Doug - Yeah, I’m not a waste water treatment guy.
Ann asked for the view from recyclers, and I’m connecting her to folks at
EBMUD. Good questions, though. I’m sure there’s a world
of literature on the first one.
Regarding the second, my understanding is that greater energy
value can be yielded from source-separated food scraps because they can tailor
the digestion process for food scraps for greater efficiency & higher energy
production. This has to be considered together with the other benefits I’ve
mentioned - solids from a food scrap –dedicated digester can go to
compost facilities that don’t’ accept bio solids, their energy
value degrades less when separated and not piped in, and those solids
represent lower VOCs/ton of feed stock. The latter is a considerable
factor in California where our compost facilities are facing mounting and
critical regulatory obstacles related to VOC emissions. These are
complementary, cascading benefits. Add the stranded capacity in proximity
to available feed stock, and EBMUD’s effort comes into greater focus, I
From: Doug Koplow
Sent: Tuesday, June 10, 2008 11:03 AM
To: GreenYes; Slote, Peter
Subject: [GreenYes] Re: Anaerobic Digestion of Food Waste Final Report
Is there any data on
the fugitive emissions from food wastes delivered "by pipe"? Would
the fugitive emissions from food wastes be higher than what must also be
occurring with standard sewage?
Also, I was curious
about your point that much of the value of food waste is being lost if it isn't
source separated. Don't most of the larger POTWs capture and reuse
methane from all organic matter that is delivered "by pipe"? If
so, this would seem to capture the energy value of the food waste, regardless
of which way it reached the plant. Are you mostly worried about the
degradation of the biosolids due to commingling with more contaminated wastes?
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>>> <firstname.lastname@example.org> 6/10/2008 12:35 PM >>>
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,
City of Oakland Public Works Agency
Solid Waste and Recycling Programs
Visit www.zerowasteoakland.com 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 sludge.
> 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 sustainability
> 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
> --------- 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
> The US EPA, Region 9 Office of Pollution Prevention and Solid Waste is
> pleased to announce the final report "Anaerobic Digestion of Food
> In 2006 EPA Region 9 awarded a $50,000 grant to East Bay Municipal
> District (EBMUD), a wastewater treatment facility in Oakland, California
> 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
> recovered significant quantities of energy from food waste as well as
> high volatile solids reduction, showing the potential of diverting large
> quantities of valuable food waste from landfills.
> The final report and a fact sheet summarizing the results can be found
> on our website athttp://www.epa.gov/region09/waste/organics/ad/index.html
> 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
> 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.
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