Re: On the topic of fly ash

[Alan Muller <amuller@dca.net>]

At 11:57 8/4/98 -0400, you wrote:
> At 08:57 AM 8/4/1998 -0400, you wrote:
>>Does anyone have any idea what players in the incineration business mean
>>when they describe fly ash as being 'neutralized'?  Canadian Waste
>>(formerly Laidlaw) uses a patented technique to 'neutralize' bottom and fly
>>ash prior to shipping the ash off to landfill.  The claim is that this
>>technique 'renders bottom ash non-hazardous'  - not clear what becomes of
>>the fly ash.  Because the method used is patented, community members have
>>been denied any explanation of what exactly is done to the ash.  
>>
>>Anyone have any understanding of this method and whether it really does
>>render  bottom ash non-hazardous?
>
>
>This probably refers to the practice of adjusting the pH of MSW ash upward
>by using lime as an additive.    In general, toxic metals contained in the 
>ash are less available for leaching at higher pH levels.    However even this
>technique is not likely to be of much use if the MSW ash is co-disposed with 
>ordinary solid waste.

More directly, this usually refers to the (controversial) practice of
mixing the bottom ash with spray dryer residue/fly ash.  An excess of lime
is present due to amounts needed for acid gas removal.  Many feel that EPA
gave the garbage incineration industry a free ride by allowing testing of
mixed bottom/fly ash at a pH level that minimizes availability of metals
but isn't likely to prevail long-term in landfills.

am