Municipal Organic Waste: back to the future?

“My dear, there is no such thing as waste in this world”.

My grandfather is putting away wooden skewers, with which he will build a small house to add to the nativity scene next Christmas. Being born in a peasant family in southern Italy almost a century ago, he is still proudly attached to a culture of saving, reusing, and living by what you have.

“When I was a child, people would throw their trash out of the window; that would essentially be dead leaves, vegetable peels and fish scraps. Other children and I would rush out every morning to take up as much as possible, so that it could be used on our gardens for having bigger vegetables and a bigger harvest. It was so much better back then, compared to our messy world nowadays! Clean streets and happy farmers. Why can’t we go back to that way of life?”.

Talking with always gives much to think.

I can agree on the fact that the way our society works is messy. Nutrient flows, which used to be circular in that rural society, are now separated: waste from the urban areas is generally not recycled, especially the organic fraction, and it is generally incinerated or dispersed in wastewaters, being wasted or causing eutrophication. On the other side, soil erosion and degradation are growing problems, especially in a context of climate change, and synthetic fertilizers are a nonrenewable resource.

I can agree on the fact that what we see as waste today can and must be seen as a resource. Not only durable materials like plastics and glass keep their value after being dumped: organic matter, too, has a high potential for reuse for different applications. Composting is only one possibility, and not the most efficient [1].

I can also agree on the fact that we need to be more creative in finding new ways to reuse what we have.

However, I cannot agree on the fact that our maximum aspiration is to go back to that old lifestyle. The world is different, the challenges are different, therefore the solution cannot be to go back to the past models of production and consumption. We need to be ready for the future!

A smart way to valorize waste and bring it back to the productive chain is to use is for energy production. The organic fraction of Municipal Solid Waste (MSW) could be utilized for the production of so called second generation biofuels, in particular biogas, bioethanol and renewable diesel [2]. The use of this resource would allow us to avoid the incineration of this resource, which is highly inefficient if compared to materials like plastics, and its disposal in landfills. The latter triggers anaerobic decomposition with production of methane, a greenhouse gas that is 25 times more potent than CO2 over a 100-year period [3]. On the other hand, the use of organic waste for energy would not incentivize the reduction of food waste at the source or, similarly, such reduction would negatively affect our energy availability. In the picture it is shown the food recovery hierarchy drawn by the US Environmental Protection Agency (EPA), where “industrial uses” such as rendering and fuel conversion are four steps away from the most preferred option, and right before composting and landfill/incineration.

To sum up: the top three options in the hierarchy are the ones which would create most benefit for the environment, society, and economy. When it is not possible to reduce waste at the source or use it as animal feed, then the conversion of this kind of waste into biofuels is the most efficient and appealing alternative.

“So many difficult words, you know I couldn’t go to school”

“I said that instead of burning food waste or putting it into discharges we could use it to produce something to burn instead of gasoline! It is possible today with modern technologies”

“Oh, seriously? The more you know… But I will just keep using my potato peels to grow my tomatoes”

“That’s fantastic, nonno”

____________________________________________________________________________

References

[1] EPA, “United States Environmental Protection Agency,” [Online]. Available: https://www.epa.gov/sustainable-management-food/food-recovery-hierarchy. [Accessed 20 09 2020].
[2] Pöyry Management Consulting Oy , “Food Waste to Biofuels,” 2019.
[3] IPCC, “Climate Change 2007: The Physical Science Basis – Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.,” Cambridge University Press, Cambridge, United Kingdom, 2007.

3 Comments on “Municipal Organic Waste: back to the future?

  1. Hello! Good blog post. I agree with you about the way we treat our waste today. If you look back to the seventies we had much less waste produced compared to what we generate as an average person today. I think that finding a use for the waste we produce is very important since we produce so much.

    Liked by 1 person

  2. Thank you for this great blog post. I really enjoyed reading about the views and ideas of your nonno. It is so important to listen to the older generation and to see what we can learn from them, and apply it in today’s society. I agree with you that the use of food waste as a biofuel does not contribute to reducing the production of food waste, but still, it is an improvement from just dumping it on the landfill, where it produces methane. Do you see any way to both use the food waste as a biofuel and at the same time contribute to the circularity that you refer to at the beginning of your blog post?

    Liked by 1 person

    • Converting food waste to biofuel contributes to circularity by itself, if you think that a product that used to be considered as waste with no value would be seen as a resource and exploited, at least as an energy source. A second important aspect to be considered about the production of biofuels in general is that the carbon dioxide emitted by their combustion would be derived from renewable resources, contributing to lower the amount of fossil carbon that is released in the atmosphere when we burn fossil fuels. However, about the soil degradation aspect, as you can see in the Food Recovery Hierarchy composting is not considered to be as efficient as other industrial uses. My guess on why it is so is that composting implies the digestion of the organic macromolecules, therefore the breakdown of the chemical bonds that were once created with primary production, with consequent loss of all the energy stored in them.

      Like

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