COAGULATION TREATMENT TO REMOVE DENATONIUM BENZOATE

FROM WATER

Thesis

Submitted to

The School of Engineering of the

UNIVERSITY OF DAYTON

In Partial Fulfillment of the Requirements for

The Degree of

Master of Science in Chemical Engineering

By

Hussein Alaydamee

Dayton, Ohio

May 2017

COAGULATION TREATMENT TO REMOVE DENATONIUM BENZOATE

FROM WATER

Name: Alaydamee, Hussein Hantoosh

APPROVED BY:

______Kenya Crosson, Ph.D. Kevin J. Myers, D.Sc., P.E. Advisory Committee Chairman Professor, Graduate Chemical Associate Professor Engineering Program Coordinator Department of Civil and Department of Chemical and Environmental Engineering and Materials Engineering Engineering Mechanics

______Erick S. Vasquez, Ph.D. Assistant Professor Department of Chemical and Materials Engineering

______Robert J. Wilkens, Ph.D., P.E. Eddy M. Rojas Ph.D., M.A, P.E. Associate Dean for Research and Innovation Dean, School of Engineering Professor School of Engineering

ii

© Copyright by

Hussein Hantoosh Alaydamee

All rights reserved

2017

iii ABSTRACT

COAGULATION TREATMENT TO REMOVE DENATONIUM BENZOATE

FROM WATER

Name: Alaydamee, Hussein Hantoosh University of Dayton

Advisor: Dr. Kenya Crosson

The bittering agent denatonium benzoate, DB, was mandated by the U.S. House of Representatives (H.R. 615) to be added to antifreeze containing more than 10% ethylene glycol at 30-50ppm in order to prevent accidental poisoning. 30-ppm DB concentration in water makes it unpalatable. This research addressed the optimal doses of alum and ferric chloride, and impact of water quality conditions such as pH, ionic strength, turbidity, and alkalinity on DB removal from water. Coagulation aids such as kaolin and bentonite were studied for their impact on DB removal.

After conducting several coagulation experiments on water sources at their initial ionic strength (0.01-M river and groundwater; 0.00005-M ultrapure water), it was found that 20-ppm alum was the optimal dose that removed 90% DB from ultrapure water.

iv Higher alum dosages (60-mg/l) were needed to achieve 76% DB removal from groundwater. A 50-ppm dose of alum or FeCl3 achieved 72% DB removal from river water. In comparison to alum coagulation in ultrapure water, a lower FeCl3 dose (5-ppm) achieved a similar DB removal (83%). However, in groundwater, FeCl3 treatment did not achieve better DB removal (49%) than alum. Both coagulants consumed part of water alkalinity. Higher doses (50-ppm of alum or FeCl3) were required to remove DB from river water than ultrapure water (5-ppm ferric chloride or 20-ppm alum) because river water had higher turbidity, which indicates that higher coagulant doses tended to remove

DB as well as the particles causing turbidity in river water. Coagulants lowered river water turbidity to 0.1 NTU; FeCl3 (20-ppm) was more effective than alum to lower turbidity to 0.1 NTU in groundwater.

Optimal pH conditions for alum or FeCl3 were 5.8, 6, and 7.45 in ultrapure water, river water, and groundwater, respectively. In ultrapure water, pH conditions higher than 5.8 resulted in lower DB removal, and below pH 5.8, DB removal also decreased.

An ionic strength of 0.00005 M and 0.01 M in ultrapure water and river water, respectively, achieved the best DB removal with alum. Ionic strength of 0.00005 M and

0.03 M in ultrapure water and river water, respectively, achieved the best DB removal by

FeCl3. Addition of kaolin and bentonite did not achieve higher DB removal. Coagulant aid and river water results suggest that the presence of specific clay minerals and turbidity in the water limit DB removal. Lower DB removal was obtained when the water turbidity was higher, and only increased ionic strength conditions that would reduce the electric double layer thickness and facilitates the destabilization of clay

v minerals and turbidity slightly enhanced DB removal. The coagulant aid experiments support this premise that DB likely does not adsorb to these clay minerals to be removed via coagulation.

vi

I dedicate my thesis work to my parents, my brother and sisters, my wife, and my lovely

angels Ali and Zayneb.

vii ACKNOWLEDGEMENTS

My most sincere thanks go to my advisor and mentor, Dr. Kenya Crosson. I thank her for providing the time and efforts in directing this work in an organized manner. I thank her for her guidance, encouragement and support during the development of this work. She has been teaching me all about self-discipline in laboratory work and in written scientific communication.

Special thanks are due to Dr. Kevin Myers for advising me during my academic study, and guiding me into a successful graduation through his organized thinking and tracking.

Many thanks are due to Dr. Erick Vasquez for his time, efforts, and serving on my thesis committee.

Special thanks are due to the higher committee for education development in Iraq for awarding me scholarship in chemical engineering master degree.

viii TABLE OF CONTENTS

ABSTRACT ...... iv DEDICATION ...... vii ACKNOWLEDGMENTS ...... viii LIST OF FIGURES ...... xi LIST OF TABLES ...... xiv LIST OF ABBREVIATIONS ...... xv CHAPTER I- INTRODUCTION ...... 1 1.1. Statement of Problem ...... 1 1.2. Significance of Problem ...... 2 1.3. Objectives of the Research ...... 3 CHAPTER II- LITERATURE REVIEW...... 4 2.1. Introduction ...... 4 2.2. Denatonium Benzoate as an Aversive/Bittering Agent ...... 6 2.3. Denatonium Benzoate Applications and Uses ...... 7 2.4. Antifreeze bittering agent state legislation ...... 9 2.5. Denatonium Ion Quantification ...... 10 2.6. Coagulation for Water Treatment ...... 11 2.7. Coagulants ...... 13 2.8. Taste and odor compounds ...... 16 2.9. Kaolin and bentonite ...... 17 2.10. Water Quality Impacts on the Coagulation Process ...... 18 CHAPTER III- MATERIALS AND METHODS ...... 21 3.1. Introduction ...... 21 3.2. Materials and Equipments ...... 21 3.2.1. Denatonium Benzoate ...... 21 3.2.2. Coagulants ...... 22 3.2.3. Calcium Chloride ...... 23 3.2.4. Potassium Chloride ...... 23 3.2.5. Sodium Hydroxide ...... 23 3.2.6. Hydrochloric Acid ...... 24 3.2.7. Kaolin and Bentonite Clays ...... 24 3.2.8. Ultrapure Millipore™ Water ...... 24 3.2.9. Jar Testing Apparatus ...... 25 3.2.10. UV-VIS Spectrophotometer ...... 25

ix 3.2.11. Analytical balance...... 26 3.2.12. Quartz Cuvette ...... 26 3.2.13. Digital Pipets ...... 26 3.2.14. Beakers ...... 26 3.2.15. pH Meter and Electrode ...... 27 3.2.16. Amber Vials ...... 27 3.2.17. Turbidity meter ...... 27 3.2.18. Alkalinity Measurements ...... 28 3.2.19. Conductivity Meter ...... 28 3.2.20. Laboratory oven ...... 29 3.3. Methods ...... 29 3.3.1. Denatonium Benzoate Quantification ...... 29 3.3.2. Coagulation Studies ...... 31 3.3.3. Turbidity measurement ...... 33 3.3.4. Adjusting the pH ...... 33 3.3.5. Adjusting the ionic strength ...... 33 CHAPTER IV- RESULTS AND DISCUSSION ...... 35 4.1. Introduction ...... 35 4.2. Optimal Coagulant Type and Dosage for DB Removal ...... 36 4.2.1. Ultrapure Water Results ...... 36 4.2.2. Great Miami River Results ...... 38 4.2.3. Groundwater Results ...... 40 4.3. Effect of pH on DB Removal...... 43 4.3.1. Ultrapure water Results ...... 43 4.3.2. Great Miami River Results ...... 44 4.4. Effect of Ionic Strength on DB Removal ...... 46 4.4.1. Ultrapure water Results: ...... 46 4.4.2. Great Miami River Results ...... 47 4.5. Addition of Kaolin and Bentonite Clays ...... 49 4.5.1. Addition of Kaolin Clay ...... 49 4.5.2. Addition of Bentonite Clay ...... 50 CHAPTER V- CONCLUSIONS AND RECOMMENDATIONS ...... 53 REFERENCES ...... 55 APPENDIX A ...... 59 A.1. Interpolation Formula ...... 59 A.2. Preparing Stock Solutions ...... 60 A.3. DB Standards (5 mg/l- 100 mg/l) Preparation...... 61 A.4. Calculating Ionic Strength ...... 61 APPENDIX B...... 63 B.1. Turbidity HACH Method 8237...... 63 B.2. Alkalinity HACH Method 8203...... 64

x LIST OF FIGURES

Figure 1: Denatonium Benzoate Structure...... 7

Figure 2: DR/890 colorimeter (left), Digital Direct-Reading Turbidimeter (right)...... 28

Figure 3: Portable Waterproof Conductivity/TDS Meter...... 29

Figure 4: UV-Vis Usb-650 Red Tide Spectrometer...... 30

Figure 5: Denatonium benzoate standard/calibration curve (absorbance measured at 270 nm using Uv-Vis Usb-650 Red Tide Spectrometer)...... 31

Figure 6: Phipps and BirdTM PB-700TM Jartester...... 32

Figure 7: DB removal percentages versus aluminum sulfate doses (mg/l) in ultrapure water. (pH=5.81, initial DB=15 ppm, turbidity= 0 NTU, ionic strength=0.00005 M) ...... 37

Figure 8: DB removal percentages versus ferric chloride doses in ultrapure water. (pH=5.81, initial DB=15 ppm, turbidity=0 NTU, ionic strength=0.00005 M) ...... 37

Figure 9: DB removal percentages versus alum doses in Great Miami River water. (pH=7.98, initial DB=15 ppm, influent turbidity=10.23 NTU, effluent turbidity=0.1 NTU, ionic strength=0.01 M) ...... 39

Figure 10: DB removal percentages versus ferric chloride doses in Great Miami River water. (pH=7.98, initial DB=15 ppm, turbidity=10.23 NTU, ionic strength=0.01 M) ...... 39

Figure 11: DB removal percentages versus alum doses in Miami Well Field groundwater. (pH=7.45, initial DB=15 ppm, ionic strength=0.012 M) ...... 41

