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[GreenYes] Re: Anaerobic Digestion of Food Waste

I disagree with your characterization of the issue, since a core function of POTWs is processing of organics.  In contrast, landfills have a poorly controlled, poorly monitored process for tracking and capturing methane emissions.  Peter Anderson, who follows this issue closely, also notes that landfills try to boost methane production by adding moisture, but in the process drive up fugitive releases as well.
The fact that fats, oil and grease have historically been handled by truck is not an indication of why it makes sense to do this for other organics.  FOG is segregated from the sewers because they degrade and block collection systems.  (Now, they are so valuable as a biofuels feedstock that they are actually being stolen from restaurants).  I've not heard the same concerns about standard food scraps (though large food processing plants can be a problem and are governed by the pre-treatment program).
There may be situations where separate collection of food wastes is warranted.  However, I'd be surprised if this was generally the case.  I would want to see better technical data that, for many of the generators, the cost and emissions (the pickup trucks of course use lots of diesel) associated with the collection effort leaves you with a net benefit relative to "in pipe" delivery.  While EBMUD is smart to look at new ways to use their unused digesters, truck delivery is probably not the only option.
Doug Koplow
Earth Track, Inc.
2067 Massachusetts Avenue - 4th Floor
Cambridge, MA  02140
Tel:  617/661-4700
Fax: 617/354-0463

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>>> "Slote, Peter" <PSlote@no.address> 6/10/2008 3:30 PM >>>

Ann - Remember, the EBMUD model is for commercial/institutional sources of food scraps, so residents and their garbage disposal aren't in the picture. 

But yes, our residential food scraps collection program tries to rescue food scraps from the garbage disposal as well as from the garbage can/landfill.  Only, it goes directly to composting, along with the yard trimmings. 

The collection program for commercial food scraps is not unlike a high-grade commercial paper recycling program, which has route efficiencies and processing economics that distinguish it from, say, residential curbside recycling.  That's how I frame it up for recyclers.

Regarding commercial fats/oils/grease (FOG) from restaurants & institutions, EBMUD tries to capture that, too, and yes, via truck and not by the pipe.

As I recycler, find the idea that "we should put it all down the pipe" and get energy from the sewage plant eerily like the argument for sending mixed resources to landfills with gas recovery.

Again, the EBMUD model is not the global answer to best utilization of all organics discards.  But it's a great addition to the portfolio of ZW management options, entirely complementary with composting (which EBMUD sometimes neglects to articulate).

I hope you'll be contacted by an EBMUD rep who's associated with the project and can be a more definitive source of information on this project.  I hope I've added context from the recyclers' point of view.

Best regards - Peter

Peter Slote
City of Oakland Public Works Agency
Solid Waste and Recycling Programs
Ph  510-238-7432  Fax 510-238-7286
Visit now!

-----Original Message-----
From: Ann Schneider [mailto:schneiderann@no.address]
Sent: Tuesday, June 10, 2008 11:33 AM
To: Slote, Peter
Cc: Gary@no.address
Subject: Fw: [GreenYes] Re: Anaerobic Digestion of Food Waste


Thanks for your very thoughtful reply.  We will incorporate them into our

pending Compost Guidance.

What is Oakland's position on garbage disposals and have you or StopWaste

tried any education to get people to stop pouring food waste down the




--------- Forwarded message ----------

From: =?utf-8?B?R2FyeSBMaXNz?= <gary@no.address>


Date: Tue, 10 Jun 2008 16:39:05 +0000

Subject: [GreenYes] Re: Anaerobic Digestion of Food Waste




Sent via BlackBerry by AT&T

-----Original Message-----

From: pslote@no.address

Date: Tue, 10 Jun 2008 09:35:16

To:GreenYes <GreenYes@no.address>

Subject: [GreenYes] Re: Anaerobic Digestion of Food Waste Final Report


Ann - The City of Oakland Recycling staff has been consulting with

EBMUD on their commercial food scraps program.  Some issues:

