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Record for a UF thesis. Title & abstract won't display until thesis is accessible after 2013-04-30.

Permanent Link: http://ufdc.ufl.edu/UFE0043079/00001

Material Information

Title: Record for a UF thesis. Title & abstract won't display until thesis is accessible after 2013-04-30.
Physical Description: Book
Language: english
Creator: MOSTARY,SHABNAM
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: Environmental Engineering Sciences -- Dissertations, Academic -- UF
Genre: Environmental Engineering Sciences thesis, M.E.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Statement of Responsibility: by SHABNAM MOSTARY.
Thesis: Thesis (M.E.)--University of Florida, 2011.
Local: Adviser: Townsend, Timothy G.
Electronic Access: INACCESSIBLE UNTIL 2013-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0043079:00001

Permanent Link: http://ufdc.ufl.edu/UFE0043079/00001

Material Information

Title: Record for a UF thesis. Title & abstract won't display until thesis is accessible after 2013-04-30.
Physical Description: Book
Language: english
Creator: MOSTARY,SHABNAM
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: Environmental Engineering Sciences -- Dissertations, Academic -- UF
Genre: Environmental Engineering Sciences thesis, M.E.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Statement of Responsibility: by SHABNAM MOSTARY.
Thesis: Thesis (M.E.)--University of Florida, 2011.
Local: Adviser: Townsend, Timothy G.
Electronic Access: INACCESSIBLE UNTIL 2013-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0043079:00001


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1 TRACE METALS LEACHABILITY CHARACTERIZATION OF PHOSPHOGYPSUM By SHABNAM MOSTARY A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DE GREE OF MASTER OF ENGINEERING UNIVERSITY OF FLORIDA 2011

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2 2011 Shabnam Mostary

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3 To my Parents for all their love and support

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4 ACKNOWLEDGMENTS I would like to thank my committee chairman, Dr. Timothy G. Townsend for his patience and encouragement throughout my graduate program. I also wish to thank the remaining members of my committee, Dr. Paul A. Chadik and Dr. Ben Koopman for their insight and review of this thesis. I would also like to thank my fellow graduate students in Solid and Hazardous Waste, for their assistance and support with this study. Final thanks are extended to Mosaic Fertilizer, LLC, for supporting this research. Special thanks go to Elizabeth Foeller (Research & Development Manager) and Charlotte Brittain (Engineering S uperintendent Env ironmental Solutions). A lso I want to thank the Solid Waste Management Division in Polk County, Flo rida for their help

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ ........ 10 LIST OF ABBREVIATIONS ................................ ................................ ........................... 13 ABSTRA CT ................................ ................................ ................................ ................... 15 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 17 1.1 Phosphogypsum and Its Management ................................ .............................. 17 1.2 Objectives ................................ ................................ ................................ ......... 19 2 LITERATURE REVIEW ................................ ................................ .......................... 20 2.1 Phosphoric Acid Production ................................ ................................ .............. 20 2.2 Potential Uses of Phosphogypsum ................................ ................................ ... 22 2.3 Leaching Tests in Solid Waste Management ................................ .................... 23 2.3.1 Toxicity Characteristic Leaching Procedure (TCLP) ................................ 24 2.3.2 Synthetic Precip itation Leaching Procedure (SPLP) ................................ 25 2.3.3 The US EPA Multiple Extraction Procedure (MEP) ................................ 25 2.4 Leaching Tests for Assessing the Potential for Groundwater Contamination ... 26 2.5 Characteristics of Phosphogypsum ................................ ................................ ... 27 2.6 Phosphogypsum Leaching Studies ................................ ................................ ... 28 3 METHODS AND MATERIALS ................................ ................................ ................ 33 3.1 Overview ................................ ................................ ................................ ........... 33 3.2 Sample Collection and Processing ................................ ................................ ... 33 3.3 Leaching Procedures ................................ ................................ ........................ 34 3.3.1 Toxicity Characteristic Leaching Procedure ................................ ............ 34 3.3.2 Synthetic Precipitation Leaching Procedure ................................ ............ 35 3.3.3 Extraction Procedure (EP) Toxicity Test Method ................................ ..... 35 3.3.4 Multiple Extraction Procedure ................................ ................................ .. 36 3.3.5 Batch Leaching Test with MSW Leachate ................................ ............... 36 3.3.5.1 Sulfate analysis ................................ ................................ .............. 37 3.3.5.2 Total dissolved solids (TDS) ................................ .......................... 37 3.3.6 Batch Leaching Test with DI Water ................................ ......................... 38 3.4 Total Metal Analysis ................................ ................................ .......................... 38 3.5 pH of Phosphogypsum ................................ ................................ ...................... 39

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6 3.6 Quality Assurance and Quality Contro l ................................ ............................. 39 4 RESULTS ................................ ................................ ................................ ............... 40 4.1 Total Metal Analysis Results ................................ ................................ ............. 40 4.2 pH of Phosphogypsum ................................ ................................ ...................... 41 4.3 Toxicity Characteristic Leaching Procedure (TCLP) ................................ ......... 41 4.4 Synthetic Precipitation Leaching Procedure (SPLP) ................................ ......... 42 4.5 Extraction Procedure Toxicity ................................ ................................ ........... 42 4.6 USEPA Multiple Extraction Procedure ................................ .............................. 43 4.7 Additional Leaching Testing ................................ ................................ .............. 43 4.7.1 The Deionized Water Batch Leaching Test ................................ ............. 43 4.7.2 Batch Leaching Test with MSW Leachate ................................ ............... 44 5 DISCUSSION ................................ ................................ ................................ ......... 88 5.1 Comparison to Previous Studies ................................ ................................ ....... 88 5.2 Discussion of Leaching Results ................................ ................................ ........ 89 5.3 Assessing Potential for Beneficial Reuse ................................ .......................... 91 5.4 Limitations and Recommendations ................................ ................................ ... 94 6 CONCLUSION ................................ ................................ ................................ ........ 99 APPENDIX A ICP AES DETECTION LIMITS ................................ ................................ ............. 101 B TOTAL METAL ANALYSIS DATA ................................ ................................ ........ 102 C TOXICITY CHARACTERISTIC LEACHING PROCEDURE DATA ....................... 106 D SYNTHETIC PRECIPITATION LEACHING PROCEDURE (SPLP) DATA ........... 110 E EXTRACTION PROCEDURE TOXICITY TEST DATA ................................ ......... 114 F MUTIPLE EXTRACTION PROCEDURE TEST DATA ................................ .......... 115 G BATCH LEACHING TEST WITH DI WATER ................................ ........................ 124 H MSW LEACHATE BATCH LEACHING TEST DATA ................................ ............ 128 I QUALITY ASSURANCE/QUALITY CONTROL ................................ .................... 132 LIST OF REFERENCES ................................ ................................ ............................. 137 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 141

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7 LIST OF TABLES Table page 2 1 Active phosphate rock mines in the United States in 2007 (USGS 2007) ........... 31 2 2 RCRA toxicity characteristics limits (metals only) ................................ ............... 31 2 3 US EPA drinking water standards ................................ ................................ ...... 31 2 4 Content of some trace elemen ts in Phosphogypsum (PG) produced from differ ent rock phosphate sources ................................ ................................ ........ 32 4 1 Metal concentrations (mg/kg) of PG samples ................................ ..................... 45 4 2 pH of PG samples ................................ ................................ .............................. 45 4 3 Tota l metal comparison with risk based standards for direct exposure .............. 46 4 4 pH results (Extraction Procedure Toxicity Test) ................................ .................. 46 4 5 pH results (Multiple Extraction Procedure Test) ................................ ................. 46 4 6 pH results (Batch leaching test with DI water) ................................ .................... 47 4 7 pH results (Batch leaching test with MSW leachate) ................................ .......... 47 5 1 TCLP results found in the previous studies ................................ ........................ 95 5 2 Comparisons of DI water leaching test ................................ ............................... 95 5 3 Comparison of SPLP with previous leaching studies ................................ .......... 95 5 4 Comparison of trace metal concentrations (mg/kg) ................................ ............ 96 A 1 Method Detection Limits ................................ ................................ ................... 101 B 1 Total metal analysis results of PG samples collected from north wall (mg/Kg) 102 B 2 Total metal analysis results of PG samples collected from south wall (mg/Kg) 103 B 3 Total metal analysis results of PG samples collected from east wall (mg/Kg) .. 104 B 4 Total metal analysis results of PG samples collected from west wall (mg/Kg) .. 105 C 1 TCLP test results of the samples collected from north wall (mg/L) ................... 106 C 2 TCLP test results of the samples collected from south wall (mg/L) .................. 107

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8 C 3 TCLP test results of the samples collected from east wall (mg/L) .................... 108 C 4 TCLP test results of the samples collected from west wall (mg/L) .................... 109 D 1 SPLP test results of the samples collected from north wall (mg/L) ................... 110 D 2 SPLP test results of the samples collected from south wall (mg/L) .................. 111 D 3 SPLP test results of the samples collected from east wall (mg/L) .................... 112 D 4 SPLP test results of the samples collected from west wall (mg/L) .................... 113 E 1 EPTOX test results of the samples collected from south wall (mg/L) ............... 114 F 1 MEP test results of the samples collected from south wall (extraction 1) (mg /L) ................................ ................................ ................................ ............... 115 F 2 MEP test results of the samples collected from south wall (extraction 2) (mg/L) ................................ ................................ ................................ ............... 116 F 3 MEP test results of the samples collected from south wall (extraction 3) (mg/L) ................................ ................................ ................................ ............... 117 F 4 MEP test results of the samples collected from south wall (extraction 4) (mg/L) ................................ ................................ ................................ ............... 118 F 5 MEP test results of the samples collected from south wall (extraction 5) (mg/L) ................................ ................................ ................................ ............... 119 F 6 MEP test results of the samples collected from south wall (extraction 6) (mg/L) ................................ ................................ ................................ ............... 120 F 7 MEP test results of the samples collected from south wall (extract ion 7) (mg/L) ................................ ................................ ................................ ............... 121 F 8 MEP test results of the samples collected from south wall (extraction 8) (mg/L) ................................ ................................ ................................ ............... 122 F 9 MEP test results of the samples collected from south wall (extraction 9) (mg/L) ................................ ................................ ................................ ............... 123 G 1 Metal analysis data after batch test of PG with DI water of NW PG samples (mg/L) ................................ ................................ ................................ ............... 124 G 2 Metal analysis data after batch test of PG with DI water of SW PG samples (mg/L) ................................ ................................ ................................ ............... 125 G 3 Metal analysis data after batch test of PG with DI water of EW PG samples (mg/L) ................................ ................................ ................................ ............... 126

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9 G 4 Metal analysis data after batch test of PG with DI water of WW PG samples (mg/L) ................................ ................................ ................................ ............... 127 H 1 Batch leaching test with MSW leachate for PG samples collected from north wall (mg/L) ................................ ................................ ................................ ........ 128 H 2 Batch leaching test with MSW leachat e for PG samples collected from south wall (mg/L) ................................ ................................ ................................ ........ 129 H 3 Batch leaching test with MSW leachate for PG samples collected from east wall (mg/L) ................................ ................................ ................................ ........ 130 H 4 Batch leaching test with MSW leachate for PG samples collected from west wall (mg/L) ................................ ................................ ................................ ........ 131 I 1 QA/QC for TCLP ................................ ................................ ............................... 132 I 2 QA/QC for SPLP ................................ ................................ ............................... 133 I 3 QA/QC for DI water batch leaching test ................................ ............................ 134 I 4 QA/QC for MSW batch leaching test ................................ ................................ 135 I 5 QA/QC for EPTOX ................................ ................................ ............................ 136

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10 LIST OF FIGURES Figure page 4 1 Silver (Ag) and Arsenic (As) concentrations of PG samples in TCLP test .......... 48 4 2 Barium (Ba) and Cadmium (Cd) concentrations of PG samples in TCLP test .... 49 4 3 Chromium (Cr) and Lead (Pb) co ncentrations of PG samples in TCLP test ....... 50 4 4 Selenium (Se) concentration of PG samples in TCLP test ................................ 51 4 5 Silver (Ag) and Aluminum (Al) concentrations of PG samples in SPLP test ....... 52 4 6 Arsenic (As) and Boron (B) concentrations of PG samples in SPLP test ........... 53 4 7 Beryllium (Be) and Cadmium (Cd) concentrations of PG samples in SPLP test ................................ ................................ ................................ ...................... 54 4 8 Chromium (Cr) and Copper (Cu) concentrations of PG samples in SPLP test ... 55 4 9 Iron (Fe) and Potassium (K) concentrations of PG samples in SPLP test .......... 56 4 10 Sodium (Na) and Nickel (Ni) concentrations of PG samples in SPLP test .......... 57 4 11 Lead (Pb) and Antimony (Sb) concentrations of PG samples in SPLP test ........ 58 4 12 Tin (Sn) and Strontium (Sr) concentrations of PG samples in SPLP test ........... 59 4 13 Vanadium (V) and Zinc (Zn) concentrations of PG samples in SPLP test .......... 60 4 14 Toxicity Characteristic Leaching Procedure initial an d final pH .......................... 61 4 15 Synthetic Precipitation Leaching Procedure initial and final pH .......................... 61 4 16 Aluminum (Al) and Barium (Ba) concentrations of PG samples (south wall) in EPTOX test ................................ ................................ ................................ ......... 62 4 17 Calcium (Ca) and Chromium (Cr) concentrations of PG samples (south wall) in EPTOX test ................................ ................................ ................................ ..... 63 4 18 Copper (Cu) and Potassium (K) concentrations of PG samples (south wall) in EPTOX test ................................ ................................ ................................ ......... 64 4 19 Magnesium (Mg) and Nickel (Ni) concentrations of PG samples (south wall) in EPTOX test ................................ ................................ ................................ ..... 65 4 20 Strontium (Sr) and Zinc (Zn) concentrations of PG samples (south wall) in EPTOX test ................................ ................................ ................................ ......... 66

