[Digestion] landfill vs. AD

[Jason Perry]

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
>>
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