Wintgens, Thomas

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Thomas
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Wintgens, Thomas

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  • Vorschaubild nicht verfügbar
    Publikation
    Improved phosphoric acid recovery from sewage sludge ash using layer-by-layer modified membranes
    (Elsevier, 01.10.2019) Paltrinieri, Laura; Remmen, Kirsten; Müller, Barbara; Köser, Joachim; Wintgens, Thomas [in: Journal of Membrane Science]
    We report an advanced treatment method for phosphoric acid recovery from leached sewage sludge ash. Layer-by-layer (LbL) polyelectrolyte deposition has been used as a tool to modify and convert a hollow ultrafiltration membrane into a nanofiltration (NF) LbL membrane for H3PO4 recovery. To build the LbL membrane, poly(styrenesulfonate) PSS was chosen as polyanion, while three different polycations were used: a permanently charged polyelectrolyte, poly(diallyldimethylammonium chloride), PDADMAC; a pH-dependent charged polyelectrolyte poly(allylamine hydrochloride), PAH; and a PAH modified with guanidinium groups (PAH-Gu). Based on detailed surface characterizations (AFM, XPS and Zeta-potential) it was concluded that both charge density and pH-responsiveness of the polycations are key parameters to control the final membrane surface structure and transport properties. The surface properties of LbL-coated membranes were correlated with the membrane filtration performance, when exposed to the real leached sewage sludge ash solution. The highest permeability was recorded for (PDADMAC/PSS)6, a result that was rationalized on its loose, and possibly less interpenetrated, structure, followed by (PAH-Gu/PSS)6 characterized by a more dense, compact layer. H3PO4 recovery was the highest in the case of (PDADMAC/PSS)6, but the retention of multivalent metals (Fe3+ and Mg2+) was low, leading to a more contaminated permeate. The opposite trend was observed for (PAH-Gu/PSS)6, resulting in a less metal-contaminated, but also a less H3PO4-concentrated permeate. Our LbL-modified membranes were found to improve the permeability and H3PO4 recovery compared to a commercially available acid-resistant NF membrane.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Phosphorus recovery in an acidic environment using layer-by-layer modified membranes
    (Elsevier, 15.07.2019) Remmen, Kirsten; Müller, Barbara; Köser, Joachim; Wintgens, Thomas [in: Journal of Membrane Science]
    Phosphorus (P) is a limited natural resource and essential for global food supply, particularly given our ever-growing world population. However, natural P deposits are restricted to just a few countries and the quality of exploited primary sources is declining. Phosphorus recovery from sewage sludge or sewage sludge ash leached by acids is hence gaining importance. During P recovery the removal of impurities is a challenge that can be addressed by nanofiltration retaining e. g. multivalent metals and allowing phosphoric acid to pass. However, currently available membranes show low permeability and limit this process option economically. Layer-by-layer (LbL) membrane synthesis is a technology that allows membrane performance to be tailored to individual filtration tasks. Little is known for such membranes with respect to acid resistance, acid permeability and impurity rejection. We show that LBL membranes based on PDADMAC/PSS show the desired passage of phosphoric acid with retentions values below 10%, aluminum retention was always above 95%. Permeabilities up to 4 L/(m2 h bar) were reached even up to a phosphorous recovery of 75%. Overall permeabilities were 16 times higher than a commercial benchmark membrane. Initial stability tests and upscaling into a larger module show the viability of the proposed modification approach.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Layer-by-layer membrane modification allows scandium recovery by nanofiltration
    (Royal Society of Chemistry, 07/2019) Remmen, Kirsten; Lenz, Markus; Hedwig, Sebastian; Wintgens, Thomas [in: Environmental Science. Water, Research & Technology]
    Aluminium scandium (Sc) alloys are stronger, more corrosion resistant and more heat tolerant than classical aluminium alloys and allow for 3D printing. In particular, the aerospace industry benefits from better fuel efficiency due to lighter materials as well as the advantages of additive manufacturing. However, Sc is currently not available in sufficient quantities and has recently been identified as a raw material critical to the economy. Due to the recentness of the demand, technologies for recovery of Sc from secondary sources are in their infancy. In this study, Sc recovery from titanium dioxide pigment production waste by nanofiltration was investigated. Custom-made layer-by-layer (LbL) modified membranes were optimized with regards to their elemental retention (i.e., selectivity towards Sc) as well as their acid resistance. In model solutions, the optimized membrane retained up to 64% ± 4% Sc, removing the major impurity, iron (Fe), efficiently (12% ± 7% retention) while achieving high flux [32 L m−2 h−1] at a low transmembrane pressure of 5 bar. Acid resistance was shown down to a pH of 0.1, which could be even further increased (up to ≤3 M HCl) by adding more bi-layers and changing the coating conditions. In real wastes, the optimized LbL membrane showed higher Sc retention (60% vs. 50%) compared to a commercial acid resistant membrane, while achieving considerably higher fluxes [27 L m−2 h−1 versus 1 L m−2 h−1, respectively at 5 bar]. It was possible to operate filtration at low transmembrane pressure with up to 70% permeate recovery and flux that was still high [∼10 L m−2 h−1]. In a nutshell, titanium dioxide pigment wastes contained sufficient amounts to satisfy the growing demand for Sc and can be exploited to their full extent by LbL nanofiltration due to the proven advantages of acid stability, Sc retention and selectivity and high achievable fluxes at low pressures.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Anaerobic digestion of biowastes in India: Opportunities, challenges and research needs
