Potassium permanganate to oxidize phenol from landfill leachate as treatment process

Ask the Expert Question: 

We would like to use potassium permanganate (KMnO4) to oxidize phenol from landfill leachate as a treatment process (i.e. reduce phenol below POTW required limits) prior to sending leachate to a local POTW. However, we are not sure what could potentially be formed when the KMnO4 oxidizes the phenol and how these subsequent formation products should then be removed. 

Expert Response: 

The reaction product of phenol and permanganate will be 1,4-benzoquinone. It is not regulated, and I suspect that it will be degraded in a biological treatment system. Since your treated leachate is going to a POTW, this should be sufficient to eliminate both the phenol and the by-product.

Ask the Expert Question: 

We also would need to know what potassium permanganate (KMnO4) would do to ammonia, cyanide, hydrogen sulfide and dissolved metals which are also present in the leachate at lesser concentrations than the phenol. 

Expert Response: 

Regarding the reaction of permanganate with the other constituents, I would expect ammonia to be oxidized to nitrate, cyanide to carbon dioxide and nitrate, and sulfide to sulfate. 

With the metals it would depend on the specific metals and their oxidation states.  For example, the leachate probably contains some dissolved ferrous iron because the landfill will be a reducing environment. The reaction with permanganate will convert this ferrous iron to ferric iron, and that would almost certainly result in a ferric oxide precipitate. These constituents are likely to react with permanganate more quickly than phenol, so you will have to add sufficient permanganate to oxidize these before you will get thorough oxidation of the phenol.