{"id":{"repo_id":"gatech","oai_identifier":"oai:repository.gatech.edu:1853/81522"},"canonical_url":"https://search.dev.ndltd.org/etd/gatech/oai:repository.gatech.edu:1853/81522","repository":{"repo_id":"gatech","name":"Georgia Tech","base_url":"https://repository.gatech.edu/server/oai/request"},"display":{"title":"The Minus Approach to Redefine the Standard of Practice of Drinking Water Treatment: Philosophy and Case Studies on the Adsorption of Per- and Polyfluoroalkyl Substances onto Powder Activated Carbon and Membrane Surfaces","abstract":"Victorian-aged water treatment practices that rely on chemical additions to remove contaminants (i.e., “Plus Approaches”) are ineffective at removing many known, unknown, and emerging contaminants (KUECs) and also create toxic disinfection byproducts (DBPs) in-situ. Although finished drinking water is usually compliant with permitting standards, numerous questions arise regarding its ultimate safety for human consumption. This work introduces the philosophy of the “Minus Approach,” a toolbox of practices and technologies to mitigate KUECs and DBPs in drinking water while also producing biologically stable water containing pathogens at levels having negligible human health risk. We describe how the Minus Approach contrasts with the Plus Approach and can ultimately change the standard of practice of drinking water treatment. Adsorption is a fundamental Minus Approach technology to bolster overall water quality. Herein, a commercially available powder activated carbon (PAC) is pyrolyzed to amplify its hydrophobicity and encourage greater adsorption metrics of per- and polyfluoroalkyl substances (PFAS). We perform a comprehensive examination of adsorbent surface chemistry and morphology. Adsorption isotherms, kinetic studies, and a mixed PFAS removal test are conducted to evaluate performance of the hydrophobically improved PAC compared to its precursors. A density functional theory (DFT) calculation is performed to quantitatively evaluate the adsorption energies of PFAS onto a graphene skeleton containing different organic functional groups at differing concentrations in order to further validate experimental results. Inadvertent PFAS adsorption onto membrane materials can result in concentration underestimations. Herein, we report on the adsorption of six different PFAS onto eleven syringe filters, differing in either manufacturer, polymer material, diameter, and/or pore size under various experimental conditions. We perform comprehensive materials characterization, exhibiting differences in morphology and surface roughness, area, and charge. Evaluation of post-filtration PFAS recovery demonstrated impacts of filter material and surface area, initial PFAS concentration, pH, and the co-occurrence of cations and anions. Machine learning predictions of Abraham’s solute descriptors were used to develop qualitative hypotheses describing the forces governing PFAS adsorption onto different materials.","abstract_html":"Victorian-aged water treatment practices that rely on chemical additions to remove contaminants (i.e., “Plus Approaches”) are ineffective at removing many known, unknown, and emerging contaminants (KUECs) and also create toxic disinfection byproducts (DBPs) in-situ. Although finished drinking water is usually compliant with permitting standards, numerous questions arise regarding its ultimate safety for human consumption. This work introduces the philosophy of the “Minus Approach,” a toolbox of practices and technologies to mitigate KUECs and DBPs in drinking water while also producing biologically stable water containing pathogens at levels having negligible human health risk. We describe how the Minus Approach contrasts with the Plus Approach and can ultimately change the standard of practice of drinking water treatment. Adsorption is a fundamental Minus Approach technology to bolster overall water quality. Herein, a commercially available powder activated carbon (PAC) is pyrolyzed to amplify its hydrophobicity and encourage greater adsorption metrics of per- and polyfluoroalkyl substances (PFAS). We perform a comprehensive examination of adsorbent surface chemistry and morphology. Adsorption isotherms, kinetic studies, and a mixed PFAS removal test are conducted to evaluate performance of the hydrophobically improved PAC compared to its precursors. A density functional theory (DFT) calculation is performed to quantitatively evaluate the adsorption energies of PFAS onto a graphene skeleton containing different organic functional groups at differing concentrations in