    (Elsevier, 15.04.2019) Breitenmoser, Lena; Gross, Thomas; Huesch, Ragini; Rau, Julius; Hugi, Christoph; Wintgens, Thomas [in: Journal of Environmental Management]
    The quest for improved living conditions in rapidly growing Indian communities puts pressure on natural resources and produces emissions which harm the environment, society and the economy. Current municipal solid waste (MSW) practices are an important example, as most waste remains untreated and is often deposited on unsafe dumpsites or burned on open fires. Anaerobic digestion (AD) is an option to treat the large biodegradable fraction ('biowaste'). In rural parts of India, the technology to supply energy from biogas has been promoted for 30 years. Biowaste treatment in urban MSW management and organic fertilizer ('digestate') production for agriculture via AD have more recently gained attention but with limited success so far. Recent environmental policies in waste, energy, agricultural and other sectors have, however, set important cornerstones for a broader diffusion in the coming years. On the basis of peer-reviewed literature and governmental reports, we identify barriers and enabling factors along the AD chain (biowaste to technology to product utilization), and analyse relevant boundary conditions for the new multi-sector policies. We show that AD implementation has repeatedly failed due to unrealistic assumptions on biowaste quantity and quality, underestimation of the complex biowaste supply chain, unsuitable AD designs and overestimation of economic returns from biogas and digestate. Local knowledge and capacities for planning and process control are lacking in many places and resources required for operation and maintenance in the long run have often been ignored. We found that the multi-facetted value propositions of AD - including biowaste treatment, energy and fertilizer products - have only been partially tapped due to the exclusive focus on biogas. The new sector policies provide important enabling factors for change. Decentralized AD plants operating on a few tons biowaste per day from reliable and manageable sources (e.g. fruit and vegetable markets) could be a more promising step forward than large-scale investments which rely on large biowaste volumes from various sources. The parallel development of biowaste management, planning tools for municipalities, standardized digestate monitoring protocols and studies on simple, low-cost optimization measures for methane recovery from a wide range of biowastes and innovative high-solid AD digester designs will be prerequisites for the long-term future of AD projects.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Poseidon—Decision Support Tool for Water Reuse
    (Elsevier, 2019) Oertlé, Emmanuel; Hugi, Christoph; Wintgens, Thomas [in: Water]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    Surface water treatment by UV/H2O2 with subsequent soil aquifer treatment. Impact on micropollutants, dissolved organic matter and biological activity
    (Royal Society of Chemistry, 2019) Wünsch, Robin; Plattner, Julia; Cayon, David; Eugster, Fabienne; Gebhardt, Jens; Wülser, Richard; von Gunten, Urs; Wintgens, Thomas [in: Environmental Science. Water, Research & Technology]
    Because organic micropollutants (MP) are frequently detected in river waters that are used as drinking water sources, combining a relatively cost-efficient natural treatment with upstream advanced oxidation processes (AOP) appears promising for their efficient abatement. Such a multi-barrier system can be integrated in drinking water production schemes to minimize risks from potentially hazardous MPs. This study investigates the impact of an UV/H2O2 AOP before soil aquifer treatment (SAT) on the abatement of selected MPs (EDTA, acesulfame, iopamidol, iomeprol, metformin, 1H-benzotriazole, iopromide), dissolved organic matter (DOM) (apparent molecular size distribution, specific UV absorbance at 254 nm – SUVA) and microbial parameters (intact cell count, cell-bound ATP). A pilot plant consisting of an AOP (0.5 m3 h−1, 4 mg L−1 H2O2, 6000 J m−2) and two parallel soil columns (filtration velocity: 1 m d−1, column height: 1 m) was continuously operated over a period of 15 months with Rhine river water pre-treated with rapid sand filtration. The investigations revealed a shift towards longer retention times of the humic substances peak in LC analysis of DOM, lower SUVA and higher biodegradability of DOM after UV/H2O2 treatment. In addition, an overall higher abatement of all investigated MPs by the combined treatment was observed (AOP with subsequent SAT) compared to either process alone. This observation could be explained by an addition of the single treatment effects. The strong primary disinfection effect of the AOP was detectable along the first meter of infiltration, but did not lead to any change in the column performance (i.e., similar abatement of dissolved organic matter).
