Assessment and Disposal of

Arsenic Treatment Residuals

SBRP/EPA Workshop Feb. 28 - Mar. 01, 2005

2 Philosophy and Format

Road test research Proactive environmental engineering Condense normal timeline Cut across conventional delineations Limited size

facilitate open discussion narrow focus/broad expertise solutions/directions beyond the problems

3 Changes and Impacts

•2001revised arsenic in D.W. standard •10 ppb MCL (from 50 ppb) •Implementation by 2006-2012

•Predicted impacts •4000 new utilities impacted ( >95% small) •8M lb solid residuals annually (30,000 # As /yr) •Present and future Superfund/RCRA sites

•Residuals hazard assessment •Toxicity characteristic leaching procedure (TCLP) •Waste extraction test (WET)

4 Next Steps for As Residuals

S1. Simulate landfills/repositories to determine appropriate performance bar

S2. Develop tractable protocols based on engineering critical leaching mechanisms to clear bar

S3. Evaluate (technically & economically) treatment options, including stabilization, alternative sorbents, etc.

S4. Develop and evaluate hybrid (conventional & innovative) disposal options

6 Test/Landfill Characteristics

Test pH ORP (mV)

Alkalinity (mg/L as CaCO3)

TOC (mg/L)

TDS (mg/L)

Ionic Strength

(M)

TCLP 4.95 103.5 766 38.6 1480 0.08 WET 5.05 74 7940 55.8 5160 0.10 SL1 7.03 121.4 1500 1050 5200 0.03 SL2 7.55 -37 12500 1310 8600 0.49 LL1 6.82 36.1 1100 160 3600 0.33 LL2 4.5-9.0 N/R* 300-11500 30-29000 2000-60000 N/R LL3 6.5-8.2 N/R 1250-8050 N/R 1960-16800 N/R LL4 6.2-7.1 N/R N/R 236-3160 N/R N/R

N/R* - Values Not Reported LL1 – Leachate collected from Tangerine Road Landfill, Tucson, AZ. LL2 – Leachate composition reported in Christensen et al, 2001 (21) LL3 – Leachate composition reported in Jang et al, 2003. (22) LL4 – Leachate composition reported in Hooper et al, 1998. (5)

7 Our Corollary Research

Treatment systems evaluation (IHS funding) Removal technology development (State of AZ/

SBRP) Residuals assessment (SBRP/AZ State funding)

Adequacy of TCLP and WET What is adequate? Alternative test development Other contaminants and scenarios

Residuals stabilization (SBRP/AWWARF/AZ State funding)

0

0.2

0.4

0.6

0.8

1

1.2

Extra

ctan

t Ars

enic

(m

g/L

as A

s)

AA, 18hr AA, 48hr

GFH, 18hr GFH, 48hr

Initial Loading: AA, 31 ppb; GFH, 22 ppb

TCLP LL WET SL1 SL2

8 Solid Media Leaching

9 Residuals Assessment Tests

Guiding Premise: test induces leaching as or more aggressively

than conditions of non-hazardous waste disposal

TCLP WET Mature Landfill

pH 4.95 5.05 7-9

Bioactivity abiotic abiotic biotic

Duration 18 hr 48hr weeks /months

Active Reage nt

acetate c itrate Mix of organics & inorganics

Redox Condition

oxidizing neutral reduc ing

10 Immediate Findings

•TCLP vs. WET Variables (batch test mode) •agitation method (tumbler (T) > shaker (W)) •headspace (N2 (W) > air (T)) •duration (48 hr (W) > 18 hr (T)) •reagent (citrate (W) > acetate (T))

•Landfill vs. Standard Variables (batch test mode) •pH (6.8 (LL) > ~5 (T&W)) •TOC (above 160 ppm (LL) > below 60 ppm (T&W)) •ORP (below 50 mV (LL) > above 50 mV (T&W))

•Study limitations •batch vs. continuous flow •abiotic vs. biotic •excess (non-reactive) vs. limiting (reactive) substrate

SYRINGE PUMP (FLOW RATE 0.31mL/min)

