THE PLUMBING FOUNDATION CITY OF NEW YORK, INC.
11 Park Place, Suite 1500, New York, NY 10007
Phone: (212) 233-6555 Fax: (212) 233-6683
OF FOOD WASTE DISPOSERS TO NEW YORK CITY
New York City Department of Environmental Protection (DEP) recently
concluded a 21-month study of how food waste disposers would impact
the citys environmental infrastructure. Based on this study, DEP
recommended authorizing the use of the disposers in New York City. There
will be several significant benefits to city residents, and city government,
if the City Council approves the installation of food waste disposers.
Nearly all types
of biodegradable food waste, ranging from melon rinds to fish and chicken
bones, can be safely and effectively ground by a disposer. After being
ground into small particles and mixed with a small amount of water,
food waste is carried away through a dwellings plumbing system
to sewers, which carry the wastewater to municipal treatment plants
where the solid portion is processed with other biodegradable waste
into sludge. In turn, sludge is processed into compost or soil conditioner.
According to a U.S. Environmental Protection Agency report, food waste
contributes a declining percentage of the total waste stream, due in
large part to the use of garbage disposers.
- Food waste
disposed of in the sink will mean that food garbage will no longer
have to be stored in kitchens where it attracts vermin. Also,
city residents will no longer feel compelled to take out the
garbage during inclement weather or late at night when it
may be inconvenient or unsafe, since the availability of food waste
disposers will mean that household garbage need no longer contain
messy, wet or smelly food waste.
- There will
be much less rotting food waste in garbage bags awaiting collection
on city sidewalks. Today, this waste is the major food source
of rats and other vermin, as well as the source of offensive odors,
particularly during warm weather months. Similarly, in apartment
houses that use compactors, the oozing liquids that breed pests
in basement storage rooms can be virtually eliminated. Since increased
levels of asthma have been linked to exposure to airborne roach
droppings, food waste disposers also may help to address asthma,
one of the citys most pressing health problems.
use of food waste disposers will enhance the Department of Sanitations
ability to meet critical objectives of the Citys Solid
Waste Master Plan, for starters by reducing the amount of waste
needed to be picked up by City sanitation trucks and transported
to the Fresh Kills Landfill or to in-city transfer stations for
export. Diverting food garbage from disposal at Fresh Kills will
reduce odors at the Landfill. Additionally, by reducing the amount
of decomposing food waste in Fresh Kills and out-of-state landfills,
the use of food waste disposers will reduce acidic liquids that
leach out contaminants as well as reduce the production of gases
that add to global warming.
of food waste down the drain ensures that it will be recycled along
with waste sewage solids into compost for beneficial reuse in arid
soils. And using food waste disposers will accomplish composting
sooner, more reliably and more economically than separate food waste
- By removing
a substantial amount of food waste from residential garbage, in-sink
garbage disposers will enhance source separation, making recycling
easier, since wet food waste often contaminates other refuse
which otherwise would be more efficiently recycled. This also will
reduce collection and separation costs.
the issue of water usage, according to the Department of Civil and Environmental
Engineering at the University of Wisconsin, an average home disposer
uses less water in 5 days than is required for one flush of a low-flow
industry leaders, consumer advocates and environmental experts affirm
that 90 million food waste disposers have been operating problem-free
throughout the U.S. for more than 30 years. Forty-five percent of all
households in the U.S. have food waste disposers, and 80% of all newly-built
homes are equipped with food waste disposers as a standard kitchen appliance.