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Separating powdered activated carbon (PAC) from wastewater – Technical process options and assessment of removal efficiency
    (Elsevier, 10/2018) Krahnstöver, Thérèse; Wintgens, Thomas [in: Journal of Environmental Chemical Engineering]
    Wastewater treatment plant effluents often contain anthropogenic micropollutants that can have harmful effects on aquatic ecosystems in the receiving water body. For this reason, more and more plants are being equipped with advanced treatment stages for micropollutant removal, such as ozonation or activated carbon adsorption. If powdered activated carbon (PAC) is used, it is crucial to retain the loaded PAC particles within the system and prevent PAC leakage into the environment. A range of different PAC separation processes is available today, but a systematic method comparison and derivation of practical recommendations is still missing. To fill this gap, we reviewed 27 pilot-, large- and full-scale PAC applications in the field of wastewater treatment with a specific focus on the implemented PAC separation processes. The operating conditions and removal efficiencies of all set-ups were collated and summarized. We also compared analytical methods to determine the residual PAC content in treatment plant effluents with regard to their sensitivity and selectivity. On this basis, recommendations were compiled to efficiently design and operate PAC separation stages and monitor their process quality.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    UV/H2O2 before biological treatment in drinking water: effects on the removal of micropollutants and biodegradability
    (09/2018) Wünsch, Robin; Cayon, David; Eugster, Fabienne; Plattner, Julia; Gebhardt, Jens; Wülser, Richard; von Gunten, Urs; Wintgens, Thomas
    06 - Präsentation
  • Vorschaubild nicht verfügbar
    Publikation
    Comparison of methods to assess the integrity and separation efficiency of ultrafiltration membranes in wastewater reclamation processes
    (Elsevier, 06/2018) Krahnstöver, Thérèse; Hochstrat, Rita; Wintgens, Thomas [in: Journal Water Process Engineering]
    Membrane filtration is used in many water reuse applications, thanks to its high separation efficiency with regard to particles, bacteria, cysts and in the case of ultrafiltration even viruses. However, the separation performance of a membrane system can be affected and the permeate quality can be reduced or increased by phenomena such as membrane damage, membrane fouling or microbiological regrowth on both permeate and retentate side of the membrane. Thus, in order to guarantee a sufficiently high permeate quality, the separation efficiency of a membrane system has to be assessed sensitively, reliably and, if possible, continuously. In the here presented study, a variety of different analytical methods was tested to assess the separation efficiency of ultrafiltration membranes in a pilot-scale wastewater reclamation system. After intentionally damaging the membrane to different degrees, its integrity was monitored by pressure decay testing and permeate turbidity measurements, and by continuously monitoring the concentration of micro- and nanoparticles in the permeate stream. The microbiological permeate quality was not only assessed by plate counting, but also by flow cytometric measurements. The results showed that the membrane integrity is primarily affected by physical damaging, as detectable by pressure decay testing, while the permeate quality strongly depends on particle-membrane interactions such as formation of a fouling layer or clogging of membrane defects. Nanoparticle counting was found to be a very sensitive method to continuously monitor the membrane’s separation efficiency. Additionally, flow cytometry revealed that bacterial regrowth on the permeate side can affect the microbiological permeate quality in particular.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Methane potential from municipal biowaste: Insights from six communities in Maharashtra, India
    (Elsevier, 04/2018) Breitenmoser, Lena; Dhar, Hiya; Gross, Thomas; Bakre, Milan; Huesch, Ragini; Hugi, Christoph; Wintgens, Thomas; Kumar, Rakesh; Kumar, Sunil [in: Bioresource Technology]
    Anaerobic digestion (AD) of biowaste can generate biogas with methane (CH4) as energy source and contribute to sustainable municipal solid waste management in India. Characteristic municipal biowastes sampled seasonally from household, fruit and vegetable market and agricultural waste collection points in villages, towns and cities in Maharashtra were analysed to assess the potential as substrate for AD. The mean biochemical methane potential (BMP, at 37 °C) across seasons and community sizes was between 200-260, 175-240 and 101-286 NLCH4 kgvs-1 for household, market and agricultural biowaste, respectively. CH4 yields were comparable in villages, towns and cities. Seasonal variations in CH4 yields were observed for market and agricultural biowaste with highest values during pre-monsoon season. Results underpin that municipal biowaste is a suitable substrate for AD in India. However, low purity of available biowaste resulted in lower CH4 yields compared to recent studies using source-segregated biowaste.
    01A - Beitrag in wissenschaftlicher Zeitschrift