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[GreenYes] RE: Food scraps


Matt, et al:

Not sure how to take "enjoyed," but I'm personally very proud both of my
overall legacy with respect to recycling/solid waste management in NYC, as
well as my ongoing work on behalf of Insinkerator....I once was a relative
skeptic, or at least agnostic about disposers (given their absence from MSW
management literature, it's easy to be ignorant), but have come to my own
conclusion that disposers have played a significant role in waste management
for decades -- even while principally being regarded as an appliance of
convenience -- and should play an expanded one on a more intentional basis
in the present/future, esp as the world becomes more urbanized....

As I suggested, there is surprisingly large body of research literature
available -- both domestically and internationally, some of it
company-supported, but conducted by academic institutions, and much of it
fully independent, that supports my position. {and I think Tim Jones has
had some contact with ISE re these issues....)

To your questions:

Yes, as waste prevention advocates know, 'tis very difficult to count what's
missing....which is why food waste managed via disposers is largely "lost"
in the accounting.

One study that attempted to examine that issue is the University of
Wisconsin life-cycle study (1998) that's linked with a few others at (look for 'environment' button). Page three includes a
brief table that suggests the following disposition of food waste via
management system:

O Landfilling 41%
O Disposers via WWPT 37%
O Disposers via septic 12%
O WTE 10%
O composting 0%

Allowing for margin of error, it clearly suggests "major", if not "most."

Second, studies of disposers suggests they capture @ 50% of available food
waste from residences, comparable to recycling systems generally; people
don't always think about every last bottle, magazine or morsel, and how best
to handle it. Although disposers can handle bones quite nicely, many folks
opt not to use them for that purpose -- as just one example. (In my
isolated case, see below....)

The Delft study (2004) suggests that European experience with SSO collection
is about the same, i.e, a 50% capture rate, leaving 50% in the refuse for
disposal or WTE.

In NYC's case, residential disposers only became fully legal in 1997
(following a decade of consideration and pilots; the exec summary of NYC
DEP's report also is linked), so diversion attributable to disposers is

Except in my six-person Brooklyn household: I've not put food waste at the
curb for nine years, which I roughly estimate to be @ 5 tons (70% water)
that's stayed out of collection trucks, transfer stations and distant
landfills -- instead being processed into fertilizer pellets. Even the
squirrels are trained not to bother with my bags of what is mostly soiled
paper and plastic packaging.

NYC's own massive waste characterization study is due for release this
summer -- updating the '92 study. Will show food waste @ 18% of residential
waste, and how it varies by density, HHI, etc. Of course, such percentages
are relative to what else is in wastestream....[check out
for the latest, including preliminary results]

As to penetration rates of household disposers, my best information is that
perhaps 90% of California homes have them (and that's a conservative
projection), given their development in the post-war period in which
disposers became accepted by municipalities and commonplace among
developers. Of course, having a disposer doesn't necessarily equate to use
-- either modest, or aggressive (as in my case).

But I also have a sense that disposers are generally
misunderstood/forgotten/ignored when it comes to food waste management
discussions (or even consideration under greenbuilding guidelines, but
that's another discussion), perhaps because solid waste and wastewater
management systems are generally operated under separate bureaucratic
fiefdoms in the U.S. which enables those linkages to be missed. I have
heard anecdotally that Tacoma's biosolids operation (which markets TaGro)
would like more food waste but can't get it from the solid waste agency, and
that in SF some % of its SSO is delivered to anaerobic digesters at its
wastewater treatment plants (rather than the compost facility), but would
welcome info/correction on either of those.... Following NYC's adoption of
its first comprehensive solid waste management plan in '92 that included an
aggressive composting goal, the Sanitation Commissioner begged the
Environmental Protection Commissioner for help in allowing residential
disposers as the only feasible solution....(correspondence available).

To that end, a number of recent studies attempt to compare system costs and
benefits; the UW study referenced assesses five (5) methods for managing
food waste....Sydney (AU) took a comprehensive look at few years ago, and
Japan just finished a four-year study.