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11 4 21 .......................... 67 4 22 ........................ 68 4 23 ........................ 69 4 24 .................. 70 4 25 ............................. 71 4 26 Zinc (Zn) leachability in ................................ ............................. 72 4 27 Aluminum (Al) and Barium (Ba) concentrations in DI water batch leaching test ................................ ................................ ................................ ...................... 73 4 28 Calcium (Ca) and Copper (Cu) concentrations in DI water batch leaching test .. 74 4 29 Potassium (K) and Sodium (Na) concentrations in DI water batch leaching test ................................ ................................ ................................ ...................... 75 4 30 Nickel (Ni) and Strontium (Sr) concentrations in DI water batch leaching test .... 76 4 31 Zinc (Zn) concentration in DI water batch leaching test ................................ ...... 77 4 32 Aluminu m (Al) and Arsenic (As) concentrations in MSW leachate batch leaching test ................................ ................................ ................................ ....... 78 4 33 Boron (B) and Barium (Ba) concentrations in MSW leachate batch leaching test ................................ ................................ ................................ ...................... 79 4 34 Calcium (Ca) and Cobalt (Co) concentrations in MSW leachate batch leaching test ................................ ................................ ................................ ....... 8 0 4 35 Chromium (Cr) and Copper (Cu) concentrations in MSW leachate batch leaching test ................................ ................................ ................................ ....... 81 4 36 Iron (Fe) and Potassium (K) concentrations in MSW leachate batch leaching test ................................ ................................ ................................ ...................... 82 4 37 Magnesium (Mg) and Manganese (Mn) concentrations in MSW leachate batch leaching test ................................ ................................ .............................. 83 4 38 Sodium (Na) and Nickel (Ni) concentrations in MSW leachate batch leaching test ................................ ................................ ................................ ...................... 84 4 39 Antimony (Sb) and Strontium (Sr) concentrations in MSW leachate batch leaching test ................................ ................................ ................................ ....... 85

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12 4 40 Vanadium (V) and Zinc (Zn) concentrations in MSW leachate batch leaching test ................................ ................................ ................................ ...................... 86 4 41 Sulfate concentration results of batch test with MSW leachate .......................... 87 4 42 TDS results of batch test with MSW leachate ................................ ..................... 87 5 1 Aluminum (Al) concentrations in different batch leaching tests .......................... 97 5 2 Barium (Ba) concentrations in different batch leaching tests .............................. 97 5 3 Chromium (Cr) concentrations in different batch leaching tests ......................... 98 5 4 Calcium (Ca) concentrations in different batch leaching tests ............................ 98

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13 LIST OF ABBREVIATION S ASTM American Society for Testing and Materials CFS Cancer Slope Factors DI Water Deionized Water EPA Environmental Protection Agency EPTOX Extraction Procedure Toxicity EW East Wall FIPR Florida Institute of Phosphate Research GWCTL Groundwater Cleanup Target Level ICP AES Inductively Coupled Plasma Atomic Emis sion Spectrophotometer L/S Ratio Liquid to Solid Ratio LOAEL Lowest Observed Adver se Effect Level MEP Multiple Extraction Procedure MSW Municipal Solid Waste NESHAP National Emissions Standards for Hazardous Air Pollutants NOAEL No Observed Adverse Effect Level PG Phosphogypsum RCRA Resource Conservation and Recovery Act RFD reference dose SPLP Synthetic Precipitation Leaching Procedure SW South Wall TCLP Toxicity Characteristic Leaching Procedure TDS Total Dissolved Solids UCL95 95% Upper Confidence Limit USGS United States Geological Survey

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14 WW West Wall

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15 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the R equirements for the Degree of Master of Engineering TRACE METALS LEACHABILITY CHARACTERIZATION OF PHOSPHOGYPSUM By Shabnam Mostary May 201 1 Chair: Timothy G. Townsend Major: Environmental Engineering Sciences Phosphogypsum (PG), a primary byproduct from phosphoric acid production, is accumulated in large stockpiles and occupies vast areas of land. The aim of this study was to characterize the trace metal s leachability of p hosphogypsum under different environment al conditions For th is purpose multiple batch l eaching tests were conducted to observe the leaching behavior of PG elements Based on the toxicity characteristic leaching procedure (TCLP) and ex traction procedure toxicity (EPTOX) test none of the metals (Ag, As, Ba, Cd, Cr, Pb, Se) exceeded the regulatory toxicity limits ; thus PG samples tested did not meet the definition of EP Toxicity under the Resource Conservation and Recovery Act ( RCRA ). It is notable that mercury was not tested in this study. Results from the TCLP synt hetic precipitation leaching procedure (SPLP) and deionized water (DI) extract ion, leached relatively similar concentrations of inorganic constituents (except calcium ) A luminum and iron concentrations exceed ed their respective groundwater cleanup target l evel (GWCTL) in SPLP leachates In the multiple extraction procedure (MEP) most of the metals leached at greater concentration in the second extraction than in the first. In a leaching test utilizing municipal solid waste (MSW) leachate as the extraction fluid, a few constituents of PG

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16 such as calcium and sulfate considerably leached out. Calcium leached more in the MSW leaching test than TCLP and SPLP. Aside from calcium a nd strontium there was no significant leaching of other metals in the MSW leaching test. Though concentration of arsenic (UCL 95 ) was above GWCTL in total metal analysis it was not detected in any of the leaching test.

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17 CHAPTER 1 INTRODUCTION 1.1 Phosphogypsum and I ts Management Phosphogypsum (PG ) a waste by product from the we t manufacturing process of phosphoric acid, is abundant in Florida due to the presence of this industry The composition of PG is variable and is related to the source of phosphate rock as well as the manufacturing process. Gypsum ( CaSO 4 2H 2 O) is the main component; however, PG also contains low concentrations of P and some of the impurities that were originally in the phosphate rock (F, trace elements and naturally occurring radionuclides). Some of the m inor elements that are common such as F, As, Cd, P, and S, have the potenti al to pose environmental health concern if excessive levels are transported in to ground or surface waters. Thus, there are environmental concern s in regards to the potential movement of fluoride, sulfate, certain trace elements, and radionuclides from the phosphogypsum stacks into groundwater PG is currently placed in large piles or Leachate from these gyp stacks as they are called, must be properly understood to minimize the risk of environmental contamination. Prior to 1989 PG was treat ed a s any other item of commerce The US Environmental Protection Agency ( EPA ) first issued the National Emissions Standards for Hazardous Air Pollutants ( NESHAP ) f or phosphogypsum in 1989 (54 FR 51654, December 15, 1989). The 1989 rule required that all phosphogypsum be stored in stacks. EPA also prohibited all phosphogypsum research and uses such as agricultural or indoor research and development

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18 In response to several petitions, EPA conducted risk assessments and revised the standard to permit alternate uses of PG in 1992 ( 40 CFR Part 61, Subpart R ) The 1992 revision permitted uses of PG for agricultural uses (as a conditioner for soils containing high quantities of salt or low quantities of calcium and other nutrients), research and development projects and other alternate uses that are approved by EPA on a case by case basis. In 1999 EPA increased the amount of phosphogypsum which may be used in indoor laboratory research from 700 to 7,000 pounds per experiment, with no limit on the number of experiments ( 40CFR 61.205 ) Under the 1999 rule, PG may b e lawfully removed from a stack and distributed in commerce for use in agriculture if the average radium 226 concentration of the PG does not exceed 10 picocuries per gram (pCi/g) (40CFR 61.204) T he owner or operator of the stack from which the PG is remov ed shall determine annually the average radium 226 concentration at the location in the stack from which the PG will be removed. PG may not be lawfully removed from a stack and distributed or used for any purpose other than agriculture and research purpose s without prior EPA approval (40CFR 61.204) This restriction on the maximum radium radioactivity essentially eliminates the use of southern/central Florida phosphogypsum because its radium 226 levels are commonly in the range of 20 to 3 5 pCi g 1 ( Guidry 1 990 ; May and Sweeney 1984a ) The restriction does not impact phosphogypsum from northern Florida or North Carolina, which generally have lower levels of radium 226 Considerable research has been conducted to evaluate the leachability of toxic metals (As, Ba, Cd, Cr, Hg, Pb, Se and Ag) from phosphogypsum by TCLP and

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19 EPTOX. S everal researchers have conducted leaching test s to estimate mobility of trace metals, radionuclides and rare earth metals from PG using different leaching solutions like distilled water, aqua regia, salt water etc. 1.2 Objectives The primary objective of this thesis w as t o determine typical trace metal leaching behavior of PG using standardized regulatory leaching tests for solid wa stes. Leaching tests play an important role in the reuse of raw waste materials as secondary materials. Analyses such TCLP, SPLP, EPTOX, MEP that would typically be required for a beneficial use demonstration in Florida were conducted. These analyses were conducted to evaluate the leachability of trace metals (Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mn, Na, Ni, Pb, Sb, Se, Sn, Sr, V, Zn) in PG. Laboratory leaching tests which generate leachate from waste have been used to evaluate leachability of haza rdous constituents (As, Ba, Cd, Cr, Pb, Se, Ag) from PG. The results (total and leachable concentrations of inorganic constituents) were compared to based target levels like s oil cleanup target level (SCTL) and groundwater cleanup target lev el (GWCTL) PG leachability using different solutions like MSW leachate and DI water was also examined Knowledge on leaching behavior of PG could help to e xplore disposal options and assess the risk associated with beneficial use options for PG. This study investigates one particular phosphogypsum stack in an attempt to characterize PG leachability that would be typical for many of the other stacks in central Florida. Chapter 2 investigates the literature pertinent to PG production and leachate re sulting from PG and leaching tests. Chapter 3 discusses the materials and methodology used in this research. Chapter 4 presents the results from various leaching tests. Finally, discussions o f the results are presented in C hapter 5

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20 CHAPTER 2 LITERATUR E REVIEW 2.1 Phosphoric Acid Production Phosphogypsum is the primary byproduct generated from the wet acid process for producing phosphoric acid from phosphate rock. Phosphoric acid is an industrial raw material required for the production of phosphate fer tilizer. Phosphate rock, mined in open pit mines, does not have a definite chemical composition and the composition varies in different mining areas. Phosphate ore contains roughly one third quartz sands, one third clay minerals, and one third phosphate pa rticles (USEPA 1992) I mpurities like calcium fluoride, chlorides, chromium, rare earths and radio nuclides are also common. phosphate fertilizers (USGS 2002) Extensive depo sits of phosphate rock are found in Florida, Tennessee, North Carolina and Idaho. As a result of the low aqueous solubility of calcium phosphate, the phosphate content of the rock is converted into phosphoric acid to produce fertilizer. Phosphate ore compo sition partly determines the nature of the phosphorus fertilizer and phosphogypsum. For every ton of phosphoric acid produced, 4.5 5.5 tons of phosphogypsum are produced (Saylak et al. 1988) According to a mineral industry survey conducted by U.S. Geological Survey (USGS) in 2007, a total of twelve phosphate rock producing mines were active nationwide (Table 2 1). In Florida, phosphate rock is mined an d processed by three companies: CF Industries, Inc., The Mosaic Co and PCS Phosphate Co., Inc ( U SGS 2007) Phosphate rock is usually treated by a physical process called beneficiation ; a process prior to acid treatment in order to concentrate the P content of the ore (Becker

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21 1989) Beneficiation often involves concentration by washing, screening and flotation. Phosphoric acid is produced either by dry thermal or wet acid methods. The dry thermal method produces element al phosphorus using an electric arc furnace. Phosphoric acid produced by dry thermal process is of a much higher purity and is used in the manufacture of high grade chemicals, pharmaceuticals, detergents, food products, beverages, and other non fertilizer products. In the wet acid process, p hosphate rock is treated with concentrated sulfuric acid and water to produce gypsum (CaSO 4 .2H 2 O) phosphoric acid and hydrogen fluoride. Wet process phosphoric acid is used in fertilizer production because it is more economical. The following is a simplified chemical reaction to illustrate the process (Luther et al. 1992) Ca 10 (PO 4 ) 6 F 2 + 10H 2 SO 4 + 20 H 2 4 .2H 2 0 + 6H 3 PO 4 + 2HF Once crystallized, the gypsum is separated from the acid by filtration, mixed with water and transferred as slurry to onsite disposal areas referred to as phosphogypsum stacks. The phosphogypsum stacks are an integral part of the overall wet process. The phosphogypsum slurry is pumped to the top of the stack and discharged into perimeter deposition ponds. The process water is decanted into a center storage pond and then removed from the stack for recycle via a siphon. T he ph osphogypsum slurry be gins to form a small pond on top of the stack with the growth of stack Workers dredge gypsum from the pond to build up the dike around it and the pond gradually becomes a reservoir for storing and supplying process water. As the wet p rocess requires large quantities of water, the water impounded on the stack is used as a reservoir that supplies and balances the water needs of the process

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22 2.2 Potential Uses of Phosphogypsum EPA first banned any use of phosphogypsum in 1989. Since then it has been a divisive issue on if and how to use phosphogypsum. As a local material, phosphogypsum stacks can be found ex ten sively in Florida. However, due to the 19 92 EPA ban on the use of phosphogypsum, research has slowed dramatically. As a result, special provisions must be made to FDEP and EPA be fore this material can be used other than agricultural purposes. It is of interest to the f ertilizer industr y to find eff ective and economical long term solutions for the management of PG; this would help to minimize space requirements and the potential for environmental impact caused by the accumulation of PG stacks. Several research projects have investigated practical app lication of PG for a variety of purposes, including its use as road fill material (May 198 3; Chang 1989; Lloyd 1985) and as a soil stabilizer ( Degirmenc i 2006). Several roads and parking lots were constructed u sing PG or cement PG. They are used daily in F lorida and Texas with no reported negative environmental impacts (Nifong and Harris 1993) Sulfur deficiencies exist in soils of the southeastern US Phosphogypsum soil amendment is a possible solution to correct this deficiency because it provides a sulfu r source that is slowly available to the plants and is not easily leached out of the soil by rainfall (Lloyd 2004) Stanley and Lloyd ( 1992) studied phosphogypsum reporting that PG is currently has been proven to be a suitable amendment for many soil types and is an excellent fertilizer source of sulfur, calcium and phosphorous Any soil that tends to surface harden

