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A LABORATORY SCALE ASSESSMENT OF THE EFFECT OF CHLORINE DIOXIDE PRE-OXIDATION ON DISINFECTION BY-PRODUCT FORMATION FOR TWO SURFACE WATER SUPPLIES
Title
A LABORATORY SCALE ASSESSMENT OF THE EFFECT OF CHLORINE DIOXIDE PRE-OXIDATION ON DISINFECTION BY-PRODUCT FORMATION FOR TWO SURFACE WATER SUPPLIES.
Creator
Rodriguez, Angela, Duranceau, Steven, University of Central Florida
Abstract / Description
Chemical disinfection is the cornerstone of safe drinking water. However, the use of chemical disinfection results in the unintentional formation of disinfection by-products (DBPs), an outcome of reactions between the disinfectant and natural organic matter (NOM) present in the native (raw) water. DBPs are suspected carcinogens, and as such, have been regulated by the U.S. Environmental Protection Agency (USEPA) under the Safe Drinking Water Act (SDWA). This document reports the results of a...
Show moreChemical disinfection is the cornerstone of safe drinking water. However, the use of chemical disinfection results in the unintentional formation of disinfection by-products (DBPs), an outcome of reactions between the disinfectant and natural organic matter (NOM) present in the native (raw) water. DBPs are suspected carcinogens, and as such, have been regulated by the U.S. Environmental Protection Agency (USEPA) under the Safe Drinking Water Act (SDWA). This document reports the results of a study that investigated the use of chlorine dioxide pre-oxidation for the reduction of DBP precursors, and subsequently, DBP formation potential (FP). To determine the effectiveness of the chlorine dioxide pre-oxidation process, two surface waters were studied: raw water from Lake Claire (Orlando, FL) and raw water from the East Maui Watershed (Makawao, HI). Lake Claire water contains approximately 11-12 mg/L of NOM and 35 mg/L as CaCO3 of alkalinity, while the Maui source water typically ranges between 7-8 mg/L of NOM with 2-10 mg/L as CaCO3 of alkalinity. Two chlorine dioxide doses were investigated (0.75 mg/L and 1.5 mg/L) and compared to a control to quantify the effectiveness of this advanced pre-treatment oxidation process. Water collected at each site was subject to the following treatment process: oxidation, coagulation, flocculation, sedimentation, ultrafiltration, and disinfection with free chlorine. Disinfection by-product formation potential (DBPFP) analysis showed that ClO2 pre-oxidation, in general, increased the 7-day DBPFP of the East Maui water, and decreased the 7-day DBPFP of the Lake Claire source water. For the Lake Claire water at the higher ClO2 dose, total trihalomethanes (TTHM) were decreased by 37 percent and the five regulated haloacetic acids (HAA5) by 23 percent. For the East Maui source water at the higher ClO2 dose, TTHM's were increased by 53 percent and HAA5's by 60 percent. Future research should determine the effect of alkalinity on DBPFP, which could be the reason why chlorine dioxide pre-oxidation caused one water source's DBPFP to decrease and the other to increase.
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Date Issued
2015
Identifier
CFH0004734, ucf:45393
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH0004734
Evaluating the Integration of Chlorine Dioxide into a Coagulation, Sedimentation, and Filtration Process Treating Surface Water
Title
Evaluating the Integration of Chlorine Dioxide into a Coagulation, Sedimentation, and Filtration Process Treating Surface Water.
Creator
Coleman, Martin, Duranceau, Steven, Lee, Woo Hyoung, Sadmani, A H M Anwar, University of Central Florida
Abstract / Description
Methods of optimizing the coagulation, flocculation, sedimentation, and filtration (CSF) process at a conventional surface water treatment plant (WTP) were conducted to investigate opportunities for the reduction of disinfection by-product (DBP) precursor material. The research had two primary components: (1) optimize coagulant dosage and associated operating pH and (2) investigate pretreatment oxidation with chlorine dioxide (ClO2) and potassium permanganate (KMnO4). To accomplish the first...