Figure 12: Alkalinity and turbidity versus alum doses in Miami Well Field groundwater...... 42

xi Figure 13: DB removal percentages versus ferric chloride doses in Miami Well Field groundwater. (pH=7.45, initial DB=15 ppm,ionic strength=0.012 M) ...... 42

Figure 14: Alkalinity and turbidity versus ferric chloride doses in Miami Well Field groundwater...... 43

Figure 15: DB removal percentages versus pH in ultrapure water using optimal alum dose (20 mg/l)...... 44

Figure 16: DB removal percentages versus pH in ultrapure water using optimal FeCl3 dose (5 mg/l)...... 44

Figure 17: DB removal percentages versus pH in Great Miami River water using optimal alum dose (50 mg/l)...... 45

Figure 18: DB removal percentages versus pH in Great Miami River water using optimal FeCl3 dose (50 ppm)...... 46

Figure 19: Comparing CaCl2 and KCl effects on DB removal in ultrapure water using optimal alum(20 ppm) and optimal pH=5.81...... 47

Figure 20: Comparing CaCl2 and KCl effects on DB removal in ultrapure water using optimal FeCl3(5 ppm) and optimal pH=5.81...... 47

Figure 21: Comparing CaCl2 and KCl on DB removal in Great Miami River water using optimal alum (50 ppm) and optimal pH=6...... 48

Figure 22: Comparing CaCl2 and KCl on DB removal in Great Miami River water using optimal FeCl3(50 ppm) and optimal pH=6...... 48

Figure 23: DB removal percentages and turbidity versus kaolin mass (g) in ultrapure water using optimal alum (20 ppm), optimal pH=5.81, and optimal CaCl2 concentration=0.1 M...... 50

Figure 24: DB removal percentages and turbidity versus kaolin mass (g) in ultrapure water using optimal FeCl3 (5 ppm), optimal pH=5.81, and optimal CaCl2 concentration=0.1 M...... 50

Figure 25: DB removal percentages and turbidity versus bentonite mass (g) in ultrapure water using optimal alum (20 ppm), optimal pH=5.81, and optimal CaCl2 concentration=0.1 M ...... 51

xii Figure 26: DB removal percentages and turbidity versus bentonite mass (g) in ultrapure water using optimal FeCl3 (5 ppm), optimal pH=5.81, and optimal CaCl2 concentration=0.1 M...... 51

Figure 27: Turbidity HACH method 8237...... 63

Figure 28: Alkalinity HACH method 8203...... 64

xiii LIST OF TABLES

Table 1: Aluminum sulfate and FeCl3 comparison ...... 15

Table 2: Initial water quality characteristics of ultrapure water, river water, and groundwater...... 36

xiv LIST OF ABBREVIATIONS

AOPs Advanced oxidation processes

AVMA American Veterinary Medical Association

DB Denatonium Benzoate

DOC Dissolved organic carbon

EPA Environmental Protection Agency

EFSA European Food Safety Authority

GAC Granular activated carbon

MIB 2-Methylisborneol

NOM Natural organic matter

NTU Nephelometric turbidity units

PAC Powder activated carbon

PPB Parts per billion

PPM Parts per million

PAC Poly aluminum chloride

UPW Ultrapure water

xv CHAPTER I

INTRODUCTION

1.1. Statement of Problem

Denatonium benzoate is considered to be one of the bitterest compounds known to humans [1]. The threshold of recognition for the bitter taste is 5 to 100 ppb, and the aversion threshold is between 10 and 20 ppm [2]. Denatonium benzoate can be detected by the average person at 10 ppb, and has a generally recognized bitter taste at 50 ppb [3].

The Consumer Products Specialty group that manufactures antifreeze agreed to voluntarily add the bittering agent to antifreeze and engine coolant. Engine coolant or antifreeze containing amounts higher than 10% ethylene glycol is required to contain 30 ppm denatonium benzoate as the minimum concentration and 50 ppm as the maximum

[4]. Although not required by law, DB can be found in other products. For example, the

DB concentration ranged from 13.6 ppm in glass cleaner and 21.1 ppm in nail polish remover, to 25.4 ppm in hair coloring. Although addition of DB to these products is not required, manufacturers apparently have added it as a safety feature to prevent ingesting these products [5]. The normal application range is 6-50 ppm, depending on the nature of the product to which it is added [6]. There is concern that spillage, runoff, or improper disposal of antifreeze or engine coolant that contains DB could make drinking water supplies unpalatable. Sand filtration technique is not efficient

1 in removing DB from water; however, another technique such as activated carbon sorption was found to be effective in removing DB from water [7].

On the other hand, we have no information about how well DB can be removed from water using other common processes in water treatment such as coagulation and flocculation, which has simple procedures and low capital cost. In addition, we do not yet have an idea about the impact of various coagulants and water quality conditions such as pH, ionic strength, turbidity, and alkalinity on DB removal from water. With the potential of DB release to water supplies, this research determined whether coagulation, a standard process used to remove contaminants in water, is appropriate for removing DB.

1.2. Significance of Problem

Denatonium benzoate is not only a bittering agent that could affect the taste of water, but it can also be a harmful substance. DB’s LD50 toxicity in rats is 584 mg/kg.

According to the European Food Safety Authority (EFSA), DB is harmful when swallowed; it causes skin irritation, serious eye irritation, and may result in respiratory irritation [8]. According to the DB’s chemical structure, it is soluble in water. When DB is released to water, it would not move from water to the atmosphere, as DB is not volatile. Concerns about the effect of DB on the environment exist because antifreeze containing DB could enters groundwater or surface water by stormwater runoff or illicit discharges, thereby threatening public drinking water supplies [9].

Denatonium benzoate is known to be resistant to biodegradation, so it is not expected that DB released to water could be removed by degradation. This bittering agent could arrive to the water sources in different ways. Engine coolant or antifreeze improper disposal might transfer DB to water or the antifreeze could accidentally leak

2 from vehicles resulting in DB release to water sources. In addition, many people could release DB to water when they dispose of their household products such as, hair coloring

(25.4 mg/l DB), nail polish remover (21.1 mg/l DB), or glass cleaner (13.6 mg/l DB) products. Some might know that antifreeze includes DB in certain levels, but most of them might have no idea that their daily products include DB in concentrations that could be harmful when released to water. Therefore, different techniques might be needed to remove it such as coagulation, adsorption, or oxidation.

1.3. Objectives of the Research

The main objectives of this research were to identify the efficiency of coagulation process to remove denatonium benzoate from water. The research also investigated the main parameters and conditions affecting denatonium benzoate removal, such as the coagulant type and the dose (ferric chloride or alum), pH conditions, ionic strength, and the effects of clay minerals, such as kaolin and bentonite.

3 CHAPTER II

LITERATURE REVIEW

2.1. Introduction

Denatonium benzoate (DB), which is usually marketed under the trade name

Bitrex [5], is an extremely bitter-tasting agent used in automotive coolants to prevent poisoning due to accidental ingestion. Denatonium benzoate addition to automotive antifreeze products containing more than 10 % ethylene glycol was enforced to render them unpalatable. The Consumer Specialty Products Association announced an agreement to voluntarily add a bittering agent to antifreeze and engine coolant.

Denatonium benzoate is also included in many products in the USA and elsewhere, such as denatured alcohols, cleaners, disinfectants, laundry detergents, nail-biting and thumb- sucking deterrents, and other products [6]. The highly unpalatable nature of denatonium benzoate makes this compound an effective additive to antifreeze products or household products of mild to moderate toxicity in order to successfully prevent accidental poisoning [10].

Denatonium benzoate (DB) is being added to a variety of consumer products as an aversive agent or denaturant. In 1995, Oregon was the first state to mandate the addition of DB to automobile antifreeze fluids [11]. Other marketed consumer products throughout the United States, such as cosmetics, rat bait, and household cleaning and

4 laundry products include denatonium benzoate as a deterrent agent [5]. Denatonium benzoate was considered as the potential deterrent to liquid detergent ingestion by children because of its current use in other applications [10]. For example, it was commonly used as a denaturant in alcohol. In addition, it was used commercially in thumb-sucking and fingernail-biting deterrents [10]. Denatonium benzoate’s bitter taste makes it a good agent for immediately stopping a child ingesting household liquids or chemicals [10]. The required addition of certain DB concentrations into antifreeze coolants, and its wide use in consumer products, makes it easy for DB to arrive into water supplies through the intentional or unintentional releases of products containing DB.

We have little or no information about how DB can be removed from contaminated water sources using common and traditional drinking water treatment processes such as coagulation and flocculation. DB removal by activated carbon was studied [7]; however, in the absence of activated carbon during water treatment, it would be important to understand how other water treatments such as coagulation and flocculation could impact DB removal from water. Coagulation involves the addition of a chemical to a colloidal dispersion that leads to particle destabilization by reducing the repulsive forces that tend to keep the particles apart [12]. Common coagulants used are aluminum sulfate (alum) and ferric chloride. Water or wastewater treatment using coagulants has been applied widely to lower turbidity, by removing the slowly settling or non-settled particles from source waters [13].

Researchers studied coagulation efficiency in removing taste and odor compounds from water. Although these studies showed that 2-methylisoborneol (MIB) or geosmin, which cause the odor and taste in water, are resistant to removal by conventional water

5 treatment processes such as coagulation [14], coagulation was found to be the major treatment option to deal with increased natural organic levels in water [15]. Most of the contaminants and turbidity removal from water sources was reported by several studies to be achieved using alum Al2(SO4)3.nH2O) and ferric chloride (FeCl3) [13]. Alum and ferric chloride are considered the most commonly used chemical coagulants worldwide in water treatment plants. For these reasons, this study completed to determine whether alum and ferric chloride coagulation was an efficient method for removing DB from water. This study also evaluated the effect of water quality conditions on the coagulation process and DB removal, such as turbidity, ionic strength, pH, and alkalinity. Effects of coagulation aids such as kaolin and bentonite clays on DB removal were also studied.

2.2. Denatonium Benzoate as an Aversive/Bittering Agent

Denatonium benzoate (Figure 1) is an EPA approved inert additive [6]. The full name is benzyl- diethyl (2:6-xylylcarbamoyl methyl) ammonium benzoate; it is commercially available as Bitrex, Bitrexene®, and other trade names [6]. Denatonium benzoate is listed in the Guinness Book of Records and the Merck Index as "the bitterest substance known to man”.DB’s bitter taste is caused by the denatonium ion. Denatonium benzoate was discovered some 58 years ago [3]. A related form, denatonium saccharide

(DS), was found some 36 years ago [16].