order to further validate experimental results. Inadvertent PFAS adsorption onto membrane materials can result in concentration underestimations. Herein, we report on the adsorption of six different PFAS onto eleven syringe filters, differing in either manufacturer, polymer material, diameter, and/or pore size under various experimental conditions. We perform comprehensive materials characterization, exhibiting differences in morphology and surface roughness, area, and charge. Evaluation of post-filtration PFAS recovery demonstrated impacts of filter material and surface area, initial PFAS concentration, pH, and the co-occurrence of cations and anions. Machine learning predictions of Abraham’s solute descriptors were used to develop qualitative hypotheses describing the forces governing PFAS adsorption onto different materials.","abstract_has_math":false,"creators":["Reid, Elliot Mark Stuart"],"institution":"Georgia Institute of Technology","degree_name":null,"degree_level":"Doctoral","degree_discipline":null,"degree_department":"Civil and Environmental Engineering","school":null,"contributors":[],"advisors":["Chen, Yongxin","Huang, Ching-Hua"],"committee_chairs":[],"committee_members":["Xie, Xing","Graham, Katherine","Snyder, Shane","Huang, Qingguo"],"year":2025,"date_issued":"2025-04-23","date_published":"2025-04-23","updated_at":"2026-07-27T19:51:09Z","subjects":["Drinking water treatment","Disinfection byproducts","Powder activated carbon","Adsorption","Per- and polyfluoroalkyl substances","Membranes","Density functional theory"],"languages":["en_US"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/1853/81522","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Chen, Yongxin","Huang, Ching-Hua"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Xie, Xing","Graham, Katherine","Snyder, Shane","Huang, Qingguo"]},{"key":"dc:contributor.department","label":"Department","values":["Civil and Environmental Engineering"]},{"key":"dc:creator","label":"Author","values":["Reid, Elliot Mark Stuart"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-05-21T20:40:30Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-05-21T20:40:30Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-04-23"]},{"key":"dc:publisher","label":"Institution","values":["Georgia Institute of Technology"]},{"key":"dc:type","label":"Dc Type","values":["Text"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Doctoral"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Drinking water treatment","Disinfection byproducts","Powder activated carbon","Adsorption","Per- and polyfluoroalkyl substances","Membranes","Density functional theory"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_US"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/1853/81522"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Victorian-aged water treatment practices that rely on chemical additions to remove contaminants (i.e., “Plus Approaches”) are ineffective at removing many known, unknown, and emerging contaminants (KUECs) and also create toxic disinfection byproducts (DBPs) in-situ. Although finished drinking water is usually compliant with permitting standards, numerous questions arise regarding its ultimate safety for human consumption. This work introduces the philosophy of the “Minus Approach,” a toolbox of practices and technologies to mitigate KUECs and DBPs in drinking water while also producing biologically stable water containing pathogens at levels having negligible human health risk. We describe how the Minus Approach contrasts with the Plus Approach and can ultimately change the standard of practice of drinking water treatment. Adsorption is a fundamental Minus Approach technology to bolster overall water quality. Herein, a commercially available powder activated carbon (PAC) is pyrolyzed to amplify its hydrophobicity and encourage greater adsorption metrics of per- and polyfluoroalkyl substances (PFAS). We perform a comprehensive examination of adsorbent surface chemistry and morphology. Adsorption isotherms, kinetic studies, and a mixed PFAS removal test are conducted to evaluate performance of the hydrophobically improved PAC compared to its precursors. A density functional theory (DFT) calculation is performed to quantitatively evaluate the adsorption energies of PFAS onto a graphene skeleton containing different organic functional groups at differing concentrations in order to further validate experimental results. Inadvertent PFAS adsorption onto membrane materials can result in concentration underestimations. Herein, we report on the adsorption of six different PFAS onto eleven syringe filters, differing in either manufacturer, polymer material, diameter, and/or pore size under various experimental conditions. We perform comprehensive materials characterization, exhibiting differences in morphology and surface roughness, area, and charge. Evaluation of post-filtration PFAS recovery demonstrated impacts of filter material and surface area, initial PFAS concentration, pH, and the co-occurrence of cations and anions. Machine learning predictions of Abraham’s solute descriptors were used to develop qualitative hypotheses describing the forces governing PFAS adsorption onto different materials."