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23 and resist water would benefit from PG. I t creates a more porous texture that soaks up In the past, countries such as France and Japan used phosphogypsum for construction of roadways and landfills and as a building material for houses. Research ha s been conducted in France to use PG for embankment construction (Mou ssa et al. 1984) Their stu dy showed that re utilization of PG is possible in well determined c onditions of placement and use. Studies suggest that PG along with coal fly ash can be used as an amendment to im prove rice paddy soil fertility (Lee et al. 2009) It was concluded that th e fly ash and PG mixture could be a good source of inorganic soil amendments to restore the soil nutrient balance in rice paddy soil. Extensive research has been conducted to recover sulfur from PG. In general sulfate is converted to sulfur dioxide by a h igh temperature decomposition of calcium sulfate in the PG. The sulfur dioxide is scrubbed from the gaseous emissions and sent This is then utilized in the wet acid process ( US EPA 19 92) This method is not economical if the price of sulfur is too low. 2.3 Leaching Test s in Solid Waste Management Leaching is a method to remove soluble components from a solid matrix. M any leaching test procedures have been developed to simulate the lea ching processes of wastes in landfills or other disposal scenarios ; these assist in evaluat ing potential risks to human health and environment from soli d wastes Therefore, l eaching tests are often used in the decision making process of solid waste management. Leaching tests are used to estimate the potential concentration of contaminant th at leaches from a solid

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24 waste w hen exposed to water or similar extraction solution In general, there are two types of leaching tests : b atch leaching test s and dyn amic column/lysimeter test s Some common batch leaching tests include Extra ction Procedure Toxicity (EPTOX ), Toxicity Characteri stic Leaching Procedure (TCLP) Synthetic Precipita tion Leaching Procedure (SPLP), American Society for Testing and Materials (A STM) extraction test and Multiple Extraction Procedure (MEP). While batch leaching tests are characterized by a constant liquid to solid ratio, dynamic leaching tests are characterized by increasing liquid to solid ratio as the experiment proceeds. Batch t ests typically involve adding waste to an extraction solution and then agitat ing the mixture for a short period of time (typically less than 24 hour).Thus, b atch test s offer a relatively rapid, cost effective method for the assessment of metal leachability Batch tests are primarily conducted as a regulatory tool but they can also be conducted in a manner to examine a specific variable influence on metal mobility, like impact of pH, liquid to solid ratio etc. 2.3 .1 Toxicity Characteristic Leaching Proced ure (TCLP) TCLP (EPA Method 1311) is the most frequently used batch test in the management of solid waste The TCLP was designed by the US Environmental Protection Agency (EPA) to provide a relatively quick test to determine whether a solid waste should be characterized as hazardous and thus be managed in a more controlled manner The TCLP attempts to mimic reducing, low pH environmental conditions in MSW landfills. The extraction fluid (pH 4.93 0.05) simulates a scenario where a potentially hazardous waste is co disposed with MSW. The primary extraction fluid is a buffered acetic acid solution in a liquid to solid ratio of 20:1 for 18 2 hours. Particle size reduction is required if the particle is g reater than 1 cm in its narrowest dimension. The concentrations of contaminants are compared to toxicity characteristic ( TC ) limit

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25 concentrations outlined in 40CFR261.3 to determine hazardous waste designation The TC limit s for the eight metals used in de termination of hazardous waste are presented in Table 2 2 N ote that there are a number of organic contaminants which also carry a toxicity characteristic limit TCLP uses acetic acid (weak acid) which has a strong ability to complex or chelate metals 2.3 .2 Synthetic P recipitation L eaching P rocedure (SPLP) The SPLP is an EPA SW 846 analytical method ( EPA Method 1312) designed to mimic the mobility of toxic contaminants when exposed to acidic rainfall The SPLP is thus used to evaluate the potential for met al leaching into ground and surface waters from waste exposed to rainfall (Jang and Townsend 2001; Brantley and Townsend 1999) The time and liquid to solid ratio are the same as in the TCLP, but SPLP utilizes an extraction fluid intended to simulate preci pitation or acid rain. Particle size reduction is required if the particle is greater than 1 cm in its narrowest dimension Th e extraction fluid (pH 4.2 0.05) is made of two inorganic acids (nitric and sulfuric acid ) to simulate acidic rainwater. 2.3 .3 The US EPA Multiple Extraction Procedure (MEP) The MEP simulates leaching caused by the repetitive precipitation of acid rain water ( EPA Method 1320) MEP may be used to address long term leachability. MEP is designed to simulate the leaching that a waste will undergo from repetitive precipitation of acid rain on an improperly designed sanitary landfill. The repetitive extractions will give the highest concentration of each constituent that is likely to leach in a natural environment. This test utilizes an initial acetic acid extraction (pH 5 0.2) followed by sequential extractions with simulated acid rain So, MEP combines aspects from both the TCLP and the SPLP. Extraction on the first day calls for TCLP extraction fluid at a

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26 liquid to solid ratio of 20:1 ; thereafter, the procedure calls for SPLP extraction solution (pH 3 0.2) ( at least eight subsequent e xtractions ) at the same liquid to solid ratio. Details are discussed in C hapter 3. 2.4 Leaching Tests for Assessing the Potential for G roundwater Contamination Leaching of pollutants to groundwater is a very complex process influenced by several factors such as meteorological parameters (e.g., rainfall), soil properties (particle size distribution, organic carbon content), and physical chemical char acter istics (Krdel and Klein 2006) Regulation of groundwater quality is generally under state jurisdiction; m ost states have their own risk based regulatory thresholds regarding contaminant transport from soil to groundwater. The state of Florida has wha t are known as Soil and Groundwater Cleanup target Levels (SCTL and GWCTL). The SCTLs consist of over 350 individual chemicals with pre calculated total constituent concentration thresholds based on direct human contact with soil and potential for soil con tamination to migrate to groundwater Different limits reflect different possible groundwater uses. The w orst case scenario is where the water is assumed to be use d for direct human consumption. The GWCTLs are a similar list of maximum leachable concentrat ions for various constituents. For particularly hazardous constituents, the US EPA primary and secondary drinkin g water standards (Table 2 3) are generally used for the GWCTL. SCTL were developed based on direct human contact (i.e., direct exposure), and b ased on soil acting as a source of groundwater or surface water contamination (i.e., leachability). The US EPA has developed measurements of cancer potency of carcinogens, which are termed cancer slope factors (CSFs). Risk based soil cleanup guidelines hav e been developed for both carcinogens and non carcinogens. For non

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27 cancer risks, the reference dose (Rf D) is the term used to refer to the maximum Level (LOAEL) or No Observed Ad verse Effect Level (NOAEL) measurements that have been multiplied by a series of uncertainty factors. There are separate RfDs for different pathways of exposure (Oral, inhalation). For calculating SCTL, we need to consider different pathways (ingestion, in halation, dermal exposure). As for example, equation for a cancer risk from soil exposure through ingestion will be, CTL (mg/Kg) = {Target Cancer risk X Body weight (Kg)}/ {Oral Cancer Slope Factor (mg/kg day) 1 X ingestion rate (mg/day)} The formula for c alculating GWCTL (carcinogen) is, GWCTL (mg/L) = {Target Cancer risk X Body weight (Kg)}/ {Oral cancer slope factor ((mg/kg day) 1 X Average Water Consumption Rate (L/day)} Body weight and water consumption are assumed for calculation. For non carcinogen it will be only, GWCTL= { (RFDX Body Weight)/Water consumption rate } Since metals present in land applied solid waste may leach from the waste and migrate to the groundwat er (Townsend et al. 2003) possible risk to ground water should be assessed. In Florida and many other states, leaching risk is evaluated by conducting the SPLP and comparing the results to the aforementioned risk based groundwater standards This approach is typically viewed as being more representative because the chemical nature of the waste, which can impact leaching, is tested. 2.5 Characteristics of Phosphogypsum The chemical and mineralogical characteristics of phosphogypsum var y depending upon the natu re of the phosphate ore, the type of process used in fertilizer manufacturing the efficiency of plant operation, the age and location of the stockpile,

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28 and any contaminants which may be introduced into the phosphogypsum at the production plant (Arman and Seals 1990) Calcium and sulfate dominate the composition of phosphogypsum because it is approximately >90% gypsum (Berish 1990) PG normally has a pH between 4.5 and 5.0. Acidity of PG is due to residual phosphoric acid, sulfuric acid and fluoride acids c ontained within the por e spaces May and Sweeney ( 1984a) found the pH of extracts from Florida phosphogypsum to range between 2.1 and 5.5. Metal concentrations in PG have been thoroughly characterized and typical concentrations are summarized in T able 2 4. These elemental compositions may vary greatly depending on th e source of the phosphate rock. 2.6 Phosphogypsum Leaching Studies The leaching behavior of materials depends on several parameters. These include specific element solubility and availability or release potential. Again s olubility can be influenced by pH, complexation by inorganic species or dissolved organic matter, and reducing properties (Kim 2002) May and Sweeney ( 1984a) investigated nine PG sta cks in Florida to study various physical and chemical characteristics of PG. Results for this analysis showed that the trace elements were uniformly distributed within the PG stacks. May and Sweeney ( 1984b) evaluated the leacha bility of Ra and elements the EPA has classified as toxic (As, Ba, Cd, Cr, Pb, Hg, Se, and Ag) by using the standard EPA 'EP' extraction procedure (Federal Register 1980) The concentrations of toxic elements in the extract were all below EPA maximal concentrations, therefore the mate ria l was considered non toxic by EPA standards. The authors estimated that the inclusion of Ra into the phosphogypsum crystal structure would be 89% of the amount originally present, indicating that very little Ra would be leached They concluded that phos phogypsum

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29 could not be classified as a hazardous waste because it was neither corrosive nor caustic (pH was > 2 and < 12.5) In addition the average total elemental concentrations of elemen ts classified as toxic by the EPA were less than the EPA allowable toxic elemental criteria for toxic hazardous waste (Federal Register 1980) Rusch and Seals (2004) conducted TCLP on raw PG and oven dried PG samples (oven dried at 45 o C for 12 hours and ground to pass through a US Standard sieve No.10.) collected from Lou isiana. The metal concentrations in the leachate from both type, were also well below the US EPA toxicity characteristics limits. Also, there was no significant difference between these two types of samples. Kendron (1996) conducted EPTOX and TCLP on raw PG specimens to understand the leaching behavior of As, Ba, Cd, Cr, Pb, Ag, Hg and Se through phosphogypsum. The results indicated a potential leaching of these species. Although, the leachate concentration levels were below the US EPA tox icity limits, the concentrations failed to meet the US EPA drinking water limits for several species. To determine the potential enviro nmental impact of phosphogypsum, Naff ( 1984) conducte d EPTOX on phosphogypsum. The result s were within the permissible EP A limits for toxicity; however SO 4 2 and fluoride levels exceeded drinking water standards. Haridasan (2002) conducted leaching studies on PG samples ( Kochi, I ndia) using distilled water (pH 6.0) and rainwater (pH= 5.0 5.8) as leachants They varied conta ct time and so lid/liquid ratio in the leaching procedures The laboratory results indicated that rainwater leached less 226 Ra than distilled water The leachability of Cd, Cu, U and Zn in Syrian PG was studied by Al Masri et al. (2004) They did leaching t est of PG with distilled water and concluded that Cu and Cd

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30 are easily transferrable to wate r or surrounding environment. They also grouped PG into six different particle sizes to observe the effect of particle size on leachability and found that fine particles (45 75 mm) yielded a relatively high solubility.

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31 Table 2 1 Active phosphate rock m ines in the United States in 2007 (USGS 2007) Owner Mine State CF Industries, Inc. South Pasture Florida Mosaic Co, The Four Corners Florida Do Hookers Prairie Florida Do Hopewell Florida Do South Fort Meade Florida Do Wingate Creek Florida Nu West Industries, Inc. (Agrium Inc.) Dry Valley Idaho P4 Production, LLC. (Monsanto Co.) South Rasmussen Idaho PCS Phosphate Co., Inc. Aurora North Carolina Do Swift Creek Florida Simplot, J.R., Co. Smoky Canyon Idaho Do Vernal Utah Table 2 2 RCR A toxicity characteristics l imits (metals only) Metal RCRA TC Limit (mg/L) As 5.0 Ba 100 Cd 1.0 Cr 5.0 Hg 0.2 Se 1.0 Ag 5.0 Pb 5.0 Table 2 3 US EPA drinking w ater s tandards Primary Secondary Contaminant Standard (mg/L) Contaminant Standard (mg/L) As 0.01 Al 0.2 Ba 2 .0 Cu 1.0 Be 0.004 Fe 0.3 Cd 0.005 Mn 0.05 Cr 0.1 Zn 5 Cu 1.3 Cl 250 Pb 0.015 SO 4 2 250 Sb 0.006 TDS 500 Se 0.05 Tl 0.002

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32 Table 2 4 Content of some trace elements in P hosphogypsum (PG) produced from different rock phosphate sources; also included are typical literature values for soil Element Florida Source PG a Idaho Source PG b South African Source PG c Tunisian Source PG d Typical soil e mg/Kg Ag <1 1 11 0.05 As 40 <1 2 7.2 Au ( g/kg) 3 15 B 3 <10 30 33 Ba 7 20 140 140 580 Be 1 1 2 0.92 Br 1 2 0.85 Cd 7 9 28 40 0.35 Cl <100 300 100 Co 2 <1 8 9.1 Cr <10 70 54 Cu 8 10 42 103 6 25 H g ( g/kg) <50 14000 90 Mn 15 <2 10 550 Mo 16 <1 2 5 0.97 Ni 2 3 15 15 19 Pb 1 3 7 13 19 Rb <10 20 67 Sb 100 0.3 0.8 0.66 Se 4 67 0.39 Sr 10 610 670 240 Th <1 9.4 U 6 13 2.7 V 19 10 40 80 Y 2 100 120 50 25 Zn 9 18 112 6 315 60 Zr 10 <10 110 185 230 a May and Sweeney ( 1984a ) b Luther and Dudas ( 1993 ) c Malan ( 1988 ) d Ro uis and Bensalah ( 1990 ) e Sposito ( 1989 )

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33 CHAPTER 3 METHODS AND MATERIAL S 3.1 Overview To assess the leachability of various trace metals from p hosphogypsum (PG) samples were extensively analyzed with respect to composition and leaching behavior. Inorganic element concentration from acid digestion and leaching samples were analyzed using Inductively Coupled Plasma Atomic Emission Spe ctroscopy (ICP AES).This section will describe the preparation of the samples and methods that were followed to carry out the leaching tests. 3.2 Sample Collection and Processing PG was sampled from the top of a PG stack located in Mulberry, Florida Sampl es were collected from four locations: the north, south, east, and west walls of the top stack. Samples were retrieved from depths of 1 to 2 feet from the top of the stack. PG s amples were named north wall (NW), south wall (SW), east wall (EW) and west wal l (WW) based on their locations. PG samples were collected by using cleaned scoops, trowels, shovels, and were placed in five gallon buckets (HDPE) then sealed with lids. PG samples were then transported to the UF laboratory. A total of 330 kg of PG was co llected from each of the four sampling location s In the lab, s amples collected from different locations were not mixed together. But samples collected from different depth s for each location were thoroughly mixed to get a homogenous sample for that location Samples were stored in closed containers in the lab at room temperature. To perform research on PG, the requirements of 40 CFR 61.205 were followed; all PG was accompanied by certification documents that conformed to the requirements of 40 CFR 61 .208. The total quantity of PG at a facility did not exceed 7000 lbs. Containers of PG

