[USCC] Food Waste Digestion

[Tim Evans]

Hi Ron,

I don't know whether there are an anaerobic digestion units operating in
North America which are primarily digesting food waste but if there aren't
there should be.  AD of food waste (with CHP) generally has a better
environmental footprint than composting, though to be economic the facility
has to be quite large (>10,000 t/year).  Some wastewater treatment plants in
USA are starting to co-digest food waste and sewage sludge.  This is a great
way to get more out of existing assets.  Pressure cooking the feed first
(Cambi thermal hydrolysis) increases biogas production and enable two or
three times the solids loading.  Unfortunately most USA digesters have a low
aspect ratio ("pancakes") so mixing is more difficult than taller narrower
digesters.  A key feature is to screen out any plastic before the feed goes
into the process.  The best kit I have seen for that is Dewaster, developed
in Denmark and now owned by Hese Umwelt.

It might be new in the USA but there is at least 10 years' experience in
Europe; with all of the associated mistakes that can be learnt from!  As you
know, it can be as cheap to fly 3000 miles across the Atlantic as it is to
fly 4000 miles across the USA.
 

regards


Tim

 
Dr Tim Evans
TIM EVANS ENVIRONMENT
Stonecroft, Park Lane, Ashtead, Surrey KT21 1EU England
tel/fax +44 (0) 1372 272 172 mobile +44 (0) 7816 833 991
tim at timevansenvironment.com


-----Original Message-----
From: Ron Alexander [mailto:alexassoc at earthlink.net] 
Sent: 24 September 2006 12:49
To: compost at composter.com
Subject: [USCC] Food Waste Digestion


Hello Compost World,
Does anyone know if there are any digestion units operating in North America
which are primarily digesting food waste?
Thanks,
Ron


Ron Alexander
R. Alexander Associates, Inc.
1212 Eastham Drive
Apex, NC 27502
USA
919-367-8350 - office telephone
919-367-8351 - fax
919-349-0460 - mobile telephone
alexassoc at earthlink.net - e-mail address
www.alexassoc.net - website address


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