BIOREMEDIATION OF SOILS CONTAMINATED with CHEMICAL

MIXTURES

Thavamani Palanisami

To my supervisory committee:To my supervisory committee:

Prof. Megharaj MallavarpuProf. Megharaj Mallavarpu, Director, CERAR, Director, CERAR

Prof. Ravi NaiduProf. Ravi Naidu, Managing Director CRC CARE , Managing Director CRC CARE

Mr. Ross McfarlandMr. Ross Mcfarland, , National Practice Leader, HLA ENSR

Acknowledgements

CERAR

ENVIROPACIFIC SERVICES

Structure

Introduction

Objective of the study

Methods

Results

Conclusion

Work in progress

Introduction

• Almost all contaminated soils contain a mixture of toxic

substances

• However, current focus of toxicological studies and

remediation is single toxic substances;

• Mixed contaminated systems can be extremely toxic to

environment and a challenge to remediate.

• One example of such a system is the gas work sites

containing PAHs and other inorganic toxic chemicals.

The adverse effect of mixed chemicals is demonstrated by the recent death of Heath Ledger from ingestion of mixture

of tablets

• Successful remediation of PAH contaminated soils requires a thorough understanding of both the biochemo-dynamics of PAHs as single series compound as well as its interaction with other chemicals present at gas work sites

Introduction.. ctd

Objective

To study the science

underpinning the bioremediation

of certain mixed contaminants

(specifically PAHs and heavy

metals) and develop suitable

remediation methods for mixed

contaminated soils.

Cd, CN

Research Milestones

2.2.2. Laboratory based development of bioremediation technology for organic contaminants

2.2.3. Isolation of novel metal(loid) resistant, organic contaminant detoxifying microbes.

Commercial milestones

2.3.1 Isolation of novel aerobic and anaerobic POP degrading microorganisms

2.3.2. Isolation and characterisation of novel POP degrading microorganisms

Milestones addressed

Methods

• Characterization of contaminated soils.

• Evaluation of toxicity and bioavailability in spiked soils with known concentrations of PAHs and metals

• Testing the toxicity of selected PAHs and metals using novel scientifically-defensible methods.

• Enrichment and isolation of PAH degrading bacteria that are highly resistant to selected metals.

• Bioremediation of PAHs in liquid as well as soil microcosm using MGP site soils

• 9 gas work contaminated soils were investigated

• Considerable variation in the concentration of PAHs and metals in the study soils

PAHs (mg/kg) Heavymetals(mg/kg)

LMW HMW Pb Zn Cr As Cd Ni Cu

790

(107-2299)

1884

(201-6345)

277

(93-671)

183

(63-488)

159

(33-378)

6

(4.5-8.5)

47

(8-112)

92

(28-229)

39

(18-57)LMW- Low molecular weight PAHs (up to 3 benzene rings in structure); HMW- High molecular weight PAHs (more than 4 benzene rings in structure)

Results

I. Soil Characterisation

• Model PAH compounds : Phenanthrene and Pyrene Metal : Cadmium

• Experiment was conducted in a modified microbial media optimised for maximum free Cd

• Parameters recorded: Growth, Protein, PAH concentration

• Experiment was conducted in duplicate and repeated twice

II.PAH degradation in presence of Cd by pure culture

Phenanthrene degradation

Pyrene degradation

Co-degradation

Conclusion

•Isolated cultures were able degrade PAHs in presence of toxic levels of cadmium

•The isolated cultures have potential to apply in bioremediation of MGP site soils

Work in progress

• Bioremediation of MGP site soils in microcosm

• Effect of PAH-metals on gene expression of earthworm

• Elucidating interactions of PAH-Metals

• PAH degradation pathway

• Algal diversity in MGP soils and its role in PAH degradation