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34 Levels of Na 3.3 Leaching Procedures Four regulatory based leachi ng tests were performed TCLP SPLP EPTOX and MEP The TCLP, SPLP, EPTOX, and MEP were developed by the US Environmental Protection Agency (EPA). In addition, several experiments were conducted in a similar fashion as TCLP but substituting act ual landfill leachates and DI water as the leaching solution 3.3.1 Toxicity Characteristic Leaching Procedure The TCLP method is defined in EPA Method 1311.TCLP uses one of two different extraction fluids, depending on the alkalinity of the waste. Extract ion fluid 1 is prepared by diluting a mixture of 11.4 mL acetic acid (CH 3 COOH) and 128.6 mL of 1N sodium hydroxide (NaOH) to 2L deionized water (DI). The resulting solution pH is 4.93 0.05. Extraction fluid 2 is used for highly alkaline materials. This solution is prepared by adding 11.4 mL acetic acid to 2L deionized water. pH of this solution should be 2.80.05. Because the pH of the PG sample was less than 5, extraction fluid 1 was used. The TCLP requires that samples first be size reduced to less tha n 0.95 cm in any dimension One hundred grams of the size reduced samples were placed in a 2.2 L TCLP extraction vessel, and 2.00 L of the extraction solution were added. The slurry was mixed on a rotary extractor for 18 2 hr at 30 2 revolutions per mi nute and then bottles (HDPE) and preserved by adjusting the pH to less than 2 using nitric acid. The leachates generated by the TCLP process were acid digested and a nalyzed using ICP AES

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35 3.3.2 Synthetic Precipitation Leaching Procedure SPLP leachates were prepared according to the procedure outlined in EPA method 1312. A concentrated SPLP solution was prepared by adding 100 mL of one percent (by volume) solution of c oncentrated nitric acid and 100 mL of one percent solution of concentrated sulfuric acid, and then combining these in a 2 parts nitric to 3 parts sulfuric ratio (40%:60%). Then, 0.4 0.5 mL of concentrated SPLP solution was added to reagent water in a 2 L volumetric flask and diluted to 2 L. The resulting SPLP solution pH was required to be 4.20 0.05. The SPLP requires that samples first be size reduced to less than 0.95 cm. One hundred grams of the size reduced samples were placed in a 2.2 L SPLP extrac tion vessel, and 2 L of the SPLP solution were added. The slurry was mixed on a rotary extractor for 18 2 h. After the extraction procedures, separation of the leachate solution from PG was completed using a vacuum filtration set up. The filter used was washed glass fiber filter .The rotary extractor was used during the TCLP and SPLP tests was designed to rotate eight 2 L bottles in an end over end fashion. When loaded with a full load, each extractor rotates at 30 rpm as required by the TCL P and SPLP procedures. The filtrate was collected in 500 mL plastic bottles and preserved by adjusting the pH to less than 2 using nitric acid. 3.3.3 Extraction Procedure (EP) Toxicity Test Method The method is defined in EPA Method 1310b.This test require s the continual addition of acid to maintain a constant extraction pH. For the EPTOX, 100 g of sample were placed in 1.6 L of deionized water and agitated for 24 hours. The method requires that the pH of the mixture be maintained at 5 0.2 by adding 0.5N acetic acid. The PG samples in this study did not require any further acid addition. After 24 h of extraction,

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36 deionized water was added to bring the total volume of the extraction fluid to 2 L. The leachate was filtered using 0.45 3.3.4 Multipl e Extraction Procedure This test utilizes an initial acetic acid extraction followed by sequential extractions with simulated acid rain. The initial extraction fluid is the same as the EPTOX. The simulated rainfall extraction solution is similar to the SPL P leaching fluid but with a pH of 3.0 0.2. This s ynthetic acid rain extraction fluid was prepared by adding 60% sulfuric acid and 40% nitric acid (weight percent) to distilled deion ized water until the pH is 3.0 0.2. The residu al solids after the extra ction we re re extracted nine times consecutively using synthetic acid rain extraction fluid. An initial sample size of 12.5 g was used. Each ex traction step is performed at a n L/S ratio of 20 :1 for 24 h. After each filtration, both the filter and the sampl e were added to the next extraction vessel. The final pH values of leachates and metal ion concentrations were determined for each extraction 3.3. 5 Batch Leaching Test with MSW L eachate This batch leaching test mimicked the condition that MSW landfill leachate directly contacts PG and measured any constituent change before and af ter mixing MSW leachate with PG This test method is similar to the TCLP or SPLP test except that it uses MSW landfill lea chate as the extract solution. A 100 g sample of PG was mixed with 2 L of MSW leachate and mixed for 18 2 hours using a rotating shaker at 30 rpm. after the rotation. Inorganics were analyzed after acid d igestion. For th is test, MSW landfill leachate was obtained from Polk County North Central landfill. The pH of leachate was 7.6 and totals dissolved solids (TDS) was 6300 mg/L

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37 3.3.5.1 Sulfate analysis Sulfate concentration in leachate samples from batch leaching test of PG (with MSW leachate) was determined using a spectrophotometer (DR/4000 UV VIS, HACH, Loveland, CO) with HACH Method 8051. A sample cell was filled with 25 mL of sample. One SulfaVer 4 reagent powder was added to the cell. Sulfate ions in the sample reac t with barium in the SulfaVer 4 and form a precipitate of barium sulfate. The amount of turbidity formed is proportional to the sulfate concentration. 3.3.5.2 Total dissolved solids (TDS) Total dissolved solids (TDS) of the leaching solution from the batc h leaching test with MSW leachate was determined following EPA method 160.1. For this, aluminum weighing dishes were placed in an 180 o C dryi ng oven one day before the test. Desiccators were used to cool the dishes. Pre dried dishes were weighed. A total of 100 mL sample was filtered using vacuum filtration. Filtrates were pl aced into an oven at 95 o C for 18 hours to allow the samples to evaporate to dryness. After 18 hours, temperature was increased to 180 o C and continued at least for another 4 hours The di shes are removed from the oven and place d in the desiccators to cool for 30 minutes. The n the dishes were returned to the 180 o C oven for 1 2 hours and weighed. This drying and weighing cycle was repeated until the last two weighings differ by less than 0.5 mg. Dishes were then placed in the desiccators to cool for at least one hour. Then the dish containing the oven dried sample was weighed to the nearest 0.1 m g. TDS was determined using Equation 3 1 ( 3 1 )

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38 3.3.6 Batch Leaching Test with DI Water This test is similar to TCLP/SPLP except DI water was used as the leaching solution. For this batch test 100 grams of PG was mixed with 2 L of DI water in a 2.2 L glass jar. The mixture was agitated using a rotator for 16 to 20 hrs. After tumbling, the slurry was filtered to separate PG leachate from the slurry. Then samples of this PG leachate was retained for the chemical analysis. 3 .4 Total Metal Analysis Samples were digested to prepare them for trace metal analysis. The leaching test samples from various batch tests were digested according to US EPA M ethod 3010. To determine total metal concentration of PG, samples were digested according to the US EPA 30 50B. Digestion procedure was used to prepare aqueous leachate samples that may contain insoluble colloidal particles for analysis by Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICP AES). Leached and digested samples were analyzed using I C P AES as per US EPA SW846 method 6010B. For digestion of aqueous samples nitric acid is added to a specified volume ( 50 mL) to the sample. The sample is refluxed with additional portion of nitric acid until the digestate is clear or the color is stable. Wh en the digestate reduced to a low volume, it is then finally refluxed with hydrochloric acid and brought up to volume. The digested sample is than analyzed by ICP AES For digestion of solid PG 1 gram (dry weight) sample was digested with repeated additio ns of nitric acid (HNO 3 ) and hydrogen peroxide (H 2 O 2 ). For ICP AES analyses, hydrochloric acid (HCl) is added to the final digestate and the sample is refluxed.

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39 3.5 pH of Phosphogypsum The pH values of PG samples were determined by EPA method 9045D. For this 20 grams of PG was mixed with 20 mL of reagent water and stirred continuously for 5 min. Then it was allowed to stand for 1 hour. After that, pH was measured. 3.6 Quality Assurance and Quality Control All sampling equipment and containers were cleane d and prepared according to the US EPA established standards. In the laboratory, analysis blanks, duplicates and calibration check samples were analyzed as appropriate. For total metal analysis every digestion event included (approximately 20 samples) a bl ank sample, a duplicate sample, a triplicate sample, a matrix spike, a matrix spike duplicate for digestion. All regulatory batch leaching test were conducted in triplicate. However for digestion a blank, duplicate sample, a sample spike and a sample spik e duplicate were included.

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40 CHAPTER 4 RESULTS 4.1 Total Metal Analysis Results The chemical composition, which was determined using the US EPA Method 3051b, of the PG samples from ea ch location is shown in Table 4 1. Samples were analyzed for 23 metals (silver, aluminum, arsenic, boron, barium, beryllium, calcium, cadmium, cobalt, chromium, copper, iron, potassium, m agnesium, manganese sodium, nickel, lead, antimony, selenium, tin, vanadium and zinc.) Calcium was the most abundant metal detected in PG and ranges from 113,220 ( 58,100) to 171,200 ( 25,900) mg/kg. The minor constituents of raw PG were Al, Fe and K which each had a concentration that exceeded 100.0 mg/kg. Trace elements, such as As, B, Ba, Cr, Cu, Mn, Pb Sn, V and Zn were also present. Ag, Cd, Co, Mg, Mo, Na, Ni, Sb and Se were not detectable in the samples that were tested. For PG metal analysis, triplicate samples from each location were analyzed. Of the RCRA TC limit metals barium had the highest concentration (38.6 mg/Kg) Concentr ations of other toxic metals (As, Cr, Pb) were below 3 mg/Kg. To use PG beneficially to where direct human contact with the PG is possible comparison with risk based standards is needed. Although risk assessment through direct exposure is not the focus o f this research, it is discussed briefly as it would certainly need to be considered as part of any beneficial use application. Table 4 3 compares the concentration for each metal with its respective s SCTLs examine direct exposure in two scenarios, residential and industrial settings. Of the metals detected in PG, the 95% Upper Confidence Limit ( UCL 95 ) of only one metal (arsenic) was slightly above its SCTL for residential exposure but below the indus trial limit UCL 95 was calculated using

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41 samples from all four locations. In Table 4 1 the average concentrations with standard deviations for each PG sample are presented. Detail ed total analysis results are given in Appendix B 4.2 pH of Phosphogypsum The pH of PG samples used in this study was i n the range of 4.5 4.8 (Table 4 2). One PG sample from each location was tested for pH. The pH of DI water us ed for this experiment was 6.3. Though PG is composed primarily of the slightly soluble neutral s alt, calcium sulfate dihydrate, the acidity may be due to residual phosphoric and sulfuric acids plus hydrofluoric and fluosilicic acids (Smith and Wrench 1984) 4.3 Toxicity Characteristic Leaching Procedure (TCLP) US EPA specifies toxicity characteristic limi ts based on the metal concentrations in the TCLP leachates I f any listed compound (mentioned in Chapter 2) exceeds the level specified the original waste is considered hazardous The TCLP leachates for raw PG were analyzed for trace metals that are on EP ity characteristic elements such as silver, arsenic, barium, cadmium, chromium, lead and selenium. Mercury was not tested in this study. The TCLP was performed on 12 samples (triplicate samples for each of the 4 locations). All the metal c oncentrations in the TCLP leachate analyzed f or each location were well below the respective regulatory levels. TCLP test data are presented in Figures 4 1 through 4 4. Samples whose concentrations are below detection limits are presented in the plots on the MD L (method detection limit) line In general, barium leached at hig her concentrations than chromium. The mean barium concentration of all 12 samples was 0.11 mg/L ( 0.07 0.16 mg/L).

