1. Polychlorinated Biphenyls (PCBs)
Synthetic aromatic, chlorinated hydrocarbons
Produced by directly chlorinating biphenyl
209 possible PCB compounds – likely see ~130
Monsanto Corporation made 50% of world’s PCBs and 100% of US PCBs
“Arochlors” with a 4 digit number (eg. Arochlor 1254)

4. Properties Oily liquids to waxy solids Low solubility in water
Highly soluble in lipids and polar solvents
Non-flammable, high boiling points, low electrical conductivity
Chemically and thermally stable
Industrial applications
1.5 billion pounds manufactured in US

5. Environmental Concern
Early 1970s, concern over accumulation of PCBs in environment
Had been determined to be a human carcinogen
1976 Toxic Substances Control Act (TSCA) banned manufacture of PCBs and PCB-containing products
Legislated “cradle to grave” (i.e., manufacture to disposal) management of PCBs in the US

6. Bioremediation of PCBs
Various microbial cultures capable of aerobic PCB biodegradation
Up to 85% degradation of Arochlors 1248 and 1242 shown
No significant aerobic biodegradation of Arochlors 1254 and 1260 in lab or field
Anaerobic degradation is widespread
Combination anaerobic/aerobic sequential biodegradation procedure may have most promise

7. Bioremediation cont. Studies began in early 1970s
Achromobacter species from sewage were first shown to degrade PCBs
Nocardia, Pseudomonas, Alcaligenes, Acinetobacter and various mixed cultures able to degrade highly chlorinated PCBs
Up until the 1980s, many different bacteria capable of degradation of mono-, di-, and trichlorobiphenyls
Major breakthrough was study in the Hudson River

9. Hudson River PCB Story

10. Hudson River Bioremediation
73 day study in early 1990s
6 caissons
Assessed addition of O2, N, P, biphenyl, PCB-degrading bacteria
Assessed effects of mixing rate
Tested for metabolic intermediates

12. Results – Bacterial Community
Addition of O2 and nutrients stimulated biphenyl utilizers
Total cfu <100 to 108 per liter
Alcaligenes eutrophis (PCB degrader) didn’t survive when added to sediments
Added 108 cfu/mL and dropped to <105 cfu/ml in 10 days

13. Results – PCB Degradation
Statistically significant changes in PCB concentrations in all caissons
Approximately 40% decrease in PCB concentration in low mix caisson
Found chlorobenzoate intermediates in experimental caissons
Did not find chlorobenzoates in high mix caissons

14. Taken from: http://www.nwri.ca/sande/may_jun_2002-2-e.html

15. Phytoremediation Overview

16. Phytohydraulics

17. Phytodegradation

18. Phytoextraction

19. Phytostabilization

20. Phytovolatalization

21. Rhizodegradation

22. Rhizofiltration

24. Phytoremediation practice
Normal plant
Engineered plant thrive on arsenic
Poplar trees