The Effect of Natural Organic Matter on UV/H₂O₂ Treatment and the Effect of UV/H₂O₂ Treatment on Natural Organic Matter

<p>Ultraviolet light with hydrogen peroxide (UV/H₂O₂) produces hydroxyl radicals that degrade organic micro-pollutants. However, radicals react non-selectively with natural organic matter (NOM). This research effort quantified the effect of NOM variation on the efficiency of UV/H₂O₂ contaminant destruction, explored the kinetics of hydroxyl radical/NOM reactions, determined the effect of UV/H₂O₂ on biofilm formation potential, measured UV/H₂O₂ impact on trihalomethane (TTHM) and haloacetic acid (HAA5) formation potential, and evaluated UV/H₂O₂ effects on TTHM speciation after chlorination. Granular activated carbon (GAC) adsorption was investigated to improve process efficiency and reduce by-product formation potential without creating brominated THM problems.</p><p>A year-long UV/H₂O₂ pilot study was conducted to study seasonal variations in NOM and multiple GAC breakthrough conditions. Pilot-scale reactors consistently achieved 80% atrazine degradation, allowing comparison of low pressure (LP) and medium pressure (MP) lamps for contaminant destruction efficiency and unintended by-product formation. </p><p>The effect of NOM on UV/H₂O₂ destruction of atrazine, metolachlor, methyl tert-butyl ether (MTBE), methylisoborneol, ibuprofen, gemfibrozil, and 17α-ethynylestradiol was evaluated. UV absorbance scans demonstrated changes in NOM from UV/H₂O₂ that increased under certain NOM conditions. As NOM increased, electrical energy per order (E_EO) requirements for contaminant destruction increased; requirements increased similarly for all contaminants. UV/H₂O₂ followed by GAC eliminated the contaminants, throughout the year. LP lamps had lower E_EO requirements than MP lamps. UV/H₂O₂ destruction of MTBE was evaluated with bench-scale experiments using waters with varying NOM. Destruction and E_EO values correlated well with specific-ultraviolet absorption for pilot-scale and bench-scale experiments. Changes in the kinetics of NOM/hydroxyl radical reactions were observed with different types of NOM.</p><p>Total assimilable organic carbon (AOC) concentration increased through UV/H₂O₂ by 14 to 33%, more with conventionally treated (CONV) reactor influent than with Post-GAC influent. The AOC concentration increases generated by MP and LP processes were similar. The <i>Spirillum</i> strain AOC increased through UV/H₂O₂ 50 to 65% due to formation of smaller more soluble compounds, e.g., organic acids. <i>Pseudomonas fluorescens</i> strain AOC concentration increased when CONV water served as pilot influent, but not when Post-GAC water was used. GAC effluent streams receiving UV/H₂O₂ pretreatment produced biofilms with greater heterotrophic plate counts than controls. The GAC effluent stream following the MP reactor produced the most viable biofilm.</p><p>Three-day simulated distribution system (SDS) TTHM concentration increased through the UV/H₂O₂ reactors (20 to 118%). Post-GAC reactor influent produced lower 3-day SDS TTHM concentration than CONV influent after UV/H₂O₂. Three-day SDS HAA5 concentration increased for CONV UV/H₂O₂ pilot influent, but not for Post-GAC influent. No difference in 3-day SDS DBP concentrations was observed between LP and MP processes. Brominated THMs are more toxic than chloroform, thus minimizing them is desirable. UV/H₂O₂ did not shift 3-day SDS THMs towards the brominated species. UV/H₂O₂ increased the TTHM contribution of 3-day SDS chloroform by 7 to 13%, while 3-day SDS bromoform TTHM contribution decreased by 0.5 to 7%. GAC adsorption after UV/H₂O₂ insignificantly increased 3-day SDS bromoform concentration from 0.01 to 0.02 μmole/L. </p><p>UV/H2O2 can be used with GAC for excellent contaminant removal and minimal adverse effects.</p>

Name thesis:degree_name

PhD

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Engineering and Applied Science: Environmental Science

Grantor dc:publisher

University of Cincinnati

Year dc:date

2012

Author dc:creator

• Metz, Deborah H.

Contributors dc:contributor

• Dionysiou, Dionysios

• Environmental Science
• UV H2O2
• contaminant destruction
• byproduct formation potential
• advanced oxidation
• biofilm potential
• disinfection byproduct formation potential

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=ucin1337007191

OAI identifier oai:identifier

oai:etd.ohiolink.edu:ucin1337007191