Comparative Laboratory Leaching Test Comparative Laboratory Leaching Test Methods to Study Post-Treatment Methods to Study Post-Treatment Storage Period Impacts on CCA Storage Period Impacts on CCA Leachability and Fixation in Treated Leachability and Fixation in Treated Kempas (Kempas (Koompassia malaccensisKoompassia malaccensis) ) HeartwoodHeartwood

Andrew Wong and Lai Huat ChoiAndrew Wong and Lai Huat Choi

Faculty of Resource Science & Technology, Faculty of Resource Science & Technology, University Malaysia Sarawak (UNIMAS),University Malaysia Sarawak (UNIMAS),

Kota Samarahan, Kota Samarahan,

Sarawak, MalaysiaSarawak, Malaysia

INTRODUCTIONINTRODUCTION

CCA PreservativesCCA Preservatives

CCA preservatives is one of the most CCA preservatives is one of the most effective wood protecting chemical for many effective wood protecting chemical for many yearsyears

Environment issues of CCA components Environment issues of CCA components leaching in the media - lead to restrictions leaching in the media - lead to restrictions of CCA application.of CCA application.

Many countries have even switched to Many countries have even switched to organic-based preservativeorganic-based preservative

Laboratory leaching test studiesLaboratory leaching test studies – some concerns – some concerns

Need to devise suitable harmonise leaching test Need to devise suitable harmonise leaching test methods for comparison of biocide risk methods for comparison of biocide risk assessments between labs leaching testassessments between labs leaching test

But also need to have a lab leaching test that is But also need to have a lab leaching test that is realistic to actual environmental exposures of realistic to actual environmental exposures of wood preservatives - trying to relate lab results to wood preservatives - trying to relate lab results to the “real world” - the extent of rainfall and other the “real world” - the extent of rainfall and other climatic effects between regionsclimatic effects between regions

EN84 leaching test may be too severe for natural EN84 leaching test may be too severe for natural non-aquatic exposures of treated woodnon-aquatic exposures of treated wood

Any prospects for a relatively milder lab leaching Any prospects for a relatively milder lab leaching test system?test system?

Aim of StudyAim of Study

Compare 3 laboratory leaching test Compare 3 laboratory leaching test methods (denoted as: EN84, EN84-1 and methods (denoted as: EN84, EN84-1 and EN84-2, severe to mild leaching).EN84-2, severe to mild leaching).

Leachability of CCA in heartwood of freshly Leachability of CCA in heartwood of freshly treated Kempas (treated Kempas (Koompassia Koompassia malaccensismalaccensis).).

To determine if CCA leaching from kempas To determine if CCA leaching from kempas is arrested with longer storage fixation is arrested with longer storage fixation periods.periods.

MATERIALS & METHODSMATERIALS & METHODS

Wood Material Preparation

Preservative treatment and conditioning

14-days laboratory leaching tests

Elemental analysis of leachates

Data analysis

Wood Material PreparationWood Material Preparation

Timber species:Timber species:--Kempas …permeable heartwoodKempas …permeable heartwood

((Koompassia malaccensisKoompassia malaccensis)) Structural-used Malaysian hardwood (roof truss,Structural-used Malaysian hardwood (roof truss, utility poles)utility poles) Air dried wood block samples (20 x 20 x 20 Air dried wood block samples (20 x 20 x 20

mm) cut from sawn timbermm) cut from sawn timber

Test blocks end-grain sealed with Nippon Test blocks end-grain sealed with Nippon paint and conditioned at 105paint and conditioned at 10500C, 48 hours, C, 48 hours, and weighed oven dry (g) before CCA and weighed oven dry (g) before CCA treatmenttreatment

Preservative Treatment & Storage Preservative Treatment & Storage

PeriodsPeriods Replicated Kempas wood blocks impregnated Replicated Kempas wood blocks impregnated

with Type C CCA-salt to target uptake retention with Type C CCA-salt to target uptake retention of 5.6 kg/mof 5.6 kg/m33

Freshly treated wood stored for periods of 0 day, Freshly treated wood stored for periods of 0 day, 2 days, 1 week, 2 weeks & 4 weeks at ambient 2 days, 1 week, 2 weeks & 4 weeks at ambient temperaturetemperature

Initial vacuum(1 kgf/cm2)

Pressure(14 kgf/cm2)

30 min30 min 2 hr2 hr

Laboratory Leaching TestsLaboratory Leaching Tests

TestTest EN84EN84 EN84-1EN84-1 EN84-2EN84-2

Initial Vacuum Initial Vacuum Impregnation?Impregnation?