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42 4.4 Synthetic Precipitation Leaching P rocedure (SPLP) The average concentrations (from the four samples; each sample was measured in triplicate) of 2 1 inorganic elements in the extraction fluids from SPLP test were determined. Eleven of th em were detected at concentrations above their respective detection limit As, B, Be, Cd, Co, Pb, Sb, Sn, Sr, V were not detected in SPLP. SPLP results were compared with Groundwater Cleanup Target Levels (GWCTL). Most of the metals were well below GWCTL ex cept for aluminum and iron. Aluminum concentration is greater than the GWCTL for all the samples. Iron concentration is greater than GWCTL for six samples out of twelve. Even though aluminum and iron are the secondary standards, these results may be questi oned by a regulatory agency when PG is considered for use in land application. SPLP results are presented in Figures 4 5 through 4 13 and detailed data are given in Appendix C Figures 4 1 4 and 4 15 show the i LP t est and SP LP test, respectively. The final pH in the SPLP test was consistently lower than the TCLP te st in terms of final pH. Figure 4 1 5 in the SPLP sample. 4.5 Extraction Procedure Toxicity EPTOX was conducted on PG samples of one location (SW) in triplicate and of the 22 metals analyzed aluminum, barium, calcium, chromium, copper, iron, potassium, magnesium, nickel, strontium and zinc were detected. Final pHs of extraction fluids were greater t han SPLP b ut close to TCLP test (Table 4 4 ). The TCLP extracted slightly higher concentrations of all the metals than EPTOX except copper, nickel and zinc. Both tests use acetic acid as leaching solution but they have different pH. EPTOX

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43 re sults are presented in Figures 4 16 through 4 20 and detailed data are given in Appendix E 4.6 USEPA Multiple Extraction Procedure The MEP is used to ass ess long term leachability of waste by combining aspects from both the TCLP and the SPLP The method requires sequential extraction of the same waste. With each subsequent extraction, it is usually expected that leaching con centrations will be decreased with time as there are less contaminants available for leaching. As samples from all the locations showed similar leaching concentrations, the MEP was conducted on samples from only one location (SW) in triplicate. Of the 2 1 m etals analyzed only aluminum, barium, beryllium calcium, chromium, copper, potassium, magnesium, nickel, strontium and zinc were detected above their respective detection limit. The barium copper, magnesium and potassium results are typical of most sequen tial leaching tests, with the concentrations decreasing with consecutive extractions. However, for other detected metals, an increase in concentration is observed in the second extraction compared to the first extraction. This may be due to the change in p H (Table 4 5) After the initial increase the metal concentration stabilized and began to decreas e with subsequent extractions. Results are presented in Figures 4 21 through 4 26 4.7 Additional Leaching T esting 4.7.1 The Deionized Water Batch L eaching Test Batch leaching test with DI water was conducted on samples of all four locations in duplicate (Figures 4 27 through 4 31 Table 4 6 ) Calcium, which was predominant, leached more in DI leachate than SPLP. Average c alcium concentration in SPLP leachat e is 656 mg/L and 808 mg/L in DI water leachate. Of the 22 metals analyzed

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44 only aluminum, barium, calcium, copper, potassium, molybdenum, sodium, nickel, strontium and zinc were detected above their respective detection limit. Iron, which was detected both in SPLP and TCLP test, was below its detection limit when leached with DI water. Barium concentration was also higher in both TCLP and SPLP than DI water leaching test. Again, copper concentrations leached by DI water were higher than both SPLP and TCLP. Other than these metals, when PG samples were leached with DI water; extracted c oncentrations were somewhat similar to the SPLP. 4.7.2 Batch Leaching Test with MSW Leachate F igures 4 32 through 4 40 present the results of the leaching tests where MSW leach ates were used as the extraction fluids. Table 4 7 present s the result of the final pH of MSW leaching solutions. This leaching test was carried out on samples of all four locations in triplicate. Samples were analyzed for 2 2 metals. O nly a ntimony copper, selenium and tin were below their respective detection limit. Concentrations of most cation s in the MSW leaching solution were similar to those in the MSW leachate except calcium iron and strontium While iron concentration decreased after contacting with leachate, strontium concentration increased. Calcium concentrations in MSW leaching solution were up to one order of magnitude greater than those in the MSW leachate Concentrations of sulfate and TDS in the MSW leachate were compared to those in the original M SW leaching solutions (Figure 4 41 and 4 42 ). Sulfate concentrations in the leachate ranged from 3,000 3,250 mg/L. These sulfate concentrations are 15 times greater than those in original MSW leachate. TDS measured in the leaching solutions ranged from 9,350 9,500 mg/L. TDS concentration in the original MSW leachate was about 6,300 mg/L.

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45 Ta ble 4 1 Metal concentrations (mg/kg) of PG samples Element Detected Sample ID Mean SD (mg/Kg) NW SW EW WW Ag BDL a BDL BDL BDL Al 87577 b 73856 62556 78555 As 1 9 0. 9 1.90. 7 2.11. 0 1.7 0.9 B 6018 5 7 10 222.1 5516 Ba 48.06.4 30. 8 2 0 33. 4 7. 2 42.26.6 Be BDL BDL BDL BDL Ca 171 20 0 25 9 00 138 3 00 13 ,100 147 ,600 36 5 00 113 ,200 58 ,100 Cd BDL BDL BDL BDL Co BDL BDL BDL BDL Cr 1.90. 4 1. 6 0.3 1.50.5 1.30.5 Cu 2 0 0. 8 1.90.7 1.90.6 1.90.5 Fe 90365 932130 615133 71794 K 126 24 18 7 31 1405 17529 Mg BDL BDL BDL BDL Mn 2.00. 1 4.20.4 2.80.7 1.70. 6 Mo BDL BDL BDL BDL Na BDL BDL BDL BDL Ni BDL BDL BDL BDL Pb 3.10.6 3.50. 9 2.80.4 2.70.6 Sb BDL BDL BDL BDL Se BDL BDL BDL BDL Sn 6.30. 8 3.81. 1 4. 0 1.0 3.90.4 V 1.60.6 2.30 .6 1.20.1 1.30.3 Zn 4.20.9 4.70. 8 3.10.5 5.30.9 a BDL = B elow detection limit (d etection limits are presented in Appendix A) b arithmetic mean standard deviation of three replicates Table 4 2 pH of P G samples Sample Location pH North Wall 4.5 South Wall 4.7 East Wall 4.7 West Wall 4.8

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46 Table 4 3 Total metal comparison with risk based standards for direct e xposure Metal Mean Concentration SD (mg/Kg) UCL 95 (mg/Kg) Florida SCTL Residential (mg/Kg) Industrial (mg/Kg) Al 756 108 a 817 80000 NA As 1.9 0.8 2.37 2.1 12 B 48.5 19.8 59.7 17000 430000 Ba 38.6 8.8 43.6 120 130000 Ca 142590 29550 159296 NA NA Cr 1.6 0.4 1.82 210 470 Cu 1.9 0.6 2.28 150 89000 Fe 792 166 886 53000 NA K 157 33.4 176 NA NA Mn 2.7 1.1 3.31 3500 43000 Pb 3.0 0.7 3.4 400 1400 Sn 4.5 1.3 5.26 47000 880000 V 1.6 0.6 1.93 67 10000 Zn 4.3 1.1 4.95 26000 630000 a arithmetic mean standard deviation of all (12) samples Table 4 4. pH r esults (Extraction Procedure Toxicity Test) Sample ID pH SW 1 4.71 SW 2 4.69 SW 3 4.72 DI Water 7.20 Table 4 5. pH r esults (Multiple Extract ion Procedure Test ) Extraction Number pH 1 4.71 2 3.39 3 3.44 4 3.40 5 3.26 6 3.34 7 3.34 8 3.30 9 3.15

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47 Table 4 6 pH results (Batch leaching test with DI w ater) Sample ID pH North Wall (NW) 4.53 South Wall (SW) 4.72 East Wall (EW) 4.92 West Wall (WW) 4.78 DI Water 7.4 Table 4 7. pH r esults ( Batch l eaching t est with MSW l eachate ) Sample ID pH North Wall (NW) 7.40 South Wall (SW) 7.40 East Wall (EW) 7.60 West Wall (WW) 7.60 MSW Leachate 7.70

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48 Figure 4 1 Silver (Ag) and Arsenic (As) concentrations of PG samples in TCLP t est

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49 Figure 4 2 Barium (Ba) and Cadmium (Cd) concentrations of PG samples in TCLP t est

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50 Figure 4 3 Chromium (Cr ) and Lead (Pb) concentrations of PG samples in TCLP t est

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51 Figure 4 4 Selenium ( S e) concentration of PG samples in TCLP t est

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52 Figure 4 5 Silver (Ag) and Aluminum (Al) concentrations of PG samples in SPLP t est

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53 Figure 4 6 Arsenic (As) and Boron (B) concentrations of PG samples in SPLP t est

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54 Figure 4 7 Beryllium ( Be ) and Cadmium ( Cd ) concentrations of PG samples in SPLP t est

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55 Figure 4 8 Chromium (Cr) and Copper (Cu) concentrations of PG samples in SPLP t est

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56 Figure 4 9 Iron (Fe) and Pota ssium (K) concentrations of PG s amples in SPLP t est

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57 Figure 4 1 0 Sodium (Na) and Nickel (Ni) c oncen trations of PG samples in SPLP t est

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58 Figure 4 11 Lead (Pb) and Antimony (Sb) concentrations of PG samples in SPLP t est

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59 Figure 4 12 Tin (Sn) and Strontium (Sr) concentrations of PG s amples in SPLP t est

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60 Figure 4 13 Vanadium ( V ) and Zinc ( Zn ) concentrations of PG samples in SPLP t est

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61 Figure 4 14 Toxicity Cha racteristic Leaching Procedure initial and f inal pH Figure 4 15 Synthetic Pr ecipitation Leaching Procedure initial and f inal pH 4.6 4.7 4.8 4.9 5 NW SW EW WW pH Sample Location Final Initial 3.8 4 4.2 4.4 4.6 4.8 NW SW EW WW pH Sample Location Initial Final

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62 Figure 4 16 Aluminum (Al) and Barium (Ba) c oncentrations of PG s ample s (south wall) in EPTOX t est

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63 Figure 4 17 Calcium (Ca) and Chromium (Cr) concentrations of PG s ample s (south wall) in EPTOX t est

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64 Figure 4 18 Copper (Cu) and Po tassium (K) concentrations of PG s ample s (south wall) in EPTOX t est

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65 Figure 4 19 Magnesium ( Mg ) and Nickel (Ni) concentrations of PG samples (south wall) in EPTOX t est

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66 Figure 4 20 Strontium (Sr) and Zinc (Zn ) concentrations of PG s amples (s o uth wall) in EPTOX t est

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67 Figure 4 21 Aluminum (Al) and Barium (Ba) l eachability in US MEP

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68 Figure 4 22 Beryllium (Be) and Calcium (C a) l

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69 Figure 4 23 Chromi um (Cr ) and Copper (Cu ) l eachability

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70 Figure 4 24 Potassium (K) and Magnesium (Mg ) l eachability

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71 Figure 4 25 Nickel (Ni) and Strontium (Sr ) l

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72 Figure 4 2 6 Zinc ( Zn ) l eachability

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73 Figure 4 27 Aluminum (A l) and Barium (Ba) c oncentration s in DI w ater b atch leaching t est

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74 Figure 4 28 Calcium (Ca) and Copper (Cu) c oncentration s in DI water batch leaching t est

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75 Figure 4 29 Potassium (K) and Sodium (Na) c oncentration s in DI water batch leaching t est

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76 Figure 4 30 Nickel (Ni) and Strontium (Sr ) c oncentration s in DI water batch leaching t est

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77 Figure 4 31 Zinc (Zn) c oncentration in DI water batch leaching t est

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78 Figure 4 32 Aluminum (A l) and Arsenic (As) c oncentration s in MSW l eachate batch leaching t est

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79 Figure 4 33 Boron (B) and Barium (Ba) c oncentration s in MSW l eachate batch leaching t est

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80 Figure 4 34 Calcium (Ca ) and Cobalt ( Co ) c oncentration s in MSW l eachate batch leaching t est

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81 Figure 4 35 Chromium (Cr) and Copp er ( Cu ) c oncentration s in MSW l eachate batch leaching t est

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82 Figure 4 36 Iron (Fe) and Potassium (K) c oncentration s in MSW leachate batch leaching t est

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83 Figure 4 37 Mag nesium (Mg) and Manganese (Mn) c oncentration s in MSW leachate batch leaching t est

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84 Figure 4 38 Sodium (Na) and Nickel (Ni) c oncentration s in MSW leachate batch leaching t est

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85 Figure 4 39 An timony (Sb) and Strontium (Sr) c oncentration s in MSW leachate batch leaching t est

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86 Figure 4 40 Vanadiu m (V) and Zinc (Zn) c oncentration s in MSW l eachate batch leaching t est

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87 Figure 4 41 Sulfate concentration results of batch test with MSW leachate Figure 4 42 TDS results of batch t est with MSW l eachate

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88 CHAPTER 5 DISCUSSION 5.1 Comparison to Previous Studies TCLP results found in the previous studies are presented in Table 5 1 In the present study only barium and chromium were detected above detection limits in TCLP, and both were b e low their respective TC limits. Concentrations of these toxic metals were found below their TC limits in previous studies as well. Mercury was not analyzed in this study; Kendron (1996) reported mercury concentration in TCLP leaching solution from PG below its toxicity limit. Al Masri et al. (2004) conducted leaching of PG (Syrian) using DI water as a first step of sequential leaching test. In their study they used 1 g PG and 100ml DI water for leaching (L/S ratio of 100:1). The results of the current DI wa ter leaching test are compared with the results obtained in the 2004 s tu dy for Cd, Zn and U in Table 5 2 .Though Cd was not detected in this study, Zn was leached at a much higher concentration than the previous study. This may be due to the high L/S ratio (20:1) used for this study. The bioavailability and mobility of trace metals (As, Cd, Cr, Cu, U, Zn) were estimated by Al Hwaiti et al ( 2010) using aqua regia leaching solution Res ults are presented in Table 5 3 .They used 50 mg of dried PG and 5 ml of ni tric acid and hydrochloric acid (aqua regia) and rotated for 48 hours. All the metals tested leached below 10% (fraction leached) but the concentrations of all the metals were above detection limits. In comparison to that study, SPLP performed in this stud y leached a higher percentage of Cr, Cu and Zn. Metal concentrations of PG is compared wi th gypsum wallboard in Table 5 4 Relative to gypsum wallboard, PG was elevated in total content of Al, As, Ba and K.