Denatoniurn Benzoate is a quaternary amine [11]. Denatonium benzoate is available from several sources, such as Macfarlan Smith Ltd. of Edinburgh, Scotland.

Sources in the USA include Henley Chemicals, Inc., and Atomergic Chemetals, both of

New Jersey [6].

6

Figure 1: Denatonium Benzoate Structure.

According to the European Food Safety Authority (EFSA) [8], denatonium benzoate is considered harmful when swallowed. It also causes skin irritation, serious eye irritation, or respiratory irritation. Denatonium benzoate is readily soluble in both water and alcohol [10]. Its solubility in water is 4.5% (w/v), yet it is 15 times more soluble in methanol, seven times more soluble in chloroform, and practically insoluble in ether [11].

As a general rule, polar or ionic substances dissolve in polar solvents; nonpolar substances dissolve in nonpolar solvents. When the hydrocarbon chain is short, the molecule is soluble in water. As the hydrocarbon chain becomes longer, the molecule becomes less soluble in water. As the hydrocarbon chain becomes longer, the hydrophobic character of the molecule increases, and the solubility of the molecule in water gradually decreases until it becomes essentially insoluble in water. For this reason, denatonium benzoate (C28H34N2O3) is more soluble in methanol (CH3OH) than in water

(H2O) based on the similarity in chemical structure (like dissolves like).

2.3. Denatonium Benzoate Applications and Uses

Because of its strongly bitter nature, denatonium benzoate is used as an additive to common household materials to reduce the potential risk of ingesting these materials

7 accidentally [6]. A study indicated that 14 month to 8-year-old children showed a universal dislike of Bitrex [3]. In the 1970s, denatonium benzoate was first used as a denaturant in rubbing alcohol at a concentration of 6 ppm in the USA, and 10 ppm in the

UK [17]. The bittering agent (DB) was used to denature various household products [6].

In the USA and other countries, DB was added to a variety of products, such as alcohols, cleaners, disinfectants, laundry detergents, nail-biting and thumb-sucking deterrents [18].

When adding denatonium benzoate to many dangerous substances that are inherently noxious in their taste, their unpalatability may increase still further and result in greater prevention than when adding Bitrex (DB) to a palatable substance [19]. Bitrex was found a useful material to prevent horses from chewing their stalls, deer from nibbling tree shoots, and to keep hedgehogs from eating slug pellets when developed as various animal repellents, such as cat, dog and bird repellents [3]. DB’s bitter properties and proposals for use as an adulterant to reduce potential hazards in various products was set forth in various patents, such as the US patent 3,080,327 granted in 1963 [6]. DB has been studied for field use as a gopher repellent. Witmer, Pipas, and Bucher found that denatonium benzoate can be an effective gopher repellent only when higher doses are used [20].

Although only much higher levels of denatonium benzoate than 10 ppm in solid baits would universally discourage non-target animals such as dogs, such levels would also prevent rodent consumption (ICI, unpublished). Even so, these lower levels of Bitrex may somewhat reduce the likelihood of accidental poisonings with pets, domestic animals, and wildlife. Other rodenticide manufacturers have also independently included

8 denatonium benzoate in some of their formulations. J.T. Eaton's in Ohio have 50 ppm denatonium benzoate in their BAIT BLOCKS® for mice [6].

2.4. Antifreeze Bittering Agent State Legislation

In order to stop the ingestion of antifreeze by pets and children, U.S states continue considering the addition of a bittering agent (denatonium benzoate) to antifreeze. The states required addition of 30 ppm DB as the minimum and 50 ppm DB as the maximum amount in antifreeze [21]. Oregon was the first state that required the addition of the bittering agent (DB) to antifreeze in 1991 [21]. Since 2002, California has mandated DB addition to antifreeze. The states that have passed legislation requiring the addition of the bittering agent to antifreeze were Arizona, Georgia, Illinois, Maine,

Maryland, Massachusetts, New Jersey, New Mexico, Tennessee, Utah, Vermont,

Virginia, Washington, West Virginia, and Wisconsin. In 2006 and 2007, Illinois and

Pennsylvania made decisions that support the federal legislation of adding of the bittering agent to antifreeze [21]. The legislatures of Alabama, Missouri, Nevada, New York,

Ohio, and South Carolina have considered; however, they have not passed bills requiring a bittering additive in recent years [21].

At the federal level, the Antifreeze Bittering Act (H.R. 2567) was introduced in the 108th Congress (2005-06) but did not advance after its placement on the Senate

Legislative calendar. In the U.S. House, H.R. 2567 passed the House Energy and

Commerce Committee, but it did not progress any further. The American Veterinary

9 Medical Association (AVMA) supported the passage of both bills and encourages the use of clear warning labels emphasizing the potential danger of ethylene glycol to animals

[21].

In December 2012, the Humane Society Legislative Fund and the Consumer

Specialty Products Association announced an agreement to voluntarily add a bitter flavoring agent to antifreeze and engine coolant manufactured for sale for the consumer market in all 50 states and the District of Columbia [21]. This comes as a result of years of battling over legislation addressing the issue [21]. The Humane Society Legislative

Fund estimates that 10,000 to 90,000 animals are poisoned each year after ingesting ethylene glycol, the highly toxic substance used in antifreeze and coolant [21].

2.5. Denatonium Ion Quantification

A number of methods have been proposed for the quantification of denatonium benzoate. The older of these generally involve calorimetric reaction or thin-layer chromatography, methods which suffer from a lack of specificity or quantitative accuracy and may be extremely time-consuming [11]. Kovar and Loyer, Damon and Pettitt and

Corby report high pressure liquid chromatography (HPLC) methods for analyzing DB in alcoholic toilet preparations, rapeseed oil and automotive coolants, respectively [5].

Other techniques used for the determination of Bitrex include thin layer chromatography potentiometry using ion-selective electrodes [22].

DB concentration can also be easily detected using UV-VIS spectrophotometry, which works at the 200-880 nm wavelength ranges. DB can be detected at about 270 nm wavelength [40], which is considered within the working range of a UV-VIS

10 spectrophotometer. DB detection can be achieved using the absorbance technique that is used widely due to its simplicity, accuracy, and ease of use.

2.6. Coagulation for Water Treatment

Water that has been contaminated naturally or due to human activity, must be treated by various treatment processes to convert it to drinking water [23]. Coagulation, flocculation, sedimentation, filtration and disinfection are the most common treatment processes used in the production of drinking water [24]. Coagulation/flocculation processes are of great importance in separation of solid particles from the water [25].

They play a dominant role in many water and wastewater treatment schemes [26].

Especially, coagulation has been widely adopted in water and wastewater treatment schemes [27]. Coagulation is a simple and efficient physico-chemical method for wastewater treatment that is widely used to treat contaminated water [28]. Coagulation destabilizes dissolved and colloidal impurities and transforms small particles into larger aggregates (flocs), which can be removed from the water in subsequent clarification/filtration processes [29]. The function of coagulation is to overcome those factors that promote the stability of colloids in suspension. Primary coagulant refers to that chemical or substance added to a given suspension or solution to effect destabilization [26].

On the other hand, flocculation is the process whereby destabilized particles, or particles formed as a result of destabilization, are induced to come together, make contact and thereby form large(r) agglomerates. The unstable particles are being gently stirred to create collisions, and these collisions can result in the formation of flocs [23]. Ultimately, the water containing these flocs enters the settling basin where the flocculated solids will

11 be removed by sedimentation [23]. The terms ‘coagulant’ and ‘flocculant’ are often used interchangeably, although coagulation and flocculation have been identified as two mechanisms in a two-step operation. Coagulation is a charge-neutralization reaction, while flocculation is a bridging of the destabilized particles to form larger particles [30].

Coagulation requires rapid dispersion of the coagulant and for this reason high mixing energy is generally provided at the point of coagulant addition. In contrast, flocculation requires a gentle mixing energy, which will allow floc formation to occur without damaging or breaking up the floc. For this reason flocculation generally occurs in baffled flocculation chambers or in the floc blanket of a clarifier or pulsating clarifier where sufficient energy is provided for inter-particle collisions to occur, but not to break up the floc [30].

The efficiency of coagulation-flocculation process depends on several factors such as type and dose of coagulant/flocculant, pH, mixing speed and time, temperature

[28], ions in solution (ionic strength of water), and water temperature [23]. Other parameters that may affect the coagulation-flocculation process are initial turbidity, physical and chemical characteristics of coagulant, and jar configuration/container geometry [31]. The effectiveness of coagulation also has a complex dependency upon the nature of the raw water quality, including total organic carbon, dissolved organic carbon, and alkalinity [32]. The most important parameters are coagulant dose and pH [33].

Effects of an iron (coagulant) on water sources with high turbidity during hardness removal have been tested and observed that with increasing iron doses, the removal of total organic carbon increased [34].

12 Turbidity is a principle physical characteristic of water. Suspended matter or impurities that interfere with the clarity of the water cause the turbidity in water. These impurities may include clay, silt, finely divided inorganic and organic matter, soluble colored organic compounds, plankton and other microscopic organisms [23].

2.7. Coagulants

A coagulant is a chemical that produces positive charges to neutralize the negative charges on the particles in water leading to destabilized pasrticles to form larger particles, which can be removed more easily from water. Aluminum sulfate (alum), ferrous sulfate, ferric chloride, and ferric chlorosulfate are commonly used coagulants [33]. Aluminum sulfate (Al2(SO4)3·nH2O) and ferric chloride (FeCl3) are the mostly widely used coagulants in water and wastewater treatment [31]. Both coagulants were found to be efficient in removing turbidity [25]. Coagulant efficacies depend on the physical and chemical characteristics of the raw water and the operating conditions [35]. Aluminum sulfate is often called alum, but ‘alum’ is not an accurate description because chemically, the alum compound is a much more complex salt of aluminum; alum is a group of hydrated double salts, usually consisting of aluminum sulfate, waters of hydration, and the sulfate of another element e.g. hydrated aluminum potassium sulfate

KAl(SO4)2·12H2O [30]. Aluminum sulfate (Al2(SO4)3·nH2O ) is acidic in nature [30], therefore it is expected to lower the pH when added as a coagulant. When adding aluminum sulfate as a coagulant, it reacts with natural alkalinity present in the water, leading to a reduction of pH [31]. It effectively attracts inorganic suspended solids. Due to its poor efficiency for attracting organic suspended solids, a large alum dose is typically required based on the water quality [32]. Postolachi, Rusu, and Lupascu studied

13 the influence of the aging of an aluminum sulfate solution on turbidity removal from water. Their results revealed that using an optimal aging coagulant solution improves the coagulation process [29]. Aluminum sulfate was commonly used as a chemical in removing phosphate, fluoride, and other harmful compounds such as arsenic along with the other coagulants such as ferric chloride or ferric sulfate, because of their low cost and relative ease of handling [35].

