nano silicate to remove Se in FGD wastewater?

[davefitz]

Is there any truth to the rumor that the additon of nano silcate to the FGD wastewater stream will precipitate selenate and selenite?

 

[orenda1168]

I can't speak to nano silicate as a Se removal mechanism, but there has been some Japanese work with the use of lanthanum, probably as the chloride, for this purpose.

Orenda

 

[davefitz]

There are reports that nano-silicates will lower the water ORP to -550 mV to -860 mV, and oxidize and precipitate all selenate and selenite. I have also recieved reports that this is also achieved using nano-titania. I'm looking for a published paper or other written confirmation.

 

[chemgirl5789]

I don't know about nano silicate, but I found a patent for selenium removal in FGD wastewater using ferrous ions.

http://www.freepatentsonline.com/6235204.html

I've done similar testwork and have had success with it.

 

[luckobucko]

I have seen consistent removal results of >95% removal of Se with iron co-precipitation in FGD wastewater. This is operating full scale at ~500gpm blowdown from FGD using ferric chloride and polymer as coagulant.

 

[davefitz]

luckobucko:

that sounds almost too good to be true- I thnk it depends on the particular form of Se that is present in the FGD purge.

Other means being studied, besides bioreactors, is a trickle filter ( packed bed) of AC activated carbon or , better yet, sawdust or powdered torrefied wood dust.