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