Show moreMethods of optimizing the coagulation, flocculation, sedimentation, and filtration (CSF) process at a conventional surface water treatment plant (WTP) were conducted to investigate opportunities for the reduction of disinfection by-product (DBP) precursor material. The research had two primary components: (1) optimize coagulant dosage and associated operating pH and (2) investigate pretreatment oxidation with chlorine dioxide (ClO2) and potassium permanganate (KMnO4). To accomplish the first component, jar tests were conducted at various pH and aluminum sulfate (alum) dosages to model current and potential treatment conditions during the CSF process at a WTP. Isopleths were developed to examine the removal efficiencies of turbidity and natural organic matter (NOM). NOM is a DBP precursor material and was represented by non-purgeable dissolved organic carbon (DOC) throughout the research. Isopleths indicated that at pH 6.2 and a corresponding alum dosage of 20 mg/L (control condition), turbidity and DOC were reduced by 90 and 35 percent, respectively. However, at pH 5.5 and 30 mg/L alum dosage, turbidity removal decreased to 80 percent whereas, DOC removal improved to 50 percent. Jar testing was conducted to evaluate differences in the use of KMnO4 and ClO2 as a pretreatment chemical to observe the reduction of DBP precursor material (i.e., NOM), dissolved iron, and dissolved manganese. Addition of ClO2 was able to reduce total trihalomethanes and haloacetic acid formation potentials (168-hours) up to 40 percent and 15 percent, respectively, and was dependent on chlorine dioxide generation method, dosage, and raw water characteristics. Chlorine dioxide also was shown to remove iron and manganese at levels greater than 99 percent.
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Date Issued
2018
Identifier
CFE0007396, ucf:52078
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007396
Study of the Formation and Control of Disinfection By-Products Originating from a Surface Water Supply on the Volcanic Island of Guam
Title
Study of the Formation and Control of Disinfection By-Products Originating from a Surface Water Supply on the Volcanic Island of Guam.
Creator
Laberge, Erica, Duranceau, Steven, Randall, Andrew, Lee, Woo Hyoung, University of Central Florida
Abstract / Description
Three oxidants have been evaluated for use as alternative chemical pretreatments for Fena Lake, a surface water that supplies the U.S. Navy's Public Water System (PWS) on the volcanic island of Guam. The study consisted of two investigative components. The first and primary component included a bench-scale evaluation to study the effects of different pre-oxidant chemicals on the formation of chlorinated disinfection by-products (DBPs). The second and ancillary component included a series of...
Show moreThree oxidants have been evaluated for use as alternative chemical pretreatments for Fena Lake, a surface water that supplies the U.S. Navy's Public Water System (PWS) on the volcanic island of Guam. The study consisted of two investigative components. The first and primary component included a bench-scale evaluation to study the effects of different pre-oxidant chemicals on the formation of chlorinated disinfection by-products (DBPs). The second and ancillary component included a series of water treatment and distribution system management studies that analyzed DBP formation within the treatment plant and water distribution system. The goal of this research was to reduce total trihalomethane (TTHM) and the five haloacetic acid (HAA5) formations in the PWS.In the primary component of the research, raw surface water from Fena Lake was collected by U.S. Navy personnel and shipped to University of Central Florida (UCF) laboratories for experimentation. Bench-scale tests that simulated the coagulation, flocculation, sedimentation and filtration (CSF) that comprises the Navy Water Treatment Plant (NWTP) were used to evaluate the use of two alternative pre-oxidants, potassium permanganate (KMnO4) and chlorine dioxide (ClO2) in lieu of gaseous chlorine (Cl2). The research assessed DBP formation by comparing several pretreatment scenarios, namely: (1) no pretreatment, (2) chlorine pretreatment, and (3) alternative oxidant pretreatment. KMnO4 pretreatment resulted in the lowest percent reduction of TTHMs and HAA5 relative to chlorine pretreatment, at 5.7% and 22.7%, respectively; however, this amount was still a reduction from the results demonstrated for the chlorine pretreatment condition. Without using a pre-oxidant, TTHM and HAA5 formation were reduced by 22.8% and 37.3%, respectively, relative to chlorine pretreatment. Chlorine dioxide demonstrated the greatest TTHM and HAA5 reduction relative to chlorine pretreatment at 34.4% and 53.3%, respectively.The second component of research consisted of a series of studies that evaluated distribution system operations and management alternatives to identify opportunities that could achieve DBP reduction within the PWS. Three concerns that were addressed were the NWTP's compliance with the U.S. Environmental Protection Agency's (USEPA's) Stage 2 Disinfectants/Disinfection By-Products (D/DBP) Rule, variable hydraulic detention times within a small subdivision in the distribution system, and severe weather. It was determined that: (1) A decision based on in-plant studies to cease prechlorination at the NWTP resulted in a decrease in TTHMs and HAA5s throughout the distribution system by 62% and 75%, respectively; (2) A fluoride tracer study led to the discovery of a valved pipeline responsible for elevated DBPs because of excessive water age that when exercised and managed resolved intermittent DBP spikes in the PWS; and (3) when the NWTP's ballasted floc clarifier (BFC) was operated in-series prior to the conventional CSF process during severe weather conditions the TTHM and HAA5 were below 39 ug/L and 29 ug/L, respectively, proving BFC in-series is a practical option for the plant during severe weather.
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Date Issued
2014
Identifier
CFE0005515, ucf:50299
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005515