed polyethersulfone and β-cyclodextrin (CD) solutions at optimal conditions. The composite-fibers were compared to bare polyethersulfone nanofibers prepared by the same method. Scanning electron...
Article
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Magnetic ion exchange resins (MIEX) were combined with nanofiltration (NF) in one single process to mitigate fouling by humic acids (HA). MIEX effectiveness in controlling NF fouling was investigated under different feed chemical conditions and employing two types of NF membranes (NF270, NF90). Fouling layer thickness was determined using novel hel...
Article
Full-text available
Real water pH and ionic strength vary greatly, which influences the performance of membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Systematic variation of pH (3 − 12) and ionic strength (2–10 g/L as total dissolved solids (TDS)) was undertaken with a real Tanzanian water to investigate how water quality affects retention me...
Article
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Water and energy are inextricably linked in today's society. This paper broadly introduces the water-energy nexus before focusing on sub-Saharan Africa, where residents have the poorest access to both clean drinking water and electricity worldwide. Given that many of the affected people live in remote areas, new solutions are required to improve th...
Article
Full-text available
The removal of inorganic trace contaminants from a real brackish groundwater from a remote Australian community using electrodialysis was investigated. Systematic investigation of applied voltage and solution pH was aimed to elucidate removal and deposition mechanisms in a complex water. A higher applied voltage enhanced removal of arsenic (V), bor...
Article
Full-text available
Removal and interaction mechanisms of four different steroid micropollutants, estrone (E1), estradiol (E2), progesterone (P) and testosterone (T) were determined for different types of polymer-based spherical activated carbon (PBSAC). Higher than 90% removal and significantly faster kinetics compared to conventional granular activated carbon (GAC)...
Chapter
This chapter discusses both products representing recent incremental innovations with conventional nanomaterials that are already produced on the scale of megatons per year as well as disruptive innovations based on novel nanomaterials. It presents the case studies for composite systems, nanoporous systems, and particle-based systems. The overview...
Article
Full-text available
The impact of pH and humic acid (HA) on the retention of fluoride (F) and inorganic carbon (IC) by nanofiltration (NF) and reverse osmosis (RO) membranes was determined. Synthetic waters were prepared using realistic ranges of F, IC and HA for carbonaceous waters found for example in the fluoride rich waters in Tanzania. These waters were filtered...
Article
Full-text available
Background: Estrogens and their synthetic analogues are widely used as pharmaceuticals. Upon oral administration these drugs are eventually excreted via urine. The persistence of these pharmaceuticals and inefficient removal by water treatment lead to accumulation in surface water and effluents with negative effects for aquatic life and human heal...
Article
Full-text available
Aqueous micropollutants such as estradiol can have a large environmental impact-even at low concentrations. Part of understanding this impact involves determining the extent to which the micropollutants interact with macromolecules in water. In environmental samples, relevant macromolecules to which micropollutants bind are referred to as dissolved...
Article
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A brackish borehole located at a rural school in northern Tanzania contains excessive salinity (TDS=3632 mg/L) and fluoride concentration (F–=47.6 mg/L). This field study evaluated the feasibility of a solar-powered nanofiltration/reverse osmosis (NF/RO) system in treating this brackish water to make it potable. Key performance parameters such as p...
Article
Full-text available
Many waters in Tanzania exhibit high concentrations of organic matter and dissolved contaminants such as fluoride. Due to bacteria and virus removal, ultrafiltration (UF) is an attractive option for drinking water treatment, and when coupled with adsorbents, may compete with other established processes like nanofiltration (NF) for lower contaminant...
Article
Full-text available
Fluctuations in solar irradiance were varied in frequency and magnitude to investigate the performance of a directly-connected solar energy powered reverse osmosis (RO) membrane system. Typically, the system produced acceptable quality water with constant solar irradiances ranged from 400 – 1200 W.m-2. Low average motor powers were encountered duri...
Article
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This study examined the feasibility of nanofiltration (NF) and reverse osmosis (RO) in treating challenging natural tropical waters containing high fluoride and natural organic matter (NOM). A total of 166 water samples were collected from 120 sources within northern Tanzania over a period of 16months. Chemical analysis showed that 81% of the sampl...