Groundwater BTEX Removal

[caneng2002]

I'm doing a preliminary selection on process units for the removal of BTEX contaminents (Benzene, Toluene, Ethyl-Benzene, and Xylene) from a potential groundwater source.

The recorded levels have been actually been below the drinking water standards. So why am I considering treating it? Well client/consultant has yet to take many water samples but a nearby aquifer was contaminated by a LUST (Leaking Underground Storage Tank) from an old gas station. So under the belief of "where there's smoke, there's fire" I'm hedging my bets and allowing for treatment at the preliminary stage.

The first process that comes to mind for organics removal is GAC and ultra-filtration. However a search on the net returned a hit for a proprietry product called "Nochar" which basically said the GAC blinds up to quickly.

Any comments on removal processes?

 

[vintage70]

Can,

There are different methods to remove BTEX from groundwater. There are in-situ processes where you inject the treatment and monitor. But the classic method is the air stripper with vapor phase GAC. If you can pumped the water out then you pretty well assured of success. There's not as many contraints as in the others. Costs are relatively average to low. I have even applied an air bubbler in a closed tank and got good results. There are tray air strippers that are configured as a box as opposed to the typical column. Liquid phase GAC can get expensive.
Stay in touch.

V

 

[lafroste]

You did not specify if you want a continuous pumping operation (as in a water supply well), in-situ (as in strict remediation), or a pump and treat (extraction just for treatment, then discharge to a municipal storm sewer). I assume that you want a water supply, and that supply must be treated first.
I would suggest looking at a continuously regenerable GAC system followed by the appropriate amount of filtration for desired water quality.
My son is insisteing I stop now, so let me know if you are interested in discussing this further.

 

[caneng2002]

Thanks for your comments "Vintage70" and "Lafroste".

The project hydrogeologist recently dug two new wells upgradient from the LUST. Following a week long pump test (in dry weather) no hydrocarbons were detected. The only water quality issues to deal with at the new wells are low levels of colour (5 TCU )and manganese (0.09 mg/l). So the water treatment process has become somewhat simpiler using polyphosphate for sequestering followed by chlorination for disinfection.