1,780 research outputs found
Removal of organic pollutants from landfill leachate by electrochemical oxidation - Assessment of performance and applicability in Northern Norway
Full text linkLandfill leachate treatment by advanced oxidation processes has gained much attention in the past decades. The removal of organic pollutants from landfill leachate in particular has been in focus due to their detrimental effects on the environment. This fact also leads to increasingly stringent regulations put in place by the authorities regarding the pollutant removal and adherence to treatment goals. More stringent regulations for landfill leachate treatment are also expected to be effective in Norway in the near future. The new regulations contain a list of priority substances that need to be removed below their detection limit in order to release the effluent after treatment into nearby waterbodies. An appropriate treatment process that is able to accomplish the treatment goals and takes the given local climate conditions into consideration is required. Low average temperatures in subarctic climates provide a significant challenge.
The motivation of the present thesis was to find a suitable landfill leachate treatment process that is able to remove priority substances while withstanding cold operating temperatures. An extended literature study was the basis for choosing electrochemical oxidation, an advanced oxidation process, as a suitable treatment process. The majority of electrochemical oxidation studies have been carried out at room or elevated temperatures, while there is a lack of focus on wastewater treatment in cold climates. Furthermore, none assessed the application of advanced oxidation processes. This thesis bridges this knowledge gap and contributes to the applied field of electrochemistry by assessing its applicability under cold operating temperatures. The work is therefore of great interest in light of the increased focus on the technology in arctic regions.
This thesis consists of three separate studies:
1. A mechanistic study that helps to understand the ongoing different oxidation processes during the electrochemical oxidation of organic pollutants.
2. A laboratory scale study with a model organic pollutant from the priority list where the influence of different parameters on its oxidation was assessed, with a special focus on temperature.
3. A laboratory scale study with pre-treated landfill leachate that contains the same model organic pollutant, where the matrix effect and more applied parameters were assessed under cold climate conditions.
The mechanistic study of the model pollutant salicylic acid confirmed that three different oxidation pathways take place during the electrochemical oxidation: Direct electron transfer from the pollutant to the electrode surface, electrochemical oxygen transfer reaction from hydroxyl radical to the organic pollutant, and mediated oxidation via an intermediately formed oxidant, such as active chlorine. Density functional and natural bond theory were able to successfully predict the salicylic acid intermediates that were formed during electrochemical oxidation.
In the second study, Bisphenol A (5 µM) was used as the model compound as it is listed on the Norwegian priority substance list. Complete removal of Bisphenol A was achieved at low temperatures (6 °C) with the major drawback of extended treatment times. Besides temperature, pH also had a significant effect on the removal of Bisphenol A, and an alkaline pH (10) was found to be favourable. The anode material was found to have a major impact on the formation of disinfection by-products, favouring perchlorate formation on BDD anodes and trihalomethanes on Pt.
The final study confirmed increased treatment times at low operating temperatures (6 °C). The study further showed that a relatively high current density (43 mA/cm2 ) has to be applied in order to achieve complete Bisphenol A removal (5 µM) from the landfill leachate. The matrix effect of the landfill leachate disclosed lower Bisphenol A degradation rates compared to the ones obtained in the second study in clean electrolyte (3.3 mM NaCl & 0.3 mM Na2SO4). Formation of disinfection by-products increased with the application of higher current densities (10 – 86 mA/cm2 ) and temperatures (6 – 20 °C) while the anode material influenced their nature as previously.
