A Counterpoint to Composting (If you’re listening)

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I once heard that had the food waste disposer not been invented in 1927, now would be the perfect time. Why? Well, because of the convergence of two environmental megatrends – landfill diversion of organics and resource recovery at wastewater treatment plants, where municipalities produce clean water, and sometimes fertilizer and energy.

Think about it, food waste is at least 75% water, and with the trend of keeping organics out of landfills, it makes sense to leverage disposers, already present in 60 million households in the U.S. (52% of all homes), to manage this waste as a liquid rather than a solid. Right?

Unfortunately, it is difficult to even have a civil conversation with staunch environmentalists that favor composting because of four universal myths and misconceptions about disposers. Never mind that composting is only available to 2.74 million households across 198 cities across the U.S., or less than 2% of all U.S. citizens! I sometimes get exasperated in trying to have a lucid conversation on this subject because many times I don’t even get beyond the myths of environmentalists. For example:

Myths 1 & 2 – Water and Electricity Use
“Disposers can’t be good for the environment – they use water and electricity.”

Ugh! To have a rational discussion, we must move past the debate on water and electricity use associated with disposers, moot points and already discussed ad nauseum in this blog. The perception is disposers use a lot of water simply because they use water. The truth is it is not exorbitant. In fact, it is negligible and totals only 1% of the total household usage. Electricity usage is almost laughable at a mere 3-4 kwh or $0.50 per year. And all treatment plants produce clean water, which is why some of them have adopted the name water reclamation plant! Here’s a little factoid: for every ton of food waste diverted from a landfill to a treatment plant, we recover about 165 gallons of water, because food waste is around 75% water. Enough said.

Myths 3 & 4 – Impacts to Plumbing and Sewers and Overloading of Treatment Plants
“Sewers and treatment plants were made for sewage, not food waste, and mixing food waste with sewage contaminates a potential resource; food waste is just not good for these systems. Besides, sending food waste to the treatment plant disallows composting?”

We inevitably come to the concern that not all wastewater infrastructure is the same, and that is very true, but the only difference between food waste and sewage solids, is one has been eaten first! Since food waste and human waste is essentially the same density, sewers designed to transport sewage are perfectly designed to transport finely ground food waste.

And yes, many treatment plants actually do make fertilizer instead of landfilling their biosolids. According to research gathered by the Northeast Biosolids and Residuals Association, about 55% of all biosolids are beneficially reused. We could do better, but responsible environmentalists should help debunk the myths associated with their safety to increase beneficial use of biosolids. Land application of biosolids is sustainable and completes the circular economy.

As far as energy production, of the 16,000 wastewater treatment plants in the U.S., over 1,200 have anaerobic digestion. This means that only about 8% of all plants have the ability to create energy, either heat or power, or both. Although this seems like a relatively small number of all treatment plants, these plants account for around 50% of all wastewater flows in the U.S. In other words, most major metropolitan areas have anaerobic digestion employed to help manage sewage solids.

Not too long ago, we dumped all our raw sewage into streams and rivers – Cincinnati did so until the late 1950’s! Even after building wastewater treatment plants, some cities like NYC still dumped their sludge into the ocean up until the 1980’s. But cities are moving forward with sustainability efforts. Just this week it was reported that citizens in a Milwaukee program can pay $12.75 to participate in a pilot composting program. Instead of trying to invest in municipal composting programs, which requires new collection and processing systems at very high costs, city leaders should consider leveraging wastewater treatment plants and the existing base of disposers already present in homes.
I wonder if a U.S. city will ever consider subsidizing the purchase and installation of disposers?

By the way, the City of Milwaukee issued a press release in 2009 encouraging residents to use their disposer, and the Milwaukee Metropolitan Sewerage District also encourages their use. In essence, why not feed a disposer and starve a landfill?


4 Replies to “A Counterpoint to Composting (If you’re listening)

  • Rick Jake on said:

    Can you address where the heavy metal contaminants come from in the sewage plant fertilizers? I see this as a serious problem.

    • kelemanm on said:


      Great question. Industries used to be a potential source of significant amounts of heavy metals, but pretreatment regulations require them to reduce these contaminants at the source. Over the last few decades heavy metals in biosolids have decreased signicantly to the point where they are not a huge concern, but are still monitored and regulated. I covered this subject in a prevous post. Check the two posts from December 2015. 

  • Craig Martin on said:

    Your points make so much sense I can't believe that the U.S. is not closer to 100% installation of disposers in the household. 

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