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Mayer Lab Projects

Research Projects

Current

Recent

Coupled titanium dioxide photocatalysis and filtration for simultaneous mitigation of organic matter, viruses, and estrogenic compounds

As water demand and reuse increase, so does pressure on the water industry to mitigate emerging contaminants, including viruses, estrogenic compounds, and disinfection byproducts (DBPs). Development of sustainable, economically feasible treatment options is essential. Low-energy titanium dioxide (TiO2) photocatalysis coupled to filtration is being evaluated as a sustainable water treatment process to address these concerns. It is hypothesized that low-energy photocatalysis can partially oxidize organic compounds to benefit downstream filtration – extend bed life and reduce fouling while removing
organic DBP precursors – and simultaneously mitigate contaminants that are not adequately treated by conventional processes, such as estrogenic compounds and UV-resistant viruses. This project is being conducted in collaboration with Arizona State University and is being supported by the National Science Foundation and the NSF I/UCRC “Water Equipment and Policy” Center.

This work is being performed with Prof. Patrick McNamara, in collaboration with Prof. Daniel Zitomer.

Electrocoagulation for the mitigation of emerging biological and chemical contaminants

This project seeks to address some of the critical knowledge gaps in the understanding of electrocoagulation by elucidating the mechanisms of mitigation of Contaminant Candidate List (CCL) viruses and estrogens using electrocoagulation as a sustainable alternative for drinking water treatment. It is hypothesized that electrocoagulation will provide an enhanced degree of treatment for a suite of microbial and chemical contaminants, beyond that which can be achieved using either conventional coagulation or chemical oxidation processes alone. This research will substantially advance knowledge of CCL contaminants, and will also stimulate improved development and implementation of innovative approaches to drinking water treatment. This project is supported by the National Science Foundation.

This work is being performed with Prof. Patrick McNamara, in collaboration with Prof. Daniel Zitomer.

Removal of Micropollutants and Recovery of Nutrients in Anaerobic Wastewater Treatment

Graduate Researcher: Yiran Tong

The NEW (Nutrients, Energy, Water) paradigm, which highlights resource recovery as an integral part of wastewater treatment, guides this research exploring sorption technologies targeting simultaneous recovery of nutrients and removal of micropollutants from wastewater.  Combined with anaerobic treatment to improve energy efficiency (see Dr. Zitomer's work), these processes contribute to the NEW paradigm with a focus on the use of nutrient ion exchange materials and biochar.

This work is being performed with Prof. Patrick McNamara, in collaboration with Prof. Daniel Zitomer.

Evaluation of Electrocoagulation-Microfiltration for the Removal of Trace Heavy Metals, Hardness, and Viruses

Graduate Researcher: Joseph Heffron
Undergraduate Researcher: Matthew Marhefke

In electrocoagulation, Al or Fe-based coagulants are generated in-situ using electrical current to initiate electro-oxidation of a sacrificial anode, while the cathode undergoes reduction.  This facilitates removal of an array of contaminants via flotation, floc sedimentation or filtration, or direct REDOX reactions.  In this project, the efficacy of electrocoagulation as a pretreatment for microfiltration is assessed.  Specific goals include evaluating the ability of electrocoagulation-microfiltration to: i) achieve ultra-low levels of heavy metals in water with initial concentrations of relevance to drinking water or domestic wastewater, ii) reduce hardness, and iii) enhance virus removal.  This project is supported by the National Science Foundation I/UCRC “Water Equipment and Policy” Center.

Sustainable Treatment System for Municipal Anaerobic Wastewater Treatment

Graduate Researcher: Patrick Mullen

This project focuses on the recovery of phosphorus and nitrogen from wastewater.  While historical wastewater treatment technologies focused on the removal of nutrients from wastewater discharges to reduce the risk of eutrophication in environmental waters, the focus is now shifting to recovering these same nutrients for beneficial reuse, i.e., Waste à Resource.  The use of these recovered products as agricultural fertilizer helps to sustain the global food supply, which relies on mineral reserves of phosphorus, an essentially non-renewable resource.  Ion exchange is a promising technology for capturing and concentrating P and N in fertilizer-ready forms.  This project seeks to improve and evaluate ion exchange materials to optimize nutrient recovery.

