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)

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

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

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

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

Hudson River PCB Story

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

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

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

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

Phytoremediation Overview

Phytohydraulics

Phytodegradation

Phytoextraction

Phytostabilization

Phytovolatalization

Rhizodegradation

Rhizofiltration

Phytoremediation practice Normal plant Engineered plant thrive on arsenic Poplar trees