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89 5.2 Discussion of Leaching Results Arsenic was de tected above SCTL in total metal analysis. But it was not detected in any of the leaching tests. When metal concentrations extracted by the SPLP are compared to those of the TCLP, calcium was leached to a greater extent in the TCLP than in the SPLP ; silver arsenic, boron, cadmium, cobalt, magnesium, lead, antimony, tin and vanadium were not d etected in either test. Barium, chromium, iron and s trontium concentrations in the TCLP leachate were higher than the SPLP leachate, but relatively similar Only sodiu m was dramatically greater in the TCLP compared to the SPLP, but this was because sodium is used in the TCLP solution. The TCLP and SPLP extracted statistically similar concentrations of aluminum, copper, potassium, nickel and zinc. Comparisons of TCLP and SPLP for other wastes have found that TCLP typically extracts more metals than SPLP because of the buffered pH of the TCLP and the ability of acetic acid to complex heavy metals. The degree of complexation differs depending on the metal. Differences in me tal leachability between TCLP and SPLP could be result from several other factors. The initial pH of the SPLP solution (4.2) is less than the initial pH of the TCLP solution (4.9). Also changes in the solution pH that occur during the 18 h our of leaching m ay differ between SPLP and TCLP, and thus result in different amounts of metal leaching. In the case of PG, the pH difference between the two tests was not very pronounced. The difference in metal concentrations between SPLP and TCLP for PG are relatively small. Figures 5 1 through 5 4 c ompare the ave rage leachate concentrations using SPLP, TCLP, DI and EPTOX for aluminum, barium, chromium and calcium. For aluminum, all the tests leached similar concentrations and all of them were above GWCTL. Barium was be low TC limit for all the tests and TCLP leached barium greater

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90 than SPLP and EPTOX. While MSW leaching solution leached calcium more than TCLP, EPTOX and DI showed similar concentrations of calcium. When the PG samples were leached with DI water, extracted c oncentrations were relatively sim ilar to the SPLP except calcium DI water leached more calcium than SPLP. The pH of DI water used for this test was greater than the TCLP and SPLP extraction solutions. The pH is known as a major controllin g factor for me tal leachability (Van der Sloot et al. 2001; Townsend, et al. 2004) The solubility of some metals increased under extreme pH but this may not be applicable for all. For some metals the change in pH had no effect (Tolaymat et al. 2008; Chuan et al. 1996) For some wastes like wood, tire ash and wood ash, calcium, potassium and sodium concentrations were controlled by solubility rather than pH (Tolaymat et al. 2008 ).This may be the case for PG also. The fact that most of the metals (except calcium) leached l ess in the MSW landfill leachate relative to TCLP and SPLP is likely a result of the higher pH Average pH of leaching solution after 18 hours of agitation was 7.5 and initial pH of MSW leachate was 7.7 (Table 4 7 ). MSW leachate also leached considerable amount of sulfate from PG. Under anaerobic land fill conditions, sulfate reducing bacteria produce hydrogen sulfide (H 2 S) from the sulfate (SO 4 2 ) in gypsum and the organic carbo n in waste material: SO 4 2 + 2CH 2 O -> 2HCO 3 1 + H 2 S Here a simple hydrocarbon is used as a surrogate for organic wastes. This may cause odor issues and possible health problems for workers. For MEP some metals showed an increase in concentration in the second extraction from the first ext raction. As a reminder, the first extraction of the MEP was

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91 performed using EPTOX extraction fluid (at a pH of 5.0). The subsequent extractions we re performed using a pH 3 synthetic r ainwater solution. After first extraction, average pH of leaching solutio ns was 4.71 (after 20:1 dilution) and after second extraction, the pH decreased to 3.39. Studies have demonstrated that as pH decreases, metal desorption increases; thus, metals are more soluble under acidic conditions, which could be attributed to the ten dency of metals to form soluble metal oxides in acidic environments After second extraction metal concentrations decreased with subsequent extractions as there are less contaminant available for leaching. 5 .3 Assessing Potential for Beneficial Reuse The r esearch presented here provides helpful information for making preliminary assessments for phosphogypsum uses Of all the trace elements analyzed in total metal analysis test, only arsenic (UCL 95 ) was found to exceed its respective SCTL value (residential exposure). Following typical risk assessment procedu res for the s tate of Florida, this suggests that PG cannot be land applied in a setting where direct human exposure might occur. When the SCTLs ar e utilized to assess risk from land application of a waste the waste materials are assumed to be present in a manner where they replace the soil. In the case of an amendment such as PG, the waste is mixed with soil and the concentration of chemicals that an individual is exposed to is not only a function of the PG composition, but also of the background soil concentration and the rate of application (Tolaymat et al. 2008) Also PG can be used in conjunction with other materials such as coal ash for soil amendment (Lee et al 2008 ). F u r ther study with mixed materi als may explore beneficial use options. One important factor in the use of phosphogypsum on agricultural lands is the possibility of radioactive element uptake by plants. Mays and Mortvedt (1986) applied phosphogypsum containing 25 pCi g 1 226 Ra

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92 at rates u p to 112 Mg ha 1 to the surface of a silt loam soil and grew successive crops of corn, wheat, and soybean. Applicat ion of phosphogypsum at a rate of 112 Mg ha 1 had no effect on the radioactivity levels in grain of corn, wheat, or soybeans. Analyses of soi l after soybean harvest showed that the level of radioactivity in the surface 15 cm layer increased from 35 Bq kg 1 to 73 Bq kg 1 at 112Mg ha 1 PG rate; the radioactivity level in the subsurface layer was not affected. The 112 Mg ha 1 rate was more than 200 times the normal rate of gypsum used for peanut fertilization. Additionally, they noted no increases in grain Cd levels, but at the highest rate they found that corn growth slowed. They speculated that the slower growth was due to an imbalance of Ca and M g. PG leached Al and Fe above GWCTL in SPLP, therefore can not be reuse d in Florida for land application however, Al and Fe are secondary standards, and the other leaching tests showed low leachability of heavy metals, so beneficial use possibilities may e xist under different regulatory scenarios. In fact PG can be used to alleviate AI toxicity (In soil solutions containing abundant SO 4 2 and F AI that is not complexed with either of the ligands ) from acid soil due to its precipitation and complexation reactions with SO 4 2 and F The reduction of Al toxicity in the subsoil by PG is a result of complex set of mechanisms, including precipitation of aluminum as the result of liberation of OH ions from oxidic surf aces by ligand exchange with SO 4 2 formation of insoluble basic Al sulfates, formation of complexes of Al with F (AlF 2+ AlF + 2 and AlF 3 ). which are less toxic than the uncomplexed forms of Al ( Carvalho and Raij 1997, Alva and Sumner 1991 ). From the leachin g tests (TCLP, EPTOX, MSW leaching) it can be said that none of the toxic metals that were tested in this study leached above TC limits. One potential beneficial use of PG is its utilization as part of MSW landfill construction and

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93 maintenance activities. Other possibilities are using PG as daily and intermediate landfill cover and landfill foundation. At new landfill sites, compacted PG may be used as a substitute for the large volume of soil required to be placed under the liner to provide necessary grade s. When MSW leachate contacts with PG, a few constituents of PG such as calcium and sulfate, may be considerably leached out. PG samples released considerable amount of calcium in all the leaching tests. Increased calcium concentration in MSW leachate may enhance scaling in the leachate collection and removal system. Sulfate also was considered as an easily mobile constituent from PG to MSW leachate. Increasing sulfate in MSW leachate may be a concern in terms of odor issues. On the other hand, i n an anaero bic environment of landfill, PG could enhance biodegradation of municipal solid waste (MSW) in the landfill. Since PG is enriched with sulfate, it is reasonable to assume that a sulfate using bacterial colony present in landfills will use phosphogypsum as an energy source after oxygen is depleted. So use of phosphogypsum as landfill cover could enhance biological decomposition of MSW. However, if PG is utilized as a base material under a landfill bottom liner, these issues may not be concerns because the co ntact of PG with MSW leachate would be prevented by the landfill liner. However use of PG, in applications where it is in contact with the MSW (either as cover material or as a direct amendment), needs to balance the potential benefits (less soil usage, gr eater stabilization) with the potential deleterious impacts (odors, impact on biogas collection and conversion systems). Exploration of these uses was not the main focus of this study But results of this study can be used for the feasibility study.

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94 5 .4 Li mitations and Recommendations In this study, leachability characterization of PG was conducted using only batch leaching test. For better understanding of PG leachability, dynamic leaching test and other batch leaching test using different pH solutions and solid liquid ratios could help evaluate how several test variables can affect leaching behavior of PG Also leachability studies could be conducted on PG along with other materials to see how they affect leachability characteristics of PG.

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95 Table 5 1. TCLP results found in the previous studies Element Regulatory limit (mg/L) FIPR 1995 (Kendron) (mg/L) FIPR, 2005 (Rusch & Seals) (mg/L) In this study (mg/L) As 5.0 0.882 N D a <0.002 Ba 100 0.17 ND 0.16 0.07 Cd 1.0 0.01 ND <0.001 Cr 5.0 0.05 0.04 0.02 Pb 5.0 0.1 ND <0.003 Ag 5.0 0.05 <0.005 Hg 0.2 0.005 Se 1.0 0.1 ND <0.004 a ND = Not detected Table 5 2 Comparisons of DI w a ter leaching t est Element % Fraction l eached a % Fraction l eached b Cr 10 BDL c U 20 -Zn 58 82 a Al Masri et al. (2004) b In this study c BDL = B elow detection limit (d etection limits are presented in Appendix A) Table 5 3 Compariso n of SPLP with previous leaching studies Element % Fraction l eached a % Fraction l eached b ( SPLP ) As 3 BDL c Cd 1 BDL Cr 5 15 Cu 9 21 U 4 -Zn 3 51 a Al Hwaiti et al. (2010 ) b I n this study c BDL = B elow detection limit (Detection limits are presented in Appendix A )

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96 Table 5 4 Compariso n of t race metal concentrations (mg/kg) Element Gypsum Wallboard a Phosphogypsum b Al 295 756 As -1.9 B 42.5 48.5 Ba -38.5 Ca 169360 142590 Cd 3.1 BDL c Co 9.2 BDL Cr 11.6 1.6 Cu 7.1 1.9 Fe 942 792 K -157 Mg 8475 BDL Mo 2.7 -Mn 45.6 2.7 Ni 20.1 BDL S 133821 -Pb 15.6 3 Se -BDL Zn 16.6 4.3 a R. P. Wolkowski ( 2000 ) b In this study c BDL = below detection limit

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97 Figure 5 1 Aluminum (Al) concentrations in different batch leaching tests Figure 5 2 Barium (Ba) concentrations in different batch leaching tests

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98 Figure 5 3 Chromium (Cr) concentrations in different batch leaching tests Figure 5 4 Calcium (Ca) concentrations in different batch leaching tests

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99 CHAPTER 6 CONCLUSION produces approximately 40 million tons of waste material per year (Burnett et al. 1996) The total and leachable concentrations in PG were characterized for a number of met als These data were then used to examine a variety of issues associated with determining whether the PG could be beneficially used outside of a landfill (e.g., land application as fill material, soil amendment). Metal release was assessed using standardiz ed batch leaching tests and additiona l leaching experiments using specific leaching solutions. To identify potential chemicals of concern, the concentrations of pollutant s in the samples were compared with the risk based standards. Based on the TCLP test, n one of the TCLP results exceeded the regulatory toxicity limits showing PG samples did not meet the definition of EP A Toxicity Characteristic under RCRA (40 CFR Part 261 .30 ). Note that Mercury and radionuclide were not tested in this study. However, in th e SPLP tests aluminum and iron exceeded their respective Florida gr oundwater cleanup target levels. When MSW leachate contacts with PG, a few constituents of PG such as calcium and sulfate, may be considerably leached Increasing sulfate in MSW leachate ma y be a concern in terms of increased hydrogen sulfide generation; hydrogen sulfide carries concerns of odor and potential deleterious health effects to those exposed PG samples released considerable amou n ts of calcium in the TCLP, SPLP, EPTOX and in the leaching test with MSW leachate and DI water The TCLP and the SPLP extracted relatively similar metal concentrations (except calcium) Although arsenic was detected at high concentrations in the PG totals

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100 analysis, it did not leach at concentr ations that may pose a risk to human health and the environment in all the leaching tests. In terms of risk assessment, from a direct human exposure pathway, arsenic was found to be the most limiting element. The SPLP results did not find arsenic to pose a risk, but has aluminum and iron concentrations above GWCTL It is important to examine potential impacts of PG management to the groundwater because in Florida, over 90% of residents rely on groundwater for a potable water source. Also the results of this study can assist in the consideration of land application of PG.

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101 APPENDIX A ICP AES DETECTION LIMITS Table A 1 Method Detection Limits Element MDL(mg/L) Ag 0.005 Al 0.025 As 0.002 B 0.009 Ba 0.002 Be 0.001 Ca 0.07 Cd 0.001 Co 0.001 Cr 0.002 Cu 0.002 Fe 0.06 K 0.06 Mg 0.02 Mn 0.002 Mo 0.004 Na 0.44 Ni 0.002 Pb 0.003 Sb 0.006 Se 0.004 Sn 0.006 Sr 0.002 V 0.002 Zn 0.003

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102 APPENDIX B TOTAL METAL ANALYSIS DATA Table B 1. Total metal analysis r esult s of PG s amples c ollected from north w all (mg/Kg) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 955 869 801 As 1.01 2.79 2.06 B 76.66 63.87 40.79 Ba 51.88 51.56 40.59 Be BDL BDL BDL Ca 179439 191994 142179 Cd BDL BDL BDL Co BDL BDL BDL Cr 1.89 2.28 1.56 Cu 2.18 2.67 1.12 Fe 938 944 828 K 114 153 110 Mg BDL BDL BDL Mn 2.15 2.04 1.95 Na BDL BDL BDL Ni BDL BDL BDL Pb 2.66 2.86 3.87 Sb BDL BDL BDL Se BDL BDL BDL Sn 5.47 7.06 6.31 V 1.44 1.00 2.24 Zn 4.17 5.19 3.37 a BDL = B elow detection l imit

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103 Table B 2. Total metal analysis r esult s of PG samples c ollected from s outh w all (mg/Kg) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 736 683 795 As 1.19 2.07 2.54 B 46.01 58.57 65.78 Ba 32.31 28.63 31.31 Be BDL BDL BDL Ca 152259 126366 136369 Cd BDL BDL BDL Co BDL BDL BDL Cr 1.74 1.2 1.84 Cu 1.47 1.53 2.78 Fe 807 1067 924 K 204 151 206 Mg BDL BDL BDL Mn 3.77 4.56 4.20 Na BDL BDL BDL Ni BDL BDL BDL Pb 3.94 4.14 2.54 Sb BDL BDL BDL Se BDL BDL BDL Sn 3.20 3.21 5.16 V 2.72 1.64 2.62 Zn 5.29 3.78 4.93 a BDL = B elow detection l imit

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104 Table B 3. Total metal analysis r esult s of PG samples c ollected from east w all (mg/Kg) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 683 619 571 As 3.24 1.21 1.93 B 23.93 20.84 19.94 Ba 41.74 29.91 28.61 Be BDL BDL BDL Ca 182803 150123 109868 Cd BDL BDL BDL Co BDL BDL BDL Cr 2.01 1.11 1.26 Cu 2.56 1.36 1.86 Fe 762 580 502 K 140 145 135 Mg BDL BDL BDL Mn 3.67 2.3 2.56 Na BDL BDL BDL Ni BDL BDL BDL Pb 3.05 2.94 2.26 Sb BDL BDL BDL Se BDL BDL BDL Sn 4.64 4.67 2.84 V 1.14 1.14 1.30 Zn 3.65 2.72 2.78 a BDL = B elow detection l imit

