Comparison of Environmental Impacts Comparison of Environmental Impacts of Wood Treated with CCA and Three of Wood Treated with CCA and Three Different Arsenic-Free PreservativesDifferent Arsenic-Free Preservatives

Brajesh K DubeyBrajesh K DubeyGraduate Research AssistantGraduate Research Assistant

Dept. of Environmental Engineering SciencesDept. of Environmental Engineering SciencesUniversity of FloridaUniversity of Florida

Pressure Treated WoodPressure Treated Wood

• CCA : Chromated Copper ArsenateCCA : Chromated Copper Arsenate

• ACQ : Alkaline Copper QuaternaryACQ : Alkaline Copper Quaternary

• CBA : Copper Boron AzoleCBA : Copper Boron Azole

• BoratesBorates

Research ObjectivesResearch Objectives

• Compare and contrast the potential Compare and contrast the potential environmental impact of CCA-treated wood environmental impact of CCA-treated wood with that from wood treated with ACQ, CBA with that from wood treated with ACQ, CBA and Boratesand Borates

• Three specific scenarios will be evaluatedThree specific scenarios will be evaluated

Proposed ScenariosProposed Scenarios

1.1. Impact on soil from pressure treated wood Impact on soil from pressure treated wood structures (Deck Study) structures (Deck Study)

2.2. Impact on natural aquatic systems: Leaching Impact on natural aquatic systems: Leaching of treated wood in natural water bodiesof treated wood in natural water bodies

3.3. Impact on disposal in MSW landfillsImpact on disposal in MSW landfillsa) Leaching in MSW landfill leachatea) Leaching in MSW landfill leachateb) Simulated Columnsb) Simulated Columns

Impact on Soil (Deck Study)Impact on Soil (Deck Study)

Approach:Approach:

• Decks are being constructed with the wood Decks are being constructed with the wood treated with CCA, ACQ, CBA and borates treated with CCA, ACQ, CBA and borates

• Deck will be placed on soil in a controlled Deck will be placed on soil in a controlled environment (tub)environment (tub)

• An untreated wood deck and a soil only tub are An untreated wood deck and a soil only tub are used as controlsused as controls

• Leachate samples will be collected periodically Leachate samples will be collected periodically and analyzed for copper, chromium, arsenic and and analyzed for copper, chromium, arsenic and organic biocidesorganic biocides

Tubs to hold the decks for leachate collection

Elevation View

Leachate collectionLeachate collection

Sample collection

SoilDrainagematerial

5° Elevation

GeomembraneGeonet

Deck Study Cont…

• Runoff from decks will be collected and Runoff from decks will be collected and analyzed for As, Cu, Cr, and organicsanalyzed for As, Cu, Cr, and organics

• Surface soil and core samples will be collected Surface soil and core samples will be collected at the end of experiment and analyzed for total at the end of experiment and analyzed for total metal and organic biocides contentmetal and organic biocides content

• Toxicity analysis will be conducted on all Toxicity analysis will be conducted on all samples using MetPLATEsamples using MetPLATETMTM

Impact on Natural Aquatic SystemImpact on Natural Aquatic System

Leaching of treated wood in natural water Leaching of treated wood in natural water bodiesbodies

Approach:Approach:

• Wooden blocks of CCA, ACQ, CBA and borate Wooden blocks of CCA, ACQ, CBA and borate treated wood will be leached with natural water treated wood will be leached with natural water collected from different water bodies in Floridacollected from different water bodies in Florida

• For comparison these blocks will also be For comparison these blocks will also be leached with DI and Moderately hard water leached with DI and Moderately hard water (Evian)(Evian)

Impact on Natural Aquatic SystemImpact on Natural Aquatic System

• Metals, organic biocides content and toxicity Metals, organic biocides content and toxicity using MetPLATEusing MetPLATETMTM will be evaluated in the will be evaluated in the leachate producedleachate produced

Impact on Disposal in MSW landfill Impact on Disposal in MSW landfill

Leaching with landfill leachate Leaching with landfill leachate

ApproachApproach

• Generate sawdust samples from treated wood Generate sawdust samples from treated wood lumber: CCA, ACQ, CBA and Boratelumber: CCA, ACQ, CBA and Borate

• Perform TCLP, SPLP, WET and leaching Perform TCLP, SPLP, WET and leaching with 34 different MSW leachatewith 34 different MSW leachate

• Compare Metal leaching under different Compare Metal leaching under different environmentsenvironments

Impact on Disposal in MSW LandfillImpact on Disposal in MSW Landfill

Simulated ColumnsSimulated Columns

Aim: To find out whether the high copper Aim: To find out whether the high copper concentration in the treated wood shows up in concentration in the treated wood shows up in the leachatethe leachate

Approach:Approach:

• A lab-scale lysimeter experiment will be A lab-scale lysimeter experiment will be conductedconducted

• 6 lysimeters will be setup6 lysimeters will be setup

Simulated Columns ContSimulated Columns Cont…

• Columns will be immersed in a water-Columns will be immersed in a water-bathbath

• Temperature will be controlled in the Temperature will be controlled in the water bath initially at 30water bath initially at 30ooC and later on at C and later on at 5555ooC when pH stabilizesC when pH stabilizes

• Leachate produced will be analysed for Leachate produced will be analysed for leachate quality parametersleachate quality parameters