Yes (30 min)Yes (30 min) NoNo

Initial Dipping Initial Dipping in Water?in Water?

NoNo YesYes

Leaching Leaching PeriodsPeriods

2 weeks2 weeks

Immersion in Immersion in WaterWater

24 hours24 hours Only 5 hr Only 5 hr dailydaily

Water Water Change?Change?

22, 24, 48, 72, , 24, 48, 72, 96 hr and 96 hr and

every 48 hrevery 48 hr

24, 48, 72, 96 24, 48, 72, 96 hr and every hr and every

48 hr48 hr

DailyDaily

CCA Component Analysis in LeachatesCCA Component Analysis in Leachates

Cu & Cr determined by FAASCu & Cr determined by FAAS

As determined using AAS EDL Lamp As determined using AAS EDL Lamp systemsystem

Component losses expressed in Component losses expressed in µg/mlµg/ml

Cumulative leaching losses Cumulative leaching losses ((µg/ml)µg/ml) for for each of Cu, Cr & As over the leaching each of Cu, Cr & As over the leaching test durationtest duration

RESULTSRESULTS

Cumulative Cu leaching (µg/ml) by 3 lab. Cumulative Cu leaching (µg/ml) by 3 lab. methodsmethods

0

1

2

3

4

5

0 50 100 150 200 250 300 350

Hours

Cu

Lea

chin

g (

pp

m)

0

1

2

3

4

5

0 50 100 150 200 250 300 350

Hours

Cu

Lea

chin

g (p

pm

)

4 Weeks 2 Weeks 1 Week

2 Days 0 Day

0

1

2

3

4

5

0 50 100 150 200 250 300 350

Hours

Cu

Leac

hing

(ppm

)

EN84 EN84-1 EN84-2

Cumulative Cr leaching (µg/ml) by 3 lab. Cumulative Cr leaching (µg/ml) by 3 lab. methodsmethods

0

1

2

3

4

5

6

0 50 100 150 200 250 300 350

Hours

Cr L

each

ing

(pp

m)

0

1

2

3

4

5

6

0 50 100 150 200 250 300 350

Hours

Cr L

each

ing (p

pm)

4 Weeks 2 Weeks 1 Week

2 Days 0 Day

0

1

2

3

4

5

6

0 50 100 150 200 250 300 350

Hours

Cr L

each

ing

(ppm

)

EN84 EN84-1 EN84-2

Cumulative As leaching (µg/ml) by 3 lab. Cumulative As leaching (µg/ml) by 3 lab. methodsmethods

0

1

2

3

4

5

0 50 100 150 200 250 300 350

Hours

As L

each

ing

(ppm

)

0

1

2

3

4

5

0 50 100 150 200 250 300 350

Hours

As

Leac

hing

(ppm

)

4 Weeks 2 Weeks 1 Week

2 Days 0 Day

0

1

2

3

4

5

0 50 100 150 200 250 300 350

Hours

As L

each

ing

(ppm

)

EN84 EN84-1 EN84-2

Cumulative plot for leaching of Cu (ppm) among 3 Cumulative plot for leaching of Cu (ppm) among 3 leaching methodsleaching methods

0 day

2 wk 4 wk

1 wk2 days

EN84EN84-1EN84-2

Cumulative plot for leaching of Cr (ppm) among 3 Cumulative plot for leaching of Cr (ppm) among 3 leaching methodsleaching methods

0 day

2 wk 4 wk

1 wk2 days

EN84EN84-1EN84-2

Cumulative plot for leaching of As (ppm) among 3 Cumulative plot for leaching of As (ppm) among 3 leaching methodsleaching methods