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105 Table B 4. Total metal analysis r esult s of PG samples c ollected f rom west w all (mg/Kg) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 788 838 728 As 2.80 1.38 1.00 B 70.95 55.5 39 Ba 43.10 48.26 35.16 Be BDL BDL BDL Ca 107139 118809 113622 Cd BDL BDL BDL Co BDL BDL BDL Cr 1.31 0.9 1.86 Cu 2.58 1.71 1.65 Fe 808 620 725 K 170 206 149 Mg BDL BDL BDL Mn 2.41 1.35 1.46 Na BDL BDL BDL Ni BDL BDL BDL Pb 3.14 1.99 2.96 Sb BDL BDL BDL Se BDL BDL BDL Sn 4.19 4.08 3.53 V 1.62 1.19 1.04 Zn 4.3 5.45 6.25 a BDL = Below detection l imit

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106 APPENDIX C TOXICITY CHARACTERISTIC LEACHING PROCEDURE DATA Table C 1. TCLP test r esult s of the s amples c ollected from north w all (mg/L) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 1.81 1.66 1.71 As BDL BDL BDL B BDL BDL BDL Ba 0.14 0.11 0.09 Ca 956 887 889 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.03 0.03 0.03 Cu 0.02 0.01 0.02 Fe 0.38 0.58 0.51 K 1.16 1.71 1.64 Mn BDL BDL BDL Na 1559 1399 1465 Ni 0.07 0.04 0.03 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 3.37 3.08 2.96 V BDL BDL BDL Zn 0.29 0.18 0.08 a BDL = Below detection l imit

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107 Table C 2. TCLP test r esult s of the samples collected from south w all (mg/L) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 1.96 2.18 1.73 As BDL BDL BDL B BDL BDL BDL Ba 0.09 0.1 0.07 Ca 945 1030 892 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.03 0.04 0.03 Cu 0.03 0.02 0.02 Fe 0.34 0.56 0.39 K 4.04 4.37 4.88 Mn BDL BDL BDL Na 1512 1661 1435 Ni 0.03 0.04 0.02 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 3.02 3.27 2.82 V BDL BDL BDL Zn 0.15 0.12 0.08 a BDL = Below detection l imit

PAGE 108

108 Table C 3. TCLP test r esult s of the samples collected from east w all (mg/L) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 1.73 1.69 1.75 As BDL BDL BDL B BDL BDL BDL Ba 0.12 0.12 0.09 Ca 948 971 914 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.03 0.02 0.02 Cu 0.03 0.06 0.02 Fe 0.57 0.52 0.56 K 1.42 1.95 1.83 Mn BDL BDL BDL Na 1500 1552 1445 Ni 0.02 0.02 0.02 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 3.2 3.25 3.01 V BDL BDL BDL Zn 0.17 0.15 0.05 a BDL = Below detection l imit

PAGE 109

109 Table C 4 TCLP test r esult s of the s amples collected from west w all (mg/L) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 1.9 2.13 2.08 As BDL BDL BDL B BDL BDL BDL Ba 0.12 0.16 0.09 Ca 953 1003 990 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.03 0.04 0.04 Cu 0.03 0.02 0.02 Fe 0.54 0.36 0.32 K 1.81 1.09 1.92 Mn BDL BDL BDL Na 1480 1571 1576 Ni 0.03 0.01 0.03 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 3.05 3.17 3.14 V BDL BDL BDL Zn 0.1 0.26 0.1 a BDL = Below detection l imit

PAGE 110

110 APPENDIX D SYNTHETIC PRECIPITATION LEACHING PROCEDURE (SPLP) DATA Table D 1. SPLP test r esult s of the s amples c ollected from north w all ( mg /L) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL* BDL Al 2.12 1.79 1.81 As BDL BDL BDL B BDL BDL BDL Ba 0.09 0.07 0.08 Be BDL BDL BDL Ca 697 632 639 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.01 0.01 0.02 Cu 0.02 0.01 0.02 Fe 0.38 0.46 0.41 K 1.41 1.37 1.34 Na 9.25 7.53 8.66 Ni 0.02 0.03 0.04 Pb BDL BDL BDL Sb BDL BDL BDL Sn BDL BDL BDL Sr 2.41 2.4 2.42 V BDL BDL BDL Zn 0.08 0.1 0.13 a BDL = Below Detection Limit

PAGE 111

111 Table D 2. SPLP test r esult s of the samples c ollected from s outh w all (mg/L) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL* BDL Al 2.12 1.72 1.79 As BDL BDL BDL B BDL BDL BDL Ba 0.06 0.05 0.06 Be BDL BDL BDL Ca 676 521 602 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.02 0.01 0.01 Cu 0.02 0.03 0.06 Fe 0.3 0.18 0.22 K 3.3 2.26 2.51 Na 10.08 7.84 8.02 Ni 0.01 0.04 0.03 Pb BDL BDL BDL Sb BDL BDL BDL Sn BDL BDL BDL Sr 2.25 1.7 1.98 V BDL BDL BDL Zn 0.08 0.09 0.11 a BDL = Below detection l imit

PAGE 112

112 Table D 3. SPLP test r esult s of the s amples c ollected from east w all (mg/L) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 1.67 1.55 1.5 As BDL BDL BDL B BDL BDL BDL Ba 0.13 0.1 0.08 Be BDL BDL BDL Ca 675 637 628 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.01 0.01 0.01 Cu 0.01 0.01 0.01 Fe 0.45 0.31 0.27 K 1.43 1.29 1.38 Na 9.75 8.31 8.98 Ni 0.04 0.02 0.01 Pb BDL BDL BDL Sb BDL BDL BDL Sn BDL BDL BDL Sr 2.42 2.28 2.22 V BDL BDL BDL Zn 0.21 0.14 0.1 a BDL = Below detection l imit

PAGE 113

113 Table D 4. SPLP test r esult s of the s amples collected from west w all (mg/L) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 1.49 1.67 2.64 As BDL BDL BDL B BDL BDL BDL Ba 0.06 0.06 0.07 Be BDL BDL BDL Ca 593 617 644 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.01 0.01 0.01 Cu 0.02 0.02 0.02 Fe 0.39 0.17 0.22 K 1.19 1.25 1.75 Na 7.22 7.12 10.11 Ni 0.01 0.01 0.02 Pb BDL BDL BDL Sb BDL BDL BDL Sn BDL BDL BDL Sr 2.03 2.17 2.18 V BDL BDL BDL Zn 0.07 0.08 0.14 a BDL = Below detection l imit

PAGE 114

114 APPENDIX E E X TRACTION PROCEDURE TOXICITY TEST DATA Table E 1 EPTOX test r esult s of the samples collected from s outh w all (mg/L) Element Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 1.83 1.73 1.80 As BDL BDL BDL B BDL BDL BDL Ba 0.06 0.05 0.05 Be BDL BDL BDL Ca 752 743 739 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.04 0.04 0.04 Cu 0.19 0.12 0.12 Fe BDL BDL BDL K 3.46 3.12 2.67 Mg 0.71 0.77 0.78 Mn BDL BDL BDL Ni 0.06 0.06 0.05 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 2.34 2.30 2.35 V BDL BDL BDL Zn 0.26 0.21 0.17 a BDL = Below detection l imit

PAGE 115

115 APPENDIX F MUTIPLE EXTRACTION PROCEDURE TEST DATA Table F 1. MEP test r esult s of the samples collected from south wall (e xtraction 1) (mg/L) Cation Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 1.83 1.73 1.80 As BDL BDL BDL B BDL BDL BDL Ba 0.06 0.05 0.05 Be BDL BDL BDL Ca 752 743 739 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.04 0.04 0.04 Cu 0.19 0.12 0.12 Fe BDL BDL BDL K 3.46 3.12 2.67 Mg 0.71 0.77 0.78 Mn BDL BDL BDL Ni 0.06 0.06 0.05 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 2.34 2.30 2.35 V BDL BDL BDL Zn 0.26 0.21 0.17 a BDL = Below detection l imit

PAGE 116

116 Table F 2 MEP test results of the samples collected from south wall (extraction 2 ) (mg/L) Cation Sample 1 Sample 2 Sample 3 Ag BDL BDL BDL Al 2.97 2.81 2.90 As BDL BDL BDL B BDL BDL BDL Ba 0.05 0.05 0.05 Be 0.47 0.46 0.46 Ca 813 801 801 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.06 0.05 0.05 Cu 0.11 0.11 0.10 Fe BDL BDL BDL K 2.16 2.87 1.12 Mg 0.75 0.53 0.78 Mn BDL BDL BDL Ni 0.09 0. 0 9 0. 0 9 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 2.39 2.47 2.41 V BDL BDL BDL Zn 0.49 0.41 0.35 *BDL = Below Detection Limit

PAGE 117

117 Table F 3. MEP test results of the samples collected from south wall (extraction 3 ) (mg/L) Cation Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 2.87 2.75 2.67 As BDL BDL BDL B BDL BDL BDL Ba 0.04 0.04 0.04 Be 0.45 0.45 0.45 Ca 786 782 776 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.05 0.05 0.05 Cu 0.10 0.10 0.09 Fe BDL BDL BDL K 0.87 0.76 0.66 Mg 0.65 0.50 0.40 Mn BDL BDL BDL Ni 0.09 0.09 0.09 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 2.44 2.43 2.37 V BDL BDL BDL Zn 0.34 0.34 0.31 a BDL = Below detection l imit

PAGE 118

118 Table F 4 MEP test results of the samples collected from south wall (extraction 4 ) (mg/L) Cation Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 2.65 2.65 2.57 As BDL BDL BDL B BDL BDL BDL Ba 0.04 0.04 0.04 Be 0.43 0.43 0.42 Ca 813 801 801 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.05 0.05 0.05 Cu 0.09 0.09 0.08 Fe BDL BDL BDL K BDL BDL BDL Mg 0.37 0.38 0.34 Mn BDL BDL BDL Ni 0.09 0.09 0.09 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 2.34 2.28 2.28 V BDL BDL BDL Zn 0.28 0.27 0.27 a BDL = Below detection l imit

PAGE 119

119 Table F 5 MEP test results of the samples collected from south wall (extraction 5) (mg/L ) Cation Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 2.55 2.53 2.50 As BDL BDL BDL B BDL BDL BDL Ba 0.04 0.04 0.04 Be 0.39 0.39 0.38 Ca 756 747 737 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.05 0.05 0.05 Cu 0.08 0.08 0.08 Fe BDL BDL BDL K BDL BDL BDL Mg 0.23 0.21 0.21 Mn BDL BDL BDL Ni 0.09 0.09 0.09 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 2.24 2.23 2.18 V BDL BDL BDL Zn 0.24 0.21 0.20 a BDL = Below detection l imit

PAGE 120

120 Table F 6 MEP test results of the samples collected from south wall (extraction 6 ) (mg/L) Cation Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 2.31 2.30 2.26 As BDL BDL BDL B BDL BDL BDL Ba 0.04 0.04 0.04 Be 0.01 0.03 0.02 Ca 734 723 722 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.05 0.05 0.04 Cu 0.08 0.07 0.07 Fe BDL BDL BDL K BDL BDL BDL Mg BDL BDL BDL Mn BDL BDL BDL Ni 0.08 0.08 0.08 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 2.14 2.14 2.07 V BDL BDL BDL Zn 0.19 0.17 0.15 a BDL = Below detection l imit

PAGE 121

121 Ta ble F 7 MEP test results of the samples collected from south wall (extraction 7 ) (mg/L) Cation Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al 1.69 1.81 1.73 As BDL BDL BDL B BDL BDL BDL Ba 0.03 0.02 0.02 Be BDL BDL BDL Ca 720 720 714 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.04 0.04 0.04 Cu 0.06 0.06 0.06 Fe BDL BDL BDL K BDL BDL BDL Mg BDL BDL BDL Mn BDL BDL BDL Ni 0.08 0.08 0.08 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr 1.7 1.25 1.55 V BDL BDL BDL Zn 0.15 0.08 0.09 a BDL = Below d etection l imit

PAGE 122

122 Table F 8 MEP test results of the samples collected from south wall (extraction 8 ) (mg/L) Cation Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al BDL BDL BDL As BDL BDL BDL B BDL BDL BDL Ba BDL BDL BDL Be BDL BDL BDL Ca 710 714 706 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.04 0.04 0.04 Cu 0.06 0.06 0.05 Fe BDL BDL BDL K BDL BDL BDL Mg BDL BDL BDL Mn BDL BDL BDL Ni 0.08 0.08 0.08 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr BDL BDL BDL V BDL BDL BDL Zn BDL BDL BDL a BDL = Below detection l imit

PAGE 123

123 Table F 9 MEP test results of the samples collected from south wall (extraction 9 ) (mg/L) Cation Sample 1 Sample 2 Sample 3 Ag BDL a BDL BDL Al BDL BDL BDL As BDL BDL BDL B BDL BDL BDL Ba BDL BDL BDL Be BDL BDL BDL Ca 705 694 691 Cd BDL BDL BDL Co BDL BDL BDL Cr 0.04 0.04 0.04 Cu 0.05 0.04 0.04 Fe BDL BDL BDL K BDL BDL BDL Mg BDL BDL BDL Mn BDL BDL BDL Ni 0.08 0.08 0.07 Pb BDL BDL BDL Sb BDL BDL BDL Se BDL BDL BDL Sn BDL BDL BDL Sr BDL BDL BDL V BDL BDL BDL Zn BDL BDL BDL a BDL = Below detection l imit

PAGE 124

124 APPENDIX G BATCH LEACHING TEST WITH DI WATER Table G 1 Metal analysis data after batch t est of PG with DI water of NW PG samples (mg/L) Element Sample 1 Sample 2 Ag BDL a BDL Al 1.50 1.45 As BDL BDL B BDL BDL Ba 0.02 0.02 Ca 816 831 Cd BDL BDL Co BDL BDL Cr BDL BDL Cu 0.11 0.10 Fe BDL BDL K 1.55 1.42 Mn BDL BDL Mo 0.09 0.10 Na 11.51 10.79 Ni 0.02 0.02 Pb BDL BDL Sb BDL BDL Se BDL BDL Sn BDL BDL Sr 2.65 2.54 V BDL BDL Zn 0.10 0.11 a BDL = Below detection l imit

PAGE 125

125 Table G 2 Metal analysis data after batch t est of PG with DI water of SW PG samples (mg/L) Element Sample 1 Sample 2 Ag BDL a BDL Al 1.50 1.39 As BDL BDL B BDL BDL Ba 0.03 0.03 Ca 775 804 Cd BDL BDL Co BDL BDL Cr BDL BDL Cu 0.17 0.14 Fe BDL BDL K 3.45 3.50 Mn BDL BDL Mo 0.04 0.03 Na 9.65 9 .32 Ni 0.01 0.02 Pb BDL BDL Sb BDL BDL Se BDL BDL Sn BDL BDL Sr 2.23 2.34 V BDL BDL Zn 0.28 0.18 a BDL = Below detection l imit

