Comparison of ferrate and ozone pre-oxidation on disinfection byproduct formation from chlorination and chloramination

Yanjun Jiang,Joseph E Goodwill,John E Tobiason,David A Reckhow

doi:10.1016/j.watres.2019.02.051

Yanjun Jiang, Joseph E Goodwill + Show 2 more

Open Access

https://doi.org/10.1016/j.watres.2019.02.051

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Abstract

This study investigated the effects of ferrate and ozone pre-oxidation on disinfection byproduct (DBP) formation from subsequent chlorination or chloramination. Two natural waters were treated at bench-scale under various scenarios (chlorine, chloramine, each with ferrate pre-oxidation, and each with pre-ozonation). The formation of brominated and iodinated DBPs in fortified natural waters was assessed. Results indicated ferrate and ozone pre-oxidation were comparable at molar equivalent doses for most DBPs. A net decrease in trihalomethanes (including iodinated forms), haloacetic acids (HAAs), dihaloacetonitrile, total organic chlorine, and total organic iodine was found with both pre-oxidants as compared to chlorination only. An increase in chloropicrin and minor changes in total organic bromine yield were caused by both pre-oxidants compared to chlorination only. However, ozone led to higher haloketone and chloropicrin formation potentials than ferrate. The relative performance of ferrate versus ozone for DBP precursor removal was affected by water quality (e.g., nature of organic matter and bromide concentration) and oxidant dose, and varied by DBP species. Ferrate and ozone pre-oxidation also decreased DBP formation from chloramination under most conditions. However, some increases in THM and dihaloacetonitrile formation potentials were observed at elevated bromide levels.

Highlights

While crucial in the prevention of waterborne disease, drinking water disinfection with chlorine has caused concern as more than 600 disinfection byproducts (DBPs) with potential adverse health effects have been detected in chlorinated waters (Richardson et al, 2007)
This study investigated the effects of ferrate and ozone pre-oxidation on disinfection 14 byproduct (DBP) formation from subsequent chlorination or chloramination
Among the known DBP species, trihalomethanes (THMs) and haloacetic acids (HAAs) are the two most prevalent groups formed in chlorinated water and have been regulated by the United States Environmental Protection Agency (Seidel et al, 2017)

Summary

Introduction

While crucial in the prevention of waterborne disease, drinking water disinfection with chlorine has caused concern as more than 600 disinfection byproducts (DBPs) with potential adverse health effects have been detected in chlorinated waters (Richardson et al, 2007). Among the known DBP species, trihalomethanes (THMs) and haloacetic acids (HAAs) are the two most prevalent groups formed in chlorinated water and have been regulated by the United States Environmental Protection Agency (Seidel et al, 2017). The formation of brominated and iodinated DBPs in waters with elevated levels of bromide and iodide calls for increased focus because brominated and iodinated DBPs are more toxic than their chlorinated analogues (Langsa et al, 2017; Plewa 46 et al, 2004). Many utilities have turned to chloramines, which produce only trace amounts of THMs and trihalogenated HAAs (THAAs), to control regulated DBP formation in finished water (Diehl et al, 2000). Many utilities have chosen to make process changes to improve the removal of DBP precursors, and use of pre-oxidation features prominently in these strategies. Application of oxidants (e.g. ozone) can help by partially oxidizing DBP precursors within natural organic matter (NOM), and by having a beneficial impact on subsequent processes that affect final DBP concentrations (Camel and Bermond, 1998)

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