0 day

2 wk 4 wk

1 wk2 days

EN84EN84-1EN84-2

Table: Total Leaching (Table: Total Leaching (µg/ml) of CCA Components for µg/ml) of CCA Components for MenggrisMenggris by EN84, by EN84, EN84-1 & EN84-2 MethodsEN84-1 & EN84-2 Methods

Fixation periodsFixation periods Leaching Leaching methodsmethods

CuCu CrCr AsAs

-----------------(-----------------(µg/ml)-----------------µg/ml)-----------------

4 wk4 wk EN84EN84 1.1 1.1 abcdeabcde 1.6 1.6 abab 1.4 1.4 bcdbcd

4 wk4 wk EN84-1EN84-1 0.7 0.7 abcabc 1.7 1.7 abab 0.9 0.9 abab

4 wk4 wk EN84-2EN84-2 0.50.5 a a 0.60.6 a a 0.50.5 a a

2 wk2 wk EN84EN84 1.5 1.5 dede 2.1 2.1 bb 1.8 1.8 cdcd

2 wk2 wk EN84-1EN84-1 0.9 0.9 abcdabcd 1.8 1.8 abab 1.1 1.1 bcbc

2 wk2 wk EN84-2EN84-2 0.70.7 ab ab 0.60.6 a a 0.50.5 a a

1 wk1 wk EN84EN84 1.7 1.7 ee 1.5 1.5 abab 2.0 2.0 dd

1 wk1 wk EN84-1EN84-1 1.5 1.5 dede 2.1 2.1 bb 1.8 1.8 cdcd

1 wk1 wk EN84-2EN84-2 0.70.7 abc abc 0.70.7 a a 0.50.5 a a

2 days2 days EN84EN84 1.4 1.4 bcdebcde 1.6 1.6 abab 1.6 1.6 cdcd

2 days2 days EN84-1EN84-1 1.8 1.8 ee 2.0 2.0 abab 2.1 2.1 dd

2 days2 days EN84-2EN84-2 1.41.4 cd cd 1.21.2 ab ab 0.90.9 ab ab

0 day0 day EN84EN84 2.6 2.6 ff 3.73.7 c c 3.13.1 e e

0 day0 day EN84-1EN84-1 2.4 2.4 ff 4.7 4.7 cdcd 2.9 2.9 ee

0 day0 day EN84-2EN84-2 4.0 4.0 gg 5.8 5.8 dd 4.0 4.0 ff• Within- column values sharing the same letter do not differ significantly (multiple comparisons)

CONCLUSIONSCONCLUSIONS

Among the CCA components for the 3 Among the CCA components for the 3 laboratory leaching tests, the order of laboratory leaching tests, the order of leaching severity was: Cr > As > Cu.leaching severity was: Cr > As > Cu.

EN84-2 method gave expectedly milder EN84-2 method gave expectedly milder leaching than EN84 and EN84-1.leaching than EN84 and EN84-1.

No significant difference (P<0.05) in CCA No significant difference (P<0.05) in CCA leachability between methods EN84 and leachability between methods EN84 and EN84-1EN84-1

Wood blocks (4 wk fixation / EN84-2 Wood blocks (4 wk fixation / EN84-2 method) showed the lowest CCA method) showed the lowest CCA components leaching.components leaching.

Obviously, wood blocks (0 day fixation / Obviously, wood blocks (0 day fixation / EN84-2 method) showed the highest CCA EN84-2 method) showed the highest CCA components leaching.components leaching.

Overall increasing storage period improves Overall increasing storage period improves CCA fixation (reduces leachability) but CCA fixation (reduces leachability) but does not appear to completely fix CCA on does not appear to completely fix CCA on to Kempas heartwoodto Kempas heartwood

ACKNOWLEDGEMENTACKNOWLEDGEMENT

Unimas Fundamental Research Grant Unimas Fundamental Research Grant

Unimas Postgraduate Fellowship for H.C.LaiUnimas Postgraduate Fellowship for H.C.Lai

Mr Nigel Lim from Sarawak Forestry Mr Nigel Lim from Sarawak Forestry CorporationCorporation

IUFRO SAP partial travel support donated by IUFRO SAP partial travel support donated by Korea Forest Research Institute (FRFI)Korea Forest Research Institute (FRFI)

THANK YOU!THANK YOU!