Ferric chloride is used in both drinking water and wastewater treatment although the application is completely different in each. In drinking water, ferric chloride can be used as a coagulant both for turbidity removal and for the removal of color or other organic contaminants. When carrying out turbidity removal only, ferric chloride is usually used at pH values of around neutral pH where sweep coagulation tends to be the predominant reaction [30]. When using ferric chloride for the removal of color and other organic contaminants, the coagulation reaction is most efficient at a pH of around 5 [30].

Research showed that the coagulation process could be effective in removing turbidity

(250 NTU) using relatively low levels of alum and ferric chloride (20-40 mg/l) [25].

Ferric chloride was found to be more effective than aluminum sulfate in turbidity removal [33]. Another result of previous studies on coagulation with aluminum and ferric salts for arsenate removal found that ferric salts are more effective than aluminum salts on a weight basis [35]. However, several cost items are imbedded in chemical coagulation, mainly, the cost of the chemical, its transportation, storage, and handling

[24]. Other researchers found that iron salts are often more efficient than aluminum salts

[28]. Ferric chloride (FeCl3) can efficiently remove inorganic suspended solids and provides more compact sludge than alum [32]. Generally, a possible comparison between

14 aluminum sulfate and ferric chloride can be illustrated in Table 1.

In recent years, there has also been a rising interest in the use of polymerized forms of metal coagulants, such as powder activated carbon (PAC), for water treatment in

Europe, Japan, and North America due to their economic benefits and potential for wider use [32].

Table 1: Aluminum sulfate and ferric chloride comparison

Coagulant Chemical Advantages Disadvantages formula Aluminum Al2(SO4)3·nH2 Relatively low Lower DOC removal sulfate O cost Improper doses cause high n=14-16 Less acidic Alum residuals may cause Attracts health risk inorganic Poor efficiency for attracting suspended solids organic suspended solids effectively Ferric chloride FeCl3 Best removal of Improper doses cause reddish organics color Low cost High iron residuals can plug Easy to detect filters high iron Very acidic residual. Aesthetically unpleasing sludge (brown)

15 2.8. Taste and Odor Compounds

Problems due to the taste and odor in drinking water are common in treatment facilities around the world. Taste and odor are recognized by the public as the primary indicators of the safety and acceptability of drinking water and are mainly caused by the presence of two semi-volatile compounds – 2-methyl isoborneol (MIB) and geosmin.

MIB and geosmin in surface water mainly result from cyanobacteria metabolism and biodegradation that normally bloom in the presence of nutrients at warmer temperatures

[14]. Presence of taste and odor in drinking water may result in decreased consumer trust and subsequently, decreased water consumption and could eventually cause the public to switch to alternate sources of drinking water such as bottled water and in-home treatment systems [14]. The treatment methods that have been successfully employed by water treatment plants to remove MIB and geosmin are adsorption by activated carbon or oxidation by strong oxidants such as ozone.

Conventional treatment processes in water treatment plants, such as coagulation, sedimentation, and chlorination, have been found to be ineffective for removal of MIB and geosmin. Studies have shown that MIB and geosmin are extremely resistant to removal by conventional water treatment processes such as coagulation, sedimentation and filtration. Some researchers who investigated coagulation for removal of these taste and odor compounds found that alum coagulation could not be optimized for MIB and geosmin removal. No removal was observed under a range of pH and coagulation conditions including different alum doses. It was observed that common oxidants such as chlorine (Cl2), chlorine dioxide (ClO2) and potassium permanganate (KMnO4) were not very effective for removal of these compounds [14]. In a pilot plant study comparing

16 MIB and geosmin removal with different oxidants, removal efficiencies with Cl2 and

ClO2 were very low and only ozone (O3) showed any appreciable removal of MIB/ geosmin (85% for 3.8 mg/ L dosage at a contact time of 6.4 min) [14]. Currently, polyaluminum chloride is the most commonly used treatment technology for removal of seasonal tastes and odors in water. However, its effectiveness for removal of MIB and geosmin is less when compared to some other contaminants. Presence of natural organic matter (NOM) reduces the coagulant capacity further but studies have also showed that upstream application of oxidants such as chlorines or chloramines has a negative impact on MIB adsorption by powder activated carbon (PAC) [14]. Use of advanced oxidation technologies such as ozone or UV with hydrogen peroxide (H2O2) was found to be effective in destroying MIB and geosmin. Technologies used for removing taste and odor compounds may include GAC/PAC adsorption, advanced oxidation processes (AOPs), and biological treatment [14].

2.9. Kaolin and Bentonite

Kaolin and bentonite are categorized as coagulant aids. The term ‘coagulant aid’ is often found in water and wastewater treatment handbooks. The use of coagulants to destabilize the colloidal material in water and form a settleable floc is not always successful and additional chemicals or compounds need to be added to assist the coagulation process. One of the most commonly used coagulant aids is bentonite [30]. A coagulant aid is a chemical or material, which is not a coagulant, used to assist or modify coagulation. Coagulant aids add density to slow-settling flocs and add toughness to the flocs so that they do not break up during the mixing and settling processes. A coagulant

17 aid improves the effectiveness of a coagulant by forming larger or heavier particles, speeding reactions, and permitting lower coagulant doses. Coagulant aids are also known as flocculants. When added during the coagulation process, the contaminant particles may adsorb onto the clays and thus help remove that contaminant from water. Kaolin and bentonite are usually added to water to help floc formation.

Bentonite is used more frequently, although the effects of both aids are similar.

Generally, bentonite is added to the raw water prior to the addition of the coagulant so that it adds weight to the resulting floc and also acts as a seed for floc formation.

Bentonite doses of are often quite low being of the order of 1 to 5 mg/ℓ. Bentonite does not modify the pH or the chemical characteristics of the water apart from providing additional weight to the floc which is formed [30]. Bentonite has been widely studied in nuclear waste management because of its special physicochemical properties [36].

Bentonite is a very highly plastic, expansive and colloidal clay [36].

Kaolin is one of the most important industrial clay minerals [37]. It is chemically inert over a wide pH range (4–9). Kaolin disperses readily in water and has low surface area compared with other clay minerals. A recent study showed that the use of clay mineral sorbents or activated carbon for the removal of denatonium ions from solution by treatment facilities is expected to be feasible and of great utility under various environmental conditions [7].

2.10. Water Quality Impact on the Coagulation Process

In order to relate the effects of ionic strength to coagulation, a study showed that by increasing the coagulant concentration, the ionic strength was increased and alkalinity

18 was reduced [23]. The coagulation pH is another main factor that influences the removal effect of coagulation. pH effects on coagulation using ferric based coagulants were studied and determined that the optimum pH range is 5.5− 6.5 [38]. A study of the effects of water quality on the coagulation performance of humic acids (HA) irradiated with UV light showed that the removal efficiency of the HA in coagulation is not only dependent on the coagulant dose but also on the raw water quality, such as pH, temperature, turbidity, alkalinity, and hardness [39]. It is ,ore difficult to achieve high HA removal rates in solutions with low temperatures and turbidities, as less adsorption surfaces for the destabilized colloidal particles are available [39]. It was shown that the presence of hardness causing materials improved the coagulation efficiency of HA even in the raw waters with low ionic strength [39]. Alkalinity of the water was dropped since coagulants consume some of the available alkalinity in water when added.

A recent study done on the constant temperature sorption of denatonium ions to common sorbents utilized in water treatment processes (i.e. bentonite clay and activated carbon) evaluated denatonium ion sorption to smectites and granular activated carbon at constant pH and ionic strength and examined the impact of pH on denatonium ion sorption to each solid material [7]. It was determined that the efficiency of activated carbon removal of denatonium ions increased when pH decreased and activated carbon dose increased which suggests that electrostatics and increased sorption site availability impact denatonium ion sorption. Although the adsorption method was proven effective for the removal of denatonium benzoate from water, this research focuses on coagulation treatment because it is a relatively common method in wastewater and water treatment.

Coagulation treatment uses relatively low cost, simple chemical reagents, it has low

19 capital cost, and it does not require monitoring of the breakthrough point. No known prior research results have been published about the removal of denatonium benzoate by coagulation. Furthermore, the effectiveness of using aluminum sulfate and ferric chloride in removing denatonium benzoate from water, the effects of pH on this process, the effects of ionic strength, or the effect of clay minerals such as kaolin and bentonite on DB removal during coagulation have not been studied.

20 CHAPTER III

MATERIALS AND METHODS

3.1. Introduction

This research study involved treating three different water sources by coagulation.

Baseline experiments completed with ultrapure water evaluated two different coagulants, alum (Al2(SO4)3·nH2O) and ferric chloride (FeCl3). These baseline experiments determined the optimal coagulant dose and the most efficient coagulant for denatonium benzoate (DB) removal from ultrapure water. The baseline experiments also examined the effects of pH, ionic strength, and the addition of clays such as kaolin and bentonite on

DB removal. Great Miami River water (Dayton, Ohio) and Miami Well Field untreated groundwater (Dayton, Ohio) were also used to examine the effects of coagulant type, coagulant dose, solution conditions (pH, ionic strength, alkalinity), and clay minerals on

DB removal. Turbidity removal was also monitored. Baseline and natural water experiments were conducted using the jar test method.

3.2. Materials and Equipment

3.2.1. Denatonium Benzoate

All experiments were conducted with water that was spiked with 15 ppm of denatonium benzoate under room temperature conditions. Denatonium benzoate

21 (Sigma-Aldrich, Missouri) is available as a solid. A 2000 ppm of DB stock solution was prepared in ultrapure water. Before conducting any coagulation experiment, an appropriate volume of DB stock solution was added to each jar/beaker to achieve a 15- ppm DB concentration in each jar. The stock solution was also used to prepare DB standards to develop a DB standard curve for determining the DB concentration in experimental samples. The following DB standards were prepared: 5 ppm, 10 ppm, 30 ppm, 50 ppm, 75 ppm, and 100 ppm.

