I was wondering if there is any natural process which breaks down PCBs (Polychlorinated biphenyl).

This is an extremely harmful contaminant that was pumped into various lakes by chemical plants up until about the 1950s. It is very stable, which is why it was used a coolant in these chemical plants. However this toxic substance has greatly impacted lake systems, as the concentration of the PCB is increased in each trophic level of the lake ecosystem (due to biomagnification). Anyways, I was wondering if there was any method to break down the PCBs.

Since they are a chlorine-containing compound, would I have to use something like a sodium or potassium based compound to safely break them down chemically. What do you guys think? Thanks!

  • $\begingroup$ Have a look at advanced oxidation processes, such as Fenton and photo-Fenton reactions, as well as photochemical degradation processes using titanium dioxide. $\endgroup$ – Klaus-Dieter Warzecha Oct 12 '16 at 4:55
  • $\begingroup$ Thanks so much. This is a good idea. I will look into this and post results! $\endgroup$ – manavjain8 Oct 14 '16 at 22:09
  • $\begingroup$ The problem is complex. PCBs would be easy to chemically decompose if you could isolate them. But some chemical that you'd put in a lake or river would have to be at high concentration and be more toxic than the PCBs. If you try to dig up the sediment in the Hudson River for 100 miles that is just an impossible task. That frankly is why we need the EPA. The only real answer is to prevent such pollution in the first place. $\endgroup$ – MaxW Mar 2 '17 at 7:25

According to this abstract$\mathrm{^{[1]}}$, both aerobic and anaerobic processes play a role in the natural degradation of PCB's.

Studies have identified two distinct biological processes capable of biotransforming polychlorinated biphenyls (PCBs): aerobic oxidative processes and anaerobic reductive processes. It is now known that these two complementary activities are occurring naturally in the environment. Anaerobic PCB dechlorination, responsible for the conversion of highly chlorinated PCBs to lightly chlorinated ortho-enriched congeners, has been documented extensively in the Hudson River and has been observed at many other sites throughout the world. The products from this anaerobic process are readily degradable by a wide range of aerobic bacteria, and it has now been shown that this process is occurring in surficial sediments in the Hudson River. The widespread anaerobic dechlorination of PCBs that has been observed in many river and marine sediments results in reduction of both the potential risk from and potential exposure to PCBs. The reductions in potential risk include reduced dioxinlike toxicity and reduced carcinogenicity. The reduced PCB exposure realized upon dechlorination is manifested by reduced bioaccumulation in the food chain and by the increased anaerobic degradability of these products.

1) Aerobic and anaerobic PCB biodegradation in the environment, Environ Health Perspect. 1995 Jun; 103(Suppl 5): 97–99

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