INFLUENT GAS COLLECTION

MARIOTTE

FLASK

10% NaOH SOLUTION

UNSATURATED ZONE

SATURATED ZONE

GRAVEL

GRAVEL

WATER WITH pH LEVEL INDICATOR

DEAERATED, COLLECTION DEIONIZED FLASK WATER

SAMPLING PORTS • 23% SHREDDED PAPER • 46% YARD WASTE • 31% SOLID RESIDUAL • 4L ANAEROBIC DIGESTOR SLUDGE

EFFLUENT

11 S1. Setting the bar

Landfill Simulation Columns

As

(ppb

) 2500

3000 3500

4000 As(III)

DMA(V)

As(dissolved)

MMA(V)

As(V)

As(digested)

1000

1500 2000 HCO3

VFA

500

0 0 200 400 600 800

time (days)

12 S1. Setting the bar

GFH Column Leachate

Equilibrium As Concentration : 25.66ppb

13 S1. Setting the bar

GFH Column Leachate

0.00

100.00

200.00

300.00

400.00

500.00

600.00

0 200 400 600 800

Time (days)

Fe

(in

pp

m)

0

1000

2000

3000

4000

As(

in p

pb

)

Fe (total) As(total)

S1. Setting the bar

Sorb-33 Column Leachate 14

0 50

100 150 200 250 300 350 400 450 500 550 600

0 50 100 150 200 250 300

Time (days)

Tot

al F

e (m

g/L

)

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Tot

al A

s (p

pb)

Total Fe Total As

0

0.1

0.2

0.3

0.4

0.5

0.6

Frac

tion

As

deso

rbed

AA

GFH

4.59

14.96

12.25

50.84

28.21

152.5

7 8 9pH

15 S2. New Protocol Development

pH Effects

10

16 S2. New Protocol Development

Anion’s Effects

Anion Landfill Leachate Range (in mg/L) (Bagchi, 1994)

Concentration Used in

Competition Trials

(in mg/L)

Fraction As expected to leach due to

concentration of anion in LL

Fraction of total leaching attributable to each anion in the

SLL-theo

Activated Alumina Phosphate 0.11- 234 20 0.002 0.04

Bicarbonate 34- 15,050 1,200 0.008 0.15 Sulfate 105- 4,900 500 0.002 0.04 Silicate 5.1-51 10 0.001 0.02 NOM 76-40,000 200 0.04 0.75

Granular Ferric Hydroxide Phosphate 0.11- 234 20 0.0007 0.03

Bicarbonate 34- 15,050 1,200 0.012 0.48 Sulfate 105- 4,900 500 0.0008 0.03 Silicate 5.1-51 10 0.0013 0.05 NOM 76-40,000 200 0.01 0.4

TCLP LL WET SL1 SL2 0

0.2

0.4

0.6

0.8

1

1.2

Extra

ctan

t Ars

enic

(m

g/L

as A

s)

AA, 18hr AA, 48hr

GFH, 18hr GFH, 48hr

Initial Loading: AA, 31 ppb; GFH, 22 ppb

17 S2. New Protocol Development

Reductant + TOC Effect

18 S3. Treatment & Stabilization Options

AFH Crystallization

D7

0

100

200

300

D14

0

500

1000

D24

0

500

1000

1500

D0

0 100 200 300 400

20 30 40 50 60 70

D42

0 200 400 600 800

1000 1200 1400 1600 1800

19 S3. Treatment & Stabilization Options

As Release & Crystallization

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 300 600 900 1200 AGING TIME(Hrs)

As(t)

/As(T

)

pH7

pH8

pH9

pH10

pH11

pH12

20 Broader Implications

•Arsenic as an elemental contaminant •no destructive technologies •media and speciation transformations only •surrogate for heavy metals, metalloids, radionuclides

•Arsenic as a redox-sensitive, oxyanion •inverse pH behavior to metals •microbially mediated fate and transport •typically most mobile in reduced form •surrogate for V, Mo, Se, S, Cl, N, P

•Arsenic as a ‘natural’ contaminant •primarily non-anthropogenic sources •naturally diffuse but anthropogenically concentrated •surrogate for Rn, U, Se, S, F, Br, V

21

Batch Adsorption Experiments

22 AA Adsorption Edge

0

0.2

0.4

0.6

0.8

1

4 6 8 10 12 pH

C/C

o

Co = 0.125mM Co = 0.05mM Co = 0.0125mM Co = 0.005mM Co = 0.00125mM

• Co - Initial arsenic concentration in solution • C - Equilibrium arsenic concentration in solution