3.2.2. Coagulants

Aluminum sulfate, Al2(SO4)3·nH2O, (Fisher Scientific, USA) and ferric chloride,

FeCl3, (Fisher Scientific, USA) were used as a coagulant in experiments. The coagulant chemicals were stored under room temperature conditions. A 2000 ppm aluminum sulfate stock solution was prepared using ultrapure water. Alum or ferric chloride doses ranging from 5 ppm-60 ppm were used in experiments because these coagulant doses were found the most common effective ranges used in removing contaminants in water as well as turbidity [25]. Appropriate volumes of the 2000 ppm alum or ferric chloride stock solutions were added to 800 ml of a given water source (ultrapure water, river water, groundwater) contained in jars/beakers. These jars/beakers were used in the jar test.

22 3.2.3. Calcium Chloride

Calcium Chloride, CaCl2, (Hach Company, Loveland, CO) was used for changing the ionic strength of the solution for determining the optimal ionic strength conditions for removing DB. A 2000 ppm calcium chloride stock solution was prepared in ultrapure water. This stock solution was used to adjust the ionic strength of the solution in experiments.

3.2.4. Potassium Chloride

Potassium Chloride, KCl, (Fisher Scientific, Fair Lawn, NJ) was in powder form, and it was used to adjust the ionic strength of the water spiked with 15 ppm DB. The effects of ionic strength on the coagulation process were examined using KCl. In particular, the effects of the magnitude of the electrolyte’s cation charge on DB removal were discerned by comparing KCl to CaCl2. A 2000 ppm KCl stock solution was prepared (Appendix A). To adjust the ionic strength of the water spiked with 15 ppm DB, appropriate volumes of the 2000-ppm KCl stock solution were added to the water samples containing DB.

3.2.5. Sodium Hydroxide

Sodium Hydroxide, NaOH, (LabChem Inc, Pittsburgh, PA) was used to adjust the water pH in experiments. A 20% NaOH solution (v/v) was prepared from 1 N NaOH.

The 20% NaOH solution was used to raise the pH of water samples to the desired level between pH 4 and 10.

23 3.2.6. Hydrochloric Acid

Hydrochloric acid, HCl, (Fisher Scientific, Fair Lawn New Jersey) was used for adjusting the pH in order to bring the water sample to the desired pH level. Concentrated

HCl was diluted and used to adjust the experimental pH. A 20% HCl solution (v/v) was used to lower the pH of water samples. For experiments, the pH was varied between 4 and 10.

3.2.7. Kaolin and Bentonite Clays

Kaolin clay (Sigma-Aldrich, U.S.) and bentonite clay (Corning Inc., Mexico) were used in the coagulation process to study the effects of minerals on removing DB from water.

3.2.8. Ultrapure Millipore™ Water

A Millipore™ filtration system (Millipore, Bedford, MA) was used to produce the ultrapure water from reverse osmosis filtration. Ultrapure water was used in the baseline coagulation experiments to rinse electrodes and other experimental equipment and containers (clean amber sample vials and quartz cuvettes). The ultrapure water was also used to prepare standards, stock solutions, and experimental samples. The ultrapure water was used at room temperature conditions.

24 3.2.9. Jar Testing Apparatus

A Phipps and BirdTM PB-700TM Jar Tester (Fisher Scientific, U.S.) was used to conduct the coagulation experiments. The jar test can be operated at wide range of mixing speeds; 100 rpm and 20 rpm were the rapid mixing and slow mixing speeds, respectively, during the coagulation process. The experiments were conducted in high mode to rapidly mix at 100 rpm. Since the coagulation process requires rapid mixing at the beginning, the mixing was maintained at 100 rpm for 2 minutes when running each experiment.

3.2.10. UV-VIS Spectrophotometer

UV-VIS USB-650 Red Tide Spectrometer (Ocean Optics, Dunedin, Florida) was turned on 30 minutes prior to beginning each experiment to adequately and consistently warm the lamp. DB standards and samples were analyzed using UV-VIS spectrophotometry to determine the DB concentration remaining in samples after coagulation experiments. Samples and standards were placed in quartz cuvettes. The cuvettes were placed in the UV-VIS spectrophotometer to measure the absorbance of the desired sample at 270 nm. Cuvettes were wiped with Kimwipes™ before being placed in the spectrophotometer.

The DB standards were measured before each experiment to check the accuracy of the measurements as well as to obtain a DB standard curve, which relates the DB concentration and its absorbance, that was used to determine the DB concentration remaining in experimental samples (Figure 5). The characteristic peak for DB is located at the 270 nm wavelength, so the absorbance at this wavelength was used to develop a standard curve (Figure 5) and determine the DB concentration in experimental samples.

25 3.2.11. Analytical Balance

High precision analytical balance (Mettler-Toledo, Ohio) was used to measure the chemical materials needed in the experiments for stock preparations.

3.2.12. Quartz Cuvette

Two Quartz Cuvettes (Fisher Scientific, U.S.) were used to measure the absorbance of the desired water sample in order to find out the remaining DB in the water sample after the coagulation process. They can be inserted into the UV-VIS

Spectrophotometer to measure the DB absorbance using the UV-VIS Spectrophotometer software. They were wiped before each reading to ensure accurate reading.

3.2.13. Digital Pipets

After each experiment, the research pipet, 1-1000 L, (Fisher brand Elite,

Mexico) and sterile pipet tips were used to collect the water sample for measuring the DB remaining with the UV-VIS spectrophotometer. Each pipette tip was discarded after use, and each tip was only used once. A larger volume 25 ml pipet was used to add the desired coagulant dose into the water sample.

3.2.14. Beakers

Six beakers (Pyrex, NY USA) of 1000 ml capacity were used in each coagulation experiment. An 800 mL sample volume was used in experiments to avoid any spillage or overflow when adding coagulants, acids or bases for pH adjustment, electrolytes for ionic

26 strength adjustment, or clay additives. This volume also prevented overflow while rapidly mixing at 100 rpm.

3.2.15. pH Meter and Electrode

The Accumet-AR15 pH electrode meter (Fisher Scientific, Denver, CO) was used to measure the pH of the water samples. Water sample pH was measured before and after each experiment. The pH meter was calibrated before measuring the water sample’s pH by using pH buffer solutions. The meter’s electrode was stored in a solution of potassium hydrogen phthalate, water, and potassium chloride (Fisher Scientific, Fair Lawn, NJ).

The electrode was rinsed with ultrapure Millipore™ water before and after each measurement.

3.2.16. Amber Vials

Amber vials (Fisher Scientific, USA) of 0.024-liter capacity were used to store the

DB standards ranging from 5 ppm DB to 100 ppm DB. Each standard was labeled before adding the desired solution. Other 0.024-liter amber vials were used to collect the water samples after the coagulation process. Amber vials were cleaned using the dish and washer machine, then dried and washed with 20% (v/v) nitric acid.

3.2.17. Turbidity Meter

Turbidity was measured using a HACH DR/890 colorimeter (Hach Company,

USA) (Figure 2). HACH method 8237 in the DR/890 Data Logging Colorimeter

27 Handbook was used to measure the turbidity of samples. An Orbeco-Hellige Digital

Direct-Reading Turbidimeter (Fisher Scientific, U.S.) was used to validate the measured

DR 890 colorimeter turbidity measurements.

Figure 2: DR/890 Colorimeter (left), Digital Direct-Reading Turbidimeter (right).

3.2.18. Alkalinity Measurements

A HACH Digital-Titrator (Hach Company, U.S.) was used to determine the alkalinity of the water sample using the HACH 8203 (Appendix B) titration method with

1.60.0008 N sulfuric acid. Two powder pillow reagents were used when measuring alkalinity-- phenolphthalein indicator powder (Hach Company, U.S.) and the bromocresol green-methyl red indicator powder pillows (Hach Company, U.S.). The powder pillow reagents were added according to HACH method 8203 (Appendix B).

3.2.19. Conductivity Meter

The Portable Waterproof Conductivity/TDS Meter (Fisher Scientific™

Accumet™, U.S.) (Figure 3) was used to measure the conductivity and thus determine the ionic strength of the water samples. The device was calibrated before each reading to ensure accurate measurements.

28

Figure 3: Portable Waterproof Conductivity/TDS Meter.

3.2.20. Laboratory Oven

Laboratory oven (VWR Scientific Products, U.S.) was used at 100o C to dry the beakers or other tools needed in the experiments.

3.3. Methods

3.3.1. Denatonium Benzoate Quantification

The denatonium benzoate concentration was determined by analyzing the absorbance readings of the experimental samples using the UV-VIS USB-650 Red Tide

Spectrometer (Ocean Optics, Dunedin, FL) (Figure 4). To obtain consistent, accurate readings, the UV-VIS USB-650 Red Tide Spectrometer was turned on 30 minutes prior to sample analysis. If the lamp is not turned on for the same consistent amount of time

(e.g. 30min), it can cause a variation in the results. DB standards were run to prepare the

DB calibration/standard curve. A characteristic peak for DB can be located at approximately 270 nm [40]. As the DB concentration increases, the absorbance detected at the 270nm wavelength increases.

29

Figure 4: UV-Vis Usb-650 Red Tide Spectrometer.

About 3000-4000 l of the sample was placed into a quartz cuvette, which has volume of 10 ml, using a Eppendorf Research (1-1000 l) pipet. The cuvette was rinsed with ultrapure Millipore™ water before and after each absorbance reading. A standard/calibration curve was created before each sample measurement commenced.

The linear standard/calibration curve represents the DB absorbance (at 270 nm) of six DB standards (concentration ranging from 5 ppm to 100 ppm). DB standard concentrations

(5-100 ppm), which were prepared previously (Appendix A) versus their corresponding absorbance, which has been measured by the UV-Vis spectrophotometer, were plotted to give linear relationship as shown in Figure 5. As DB concentration increased, its absorbance increased.

DB standards were prepared (see Appendix A) and stored in 0.024-liter amber vials. DB standards (5ppm, 10ppm, 30ppm, 50ppm, 75ppm, 100ppm) were tested for absorbance reading of DB, which can be found at the peak of approximately 270 nm. For each DB concentration, absorbance was recorded in spreadsheet. The resulting graph was close to linear relationship between DB concentration and absorbance (AU) (Figure 5).

