Well, howdy and Happy Earth Day, sustainable friends.
As some of you know, my beloved GF works in porcelain and, like many ceramic artists, subscribes to a number of sites, services and trade mags, always looking to learn something new. And, perusing this month’s Ceramics Monthly, boy, did she.
American Ceramic Society science writer Lisa McDonald reprinted an article she published in 2019 on the Society’s website about biosolids, which are politely described as
“nutrient-rich organic materials that come from dewatered and appropriately-treated wastewater sludge, which itself comes from the wastewater treatment process.”
Which means, yes, poo.
Now, biosolids are pretty useful stuff, most commonly tossed on crops as fertilizer or used in soil reclamation projects, also in road construction and concrete. But, even with those and other applications, there’s a whole lot of the, uh, stuff left over that just gets tossed in landfills or stockpiled to merrily waft away it’s greenhouse gases.
McDonald highlights the work of Abbas Mohajerani of the Royal Melbourne Institute of Technology, who has been studying the feasibility of substituting that leftover, er, personal by-product for some of the clay used in making bricks.
The world digs a staggering 3 billion cubic meters of clay soil every year, another huge eco-mess, but one that can be ameliorated with a little ingenuity.
Because brick composition is quite flexible, bricks are capable of incorporating a high percentage of waste. And with about 1,500 billion bricks produced globally each year, that offers a lot of opportunities to incorporate waste. Already, researchers have tried incorporating other troublesome waste materials, including cigarette butts, paper processing residue, and glass. Last November, we reported on a team of University of Cape Town researchers who successfully made bio-bricks out of human urine.
Because brick composition is quite flexible, bricks are capable of incorporating a high percentage of waste. And with about 1,500 billion bricks produced globally each year, that offers a lot of opportunities to incorporate waste. Already, researchers have tried incorporating other troublesome waste materials, including cigarette butts, paper processing residue, and glass.
Last November, we reported on a team of University of Cape Town researchers who successfully made bio-bricks out of human urine.
Ain’t that a… oh, sorry.
Now Mohajerani and his team have taken the next logical step, incorporating our, ah, end results into bricks. And he’s found that by substituting 10-25% of the clay soil in bricks with non-shinola, the result is a better brick all around.
The researchers found biosolids-enhanced bricks passed compressive strength tests and largely trapped heavy metals within the brick after firing. Additionally, bio-bricks showed lower thermal conductivity than traditional bricks, thereby enhancing the bricks’ insulating abilities.
Not only that, but the, er, human-supplemented bricks fired at lower temperatures than all-clay bricks, reducing the energy required to make them by 12.4-48.6%. Yeah, up to nearly half the energy saved. Had to double-check it to believe it.
With that kind of, um, solid performance, the bio-bricks could offer a cheaper, greener alternative to their conventional counterparts while offering something useful to do with our doo. Mohajerani estimates that substituting just 15% of clay in 15% of bricks made every year could use up all of the excess “dewatered and appropriately-treated wastewater sludge” in the US, Canada, the EU, Australia and New Zealand.
And that, my friends, is some pretty cool…
McDonald helpfully links the open-access paper by Mohajerani, et. al., published in Buildings “A proposal for recycling the world’s unused stockpiles of treated wastewater sludge (biosolids) in fired-clay bricks” (DOI: 10.3390/buildings9010014).
Those who wish to see more of my lovely GF’s work should visit her Instagram page to see recent works.
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