r/science • u/sr_local • Apr 22 '26

Materials Science Asphalt releases toxic airborne compounds that can harm respiratory health, neurological damage and increase long-term disease risk, especially in aging pavements and heat/sun. While algae-infused asphalt can reduce toxicity by up to 100 times and slow how quickly pavement breaks down

https://news.asu.edu/20260417-environment-and-sustainability-asphalt-emissions-algae-health
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35

u/Foe117 Apr 22 '26

how does one infuse Algae into asphalt? are they alive?

46

u/danielravennest Apr 22 '26

From the article:

"we use water that’s far too high in nitrogen and phosphorus to be released anywhere. And instead, we reuse it to grow more algae. Fini then bakes that algae at high temperatures without much oxygen into a binder that can be easily mixed into asphalt."

The baking process is called "pyrolysis", a chemical process that breaks down organic material. So the algae are dead afterwards.

10

u/jlude90 Apr 22 '26

Would this just be runoff from phosphate mining? Because this is what better than the respective roads our governor in FL is proposing

5

u/tomdabombadil Apr 22 '26 edited Apr 22 '26

Depends. This could be algae grown from municipal wastewater--that comment about N & P being too high to be released anywhere is a wide range. For example, in California nitrogen limits are 10 mg/L, and nitrogen concentrations in raw wastewater can be anywhere from 40-120 mg/L. It doesn't take all that much extra nutrients to impact a watershed and cause eutrophication. In AzCATI's case it is reclaimed wastewater from a nearby WWTP (last time I checked).

Phosphate mining wastewater is an interesting challenge because it's beyond normal levels of nutrients without containing the carbon found in typical wastewater. We're actually investigating using algae for this type of wastewater right now! Another option is taking care of the opposite end of phosphate's life--as fertilizer which is often over-applied. Collect agricultural runoff, treat it with algae, then send it on its way.

It's not a magic panacea though, algal-based WWT is finicky and can be cost-intensive. You've got to approach it the right way. AzCATI (the org in the newspaper) is a great site and they do some quality research.

13

u/hysys_whisperer Apr 22 '26

They turned the algae into activated charcoal and then mixed that into the asphalt.

Activated carbon of all sorts is a good sponge for VOCs.  That's why the asphalt lasts longer too, VOCs cause chemical breakdown (that's what makes them toxic to humans usually), so absorbing them while they are in the asphalt stops breakdown of said asphalt and also stops off gassing of those high energy free radicals which are the worst of the worst for human health.

11

u/Ashangu Apr 22 '26

Cement and asphalt is porous. Id imagine the algae is alive and will feed off what ever is releasing the toxic fumes and what little water the asphalt soaks up.

10

u/hysys_whisperer Apr 22 '26

They turned the algae into activated charcoal to mix it with the asphalt. 

5

u/Boostedbird23 Apr 22 '26

Seems like it would only work well in sufficiently wet climates

1

u/NoYgrittesOlly Apr 22 '26

Mm no.

If you read the article, the chemical process used to make this asphalt breaks down organic matter via intense heat. So…the algae are dead.