From Micro to Macro-Contaminants: The Impact of Low-Energy Titanium Dioxide Photocatalysis Followed by Filtration on The Mitigation of Drinking Water Organics

Authors

Brooke K. Mayer, Marquette UniversityFollow
Carlan Johnson, Marquette University
Yu Yang, Marquette UniversityFollow
Nicole Wellenstein, Marquette University
Emily K. Maher, Marquette University
Patrick J. McNamara, Marquette UniversityFollow

Document Type

Article

Language

eng

Publication Date

2-2019

Publisher

Elsevier

Source Publication

Chemosphere

Source ISSN

0045-6535

Abstract

This study evaluated strategies targeting macro- and micro-organic contaminant mitigation using low-energy titanium dioxide photocatalysis. Energy inputs of 1, 2, and 5 kWh m⁻³ resulted in incomplete oxidation of macro-organic natural organic matter, signified by greater reductions of UV₂₅₄ and specific ultraviolet UV absorbance (SUVA) in comparison to dissolved organic carbon (DOC). The rate of UV₂₅₄ removal was 3 orders of magnitude greater than the rate of DOC degradation. Incomplete oxidation improved operation of downstream filtration processes. Photocatalysis at 2 kWh m⁻³ increased the bed life of downstream granular activated carbon (GAC) filtration by 340% relative to direct filtration pretreatment. Likewise, photocatalysis operated ahead of microfiltration decreased fouling, resulting in longer filter run times. Using 2 kWh m⁻³ photocatalysis increased filter run time by 36 times in comparison to direct filtration. Furthermore, levels of DOC and UV₂₅₄ in the membrane permeate improved (with no change in removal across the membrane) using low-energy photocatalysis pretreatments. While high-energy UV inputs provided high levels of removal of the estrogenic micro-organics estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethynlestradiol (EE2), low-energy photocatalysis did not enhance removal of estrogens beyond levels achieved by photolysis alone. In the cases of E1 and E3, the addition of TiO₂ as a photocatalyst reduced degradation rates of estrogens compared to UV photolysis. Overall, process electrical energy per order magnitude reductions (EEOs) greatly improved using photocatalysis, versus photolysis, for the macro-organics DOC, UV₂₅₄, and SUVA; however, energy required for removal of estrogens was similar between photolysis and photocatalysis.

Comments

Accepted version. Chemosphere, Vol. 217 (February 2019): 111-121. DOI. © 2019 Elsevier. Used with permission.

Recommended Citation

Mayer, Brooke K.; Johnson, Carlan; Yang, Yu; Wellenstein, Nicole; Maher, Emily K.; and McNamara, Patrick J., "From Micro to Macro-Contaminants: The Impact of Low-Energy Titanium Dioxide Photocatalysis Followed by Filtration on The Mitigation of Drinking Water Organics" (2019). Civil and Environmental Engineering Faculty Research and Publications. 216.
https://epublications.marquette.edu/civengin_fac/216