To quantify the DB concentration remaining in a sample after a coagulation experiment,

30 the absorbance of the sample at 270 nm was measured with the UV-VIS spectrophotometer. Once the sample’s absorbance was measured by UV-VIS spectrophotometer, the corresponding DB remaining concentration was calculated using the interpolation formula (Appendix A).

0.4 Denatonium Benzoate Standards ppm 0.3 Linear (Denatonium Benzoate Standards ppm) 0.2 ABS ABS = 0.0029(DB) + 0.0239 0.1 R² = 0.9994

0 0 10 20 30 40 50 60 70 80 90 100 DB mg/l

Figure 5 : Denatonium benzoate standard/calibration curve (absorbance measured at 270 nm using Uv-Vis Usb-650 Red Tide Spectrometer).

3.3.2. Coagulation Studies

A Phipps and BirdTM PB-700TM jar tester (Figure 6) was used to conduct laboratory-scale coagulation experiments. The jar testing apparatus was used for coagulating various water sources containing 15 ppm DB using alum and ferric chloride

(FeCl3). The jar tests were conducted with the jar tester that has six-spindle steel paddles.

A beaker containing 800-mL of water sample was placed underneath each paddle. The beakers were filled with water spiked with 15 ppm DB. Simultaneously, the desired dose of the coagulant was added to each beaker while the paddles continuously stirred. The paddles were stirred at 100 rpm for 2 min. Then the samples were slowly mixed at 20 rpm for 20 minutes. After agitation, the suspensions were allowed to settle for 30

31 minutes, and samples were collected using a pipet to measure the DB concentration remaining, conductivity (ionic strength), turbidity, and pH. All tests were performed at room temperatures in the range of 20–25˚C.

Figure 6: Phipps and BirdTM PB-700TM Jartester.

The study was conducted by varying a few experimental parameters including alum and ferric chloride dose (5 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, and 60 ppm), pH (4 to 10), ionic strength (0.01-1 M) using two different salts (CaCl2 and KCl), and kaolin and bentonite clay mass. These experimental variations facilitated an understanding of the effectiveness of coagulation and the optimum parameters for each condition. These experiments were conducted with ultrapure water (baseline experiments), Great Miami River water (natural water experiments), and Miami Well

Field untreated groundwater (natural water experiments). These waters were spiked with

15ppm DB, and the experiments determined the optimal alum and ferric chloride dosage for suitable DB removal under different water quality conditions (alkalinity, pH, turbidity, and ionic strength).

32 3.3.3. Turbidity Measurement

Turbidity was measured according to the HACH method 8237 (Appendix B).

Ultrapure Millipore™ water was used as standard water that had 0 NTU turbidity. Water samples were measured by placing the amber vials inside the DR/890 colorimeter using the 95-program number. The same experimental samples were directly analyzed using the

Orebeco-Hellige Digital Direct-Reading Turbidimeter to validate the accuracy of the DR

890 colorimeter’s turbidity measurements.

3.3.4. Adjusting the pH

The pH levels of the water samples were adjusted by using a 20% HCl (v/v) solution and a 20% NaOH (v/v) solution. The HCl solution was added to water to lower the pH to a desired level, while the NaOH solution was added to raise the water pH to a desired level. For pH experiments, the pH levels were adjusted between 4 and 10.

3.3.5. Adjusting the Ionic Strength

Ionic strength of the water samples was adjusted by using calcium chloride and potassium chloride. Different volumes of salts were taken from the stock salt solution

(e.g. 1 M of CaCl2 stock solution; see Appendix A), depending on calculations (Appendix

A at A.3), and added to the water samples to vary the ionic strength of the water samples

(e.g. 0.01-1 M) containing DB (15 mg/l) at the optimal water conditions of the water sample at which the specified coagulant (aluminum sulfate or ferric chloride) achieved highest DB removal, such as the optimal pH, and the optimal coagulant dose. All other parameters (pH, temperature, coagulant dose) were constant except for ionic strength in

33 order to study the effect of one factor on DB removal at a time. These are complex environmental systems and to really understand the effect of one parameter versus the other, the other parameters are held constant so the varied parameter is known to be the only thing that could be affecting the DB removal via coagulation.

34 CHAPTER IV

RESULTS AND DISCUSSION

4.1. Introduction

Results revealed the influence of the coagulant type and dose, the effects of pH, the effects of varying ionic strength, and the use of kaolin or bentonite clay as additives on denatonium benzoate (DB) removal via coagulation treatment. This research determined the impact of these factors on DB removal by coagulation in ultrapure water

(UPW) and natural water (groundwater and river water). Various water quality conditions such as alkalinity and turbidity were also monitored. Table 2 shows initial water quality characteristics of ultrapure water, Great Miami River water, and groundwater. Experiments were repeated in order to get the most accurate results. Error percentages were shown on the figures with ranging from 0-4%. Error percent was calculated according to the following equation:

Trial 1- Trial 2 Error percent = X 100% Trial 1

35 Table 2: Initial water quality characteristics of ultrapure water, river water, and groundwater.

Characteristic

Water Source UPW River Water Groundwater

Ionic strength (M) 0.00005 0.01 0.012

Turbidity (NTU) 0 10.23 5

pH 5.81 7.98 7.45

Alkalinity (mg/l) as CaCO3 32 259 242

4.2. Optimal Coagulant Type and Dosage for DB Removal

4.2.1. Ultrapure Water Results

These experiments were conducted with ultrapure water containing 15 ppm DB, which is within the DB concentration range at which DB’s bitter flavor can be detected in water. The ultrapure water’s initial turbidity, pH, ionic strength, and alkalinity were 0

NTU, 5.81, 0.00005 M, and 32 mg/l as CaCO3, respectively (referring to Table 2).

Aluminum sulfate (alum) was added at concentration ranging from 5ppm to 60ppm. As

Figure 7 indicates, the highest DB removal (90%) was achieved with the 20-mg/l alum dose. As shown in Figure 8, a 5 mg/l FeCl3 dose achieved the maximum DB removal of

83%). As the FeCl3 dose was increased, the DB removal percentage decreased. The maximum DB removal for coagulants was similar, and neither coagulant lowered the DB concentration below the taste threshold of 0.05 ppm. Thus, additional treatment such as

36 sorption with activated carbon or chemical oxidation would be necessary. The optimal alum dose dropped the water alkalinity to 22 mg/l as CaCO3 while the optimal FeCl3 dose dropped the alkalinity to 27 mg/l as CaCO3.

100% 90% 78% 80% 60% 60% 49%

40% 27%

DB removal % removal DB 16% 20% 7% 0% 0% 0 5 10 20 30 40 50 60 Aluminum sulfate doses (ppm)

Figure 7: DB removal percentages versus aluminum sulfate doses in ultrapure water. (pH=5.81, initial DB=15 ppm, turbidity= 0 NTU, ionic strength=0.00005 M) .

100% 83% 77% 80% 68% 60%

40% 33% 30%

DB removal % removal DB 20% 10% 7% 0% 0% 0 5 10 20 30 40 50 60 Ferric chloride doses (ppm)

Figure 8: DB removal percentages versus ferric chloride doses in ultrapure water. (pH=5.81, initial DB=15 ppm, turbidity=0 NTU, ionic strength=0.00005 M)

37 4.2.2. Great Miami River Results

The Great Miami River water had initial water conditions of turbidity, pH, ionic strength, and alkalinity conditions of 10.23 NTU, 7.98, 0.01 M, and 259 mg/L as CaCO3, respectively (Table 2). The Great Miami River water had higher turbidity, pH, ionic strength, and alkalinity than the ultrapure water. The turbidity of the coagulated water was 0.1 NTU. Both coagulants, alum and FeCl3, had the same efficiency in removing turbidity. The optimal alum dose of 50 ppm removed 71% of the initial DB. As the alum dose increased, the DB removal percentage typically increased, except for the 60mg/l alum dose, which showed the lowest DB removal compared to the other doses (Figure 9).

This indicates that over dosage of alum could adversely affect DB removal. Over dosage of alum could result in changing the coagulation mechanism. At 60 mg/l alum and a pH of 7.98, DB removal may have occurred by the sweep floc mechanism, which would not be effective for removing DB since DB is soluble in water. The sweep floc mechanism is effective in removing the turbidity instead of being effective in removing DB as the aluminum hydroxide precipitates help remove the turbidity. DB removal likely works based on charge neutralization or electrostatic interactions, thus the 60-mg/l of alum dose worked better in dropping the river water turbidity to 0.1 NTU (Figure 9). The optimal alum dose reduced the alkalinity to 234 mg/l as CaCO3.

Adding 50 mg/l FeCl3 achieved the highest DB removal percent of 71% compared to the other FeCl3 doses (Figure 10). The optimal FeCl3 dose reduced the alkalinity to 213 mg/l as CaCO3. The lowest DB removal (15%) occurred when 30-mg/l FeCl3 was added at a pH of 7.98; this is also likely because the predominant coagulation mechanism is sweep floc that tends to be more effective in removing turbidity. Some of the variations

38 in results may not be caused by these mechanisms, but other factors. For example, there might be some variation in the amount of turbidity among the six beakers that could result in allowing most of the coagulant to be used to remove DB.

100%

80% 71% 65% 60% 52% 40% 40%

DB removal % removal DB 28%

20% 15% 0% 3% 0% 0 5 10 20 30 40 50 60 Aluminum Sulfate doses (ppm)

Figure 9: DB removal percentages versus alum doses in Great Miami River water. (pH=7.98, initial DB=15 ppm, influent turbidity=10.23 NTU, effluent turbidity=0.1 NTU, ionic strength=0.01 M)

100%

80% 70% 71% 65% 60% 52% 40% 40% 28% DB removal % removal DB 20% 15% 0% 0% 0 5 10 20 30 40 50 60 Ferric Chloride doses (ppm)

Figure 10: DB removal percentages versus ferric chloride doses in Great Miami River water. (pH=7.98, initial DB=15 ppm, turbidity=10.23 NTU, ionic strength=0.01 M)

39 The optimal coagulant doses needed to remove DB in ultrapure water were lower than those needed to remove DB from river water. This indicates that initial turbidity of the water source could affect DB removal since the higher coagulant doses used in river water tended to remove the particles that caused the higher turbidity. In ultrapure water, there was no turbidity, which means there were no particles in UPW that needed to be removed by the coagulant, so the coagulant dose was only needed to remove DB in the water. The higher the water turbidity, the higher the coagulant dose needed.

