[USCC] Energy from wet sludge - look to St Paul Minn

[Maureen Reilly]

Dear Compost Companions,

Sludge can be used for energy...and the economics of doing so can be 
attractive.
I used to say, "aint nothing cheaper than haul and dump" but with
higher fuel prices this is no longer true.

The fact is that sewage sludge is being utilized as fuel very successfully  in a number of places.
 For instance:  St Paul's Minnesota has found that the least expensive 
 method to manage their sludge is the AEE Von Roll CH2MHill award winning technology they 
have now installed.

This is cheaper than land application.  They use the digested sludge to 
 fire the plant and use turbines to generate energy and have the capacity 
 to distribute heat as energy (should there be a use for it locally).  The 
fuel bill has been reduced substancially  ($2 million per year) at the 
plant.

Trucking costs and fuel prices are spiralling. Using this dewatered sludge 
(cake) as a fuel is working so well that they won an award. I understand 
that in addition to the energy benefit (which isn't even fully optimized 
at the St Paul plant) there is a capture of over 99 % of the mercury and 
99% of the dioxins from the sludge...so those contaminants are not 
 released on farmlands. All those nasty pathogens,  the heavy metals and 
 hormone disruptors are not smeared on farm fields.

 Also the methane that would be released by sludge (about 34lb/ton of 
 sludge) is not released as a greenhouse gas.
So this is Kyoto friendly.

 To read about how they save $2million per year in energy costs:
 http://www.metrocouncil.org/Directions/water/water2004/incinerators.htm

 To read and about the Engineering Awards go to:
 http://www.acecmn.org/Current%20Year%20Awards/Awards2006.htm

about how the plant saves money and the environment:
http://www.ema-inc.com/communicators/com_fall02.htm#FORESIGHT

 Now...the latest news is that two American cities are getting a treatment 
 for their sludges that involves putting undigested sludge through a filter 
 that separates the water and the solids fraction.
 The water will be used for watering lawns, parks or industrial uses, while 
 the solids fraction will go to a gassifier for energy.  When I have 
 permission to release the info I will provide the details to this forum.


 Rufus can rant about zealots if he cares to...but he is the one who can't 
 seem to understand the science and finances of sludge and energy.  He apparently doesn't have 
 the last word with Mother Nature, either.

 Me?  I still want to see waterless composting toilets come into greater 
 use. Combining industrial and toilet waste is the heart of the problem. 
 We should keep our toilet waste and our liquid industrial wastes 
 separate....Then our human manure, if properly managed...could take its 
 proper place on the soil without soil contamination.  

Composting toilets - go to it!!


 Maureen Reilly