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Re: Bioremediation or inorganic treatment?



Sherry,

I am unaware of chemical treatment options. The standard approach is to
design the capabilities into a biological wastewater treatment system. The
process is called nitrification / denitrification. Nitirification is the
conversion of urea and ammonium compounds into nitrites and nitrates
through oxidation (turns R-NH3 molecules into R-NO+ and R-NO2). This occurs
naturally in the biological treatment process, but if concentrations of NH3
are high, extended aeration times may be required. Denitrification converts
the NO and NO2 compounds in to nitrogen and oxygen molecules (N2 and O2)
which bubble to the surface and dissipate. For a system to do this, a zone
must be provided in the system where there is no aeration. Thus when
dissolved oxygen levels in the wastewater drop to zero or near zero, the
bacteria that are breaking down the waste begin to scavenge oxygen from the
nitrite and nitrate compounds turning them into nitrogen and oxygen gases
which go off into the atmosphere. The duration of the wastewater's
residence time in this quiescent zone is directly proportional to the
concentration of nitrites and nitrates (including those added in the
nitrification step).

If your application includes spray irrigation or the use of a sand mound or
other groundwater based approach, you will want to be very certain that you
are able to treat to less than the effluent limit of 10 ppm nitrates.
Nitrate levels above 10 ppm put well users at risk. Pregnant women that
consume high nitrate water (from wells, either public or private) put their
fetus at risk of "blue baby syndrome".

Hope this is helpful.

Warren

>P2techers:
>I'm dealing with a manufacturer that has a waste stream with high
>nitrites and nitrates.  Can anyone advise on a biodegradation (bug)
>system/vendor this company might use in their wastewater ponds
>(permitted industrial ponds)?  Their ponds were undersized and they
>are looking at biotreatment to reduce the nitrate levels so that some
>of this wastewater can be sent to their local POTW.
>I would also like to know if there is a chemical WWT (wastewater
>treatment) option here?
>the wastewater stream is about 2500g/d, 4 days a week; wastewater
>also has charcoal in it.  Have looked at land application and
>commercial WWT options already.
>I will be working with this company on an alternative cleaning
>process (dry cleanup for pre-clean) and ways to reduce contaminate
>loading, so will be looking at P2 options.
>If you have experience with de-nitrification systems please email me
>directly.
>Thanks,
>Sherry Davis
>