Processing food scraps at wastewater treatment plants results in less global warming potential than landfills
by Michael Smith (Veshengro)
A new study about the impact of various food waste disposal systems has shown that putting it into a garbage disposer results in lower global warming potential than putting it in the trash and sending it to a landfill. That’s a key finding of the Life Cycle Assessment (LCA) commissioned by InSinkErator, a division of Emerson, and the world’s leading manufacturer of food waste disposers.
As set forth in the report, if a community of 30,000 households (the size of Newport Beach, Calif.) switched from sending food scraps to the landfill to using a disposer instead, the reduction in global warming potential would be the equivalent of eliminating nearly 2,100 tons of carbon dioxide emissions. This is akin to eliminating about 4.6 million miles of car traffic.
According to the EPA, landfills are a major source of methane, a greenhouse gas at least 21 times more potent than carbon dioxide. Because food scraps are a significant component of waste that municipalities send to landfills, diverting it for recycling into resources is becoming a major goal of cities worldwide. Enter food waste disposers, which pulverize food scraps and send the resulting slurry to the various wastewater treatment systems evaluated in the LCA.
Many advanced wastewater treatment plants can convert food scraps into renewable energy through a process called anaerobic digestion. At these plants food scraps can also be turned into fertilizer products, also known as biosolids, which can help build healthy soils.
“The LCA confirms a multitude of research and validates that food waste disposers are more than just convenient – I like to think of them as an environmental appliance,” said Tim Ferry, president, InSinkErator. “After people look at the environmental benefits of using disposers instead of landfills, we think they will be compelled to bypass the trash can and put food scraps down the disposer instead.”
LCA Goes Further, Extends Understanding
Unlike studies that review and compare competing products, the LCA assesses the environmental impact of the four primary systems for managing food scraps – wastewater treatment, landfills, incineration and advanced composting. Camp Dresser & McKee (CDM) conducted the initial analysis used by PE INTERNATIONAL, Inc. (formerly PE Americas) to produce the LCA following ISO 14040 standards, including review by an independent panel of experts.
The LCA analyzed several critical environmental impacts: global warming potential (trapping heat that would otherwise pass out of the earth’s atmosphere), eutrophication potential (excessive vegetative growth in bodies of water from high concentrations of nutrients), acidification potential (increase in the acidity of water and soil), smog formation, and the energy demands associated with each system.
The report states that food scraps processed through a wastewater treatment plant with anaerobic digestion and cogeneration (e.g., San Francisco, Milwaukee and many others) can even result in a reduction of global warming potential. It also concludes that processing of food scraps at these advanced wastewater treatment facilities has lower energy demand – less than landfills, incineration and centralized composting.
“In thinking about systems for managing food scraps, wastewater treatment systems are often overlooked despite their surprisingly effective role in turning liquid waste into valuable resources,” said Michael Keleman, senior environmental engineer, InSinkErator. “Composting is good but it isn’t the only option.”
More information about the study and the InSinkErator environmental story is available at www.insinkerator.com/green.
Headquartered in Racine, Wis., InSinkErator, a division of Emerson, is the world’s largest manufacturer of food waste disposers and instant hot water dispensers. For more information about InSinkErator, visit www.insinkerator.com.
Emerson (NYSE: EMR), based in St. Louis, Missouri (USA), is a global leader in bringing technology and engineering together to provide innovative solutions to customers in industrial, commercial, and consumer markets through its network power, process management, industrial automation, climate technologies, and tools and storage businesses. Sales in fiscal 2010 were $21 billion. For more information, visit www.emerson.com.
Let me, personally, put it this way, however, and let me say “they would say that, wouldn't they, because they want to sell their waste disposal units” and I don't think that I would be wrong there.
Disposing of food waste down the drain is not one of the best methods, but it may still be better than sending it to landfill. However, where it really should be going is to a food recycling plant which makes the waste into valuable compost.
In the first instance, however, there should be as little food waste as at all possible though it cannot always be avoided and I know that very well myself. But a reduction is possible by buying responsibly and the supermarkets must come in for criticism here also.
Having most stuff – including fruit and vegetables – washed and pre-packaged in amounts that cannot, for instance, be used up by a single person fast enough for the stuff not to go off, is how they make a contribution to this waste.
As consumers, obviously, we have the choice to go to the greengrocers, as far as fruit and vegetables are concerned, and buy only the amount that we can use in a given time.
Tonnes of food are wasted daily in our shops, restaurants and homes, and in homes we do have the control over this and should ensure – and yes, I am guilty too – to only buy as much as we can use in a given period.
Our parents and grandparents did just that but then there were no big supermarkets around in those days and everything was sold through local stores or on the markets and they did go to the shops on a daily basis to buy the ingredients for the day's or next day's breakfast, lunch and supper, etc. This may be something that we will have to consider again too, I guess, and therefore we must find a way to square that away with working and all that.
© 2011
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