[Digestion] landfill vs. AD

Wed May 2 01:28:35 CDT 2007

Dear Jason,

just a small comment:
There are two types of organic wastes collectable in households, first  
is kitchen waste which is usually very suitable for AD and second  
garden waste which is not as appropriate for AD but for that home  
composting should be promoted.
For cow manure it is right that it is already digested, however there  
is still a  significant potential for AD and it is a good basic liquid  
substrate for AD to add solid organic wastes.

For the alternatives I highly agree with the others that a central AD  
plant or cell only for kitchen and other biodegradable wastes is the  
better idea. Landfills pose a lot of problems, after closing them they  
produce biogas in very small amounts for centuries as well as  
contaminated leachate wastewater to be treated.

Claudia

Jason Perry schrieb:

>Thanks Duncan. This is purely academic at this stage, and I appreciate 
>your input. My question is really more about comparing the efficacy of 
>the two methods in terms of useful methane output per amount of matter 
>input. I agree, the transport schemes won't be exactly the same.
>
>However, in this particular town there is no landfill, just a transfer 
>station -- the landfill is run by the county in a different town. Most 
>residents drive their rubbish and separated recyclables to the transfer 
>station every Saturday. There is some curbside collection (taken 
>directly to the landfill) but I think it's the exception. So, if people 
>were convinced to source separate their food waste in a different 
>container, and a central AD were set up at/near/on the way to the 
>transfer station, then the transport scheme would be about the same.
>
>As it is there is no official separation of kitchen waste, and the 
>county does not plan to encourage it because they are implementing a LFG 
>energy recovery system this year. There is some voluntary home composting.
>
>The reason I suggested co-digestion with cow manure is that the town has 
>nearly as many dairy animals (about 4500) as it does people (about 
>6000). Unless I am grossly mistaken the amount of food waste from 
>households is dwarfed by the quantity of cow manure.
>
>Cheers,
>Jason
>
>Duncan Martin wrote:
>  
>
>>Hi Jason
>>
>>But a similar transport scheme seems highly illogical. Have I read 
>>your proposal aright?
>>
>>If the vast majority householders can be persuaded to segregate their 
>>biowaste efficiently (challenging!) and you set and pay for a separate 
>>collection system, then an AD plant is a good option. It would be daft 
>>to go all that trouble then dump it in a landfill - with all the stuff 
>>you've kept it apart from.
>>
>>Landfill with LFG collection and use might be preferable (under US law 
>>- but not in EU) where the biowaste is left in mixed waste or in a 
>>residual waste fraction.
>>
>>However, if you had in mind some kind of biowaste AD cell within a 
>>landfill site, my own research suggests that it would biodegrade much 
>>more slowly than in a mixed landfill, because rapid acidification 
>>would effectively ensile it.
>>
>>Duncan J Martin
>>
>>Chair
>>Republic of Ireland Centre
>>Chartered Institution of Wastes Management
>>
>>================================
>>CONTACT DETAILS
>>Duncan J Martin, PhD, CEng, CSci, MIEI, MCIWM, MIChemE
>>24 Townsfield, Cloughjordan, N Tipperary, Ireland
>>Mobile: +353 86 8377 906
>>Home: +353 505 42087
>>Email: duncanjmartin at eircom.net
>>================================
>>
>>
>>
>>
>>
>>
>>----- Original Message ----- From: "Jason Perry" <perry.jason at gmail.com>
>>To: <digestion at listserv.repp.org>
>>Sent: Friday, April 27, 2007 4:54 PM
>>Subject: [Digestion] landfill vs. AD
>>
>>
>>    
>>
>>>Dear AD Listers,
>>>
>>>I may have asked this question in some form before, but I thought I'd
>>>rephrase it.
>>>
>>>Consider a rural town in the Northeastern US. If you had a choice
>>>between 1) sending the town's domestic food waste to a landfill that
>>>collects its gas and runs a generator, or 2) sending it to a central AD
>>>that co-digests food waste and dairy manure and runs a generator, which
>>>do you think is a better use of the food waste in terms of energy
>>>production? Assume similar transport schemes between the two.
>>>
>>>Many thanks,
>>>Jason Perry
>>>
>>>_______________________________________________
>>>Digestion mailing list
>>>Digestion at listserv.repp.org
>>>http://listserv.repp.org/mailman/listinfo/digestion_listserv.repp.org
>>>
>>>
>>>
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>>>      
>>>
>>    
>>
>
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>  
>

-- 
***********************************************************
Claudia Wendland
Institute of Wastewater Management and Water Protection
Hamburg University of Technology
Eißendorfer Straße 42
21073 Hamburg
Tel:+49 40 42878 3441
Fax:+49 40 42878 2684
c.wendland at tuhh.de
www.tu-harburg.de/aww
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