4.2.3. Groundwater Results

The initial turbidity, pH, ionic strength, and alkalinity of the Miami Well Field groundwater were 5 NTU, 7.45, 0.012 M, and 242 mg/l as CaCO3, respectively. Results indicated that a 60 mg/l of alum dose was needed to achieve the highest DB removal percent of 76% (Figure 11). The optimal alum dose decreased the alkalinity to 230 mg/l as CaCO3 and dropped the turbidity to 4 NTU (Figure 12). The optimal ferric chloride dose of 10 mg/L achieved 49% DB removal (Figure 13). This was much lower DB removal in comparison to alum coagulation. Ferric chloride was found to be more effective in removing the turbidity than alum; the optimal dose of the iron coagulant lowered the turbidity to 0.3 NTU and the alkalinity to 240 mg/l as CaCO3 (Figure 14 ). As shown in Figure 12, alum was expected to drop the alkalinity when added as a coagulant; alum doses of 5-mg/l, 10-mg/l, and 30-mg/l did not drop the alkalinity of the water sample. These results are considered outliers, while other doses showed a measurable drop in the alkalinity. This could be caused by several reasons. The more alum added, the more alkalinity drop is expected, so adding a low concentration of alum (5mg/l and 10

40 mg/l) will result in low alkalinity drop. The 5 mg/l of alum is expected to decrease the alkalinity by 2.5 mg/l based on the stoichiometric calculations, so that the final alkalinity was expected to drop to 239.5 mg/l as CaCO3. That small drop may not have been accurately measured using the digital titration method since the digital titrator is not very sensitive. According to the stoichiometric calculations, 20 mg/l of alum was expected to drop the alkalinity to 232 mg/l as CaCO3, which is very close to what has been measured by the titration procedures.

According to Figure 14, the turbidity increases as the FeCl3 doses (higher than 20 mg/l) increases. This indicated that some of the precipitates formed from adding more

FeCl3 did not settle out very well.

100%

76% 80% 69% 63% 60% 56% 41% 41% 40%

DB removal % removal DB 21% 20% 0% 0% 0 5 10 20 30 40 50 60 Aluminum Sulfate doses (ppm)

Figure 11: DB removal percentages versus alum doses in Miami Well Field groundwater. (pH=7.45, initial DB=15 ppm, ionic strength=0.012 M)

41 Alkanilinity Turbidity 250 10 242 242 242 242 9 8 240 234 7 230 230 230 6 230 5 5 4 4 4 3 220 NTU Turbidity 3 3 3 3 2 2 1 Alkalinity mg/l as CaCO3 as mg/l Alkalinity 210 0 0 5 10 20 30 40 50 60 Alum doses (ppm)

Figure 12: Alkalinity and turbidity versus alum doses in Miami Well Field groundwater.

100%

80%

60% 49% 41% 40% 30% 23% DB removal % removal DB 19% 16% 20% 8% 0% 0% 0 5 10 20 30 40 50 60 Ferric Chloride doses (ppm)

Figure 13: DB removal percentages versus ferric chloride doses in Miami Well Field groundwater. (pH= 7.45, initial DB=15 ppm, ionic strength=0.012 M)

42 Alkalinity Turbidity 260 10 242 242 240 240 240 8 221 218 220 5 211 6 202 200 3 3 4

2 NTU Turbidity 180 1 2 0.5 Alkalinity mg/l as CaCO3 as mg/l Alkalinity 0.3 0.1 160 0 0 5 10 20 30 40 50 60 Ferric Chloride doses (ppm)

Figure 14 : Alkalinity and turbidity versus ferric chloride doses in Miami Well Field groundwater.

4.3. Effect of pH on DB Removal

4.3.1. Ultrapure Water Results

Ultrapure water pH levels were adjusted between 4 and 10 to be 4.03, 4.95, 5.81,

7.01, 8.1, 8.98, and 9.93. The initial ultrapure water turbidity, ionic strength, and alkalinity were 0 NTU, 0.0005 M, and very low, respectively (Table 2). The optimal alum dose (20 mg/l) and the optimal ferric chloride dose (5 mg/l) were used. The optimal pH level for alum was 5.81 at which the highest DB removal of 90% was achieved

(Figure 15). On the other hand, pH levels of water were adjusted to be 4.01, 4.92, 5.81,

6.9, 8.07, 8.99, and 10.24 before adding the 5 mg/l FeCl3. Among these levels, the 5.81 pH was the best condition, where 83% of the initial DB was removed from ultrapure water (Figure 16).

43 100% 90%

80% 67% 54% 60% 48% 40% 18% 18% DB removal % removal DB 20% 11%

0% 4.03 4.95 5.81 7.01 8.1 8.98 9.93 pH

Figure 15: DB removal percentages versus pH in ultrapure water using optimal alum dose (20 mg/l).

100% 83% 80% 74% 67% 55% 60% 51% 44% 40%

DB removal % removal DB 20% 20%

0% 4.01 4.92 5.81 6.9 8.07 8.99 10.24 pH

Figure 16: DB removal percentages versus pH in ultrapure water using optimal FeCl3 dose (5 mg/l).

4.3.2. Great Miami River Results

The initial turbidity, ionic strength, and alkalinity of the Great Miami River water were 10.23 NTU, 0.01 M, and 259 mg/l as CaCO3 (Table 2). At pH 6, the optimal condition for alum and ferric chloride for DB removal was achieved. At this pH level,

72% of DB was removed by the optimal alum dose (50 ppm) and the optimal FeCl3 dose

44 (50 ppm) (Figure 17 and Figure 18). Initial turbidity of 10.23 NTU was lowered to 0.1

NTU in both coagulant experiments. Alkalinity was lowered to 234 mg/l as CaCO3 by the optimal alum dose, and to 213 mg/l as CaCO3 by the optimal FeCl3 dose, respectively. As shown in Figure 17 and Figure 18, DB removal at pH 7 was lower than DB removal achieved at pH 6 or 8. This may be because of the coagulation mechanism for removing turbidity changed. If the mechanism is more favorable at pH 6 versus 7, then less coagulant chemical may be needed to remove the turbidity, and more may be available to remove DB.

100%

80% 72% 70% 60% 60% 48% 36% 40% 25% DB removal % removal DB 20% 13%

0% 4 5 6 7 7.98 9 10 pH

Figure 17: DB removal percentages versus pH in Great Miami River water using optimal alum dose (50 mg/l).

45 100%

80% 72% 70% 61% 60% 50% 39% 40%

DB removal % removal DB 17% 20% 5% 0% 4 5.02 6 7 7.98 9 10 pH

Figure 18: DB removal percentages versus pH in Great Miami River water using optimal FeCl3 dose (50 ppm).

4.4. Effect of Ionic Strength on DB Removal

4.4.1. Ultrapure Water Results

CaCl2 and KCl concentrations were adjusted in the ultrapure water samples, ranging between 0.01 M and 1 M. At the optimal alum dose (20 mg/l) and the optimal pH of 5.81, 0.1 M of CaCl2 and KCl achieved 65% and 77% DB removal, respectively

(Figure 19). At the optimal FeCl3 dose (5 mg/l) and using the optimal pH of 5.81, 0.05 M

KCl and 0.1 M CaCl2 achieved 55% and 82% DB removal, respectively (Figure 20). At low and high ionic strength, there was no advantage because there might interactions that cause interference with the coagulant chemicals and their action. At the higher amount of ionic strength, it might create surface charge effects; if there are electrostatic interactions that really need to happen, it could create circumstances where those electrostatic interactions get screened out.

46 KCl CaCl2 100% 77% 80% 58% 60% 51% 65% 43% 40%

DB remooval % remooval DB 20% 8% 1% 21% 0% 0% 0.01 0.05 0.1 0.5 1

CaCl2 or KCl (M)

Figure 19: Comparing CaCl2 and KCl effects on DB removal in ultrapure water using optimal alum (20 ppm) and optimal pH=5.81.

KCl CaCl2 100% 82% 77% 80% 72% 61% 60% 52%

55% 40% DB remooval % remooval DB 20% 26% 24% 19% 17% 0% 0.01 0.05 0.1 0.5 1 CaCl2 or KCl (M)

Figure 20: Comparing CaCl2 and KCl effects on DB removal in ultrapure water using optimal FeCl3 (5 ppm) and optimal pH=5.81.

4.4.2. Great Miami River Results

At the optimal alum dose (50 ppm) and optimal pH of 6, the 0.01 M CaCl2 and

KCl concentrations achieved 70% and 50% DB removal, respectively. As the CaCl2 concentration was increased, DB removal decreased (Figure 21). At the optimal FeCl3

47 dose ( 50 ppm) and optimal pH of 6, the 0.01 M and 1 M concentrations were the optimal

CaCl2 and KCl concentrations achieved 91% and 71% DB removal, respectively (Figure

22). As chlorine ions increased in the solution, more repulsive charges increase and may have resulted in less DB removal.

CaCl2 KCl 100%

80% 70% 60% 50% 40% 41% 27% 29% DB remooval % remooval DB 20% 20% 20% 10% 0% 3% 1% 0.01 0.05 0.1 0.5 1

CaCl2 or KCl (M)

Figure 21: Comparing CaCl2 and KCl on DB removal in Great Miami River water using optimal alum (50 ppm) and optimal pH=6.

CaCl2 KCl 100% 91% 81% 80% 61% 71% 60% 51%

40% 41%

DB Removal % Removal DB 20% 31% 12% 21% 0% 2% 0.01 0.05 0.1 0.5 1

CaCl2 or KCl (M)

Figure 22: Comparing CaCl2 and KCl on DB removal in Great Miami River water using optimal FeCl3(50 ppm) and optimal pH=6.

48 4.5. Addition of Kaolin and Bentonite Clays

4.5.1. Addition of Kaolin Clay

Kaolin clay (1-20 g) addition to the water mixture did not raise the DB removal percentages. The highest DB removal was achieved when adding 20 g of kaolin with alum, at which turbidity was recorded to be 30 NTU (Figure 23). The kaolin clay has no internal sorption sites for DB removal. DB has the chance to adsorb onto the edges of the clay because the day’s inner layer has strong hydrogen bonding. These hydrogen bonds also cause kaolin to exhibit little to no expansion or swell. Although increasing the kaolin mass resulted in increasing DB removal from ultrapure water, its addition to the ultrapure water samples raised the turbidity of the water from 0 NTU to 46 NTU when using alum and from 0 NTU to 50 NTU when using FeCl3. In addition, although a lower amount of kaolin (10 g) was needed to achieve higher DB removal (53%) when using FeCl3 compared to when using alum (12%), the DB removal was still lower than what was achieved in the absence of kaolin clay. Also, turbidity is still a real problem when using kaolin as additive to coagulation (Figure 24). When adding 20g kaolin, the water became turbid; the suspended clay caused this after its addition to the water. Since kaolin has no sorption sites internally that DB can get into, we need to add higher amount of kaolin to provide more space for DB to get onto; however, that creates more turbidity in the water.