[Off-line, I've a summary of seventeen (17) contemporary studies, organized
by topic, that serves as a cogent resource for those interested. Much of
the research is focused on sewer, wastewater treatment, energy recovery, and
other broader system impacts, in case you're wondering how all of those
issues stack up -- and perhaps will answer Alan Muller's questions, as

But I have yet to see (perhaps you could point to one) a comprehensive study
done of SSO/composting system costs, especially in SF -- for example --
where the public utility/franchising model makes cost info/comparison more
complex, and multi-family buildings are not included in the system. A
Biocycle article (Nov. 2005) re Portland suggested that residential SSO was
too expensive to pursue....and my overall sense is that such programs are
too new to be comprehensively evaluated re their cost-effectiveness and
sustainability, esp unless accompanied by cheap/local compost facilities
(impossible in metro areas) and system-wide restructuring (including
adjusting frequency of non-recyclable waste collection, which has proved
politically impossible in NYC). (and isn't California beginning to suffer a
compost glut?)

But if your end-points are a) that too much food is 'wasted' period,
absolutely agree, and b) that there's enough food waste to be captured via
multiple systems, a qualified agreement, depending on the collection
efficiencies of residential vs commercial food waste as one key variable,
and the efficacies of capture rates.

My own view is that if biosolids are well-managed and beneficially reused,
then disposers make slam-dunk good sense....but I'd want to do everything
possible to keep food waste out of landfills and WTE (where its water
content cancels out any energy benefit).

More than enough for this post....glad to continue on or off-line...and to
provide access to studies, etc., as requested.


-----Original Message-----
From: Matthew Cotton [mailto:mattcotton@no.address]
Sent: Sunday, July 09, 2006 1:20 PM
To: Kendall Christiansen
Cc: 'GreenYes'; twj@no.address
Subject: Food scraps

Kendall -

I enjoyed your recent thoughtful post about biosolids. And I really
appreciated that you disclosed your relationship with a particular
system vendor. I'm just curious if you have any data to support the
statement that "most food waste is actually diverted from the solid
waste management system...". I've never seen any studies on this. Has
InSinkErator studied this? Did you mean in New York?

Most waste characterizations studies I've seen [including a very
comprehensive study done by Cascadia Consulting for the California
Integrated Waste Management Board
(] indicate
that food is a significant component of the (solid) waste stream. To be
fair, typical waste characterization studies only include materials
that are already on their way to a landfill; I've never seen one that
takes the wastewater flows and or solids into consideration. The
Cascadia Study indicated that food was the number one item by weight
still in the waste stream in California. Many CA jurisdictions are
currently planning food collection programs to divert this material
from landfill disposal.

Clearly way too much food is being wasted in the US. Anthropologist Tim
Jones at the University of Arizona has estimated that from field to
table a full 50 percent of food is wasted. More and more cities across
the country are looking at ways to divert food scraps from the waste
stream. And not just in CA or in big cities, Dubuque, Iowa, Hutchinson,
Minnesota, and Plano, Texas are a just a few examples of lessor known
cities diverting food scraps. One successful method in some areas is to
combine residential food scraps with curbside collected yard trimmings.
Although these programs are in relative infancy, they appear to be
growing in number.

At least here in CA, whether a residence or a business has an
under-sink disposer or not there is still a significant amount of food
scraps that currently end up in landfills and would be better off
diverted to a beneficial re-use.

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

On Jul 9, 2006, at 6:12 AM, Kendall Christiansen wrote:
> The subtle point is this: in U.S. cities/municipalities, most food
> waste is
> actually diverted from the solid waste management system via the use
> of food
> waste disposers (given that it's 70% water, it's more liquid than
> solid)
> which use the sewer system to transport organic waste (human + food) to
> wastewater treatment plants for processing....with the premise that the
> additional food waste actually improves the quality of biosolids.
> Thanks for considering...
> Kendall Christiansen
> Gaia Strategies
> kendall@no.address
> 718.941.9535
> The writer has seventeen years experience in solid waste management and
> recycling systems in NYC -- including chairing NYC's Citywide Recycling
> Advisory Board for 5+ years -- and serves as senior consultant on
> environmental affairs to InSinkErator, the leading manufacturer of food
> waste disposers. (
> >

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