Evaluation of Titanium Dioxide Photocatalysis to Improve Removal and Recovery of Phosphorus from Water and Wastewater

The primary objective of this effort was to improve the removal and recovery of phosphorus (P) from water and wastewater using titanium dioxide photocatalysis to shift the distribution of phosphorus toward inorganic species.  Nutrients such as P are essential for all biological organisms and are key ingredients in fertilizer, but can be harmful to the environment in excess.  Eutrophication (or “accelerated aging”) caused by excess environmental P loadings poses a serious risk to freshwater bodies around the world.  Treatment using advanced oxidation processes such as TiO2 photocatalysis may facilitate P capture and removal from water/wastewater by converting organically complexed-P (organic-P) to the more readily removable inorganic form, which is also the form most suitable for reuse as fertilizer.  This work was supported by a Regular Research Grant from Marquette University.

Assessment of the Removal and Inactivation of Emerging Viruses using Enhanced Coagulation and Ultraviolet Disinfection

This effort focused on alternative approaches to mitigating viruses in drinking water beyond traditional disinfection.  Physical removal through adsorption and charge neutralization resulting from enhanced coagulation (addition of higher coagulant doses and/or pH adjustment) was quantified for viruses on the USEPA's Contaminant Candidate List.  Additionally, inactivation of the viruses using UV disinfection was measured.  This work was funded by the USEPA. [link to papers: Abbaszadegan et al., 2007; Mayer et al., 2008]

Development and Validation of New Techniques for Detecting and Quantifying Infectious Waterborne Viruses

The standard method of quantifying infectious viruses is in-vitro cell culture.  While effective, cell culture is a fairly cost- and time-intensive laboratory approach which requires specialized knowledge and equipment to perform.  Furthermore, certain viruses such as norovirus (affectionately known as the “cruise ship virus”) have not yet been cultured using standard in-vitro techniques).  Thus, this research thrust focused on developing alternative quantification techniques offering advantages such as simultaneously detecting and quantifying viruses in shorter times using integrated cultural and molecular techniques and culturing human norovirus.  This work was partially supported by the Department of Homeland Security.  [link to papers: Straub et al., 2007; Ryu et al., 2008; Mayer et al., 2009]

Use of Titanium Dioxide Photocatalysis for Mitigation of Disinfection Byproducts

This work evaluated the potential for mitigation of disinfection byproducts using titanium dioxide photocatalysis.  Disinfection byproducts (DBPs) are formed when oxidizing disinfectants such as chlorine interact with the natural organic matter (NOM) found in water.  The resulting chemical species are potentially carcinogenic, and several groups have been regulated in the US on this basis.  One approach for mitigation is to remove the NOM prior to disinfection.  The hydroxyl radicals produced by irradiating titanium dioxide nanoparticles using UV light offer one possible treatment strategy.  Here, TiO2 photocatalysis operated under limited energy input conditions exacerbated DBP production regardless of the type of source water (raw, coagulation, filtered, finished), whereas higher energy inputs mineralized NOM, effectively mitigating DBP production.  Additionally, the use bulk NOM measures such as dissolved organic carbon were evaluated as indicators of DBP formation using advanced oxidation processes such as TiO2 photocatalysis.  This work was partially supported by the NSF Water & Environmental Technology I/UCRC. .  [link to papers: Gerrity et al., 2009; Mayer et al., 2014…not out yet]

Identification and Evaluation of Novel Techniques for the Removal and Recovery of Phosphorus from Water and Wastewater

Eutrophication is considered to be the biggest impairment of natural waters in the US.  Thus, environmental engineers have historically designed wastewater treatment plants to reduce nutrient discharge to acceptable levels.  However, there is growing recognition that even very low levels of phosphorus (P) can still negatively impact waterbodies, particularly in sensitive areas such as the Everglades and Great Lakes region.  This work focused on identifying i) methods to remove P to ultra-low levels and ii) processes to recover P from nutrient-rich “waste” streams.  Recovery is of growing interest as supplies of the mineral rock P used to produce agriculture fertilizer and sustain the global food supply are non-renewable resources.  [link to papers: Rittman et al., 2011; Mayer et al., 2013]