PAGE 126

126 Table G 3 Metal analysis data after b a tch t est of PG with DI water of EW PG samples (mg/L) Element Sample 1 Sample 2 Ag BDL a BDL Al 1.83 1.94 As BDL BDL B BDL BDL Ba 0.05 0.06 Ca 783 779 Cd BDL BDL Co BDL BDL Cr BDL BDL Cu 0.12 0.11 Fe BDL BDL K 1.32 1.72 Mn BDL BDL Mo 0.02 0.03 Na 9 42 9 .97 Ni 0.01 0.01 Pb BDL BDL Sb BDL BDL Se BDL BDL Sn BDL BDL Sr 2.59 2.64 V BDL BDL Zn 0.12 0.1 a BDL = Below detection l imit

PAGE 127

127 Table G 4 Metal analysis data after batch t est of PG with DI water of WW PG samples (mg/L) Element Sample 1 Sample 2 Ag BDL a BDL Al 1.20 2.21 As BDL BDL B BDL BDL Ba 0.04 0.06 Ca 779 772 Cd BDL BDL Co BDL BDL Cr BDL BDL Cu 0.12 0.09 Fe BDL BDL K 2.07 1.47 Mn BDL BDL Mo 0.06 0.02 Na 9.5 5 11.33 Ni 0.0 4 0.01 Pb BDL BDL Sb BDL BDL Se BDL BDL Sn BDL BDL Sr 2.39 2.49 V BDL BDL Zn 0.26 0.29 a BDL = Below detection l imit

PAGE 128

128 APPENDIX H MSW LEACHATE BATCH LEACHING TEST DATA Table H 1 Batch leaching test with MSW l eachate for PG samples collected from north w all (mg/L) Element Blank Sample 1 Sample 2 Sample 3 Al 0.2 0.2 0.19 0.17 As 0.16 0.14 0.16 0.15 B 6.47 6.59 6.97 6.43 Ba 0.05 0.05 0.04 0.04 Ca 85 1051 1170 1080 Co 0.03 0.03 0.03 0.03 Cr 0.08 0.08 0.08 0.07 Cu 0.02 BDL a BDL BDL Fe 5.96 2.60 3.53 2.99 K 847 858 928 853 Mg 36.43 36.09 38.76 35.86 Mn 0.14 0.12 0.13 0.17 Na 1558 1574 1711 1558 Ni 0.11 0.11 0.12 0.13 Sb 0.11 BDL BDL BDL Se BDL BDL BDL BDL Sn BDL BDL BDL BDL Sr 0.27 3.16 3.48 3.2 V 0.05 0.05 0.05 0.04 Zn 0.05 0.03 0.02 0.03 a BDL = Below detection l imit

PAGE 129

129 Table H 2 Batch leaching test with MSW leachate for PG samples collected from south w all (mg/L) Element Blank Sample 1 Sample 2 Sample 3 Al 0.2 0.19 0.23 0.24 As 0.16 0.15 0.15 0.16 B 6.47 6.76 6.93 6.99 Ba 0.05 0.03 0.04 0.04 Ca 85 1061 1175 1217 Co 0.03 0.03 0.03 0.03 Cr 0.08 0.08 0.08 0.08 Cu 0.02 BDL a BDL BDL Fe 5.96 2.57 3.50 3.66 K 847 903 903 933 Mg 36.43 37.2 37.11 38.13 Mn 0.14 0.12 0.12 0.13 Na 1558 1639 1638 1700 Ni 0.11 0.10 0.10 0.12 Sb 0.11 BDL BDL BDL Se BDL BDL BDL BDL Sn BDL BDL BDL BDL Sr 0.27 2.95 3.19 3.32 V 0.05 0.06 0.05 0.05 Zn 0.05 0.03 0.03 0.04 a BDL = Below detection l imit

PAGE 130

130 Table H 3 Batch leaching test with MSW leachate for PG samples collected from east w all (mg/L) Element Blank Sample 1 Sample 2 Sample 3 Al 0.2 0.18 0.13 0.21 As 0.16 0.16 0.14 0.14 B 6.47 7.00 6.34 6.37 Ba 0.05 0.06 0.05 0.03 Ca 85 1119 1154 1157 Co 0.03 0.03 0.03 0.03 Cr 0.08 0.08 0.07 0.07 Cu 0.02 BDL a BDL BDL Fe 5.96 2.96 2.74 2.51 K 847 917 869 855 Mg 36.43 37.72 36.06 35.57 Mn 0.14 0.11 0.1 0.1 Na 1558 1670 1577 1550 Ni 0.11 0.11 0.10 0.09 Sb 0.11 BDL BDL BDL Se BDL BDL BDL BDL Sn BDL BDL BDL BDL Sr 0.27 3.32 3.38 3.38 V 0.05 0.05 0.04 0.04 Zn 0.05 0.03 0.03 BDL a BDL = Below detection l imit

PAGE 131

131 Table H 4 Batch leaching test with MSW l eachate for PG samples collected from west w all (mg/L) Element Blank Sample 1 Sample 2 Sample 3 Al 0.2 0.19 0.2 0.14 As 0.16 0.14 0.13 0.15 B 6.47 6.79 6.27 6.3 Ba 0.05 0.04 0.06 0.03 Ca 85 1169 1034 903 Co 0.03 0.03 0.02 0.02 Cr 0.08 0.07 0.06 0.07 Cu 0.02 BDL a BDL BDL Fe 5.96 2.62 2.41 2.75 K 847 889 819 816 Mg 36.43 36.9 34.34 34.36 Mn 0.14 0.1 0.09 0.1 Na 1558 1620 1485 1480 Ni 0.11 0.1 0.17 0.12 Sb 0.11 BDL BDL BDL Se BDL BDL BDL BDL Sn BDL BDL BDL BDL Sr 0.27 3.22 2.87 2.56 V 0.05 0.05 0.05 0.05 Zn 0.05 0.04 0.16 0.13 a BDL = Below detection l imit

PAGE 132

132 APPENDIX I QUALITY ASSURANCE/QUALITY CONTROL Table I 1 QA/QC for TCLP Element NW1Dup (mg/L % Recovery MS MSD Ag BDL a 91 94 Al 1.81 82 91 As BDL 110 107 B BDL 88 87 Ba 0.14 87 103 Ca 960 83 81 Cd BDL 101 111 Co BDL 99 109 Cr 0.03 97 107 Cu 0.02 88 91 Fe 0.38 88 98 K 1.17 110 106 Mn BDL 104 106 Na 1559 85 87 Ni 0.07 83 87 Pb BDL 101 103 Sb BDL 86 82 Se BDL 93 94 Sn BDL 96 94 Sr 3.37 87 80 V BDL 92 98 Zn 0.29 88 94 a BDL = Below detection limit

PAGE 133

133 Table I 2 QA/QC for SPLP Element NW1Dup (mg/L % Recovery MS MSD Ag BDL a 104 105 Al 2.2 110 106 As BDL 103 107 B BDL 96 99 Ba 0.09 95 100 Be BDL 93 97 Ca 700 90 95 Cd BDL 95 97 Co BDL 95 99 Cr 0.01 93 98 Cu 0.02 102 108 Fe 0.38 85 84 K 1.41 101 108 Na 9.25 85 94 Ni 0.02 93 98 Pb BDL 97 101 Sb BDL 87 96 Sn BDL 95 102 Sr 2.41 98 100 V BDL 90 91 Zn 0.08 90 97 a BDL = Below detection limit

PAGE 134

134 Table I 3 QA/QC for DI water b atch l eaching t est Element NW1Dup (mg/L % Recovery MS MSD Ag BDL a 97 95 Al 1.50 81 85 As BDL 98 94 B BDL 84 87 Ba 0.023 93 97 Ca 816 104 100 Cd BDL 97 99 Co BDL 87 86 Cr BDL 98 104 Cu 0.11 85 88 Fe BDL 93 95 K 1.55 105 102 Mn BDL 101 99 Mo BDL 100 103 Na 11.51 83 88 Ni 0.018 85 84 Pb BDL 118 110 Sb BDL 95 103 Se BDL 105 105 Sn BDL 101 102 Sr 2.65 100 96 V BDL 85 87 Zn 0.103 94 98 a BDL = Below detection limit

PAGE 135

135 Table I 4 QA/QC for MSW b atch l eaching t est Element NW1Dup (mg/L % Recovery MS MSD Al BDL a 105 103 As 0.14 101 98 B 6.59 100 95 Ba 0.05 91 93 Ca 1051 95 98 Co 0.03 108 104 Cr 0.08 95 98 Cu BDL 104 101 Fe 2.60 98 99 K 858 97 99 Mg 36.1 109 103 Mn 0.12 82 86 Na 1574 87 89 Ni 0.11 100 96 Sb BDL 105 101 Se BDL 94 97 Sn BDL 87 93 Sr 3.16 88 94 V 0.05 94 99 Zn 0.03 95 102 a BDL = Below detection limit

PAGE 136

136 Table I 5 QA/QC for EPTOX Element SW1Dup (mg/L % Recovery MS MSD Ag BDL a 94 99 Al 1.83 87 92 As BDL 102 97 B BDL 98 104 Ba 0.06 99 98 Be BDL 95 98 Ca 752 108 104 Cd BDL 95 98 Co BDL 104 101 Cr 0.04 95 98 Cu 0.19 104 101 Fe BDL 98 99 K 3.46 97 99 Mg 0.71 109 103 Mn BDL 82 86 Ni 0.06 97 99 Pb BDL 87 86 Sb BDL 98 104 Se BDL 85 88 Sn BDL 89 94 Sr 2.34 100 102 V BDL 99 103 Zn 0.26 94 96 a BDL = Below detection limit

PAGE 137

137 LIST OF REFERENCES Al Hwaiti M. S. Ranville J. F. and Ross P.E. Bioavailability and mobility of trace metals in phosphogypsum from Aqaba and Eshidiya, Jordan Chemie der Erde 70, 283 291. Al Masri, M. S., Amin, Y., Ibrahim, S. and Al some trace metals in Syrian phosphogypsum Appl. Geochem. 19 747 753. Alva, A. K ., and Sumner M E (1991) Characterization of p hytotoxic aluminum Water, Air, and Soil Pollution 57 58, 121 130. Arman, A. and Seals, R. K. ( 1990 ) A preliminary assessment of utilization alternatives for phosphogypsum Proc ., Int. Symp. on Phosphogypsum FIPR, Orlando, FL, 562 575. Becker, P. ( 1989 ) Phosphates and phosphoric acid: raw m aterials technology, and economics of the w e t p rocess Marcel D ekker, New York, 752. Berish, C. W. ( 1990 ) Potential environmental hazards of phosphogypsum storage in central Florida Proc., Int. Symp. on Phosphogypsum FIPR, Orlando, FL, 1 29. Brantley, A. S. reclaimed asphalt pavement Environ. Eng. Sci., 16 (2), 105 116. Burnett, W. C., Schultz, M. K. and Hull, C. J. Environ. Radioactivity, 32 33 52. Carvalho, M. C. S ., and Raij, B. van (1997) Calcium sulphate, phosphogypsum and calcium carbonate in the amelioration of acid subsoils for root growth Plant and Soil 192 37 48 Chang, W. F., Chin D. A., and R obert, H (1989). Phosphogypsum for secondary road construction Final Rep ., Florida Institute for Phosphate Resea rch, Bartow, FL Chuan, M., Shu, G., and Liu, J. Water Air Soil Poll ., 90, 543 556. Federal Register. (1980). 45 (98), 33122 33127 33131.

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138 Guidry, J. J. ( 1990 Environmental impact of airborne radioactivity emissions from a phosphogypsum stack Proc., Int. Symp. on Phosphogypsum FIPR, Orlando, FL, 74 86 Haridasan P. P. Maniyan C. G. Pillai P. M. B. and Khan A. H. ( 2002 ). Dissolution characteristics of 226 Ra from phosphogypsum J. Environ. Radioactivity 62 287 294 Jang Y. and Townsend, T. ( 2001 ) Occurrences of organic pollutants in recovered soil fines from construction and demolition waste. Waste Manag. 21 703 715. Krdel, W., and Klein, M. (2006). Prediction of leaching and groundwater contamination by pesticides. Pure Appl. Chem. 78(5), 1081 1090. Kendron, T. J. (1996). Sulfur recovery from p hosphogypsum. Proc., Ph osphogypsum Fact Finding Forum, Tallahassee, FL. Proc., Technical Interactive Forum Coal Combustion By Products and Western Coal Mines Le e, C. H., Ha, B. Y., Lee Y. B., and Kim, P. J. (2009). lkalized p hosphogy psum on soil chemical and biological p roperties. Comm., Soil Science and Plant Analysis 40( 13/14 ), 2072 2086 Lloyd, G. (1985). Phosphogypsum: a review of the Florida Institute of Phosphat e Research programs to develop uses for phosphogypsum. Final Rep ., Florida Institute for Phosphate Research, Bartow, FL. Luther, S. M., Dudas, M. J. and Rutherford, P. M. ( 1992 chemical characteristics of Alberta phosphogypsum Water Air Soil Poll. 69, 277 290 Luther, S. M. and Dudas, M. J. phosphogypsum J. Environ. Qual. 22 103 108. Malan, J. J. of a cooperative research programme. Proc., Int. Symp. on Phosphogypsum FIPR, Miami, FL 131 139. May, A. (1983). Use of Florida p hosphogy psum in synthetic construction a ggregate. Final Rep ., Florida Institute for Phosphate Research, Bartow, FL.

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141 BIOGRAPHICAL SKETCH Shabnam Mostary was born in Cox's Bazar, a city in Bangladesh. She started her education in Little Jewels School, and continued in Ispahani Public School and College and Chittagong College. She joined to the Civ il Engineering Department at Bangladesh University of Engineering and Technology (BUET), where she got her B.Sc. Degree in January 2008. She was accepted into the graduate program in the Department of Environmental Engineering at University of Florida in A ugust 2009. Her research interests include water, wastewater and solid and hazardous waste management. She received her ME from University of Florida in the spring of 2011.