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph.D."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The Minus Approach to Redefine the Standard of Practice of Drinking Water Treatment: Philosophy and Case Studies on the Adsorption of Per- and Polyfluoroalkyl Substances onto Powder Activated Carbon and Membrane Surfaces"]}]}],"canonical_facts":{"dc:contributor.advisor":["Chen, Yongxin","Huang, Ching-Hua"],"dc:contributor.committeemember":["Xie, Xing","Graham, Katherine","Snyder, Shane","Huang, Qingguo"],"dc:contributor.department":["Civil and Environmental Engineering"],"dc:creator":["Reid, Elliot Mark Stuart"],"dc:date.accessioned":["2026-05-21T20:40:30Z"],"dc:date.available":["2026-05-21T20:40:30Z"],"dc:date.issued":["2025-04-23"],"dc:description.abstract":["Victorian-aged water treatment practices that rely on chemical additions to remove contaminants (i.e., “Plus Approaches”) are ineffective at removing many known, unknown, and emerging contaminants (KUECs) and also create toxic disinfection byproducts (DBPs) in-situ. Although finished drinking water is usually compliant with permitting standards, numerous questions arise regarding its ultimate safety for human consumption. This work introduces the philosophy of the “Minus Approach,” a toolbox of practices and technologies to mitigate KUECs and DBPs in drinking water while also producing biologically stable water containing pathogens at levels having negligible human health risk. We describe how the Minus Approach contrasts with the Plus Approach and can ultimately change the standard of practice of drinking water treatment. Adsorption is a fundamental Minus Approach technology to bolster overall water quality. Herein, a commercially available powder activated carbon (PAC) is pyrolyzed to amplify its hydrophobicity and encourage greater adsorption metrics of per- and polyfluoroalkyl substances (PFAS). We perform a comprehensive examination of adsorbent surface chemistry and morphology. Adsorption isotherms, kinetic studies, and a mixed PFAS removal test are conducted to evaluate performance of the hydrophobically improved PAC compared to its precursors. A density functional theory (DFT) calculation is performed to quantitatively evaluate the adsorption energies of PFAS onto a graphene skeleton containing different organic functional groups at differing concentrations in order to further validate experimental results. Inadvertent PFAS adsorption onto membrane materials can result in concentration underestimations. Herein, we report on the adsorption of six different PFAS onto eleven syringe filters, differing in either manufacturer, polymer material, diameter, and/or pore size under various experimental conditions. We perform comprehensive materials characterization, exhibiting differences in morphology and surface roughness, area, and charge. Evaluation of post-filtration PFAS recovery demonstrated impacts of filter material and surface area, initial PFAS concentration, pH, and the co-occurrence of cations and anions. Machine learning predictions of Abraham’s solute descriptors were used to develop qualitative hypotheses describing the forces governing PFAS adsorption onto different materials."],"dc:description.degree":["Ph.D."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["https://hdl.handle.net/1853/81522"],"dc:language.iso":["en_US"],"dc:publisher":["Georgia Institute of Technology"],"dc:subject":["Drinking water treatment","Disinfection byproducts","Powder activated carbon","Adsorption","Per- and polyfluoroalkyl substances","Membranes","Density functional theory"],"dc:title":["The Minus Approach to Redefine the Standard of Practice of Drinking Water Treatment: Philosophy and Case Studies on the Adsorption of Per- and Polyfluoroalkyl Substances onto Powder Activated Carbon and Membrane Surfaces"],"dc:type":["Text"],"thesis:degree_level":["Doctoral"]},"updated_at":"2026-07-27T19:51:09Z"}