Arsenic Leaching From Mulch Arsenic Leaching From Mulch Made from Recycled C&D Made from Recycled C&D

Wood Wood

a1Tomoyuki Shibata, 1Helena Solo-Gabriele,

2Timothy Townsend and 2Brajesh Dubey 1University of Miami and 2University of

Florida

Objectives: Quantifying the releases of arsenic from

C&D wood mulch and evaluation of the effect of colorant on arsenic leaching

FAQ: MulchFAQ: Mulch

RolesRoles– Prevention ofPrevention of

Evaporation of Evaporation of moisture & soil moisture & soil erosionserosions

– Aesthetic Aesthetic ApplicationsApplications

– Gardens, parks, Gardens, parks, PlaygroundsPlaygrounds

Made ofMade of– Trees, leaves, Trees, leaves,

straws, peat, or straws, peat, or rrecycled C&D woodecycled C&D wood

Wood Recycling Wood Recycling FacilityFacility Facilities, Florida Facilities, Florida

USAUSA– CCA up to 30 %CCA up to 30 %– Will increaseWill increase

Colored MulchColored Mulch

Red dye (popular in

FL) – Iron oxide

Combine with As May inhibit As

leaching ?

Materials & MethodsMaterials & Methods

Collection & Sorting C&D wood

Shredding wood

Mixing mulch Leachate generation

Mixing handmade Mixing handmade mulchmulch

ColoreColoredd

mulchmulch

MulchMulch

mulchmulch

% %

treated treated woodwood

NonNon

colorecoloredd

0%0% mulchmulch

5%5% mulchmulch

100%100% mulchmulch

Materials & Methods Materials & Methods

Collection & Sorting C&D wood

Shredding wood

Mixing wood Leachate generation

0% 0% treated treated woodwood

MulchMulch MulchMulch

5% 5% treated treated woodwood

Mulch Mulch MulchMulch

100%100%TreateTreated woodd wood

MulchMulch MulchMulch

Leachate GenerationLeachate Generation

SPLP leachateUniversity of Florida

Field leachateUniversity of Miami

Non-colored Colored

0 %treated

5 %

100 %

5 cm mulch(800g/box)

Geotextile

EPA 7060A & GFAA

Field leachate:Field leachate: 1 year monitoring1 year monitoring

SPLP Leachate SPLP Leachate Field leachateField leachateAverage/year Average/year

%CCA%CCA

mulchmulchNonNon

Colored Colored ColoredColored NonNon

Colored Colored ColoredColored

0 %0 %(untreated)(untreated)

<0.012<0.012 < < 0.0120.012

< 0.003< 0.003 < 0.003< 0.003

5 %5 % 0.9200.920 0.3800.380 0. 3410. 341 0.2580.258

100 %100 % 9.85 9.85 1.321.32 4.494.49 3.493.49

Results: Results: As in the leachate (mg/L)As in the leachate (mg/L)

-59%

-73%

-22%

-24%

DiscussionsDiscussions

0.00

0.01

0.10

1.00

10.00

100.00

1/11

/04

2/11

/04

3/11

/04

4/11

/04

5/11

/04

6/11

/04

7/11

/04

8/11

/04

9/11

/04

10/1

1/04

11/1

1/04

12/1

1/04

1/11

/05

Days (month/day/year)

Ars

en

ic i

n t

he

mu

lch

le

ac

ha

tes

(m

g/L

)

From 100%CC

AFrom

5%CCA

From 0%CCA

FL GWCTL 0.05 mg/L

A half yearcolorant effect

%CCA, time, pH of

rainfall

Detection limit 0.003 mg/L

Mathematical modelMathematical model%CCA, time, pH %CCA, time, pH

0.000

5.000

10.000

15.000

20.000

25.000

0 50 100 150 200 250 300 350 400

t (days)

Ars

en

ic i

n t

he

mu

lch

le

ac

ha

te (

mg

/L)

N100

N100 model

r = 0.836 ~ 0.954

from non-colored much

As = %/100(2+40t-0.7+32(7-pHrain)5/t2)

from colored much

As = %/100(1+40t-0.7+12(7-pHrain)5/t2)

ConclusionConclusion

5%CCA mulch5%CCA mulch

Colorant Colorant

Sorting C&D wood before the Sorting C&D wood before the production production

AcknowledgementsAcknowledgements

Funding Agency Funding Agency – Florida Center for Solid and Hazardous Florida Center for Solid and Hazardous

Waste ManagementWaste Management Extra HelpExtra Help

– Gary Jacobi, Geoff KlugGary Jacobi, Geoff Klug, Michael Laas, , Michael Laas, Caitlin Feikle, Colleen Block, Yuki Caitlin Feikle, Colleen Block, Yuki Sotome, and Alicia Muniz: University of Sotome, and Alicia Muniz: University of MiamiMiami

Thank youThank you