GFH Adsorption Edge

Co = Initial concentration of As in solution (total As in the system) C = Concentration of As in solution at equilibrium Solid Loading = 25g/L

23

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

5 6 7 8 9 10 11

pH

C/C

o

Co= 1.66mM Co= 8.33mM Co= 16.6mM Co= 83.3mM

24

Comparative Leaching Tests

25

26

27 Activated Alumina

0 100 200 300 400 500 600 700 800 900

1000

TCLP WET LL SL1 SL2

Leac

hate

As

Conc

. (pp

b as

As) 18hr

48hr

Concentration of As in solution at equilibrium prior to leaching tests = 21.8ppb Sorbed concentration of As = 1.27mgAs/gAA. Test conditions: No N2 headspace, end-over-end tumbler.

28 Granular Ferric Hydroxide

0

200

400

600

800

1000

1200

TCLP WET LL SL1 SL2

Leac

hate

As

Con

c. (p

pb a

s A

s)

18hr

48hr

Concentration of As in solution at equilibrium prior to

leaching tests = 31ppb Sorbed concentration of As = 7.2mgAs/gGFH. Test conditions: No N2 headspace, end-over-end tumbler.

29 Ferric Hydroxide Sludge

1

10

100

1000

10000

100000

1000000

10000000

TCLP WET LL

Leac

hate

As

Con

c. (p

pb a

s A

s) 18hr 48hr

Concentration of As in solution at equilibrium prior to

leaching tests = 1040ppb Sorbed concentration of As = 20.3mgAs/gFe. Test conditions: No N2 headspace, end-over-end tumbler.

30

Competitive Anion Effects

31 Activated Alumina Anion Effect Anion (Moles As

released/ mole

(Moles As released/

mole

(Moles As released/

mole

Fraction sorbed As expected to leach due to concentration of anion in LL

pH7anion pH9)high pH7anio pH9n)low pH7anion)a pH9verage

Phosphate 279 113 3.05 1.52 9.24 4.69 0.002

Bicarbonate 0.92 0.58 0.014 0.007 0.043 0.025 0.008

Sulfate 0.352 0.143 0.017 0.014 0.045 0.028 0.002

Silicate 12 8.6 0.56 0.68 2.6 2 0.001

NOM 391 336 0.41 0.23 2.35 1.13 0.04

32 GFH Anion Effect Anion (Moles As

released/ mole

(Moles As released/

mole

(Moles As released/

mole

Fraction sorbed As expected to leach due to concentration of anion in LL

pH7anion pH9)high pH7anio pH9n)low pH7anion)e

pH9averag

Phosphate 357 244 4.02 2.09 10.5 6.07 0.0007

Bicarbonat e

8 4 0.027 0.023 0.24 0.11 0.012

Sulfate 0.698 0.458 0.021 0.005 0.098 0.054 0.0008

Silicate 32 21 2.1 0.62 5.4 3.7 0.0013

NOM 1064 374 0.7 0.19 3.9 0.97 0.01

33

Column Experiment Methods

34 Column Packing Composition Specifications Activated

Alumina GFH E-33

Mass of Residual

1017g 527g 509g

Total Amount of As

1.29g 2.86g 2.61g

Initial Sorbed As Conc.

1.27mgAs/gAA 5.42mgAs/gGF H

5.13mgAs/gE33

Initial equilibrium As

conc.

193ppb 25.6ppb 11ppb

Duration of run 302 days 808 days 274 days

35

Activated Alumina Column

36 pH

6

6.5

7

7.5

0 50 100 150 200 250 300 350

time (days)

pH

37 Alkalinity

0 1000 2000 3000 4000 5000 6000

0 50 100 150 200 250 300 350

time (days)

alk

alin

ity

(m

g/L

)

38 ORP

-25

-15

-5

5

15

25

0 50 100 150 200 250 300 350

time (days)

OR

P (

mV

)

39 DOC

0

1

2

3

4

5

6

7

0 50 100 150 200 250 300 350

time (days)

DOC

(g/L

)

40 Arsenic

0

500

1000

1500

2000

0 40 80 120 160 200 240 280 320

Time(days)

Co

nc

(pp

b)

As(III) As(V)

As(dissolvedl) As (total)

* Small amounts of MMA(V), DMA(V) and MMA(III) were also observed in the effluent.