In fact, more than 90 communities nationwide -- including major metropolitan
areas like Detroit, Los Angeles and Indianapolis --- actually require
the installation of disposers in all new housing construction and kitchen
to environmental expert and advocate Carolyn Konheim, who serves as
a consultant to industry in this area, Because New York City now
converts the solids from wastewater treatment plants into a compost
that enriches soil, it is environmentally better to add food wastes
to wastewater than to haul waste that is 70% water -- in trucks that
contribute to air pollution -- to distant landfills where it generates
global warming gases. It is also far more economical than separating
food waste for collection and composting. Since there have been no reported
operational problems related to food waste in sewer lines anywhere in
America, I expect that the New York experience will be just as positive.
from both the New York City Department of Environmental Protection study
and studies conducted over a number of years by the University of Wisconsin
indicate the following:
- Use of food
waste disposers would not precipitate any perceptible increase in
water rates. The DEP projects increases in water rates in 2005 due
to food waste disposers ranging from 0.16% to 0.61% over 1997 levels,
depending on which degree of nitrogen control is imposed on the
City, irrespective of food waste disposers. The actual increase
in any one year would never exceed 0.15%. Thus, it is clear that
no significant increase in water rates would be attributable to
the use of food waste disposers.
- Food waste
disposers have not strained sewage systems anywhere, nor would they
in NYC. After having examined all potential effects on sewers and
having performed a detailed analysis of each wastewater treatment
plant, DEP concluded there would be a minimal impact on the sewage
infrastructure of the city. Even though other cities in which food
waste disposers are widely used report no sewer maintenance problems
attributable to the waste disposer, and the DEPs videotapes
of sewers found no noticeable deposits of suspended material, DEP
used conservative standards in the literature to estimate the potential
deposition in those sections of sewers that, due to their diameter
or grade, do not have a self-cleaning velocity. They concluded that
sewer maintenance costs would increase by less than 2% in 2005.
- Since wastewater
in New York City is typically very dilute, the additional biosolids
from food waste disposers would be well within the design capacities
of wastewater treatment plants, and would be limited primarily by
capacities of the sludge-handling systems at a few plants. These
include six plants that are limited by sludge and thickener capacities,
and two more that will need additional aerator capacity after 2025.
The modest scale of modifications needed to manage the additional
solids due to food waste disposers can be seen by the insignificant
rate increases needed to cover the cost of the modification.
- Food waste
disposers would have no adverse effect on New Yorks waterways.
After applying its haborwide forecasting model, in both open waters
and the worst-case tributary (Flushing Bay), DEP concluded that
increases of oxygen-demanding pollutants from food waste disposers
would cause minimal effect on compliance with the New York State
standard of 4.0 mg/L DO for fishable waters in the harbor
and tributaries, adding less than 0.01 mg/L DO; the only quantifiable
effect would be about a 1.5% increase in time that the State standard
is exceeded at the mouth of Flushing Creek. This assessment includes
the effects of wet weather flows.
- Food waste
disposers would cause no significant increase in water consumption.
While the food waste disposers pilot test data showed no change
in water use, to be conservative, DEP assumed that food waste disposers
would result in an increase of 1.0 gallon of water per capita per
day, and concluded that this worst- case consumption would represent
a minor increase of water demand -- approximately 20¢
of the 1.3 billion gallons per day average. Research conducted at
the University of Wisconsin Department of Civil and Environmental
Engineering shows that, based on a review of 33 studies, the mean
increase in water use due to food waste disposers is 0.28 gal/cap/day.
Further study at the University using two-week tests before and
after the installation of food waste disposers in a variety of households
concluded that there was no significant difference in water consumption
with or without food waste disposers.
long-term impacts of food waste disposers have been exhaustively studied
by DEP. While DEP, prudently, plans to closely monitor the incremental
effects of food waste disposer use, the 21-month pilot study consistently
used worst-case assumptions upon finding no discernible effect during
the course of the study (including video monitoring of the sewers) to
make long-term forecasts. Anticipating concerns, the DEP study examined
basin-by-basin costs. The issue of energy use was not examined because
of its insignificance. Appendix B of the DEP report states that food
waste disposers are used 2-3 times a day for a total of 0.6 minutes.
If, to be conservative, using the industry upper limit of 2 minute/day,
the 0.5 horsepower motor of a food waste disposer consumes less than
a 75 watt light bulb uses in 10 minutes.
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