49 DB removal % Turbidity

100% 60

80% 59% 46 40 60% 43 37 39 32% 40% 30 20 DB removal % removal DB Turbidity NTU Turbidity 20% 10% 12% 0% 0% 0 0 5 10 15 20 Kaolin Clay (gram)

Figure 23: DB removal percentages and turbidity versus kaolin mass (g) in ultrapure water using optimal alum (20 ppm), optimal pH=5.81, and optimal CaCl2 concentration=0.1 M.

DB removal % Turbidity 100% 50 60 44 80% 40 40 60% 30 33 53% 40% 20 36% 33% Turbidity NTU Turbidity

DB remooval % remooval DB 20% 19% 23% 0% 0 0 5 10 15 20 Kaolin Clay(gram)

Figure 24: DB removal percentages and turbidity versus kaolin mass (g) in ultrapure water using optimal FeCl3 (5 ppm), optimal pH=5.81, and optimal CaCl2 concentration=0.1 M.

4.5.2. Addition of Bentonite Clay

Results showed that when using alum, 15 grams of bentonite is enough to achieve the same DB removal percent that was achieved by adding higher amount of kaolin (20 grams) (Figure 25 and Figure 23). Addition of 15g bentonite resulted in achieving the

50 highest DB removal percent of 59% compared to the other bentonite masses. Bentonite also resulted in lower turbidity value (4 NTU) than adding kaolin (30 NTU).

It was also found that when using FeCl3 as a coagulant, 1g of bentonite is enough to get higher DB removal than when adding 10 g kaolin. In addition to the higher DB removal achieved, bentonite produced much lower turbidity of 6 NTU (Figure 26) and

(Figure 24). Optimal DB removal achieved by the addition of bentonite was 63%.

DB removal % Turbidity 100% 25

80% 16 17 20 63% 20 60% 46% 15 40% 10 6 10 43%

9% NTU Turbidity DB remooval % remooval DB 20% 26% 5

0% 0 1 5 10 15 20 Bentonite Clay(gram)

Figure 25: DB removal percentages and turbidity versus bentonite mass (g) in ultrapure water using optimal alum (20 ppm), optimal pH=5.81, and optimal CaCl2 concentration=0.1 M

DB removal % Turbidity 100% 13 15 16 11 80% 12 59% 12 60% 54% 8 40% 34% 20% 29% 12% 4

4 NTU Turbidity DB remooval % remooval DB 0% 0 1 5 10 15 20 Bentonite Clay(gram)

Figure 26: DB removal percentages and turbidity versus bentonite mass (g) in ultrapure water using optimal FeCl3 (5 ppm), optimal pH=5.81, and optimal CaCl2 concentration=0.1 M.

51

Adding the coagulation aids such as kaolin or bentonite clays was not effective in achieving higher DB removal percentages as they disperse in the water sample and result in lower DB removal (59% as maximum) and turbid water (50 NTU as the worst). The expected mechanism was that DB first adsorbs onto the clays and then be removed by the coagulant via coagulation process. However, what happened indicated that the coagulation aids (kaolin and bentonite) dispersed in water causing high turbidity, thus resulting in making coagulant remove the turbidity that was generated by kaolin or bentonite instead of helping the coagulant remove DB only. Results revealed that the turbidity present was not an aid to DB removal. Bentonite did better than kaolin because of the structure. Bentonite is more expansive clay and is more likely to be dispersed in the water so that the denatonium will have more active sites to adsorb to bentonite. The kaolin is not that type of clay; there are no sorption sites internally that DB can get into.

The only possibility for DB is on the edges of the clay. In addition, kaolin does not expand, which resulted in having less advantage than bentonite clay.

52 CHAPTER V

CONCLUSIONS AND RECOMMENDATIONS

The common method in water and wastewater treatment, coagulation, was effective for removing the bittering agent, denatonium benzoate, from various water sources including ultrapure water, Great Miami River water, and Miami Well Field groundwater. Aluminum sulfate and ferric chloride can remove lower denatonium benzoate concentrations (15 mg/l) from water. The optimal conditions for removing denatonium benzoate from low ionic strength (0.00005 M) ultrapure water are using 20 mg/l aluminum sulfate and conducting the coagulation process at pH level of 5.81 (90%

DB removal) without adding the coagulation aids such as kaolin or bentonite clays as they disperse in the water sample and result in lower DB removal (59%) and turbid water

(50 NTU as the worst). Using similar water quality conditions (pH, ionic strength), ferric chloride can be used in lower doses than alum (5 mg/l) to achieve 83% denatonium benzoate removal from ultrapure water. After conducting several coagulation experiments on Great Miami River water, aluminum sulfate and ferric chloride were found to achieve the same DB removal (72%) from the river water at the initial river water ionic strength (0.01 M); the optimal coagulant dose and pH were 50 mg/l and 6, respectively. Ferric chloride could achieve higher DB removal (91%) when increasing the solution ionic strength to 0.03 M by maintaining CaCl2 concentration at

53 0.01 M in the solution. The optimal coagulant choice in removing DB from groundwater was to add 60 mg/l alum instead of ferric chloride, since alum showed much more success in DB removal (76%) compared to ferric chloride which removed 49% of DB.

This indicated that alum had more efficiency than FeCl3 in destabilizing dissolved DB particles and transformed them into larger flocs to remove them in subsequent sedimentation process.

Future work related to removing DB from water by coagulation may include the impact of the existence of various metals in the water that contain certain DB concentrations, and how do various types of metals influence the DB removal by coagulation. It may include studying the efficiency of other types of common coagulants such as ferric sulfate, poly aluminum sulfate, etc. and comparing them to the results achieved by alum and ferric chloride in this research. The groundwater quality conditions that impact DB removal with the coagulants may be explored more deeply. It may also include determining if adding DB and other coagulant aids or different types of turbidity and allowing them to mix for a certain amount of time will enhance the DB removal. DB removal after coagulation followed by biochar sorption can be investigated. Another future work may include settling characteristics studies, pH effects on groundwater, looking at lime softening for DB removal in groundwater, and oxidation or pre-oxidation with coagulation.

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58 APPENDIX A

A.1. Interpolation Formula

The following formula was used in spreadsheet to determine the denatonium benzoate remaining concentration after measuring the absorbance of the water sample using the UV-VIS spectrophotometer. The remaining DB concentration was expected to be between 0, which means 100% DB removed, and 15 mg/l, which means 0% DB removal since the initial denatonium benzoate concentration was 15 mg/l. Since the relationship between DB concentration and its absorbance is linear (Figure 5), the following formula was derived.

X2−X1 X=X1+ (Y-Y1) ( ) Y2−Y1

Where:

X=DB remaining concentration in the water sample after running the coagulation process.

X1=0 ppm DB

X2= 30 ppm DB, which is chosen because DB remaining concentration cannot be higher than 15 ppm.

Y=Absorbance of the water sample for which DB concentration need to be determined

59 Y1=Absorbance of water containing 0ppm DB

Y2= Absorbance of water containing 30ppm DB, since the initial DB concentration was

15ppm, so the remaining DB concentration should not exceed 15ppm.

A.2. Preparing Stock Solutions

Stock solutions were prepared according to the following calculations:

Example 1: Preparing 2000 mg/l DB in 1 liter flask.

2000 mg DB 1 g 1 L

L 1000 mg = 2 g of denatonium benzoate should be

weighed and dissolved in 1 liter ultrapure water

to get a stock solution of 2000 ppm DB.

Same procedures can be used to prepare the other materials stock solutions such as alum and ferric chloride.

Example 2: Preparing 1 M CaCl2 (1 mole of CaCl2 per 1 liter solution).

1 mole CaCl2 1 Liter 110.98 g CaCl2

Liter 1 mole CaCl2 = 110.98 g of CaCl2 should be

weighed and dissolved in 1 liter

ultrapure water to get a stock solution

of 1 M CaCl2 in 1 Liter.

Same procedures can be used to prepare potassium chloride (KCl).

60 A.3. DB Standards (5 mg/l- 100 mg/l) Preparation

The following equation was used to prepare DB standards 5 mg/l, 10 mg/l, 30 mg/l, 50 mg/l, 75 mg/l, and 100 mg/l:

C1 V1 = C2 V2 where: C= DB concentration mg/l.

V= solution volume (L).

Example: Preparing 5 mg/l DB standard in 0.024 liter from the DB stock solution (2000 mg/l).

C1 V1 = C2 V2

C1= 2000 mg/l, C2= 5 mg/l, V2= 0.024 liter, V1= unknown.

C2 V2 (5 mg/l) (0.024 liter)

V1= C1 2000 mg/l = 60 μL is taken from the

2000 mg/l DB stock and

added to 0.024 liter amber

vial and filled with ultrapure

water to 0.024 L.

The other DB standards (10-100 mg/l) were prepared using the same procedure.

A.4. Calculating Ionic Strength

A.4.1. Given salt concentration such as CaCl2

Example: Calculating ionic strength for the solution containing 0.01 M CaCl2

Ionic strength (M)= 1 ∑ Zi2 Ci 2

Where: Zi=charge of species (i).

61 Ci=Concentration of species (i) in Molar.

Ionic strength (M)= 1 ∗ [((+2)2 ∗ 0.01) + ((−1)2 ∗ 0.02) ] = 0.03 M 2

A.4.2. The measured conductivity of a solution

Ionic strength in (M)=0.000016* the measured conductivity by the conductivity meter (Figure 3) in microsiemens/cm.

Example: The initial Miami Well Field groundwater containing 15 mg/l DB had measured conductivity of 796 μS/cm, the corresponding ionic strength in

(M) = 0.000016*796 μS/cm=0.012

62 APPENDIX B

B.1. Turbidity HACH Method 8237

Figure 27: Turbidity HACH method 8237

63 B.2. Alkalinity HACH Method 8203

Figure 28: Alkalinity HACH method 8203

64

Figure 28: Alkalinity HACH method 8203 (cont’d).

65