Research

Role of environmental buffers in potable water reuse

This project, funded by NIWR and USGS, evaluates whether various environmental buffers used in potable water reuse remove or introduce a variety of conventional and emerging contaminants.  Wetlands, river, lake, groundwater storage and riverbank filtration are studied.  The contaminants evaluated include pharmaceuticals of various environmental fate, microbial contaminants and antibiotic resistance genes, contaminants indicative of urban atmospheric deposition, farm and road runoff, as well as a range of conventional water quality parameters.

Quenching of hydrogen peroxide after UV/H2O2 advanced oxidation

Advanced oxidation is a highly effective process for treatment of organic contaminants and is frequently used for taste and odor mitigation and for treatment of water from sources impacted by human activity (indirect potable water reuse).  However, it has some operational challenges on full-scale.  One of the major challenges is dealing with residual hydrogen peroxide which interferes with subsequent chlorine disinfection by reacting with chlorine.  Current methods of dealing with residual H2O2 involve adding more chlorine or using activated carbon to destroy H2O2.  Both processes are expensive for a full scale water treatment plant, and our lab is evaluating alternatives to the currently established processes.

Transformation products of antibiotics during chlorine disinfection

Transformation products of antibiotics during chlorine disinfection

Wastewater contains trace amounts of antibiotics as well as other pharmaceuticals.  During chlorine disinfection, pharmaceuticals react with chlorine and form transformation products, some of which may retain the properties of the parent molecule.  We are testing the properties of the products that form with antibacterial activity assays and identify the product with high performance liquid chromatography coupled with mass spectrometry (HPLC/MS).  Doxycycline forms products with antibacterial activity.  The formation of the products is more prominent in clean water than in wastewater effluent matrix due to selective competitive reactions between chlorine and either organic matter or doxycycline.  Testing of other antibiotics is planned in the near future.

Treatment of hydraulic fracturing flowback water components with O3 and O3/H2O2

Treatment of hydraulic fracturing flowback water components with O3 and O3/H2O2

In this study ozone (O3) and ozone with hydrogen peroxide advanced oxidation (O3/H2O2) were used to treat typical constituents of hydraulic fracturing wastewater.  The water contained guar gum (GG, a thickening agent) and glutaraldehyde (GLU, biocide).  Both treatment processes were successful in improving biodegradability of the components as expressed by the BOD/COD biodegradability ratio.

Leachate treatment with the Fenton’s Process

Leachate treatment with the Fenton’s Process

The goal of the study was to improve the UV transmittance of landfill leachate.  As wastewater treatment plants switch their disinfection process from chlorine to UV, they realize that landfill leachate interferes with the effectiveness of the disinfection process by blocking UV.  The Fenton’s Process achieved moderate improvement in UV transmittance, but generation of solids was considered prohibitive by the landfill.