Assessment of Biodegradability of Mulches

Sathiskumar Dharmalingam(MATERIALS WG)

Dr. Douglas G HayesSCRI MEETING,06/02/2011

Objective of My Research project

• To compare and understand fundamental aspect of Biodegradation studies in the open fields and high tunnels to greenhouse to ASTM D5988-3(Standard Test Method for Determining Aerobic Biodegradation of Plastic materials in soil or Residual Plastic materials After Composting)

• Improve methodology for biodegradation of agricultural plastics in the soil

Greenhouse Study II of Biodegradable Mulches(BDMs) at UTK

• Duration(15 week, started on 1st April,2011)• 3 Mulches (2 replicates of each)

– Meltblown(“MB”) Polylactic acid(PLA)i. 100% Polylactic acid (PLA)(W/W)ii. 75%PLA & 25%Polyhydroxybutyrate(PHB)

– Spunbond(“SB”-2011) PLA ------------> black(Low MW)(Dr.Wadsworth)

• 3 Soil treatments(Manure +Water, Manure + Water+ Pineapple juice(PJ) and Manure+ Water+ No Pineapple juice(PJ))

• Mulches buried 2 cm below surface of soil• Treatment per tray per 48 hr

RBD with sampling-Strip plot SOIL+

MB-75%PLA

1L H2O+

MB-100%PLA

PJ

SB PLA

SOIL+

MB-75%PLA

0.5L H2O+

MB-100%PLA

PJ

SB -PLA

SOIL+

MB-75%PLA

1L H2O+

MB-100%PLA

NO PJ

SB-PLA

SOIL+

MB-75%PLA

0.5L H2O+

MB-100%PLA

NO PJ

SB-PLA

SOIL+

MB-75%PLA)

0.5L H2O

MB-100%PLA

LOW MO

SB- PLA

SOIL+

MB-75%PLA

0.5 H2O

MB-100%PLA

LOW MO

SB- PLA

SOIL+

MB-75%PLA)

1L H2O

MB-100%PLA

HIGH MO

SB-PLA

SOIL+

(MB-75%PLA)

1L H2O

(MB-100%PLA)

LOW MO

(SB-PLA)

BDMsMB-100% PLA MB-75% PLA and 25% PHB

SB2011-PLA

With and Without PJ treatment trays after 2 months

High and Low moisture content trays after 2 months

Analysis on BDMs• Tensile strength(breakage and elongation)• BDM density g m-2

• Thickness• Change in Mol Wt-Gel Permeation Chromatography• Scanning Electron Microscopy• Soil moisture and Temp-Sensor• No air permeability• No porosity• No soil testing for week 15

ASTM D5988-3(Standard Test Method for Determining Aerobic Biodegradation in Soil of Plastic materials or Residual Plastic materials

After Composting)• Require a common microbe and soil type • Desiccator• CO2 measured by Ba(OH)2

• 3 replicates required Prospective:Will learn in July by visiting Michigan State University in Dr. Ramani Narayan’s lab.

Challenges in the prospective improved methodology

• Accelerate the biodegradation rate• Higher temperature(37oC??)• Inoculating selective microbes(Abiotic or

biotic) ????• Low scale?????

QUESTIONS?????