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[GreenYes] Re: Food outside the pipe.

Hi Matthew ~

Thanks for your note. I don't think that it is 'double counting' to count VOCs from yard materials composting systems if the same amount of VOC also occurs in nature. Instead, the tally would occur under columns for both centralized composting and composting by nature in the forest or field. The DST also looks at the VOCs from landfills, and concludes that they are much lower than from composting sites. I don't know why -- which was the basis for my question; I would like hard data, rather than 'gut instincts'.

I will send you the report via separate email, since this list serve doesn't allow attachments.

I think that the fact of whether all homes have garbage disposal units or not or use them 100% of the time is not focusing on the issue of what are the environmental impacts of the alternatives.

The Oakland proposal sounds interesting -- instead of transporting the food scraps via the sewer, they will be transported by truck? What are the environmental impacts of those alternatives? A PhD thesis done here found that the truck transport impacts are far greater than the sewer transport. You could borrow it through ILL, I believe. If you want the citiation, let me know.

Best wishes,


-----Original Message-----
From: Matthew Cotton [mailto:mattcotton@no.address]
Sent: Friday, August 11, 2006 2:46 PM
To: 'GreenYes'
Cc: Reindl, John
Subject: Re: [GreenYes] Re: Food outside the pipe.

John -

Can you share the report? I'd love to see it. Yes, composting organic materials releases VOCs. However, one of the key questions to me is: If a tree (or a leaf) falls in the forest and no one is there to compost it, does it release any more or less VOCs? This is important because, from what I understand, regulatory agencies looking at this (at least in CA) believe that regulating VOCs from composting will help them achieve overall emission reduction targets. Supposedly the agencies account for naturally-occurring VOCs, but if the amount of VOCs released from composting is substantially the same as would be released naturally, we're not getting true emission reductions, we're just double counting. Another important question is what emissions would that same volume of organic material release in the anaerobic environment of a landfill? Since that is the likely destination for collected organic materials if they can't be composted (or if the required emissions controls are not cost-effective).

I would assume that a compost site would only generate significant NOx from burning diesel fuel to run grinders, turners, screens and trucks.

I haven't seen a good analysis of whether it is "better" to put food in the under-sink disposal and thus to the Wastewater Treatment Plant or in a separate container with the yard trimmings to be brought to the compost site. It would seem as if we have a very mixed system. Many (though I haven't seen reliable numbers) houses have under-sink disposers, but many don't. Even in those homes that do have them, I've seen some research (and it seems reasonable) that even in homes with under-sink disposers, people don't use them 100 percent of the time. This explains why most solid waste characterization studies continue to show plenty of food scraps in the solid waste stream. And as Rick pointed out, the Treatment Plant may or may not have the capacity to handle the increased load of food.

In Oakland, CA, a hauler and a wastewater treatment plant are experimenting with trucking source-separated commercial food scraps to the treatment plant for co-digestion with the other wastewater solids. It is believed that this practice may increase gas production. The remaining digested solids would then be composted (or land applied).

Matthew Cotton
Integrated Waste Management Consulting, LLC
19375 Lake City Road
Nevada City, CA 95959
(530) 265-4560
Fax (530) 265-4547

On Aug 11, 2006, at 12:09 PM, Reindl, John wrote:

Does anyone have a life cycle assessment of the environmental impacts of alternative methods of handling food scraps? Recently, we received a report based on the EPA Decision Support Tool that indicated that composting has a lot of negative impacts due to VOCs from the compost sites and, if I remember right, NOx.



PS - In my part of the country, we have not had the infiltration and dumping problems described below. Our POTW also has lots of capacity to handle more flow and the bio-solids are spread on ag land. How do the environmental impacts of such a system compare to establishing a separate storage, collection, transportation and processing system for composting food?

-----Original Message-----
From: GreenYes@no.address [mailto:GreenYes@no.address]On Behalf Of RicAnthony@no.address
Sent: Friday, August 11, 2006 12:38 PM
To: hspie@no.address; GreenYes@no.address
Subject: [GreenYes] Food outside the pipe.

In a message dated 8/9/2006 9:11:03 A.M. Pacific Daylight Time, hspie@no.address writes:Alan's concerns (which I share) relate to the likelihood that conventional sewer systems will sometimes fail.

Here is the problem;
1. early sewer connections did not require a lot of pre treatment (industrial chemicals)..
2. Original clay sewer pipers put in during the 60 ies are leaking (this is called infiltration). No problem in dry or average weather but in the big storm the water seeps into the pipes and they flow at full capacity which a treatment plant or wet well can not take for very long (capacity issues). When that happens the wastewater is diverted, usually to a holding basin and if necessary to a live stream.

During the big storms in SO CAL last year million of gallons of raw sewage was discharged into the ocean from San Diego to Santa Barbara.

Alan is right, taking the organics a and sorting them for composting is best practice and more consistently environmentally sound.

San Diego, California

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