1) Fully capitalized, existing digesters that aren't currently used

represent "stranded capacity" which EBMUD is planning to utilize with

source-separated, trucked-in food scraps from restaurants and

institutions, a high-value feedstock for energy production.  This is a

major part of the value proposition.  Interestingly, these digesters

have gone unused due to the flight of the food processing sector from

the EBMUD service area to the Central Valley.  Well, a lot of that

food is consumed here, and it's finding it's way back to these


2) Another critical part of the value proposition is that the solids

produced from digestion of source-separated food scraps can go to

existing composting facilities, ones that don't take bio-solids.

Furthermore, the solids from food scraps have been stabilized and

contain lower VOCs.  This is a great fit in the current environment of

tightening emissions requirements for composting facilities: it means

more tons can be composted at a fixed emissions threshold.

3) I've been told that these same food scraps sent "by the pipe" (via

sink disposals) degrade every step of the way creating fugitive


4) And of course, material sent by the pipe aren't source separated,

so a lot of potential value is lost. Source-separation is a hallmark

of highest-best use recycling.  Same thing applies, with

qualifications, to digestion of commercial food scraps.

This isn't a universal answer to management of all organic discards or

even all food scraps.  It is a great addition to the portfolio of

options for clean, source-separated food scraps, where treatment

capacity, and the other conditions supporting this effort in Oakland,


Peter Slote

City of Oakland Public Works Agency

Solid Waste and Recycling Programs

Visit now!

On Jun 8, 6:58 pm, Ann Schneider <schneider...@no.address> wrote:

> Hi ZWForum, CNRCC Energy & Climate Comm & GRRN:


> Just curious but what is the general feeling in the greater recycling

> community about sending food waste to sewage treatment plants (POTWs

> publically operated treatment works) so energy can be recovered and the

> end product I assume used as a soil amendment.  In the study just

> released below the food waste is kept separate from other materials

> entering the POTW so should be no cross contaimation with sewage



> If this is a good idea, we may want to add this to suggestions we are

> sending to Cool Cities as a good way for gargage and energy to work

> together aka achieve both composting and energy goals and


> goals (handling things close to the source) by getting each communities

> POTW to add this type of process to their operations.


> Ann Schneider

> Chair, National Zero Waste Committee

> Sierra Club

> Ann.Schnei...@no.address




> --------- Forwarded message ----------

> From: Peck.C...@no.address

> Date: Tue, 22 Apr 2008 12:37:01 -0700

> Subject: Anaerobic Digestion of Food Waste Final Report Available


> Greetings,


> The US EPA, Region 9 Office of Pollution Prevention and Solid Waste is

> pleased to announce the final report "Anaerobic Digestion of Food

> Waste."


> In 2006 EPA Region 9 awarded a $50,000 grant to East Bay Municipal

> District (EBMUD), a wastewater treatment facility in Oakland,


> to investigate anaerobically digesting food wastes from restaurants,

> grocery stores and other food-handling facilities at a wastewater

> treatment facility.  EBMUD bench-scale digesters were fed only food

> wastes, but were operated under a variety of conditions, varying

> digester loading rates, temperature, and other parameters.  The project

> recovered significant quantities of energy from food waste as well as

> high volatile solids reduction, showing the potential of diverting


> quantities of valuable food waste from landfills.


> The final report and a fact sheet summarizing the results can be found

> on our website



> Please feel free to contact me if you have any questions.


> Thank You,

> Cara Peck

> U.S. EPA Region 9

> Office of Pollution Prevention and Solid Waste

> (415)972-3382

> Peck.C...@no.address


> Recycling: It is not just about landfill diversion, it is about

> replacing virgin material production which will significantly reduce

> energy consumption and greenhouse gas emissions.


> Visa, MasterCard, AMEX & Discover. Compare Offers & Apply Online. Click


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> - Show quoted text -



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