The results of the three studies show that electrochemical oxidation is able to remove Bisphenol A from landfill leachate under cold operating temperatures. Treatment goals regarding Bisphenol A, given by the Norwegian authorities, were satisfied and indicate that results are transferrable to other organic compounds on the priority list. The major drawback are the increased treatment times, which subsequently result in higher energy demands, and ultimately in higher costs. Norway is a country driven by hydropower and lower electricity prices than the rest of Europe, so electrochemical oxidation is still a sustainable and economically feasible choice. Attention has to be paid to the choice of electrode material as they are a major matter of expense as well as influencing the disinfection by-products that are formed. This work sets iii precedent with regards to applicability of electrochemical advanced oxidation processes under cold operating temperatures
Jens Christian Grøndahl
No full textThis is a short presentation of the main works of the Danish author Jens Christian Grøndahl
Jens August Schade
No full textShort presentation of Danish author Jens August Schade and his main work
Interview with Jens Zimmermann: Author of ‘Hermeneutics: A Very Short Introduction’
Full text linkDr. Jens Zimmermann is a German-Canadian philosopher and J.I. Packer Professor of Theology at Regent College. As the author of Hermeneutics: A Very Short Introduction, he held a lecture titled “Gadamer, Ricoeur and the Future of Philosophical Hermeneutics” at SFU. Hosted by the Department of World Languages and Literatures, the lecture focused on how we can use the art of hermeneutics to interpret literature and our identities of being human
Bench Scale Demonstration of Redox Flow Battery based on Fungal Quinone Phoenicin as Negolyte: Reproducibility of phoenicin used in a bench-scaled RFB to store the energy produced by the solar panel
No full textThere is a growing need for renewable energy utilization, where the redox flow battery (RFB) is an alternative greener option in the sector of battery technologies used for energy storage. This thesis focuses on the bench scaling of the already-proven working redox flow battery containing the fungal-sourced compound. The bench scaling is led by the connection of a solar panel to the RFB to investigate if the battery can store the solar panel's produced energy.The battery properties being judged upon in this thesis are the capacity of the battery compared to the energy produced by the solar panel, the three efficiencies: coulombic (CE), voltage (VE), and energy (EE), and the capacity loss per cycle and hour. The results show that the principle of an RFB operating on phoenicin can store energy produced by the PV panel with some adjustments based on the previously conducted quality check RFBs in this project.It can be concluded that, based on the RFB, it is a viable option to store energy produced by a renewable energy source. There is a growing need for renewable energy utilization, where the redox flow battery (RFB) is an alternative greener option in the sector of battery technologies used for energy storage. This thesis focuses on the bench scaling of the already-proven working redox flow battery containing the fungal-sourced compound. The bench scaling is led by the connection of a solar panel to the RFB to investigate if the battery can store the solar panel's produced energy.The battery properties being judged upon in this thesis are the capacity of the battery compared to the energy produced by the solar panel, the three efficiencies: coulombic (CE), voltage (VE), and energy (EE), and the capacity loss per cycle and hour. The results show that the principle of an RFB operating on phoenicin can store energy produced by the PV panel with some adjustments based on the previously conducted quality check RFBs in this project.It can be concluded that, based on the RFB, it is a viable option to store energy produced by a renewable energy source
In-situ Electrochemical Regeneration of Granular Activated Carbon - Experimental and Theoretical Study Regarding the Treatment Performance of Dye and Pesticides
No full textA range of micropollutants, including several pharmaceuticals and pesticides, are inadequately treated in water treatment plants. With activated carbon, adsorption processes, can be employed as a resolution method to reduce their discharge into aquatic environments. This paper highlights and experimentally investigates the combinational treatment method of adsorption with electrochemical regeneration. Lab scale parameter studies were performed to investigate the various operational factors of the adsorption system, which consisted of temperature, the added carbon amount and adsorption combined with applied electric potential. HGR-AC was utilised in a developed electrochemical batch reactor to determine the removal efficiency of organic contaminants represented with the dye, RNO. With the change from 10 mg HGR-AC to 500 mg HGR-AC, the removal efficiency increased from 42% to 97%. The combined adsorption and applied electric potential also showed to be proficient and improved the degradation process of RNO. Results obtained from published literature were used for the investigation of electrochemical regeneration, through the evaluation of the operational parameters’ adjustment, such as the variation in regeneration time, regeneration cycles and current intensity. The found results suggested a dependency on the system’s operational conditions used; thus, final results are varied. Five regeneration cycles were the stated maximum number of practical cycles, along with a regeneration time ranging from two to five hours. The highest regeneration efficiency achieved from the published studies was 98%, which used the highest current of 3 A. The information provided in this thesis showed the success rate of electrochemical regeneration through different parameter perspectives, which can further aid advance for future research in this scientific field
Kinetic modeling and rate constant determination of Vacuum-UV oxidation of BAM in Danish groundwater
No full textPredicting Electrochemical Potential of Quinones Using Machine Learning Methods
No full textWith growing energy demands and the transition to renewable sources, the need for grid-scale energy storage systems is increasing. Quinones, a group of redox-active organic compounds that can be derived from fungi and bacteria, are promising biomolecules for use in redox flow batteries due to their tunability. This study investigates the prediction of quinone standard reduction potentials using machine learning, comparing transformer-based large language models (LLMs) and graphical neural networks (GNNs). The best-performing configurations of LLM and GNN models achieved average test set R² values of 0.734 and 0.721, respectively. However, LLMs have exhibited poorer performance on validation sets compared to test sets, indicating issues with model fitting. Within the optimal configurations, the top individual LLM and GNN models achieved an R² of 0.777 and 0.774 on the test set, respectively. While LLMs demonstrated slightly better accuracy, they require significantly higher training times and computational costs
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