41 Fractional Arsenic Leached

0

0.02

0.04

0.06

0.08

0.1

0.12

0 50 100 150 200 250 300 350

Time (days)

Fra

ctio

nal

As

Lea

ched

42

GFH Column Results

43 pH

6

6.5

7

7.5

8

8.5

9

9.5

10

0 200 400 600 800 1000

days

pH

44 Alkalinity

0

500

1000

1500

2000

2500

3000

3500

0 200 400 600 800

days

Alk

alin

ity (m

g/L)

45 ORP

-250

-200

-150

-100

-50

0 0 100 200 300 400 500 600 700 800

days

OR

P (

mV

)

46 DOC

0

500

1000

1500

2000

2500

3000

0 100 200 300 400 500 600 700

days

DO

C (m

g/L)

As

(pp

b)

4000 As(III) 3500 As(V) 3000 As(dissolved) 2500 As(digested) 2000

1500

1000

500

0 0 200 400 600 800

time (days)

47 GFH Column Results

Fe (m

g/L)

600

400

500 Fe (dissolved) Fe (digested)

300

200

100

0 0 200 400

time (days)

600 800

48 GFH Column Results

49 Overall Picture

0.00

100.00

200.00

300.00

400.00

500.00

600.00

0 200 400 600 800 1000

Time (days)

Fe

(in

pp

m)

0

1000

2000

3000

4000

As(

in p

pb

)

Fe (total) As(total)

50 Fractional Arsenic Leached

0 0.05 0.1

0.15 0.2

0.25 0.3

0.35 0.4

0.45 0.5

0 200 400 600 800 1000

time (days)

Fra

ctio

nal

As

Lea

ched

Fe(

mg

/L)

250

200

150

100

50

0 0 200

>5U 0.8U

As

(p

pb

)

2500

2000

1500

1000

500

0

>5U 0.8U

53

E-33 Column Results

54 pH

6

7

8

0 50 100 150 200 250 300

time

pH

55 Alkalinity

900

1400

1900

2400

0 50 100 150 200 250 300

time

Alk

alin

ity

(m

g/L

)

56 E-33 Column Results

0

20

40

60

80

0 50 100 150 200 250 300

time (days)

Fe

(mg

/L)

Fe(II) Fe(III) Fe(dissolved) Fe(total)

57 E-33 Column Results

0 1000 2000 3000 4000 5000

0 50 100 150 200 250 300

time (days)

As

(PP

B)

As(III) As(V) As(dissolvedl) As(total)

58 Fractional Arsenic Leached

0

0.05

0.1

0.15

0.2

0.25

0.3

0 50 100 150 200 250 300

Time (days)

Fra

ctio

nal

As

Lea

ched

59

Iron Sludge Column Results

60 pH

6

6.5

7

7.5

8

8.5

9

0 20 40 60 80 100 120 140 160

Time (days)

pH

61 Alkalinity

3000

4000

5000

6000

7000

8000

0 20 40 60 80 100 120 140 160

Time (days)

Alk

alin

ity

(mg

/L)

62 ORP

-400

-300

-200

-100

0

100

200

300

0 20 40 60 80 100 120 1

Time (days)

OR

P (

mV

)

40

63 Arsenic

0

50000

100000

150000

200000

250000

0 20 40 60 80 100 120 140

Time (days)

As

(pp

b)

As (total) As (dissolved) As(III) As(V)

64 Iron

0.00 100.00

200.00 300.00 400.00

500.00 600.00

700.00 800.00

0 20 40 60 80 100 120 140

Time (days)

Fe

(in

mg

/L)

Fe (total) Fe (dissolved) Fe(II) Fe(III)

Assessment and Disposal of Arsenic Treatment ResidualsPhilosophy and FormatChanges and ImpactsTest/Landfill CharacteristicsOur Corollary ResearchSolid Media LeachingResiduals Assessment TestsS1. Setting the barLandfill Simulation ColumnsS1. Setting the barGFH Column LeachateS1. Setting the barSorb-33 Column LeachateS2. New Protocol DevelopmentpH EffectsS2. New Protocol DevelopmentAnion’s EffectsS2. New Protocol DevelopmentReductant + TOC EffectS3. Treatment & Stabilization OptionsAFH CrystallizationS3. Treatment & Stabilization OptionsAs Release & Crystallization