Science

Shrimp shell sponge rips apart cells of toxic algal blooms

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Some types of cyanobacteria (aka blue-green algae) produce toxins which can poison humans or other animals that ingest water in which they’re present
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The cyanobacteria-killing sponge, which reportedly shouldn't produce any collateral damage when deployed in the environment
Adapted from ACS ES&T Water 2023, DOI: 10.1021/acsestwater.3c00202
Some types of cyanobacteria (aka blue-green algae) produce toxins which can poison humans or other animals that ingest water in which they’re present
Depositphotos

Commonly known as blue-green algae, toxic cyanobacteria can harm humans and wildlife alike when their populations soar in lakes or rivers. A newly developed sponge, however, could soon help bring such harmful algal blooms under control.

Led by Jiangfang Yu and Lin Tang, scientists at China's Hunan University had previously determined that oxidants based on a compound known as persulfate were lethal to Microcystis aeruginosa cyanobacteria.

That said, the oxidants had to be triggered by a catalyst such as biochar. Similar to charcoal, biochar is produced via a process called pyrolysis, in which heat is used to decompose organic material in the absence of oxygen.

Yu, Tang and colleagues recently proceeded to create powdered biochar from shrimp shells (which would otherwise go to waste), a layer of which they added to a porous three-dimensional melamine sponge. A thin layer of polyvinyl alcohol (a synthetic polymer) was placed between the two materials, linking them together when heated to 572 ºF (300 ºC).

Next, a persulfate-based oxidizing agent was added to the composite sponge, which was then left to float in a lab dish full of M. aeruginosa-tainted water.

The cyanobacteria-killing sponge, which reportedly shouldn't produce any collateral damage when deployed in the environment
Adapted from ACS ES&T Water 2023, DOI: 10.1021/acsestwater.3c00202

Within five hours the sponge killed 90% of the bacteria, causing their cell membranes to split and release their contents. Those contents quickly broke down into smaller nontoxic components. When tested on samples collected from actual lakes, the sponge still eradicated over 85% of the harmful cyanobacteria.

The research is described in a paper that was recently published in the journal ACS ES&T Water.

Source: American Chemical Society

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2 comments
Jimmy the Geek
One of the underlying causes of b-g algae is excessive phosphorus runoff from fertilizer. What happens to the phosphorus with this process? If it just goes back into the water you've really not accomplished anything except to further concentrate the phosphorus.
Karmudjun
You know Ben, Jimmy the Geek thinks similarly to me, but I have a different take-a-way. When too much phosphorus is in the water, opportunistic rapid growth organisms like Blue-Green algae flourish and then winds carry the mass to beaches. Once the algae take up the phosphorus and utilize it, it is no longer a rapid growth source material so the sponge (melemine bonded with polyvinyl alcohol - raising any flags here??) does do as predicted. The bound phosphorus is EXACTLY as the researchers stated - rendered inert and degrades rather than concentrating any phosphorus - isn't chemistry grand? But what is the risk of the sponge itself? Seriously, does it help to put more man made materials into lakes and watercourses?