A Long Strange Trip

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A long, multiple-year effort just came to a conclusion for me and my fellow travelers involved in InSinkErator’s municipal evaluation which, among other things, strived to quantify how much food waste people actually process in their disposer. We undertook this series of projects in order to also determine how much could be diverted from the city landfill via disposers.

Verifying the amount of food waste diverted would help us estimate a city’s savings in greenhouse gas generation and renewable energy production as a result of disposer usage.

So how did we decide where to go? We didn’t just take off and let fate decide (as popular culture may have urged at one time.) After considering several cities for participation based on their expressed desire for reducing food waste and increasing resource recovery at the local water resource recovery facility (also known as wastewater treatment plant), our team decided to stage the studies in Philadelphia, Tacoma, Milwaukee, Chicago and Boston.

Food waste disappears after it is processed in a disposer so it can be hard to measure. This led us to developing a plan to measure and compare the amount of food waste in the garbage from homes without disposers to the amount thrown away after installing them for the first time. The difference before and after would represent the number we were chasing. So that’s what we did. In each city we traveled to – after installing disposers in about 500 homes. We met many people, plumbers and politicians along the way – many of whom are now good friends.

Disposers present a solution for reducing and recycling unavoidable food waste by diverting it from landfills, and the research and project sought to quantify this useful existing tool and advocate for its role in public policy while engaging the community.

As Jerry Garcia would say, lately it occurs to me. . . that the cities we visited achieved uniform and statistically significant results – a 30% reduction in food waste tossed out. A reduction like this has economic and environmental implications for municipalities managing solid waste and their budgets. Visit the website to find out more and download the full report.

Will tomorrow bring more cities joining Philadelphia which is now effectively endorsing disposers as a way to reduce food waste in the trash can and at the curb? It’s hard to say. But we’re ready to hit the road again and make the scene if there are cities that are interested in the story. And we’ll just keep truckin.'

Project Results



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If you or someone you know has ever tried to make the government do something as simple as installing a stop sign on a residential street, then you have experienced firsthand how difficult it is to get government to do anything. With that in mind, you can probably understand why we at InSinkErator are so elated about what we recently brought about in the City of Philadelphia.  As a result of our efforts, the city enacted a new ordinance mandating installation of food waste disposers in new residential building.

Philadelphia Code 2

Our parent company thought this was a pretty big deal so they put out a  press release on the news.

 You think your stop sign took a long time? Even the attention being paid to food waste reduction by the EPA and other groups ReFED doesn’t speed things up much.  Moving bureaucracy takes a lot of effort over a long time. Say, three years.


Heavy Metals the Encore – Because You Asked for More

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My last post began the discussion of heavy metals in biosolids, a topic that can provoke a noisy reaction. So let’s keep rockin’! Heavy metals in compost don’t seem to get the same response as heavy metals in biosolids. For some reason, heavy metals are associated primarily with biosolids.  That is incorrect.  This post continues the analysis.

Simple reasons why heavy metals are present in both compost and biosolids

Though it’s often thought that compost is the purest of substances, it too has metals, and these are also subject to regulatory limits.

A review of research bore out that compost has regulatory limits for heavy metals similar to biosolids. This should not be a surprise because both biosolids and compost from food scraps are composed of many of the same organic materials, such as proteins and fats.

With biosolids, the difference is that the food was eaten first.

Municipalities are required to submit information on biosolids quality, which enabled me to access information. I accessed a land application report from the Water Pollution Control Department in Lafayette, IN – the plant where I started my career, as well as a land application report from Angola, IN where I spent six years as the superintendent. (Thanks to Brenda Stephanoff from IDEM for her assistance.) Data on commercial compost is publicly available. For comparison I found compost information in separate reports from a solid waste facility in Lincoln, NE and a food compost site in State College, PA.

Comparison 1Comparison 2

It’s worth noting that it appears some biosolids have much higher levels of some metals, but this is relative. Not only do the charts show all metals are below EPA standards, all the values for biosolids are certainly within an order of magnitude of the compost values. The North East Biosolids & Residuals Association has compiled a much more comprehensive evaluation on metals in compost and biosolids. Thanks to Ned Beecher.

It’s a fact that compost and biosolids have the same regulatory limits for heavy metals.

For more information on this same subject, San Francisco Public Utilities compared commercial compost against composted biosolids in 2010 to evaluate compliance with heavy metal limits.  The utility determined that pollutant metals results were lower than the pollutant limits listed in Part 503 Rule Table 2-1.

Lorraine Herity’s master’s thesis from Ireland  showed sewage sludge met limits for heavy metals more often than compost.

Comparison 3

Number and Percentage of Samples in Compliance with Irish EPA Guidelines. Lorraine Herity. 2003. A Study of the Quality of Waste Derived Compost In Ireland. Queens University of Belfast.

The conclusion – you will find that the same heavy metals of concern are present in both compost and biosolids. Presence does not equate to risk or hazard.