Nanosilver from clothing can pose major environmental problems

Nov 01, 2012
Rickard Arvidsson at the Ryaverket waste water treatment plant in Gothenburg, which provided the basis for the calculations in his studies. Credit: Oscar Mattsson

(Phys.org)—Silver nanoparticles can have a severe environmental impact if their utilisation in clothing continues to increase. If everyone buys one silver nanoparticle-treated sock a year, the silver concentration in waste water treatment plant sludge can double. If the sludge is subsequently used as fertilizer, the silver can cause long-term damage to agricultural land. These are the results of a study conducted by Chalmers researcher Rickard Arvidsson.

Rickard Arvidsson recently defended his doctoral thesis, which addressed the risks associated with nanomaterials – a field with a great many . He has developed new methods to assess the risks of nanomaterials, as well as used the methods on a few specific materials such as silver nanoparticles.

Silver nanoparticles have an antibacterial effect, and are used in a variety of consumer products such as workout clothing to prevent the smell of sweat. When the clothes are washed, nanoparticles are released and enter plants through waste water. The particles release silver ions that cannot be broken down at waste water treatment plants or in nature. The silver ions are toxic to many organisms.

"Clothing is considered to be a large source of nanosilver emissions already," says Rickard Arvidsson. "If silver usage in clothing continues to increase, the consequences for the environment can be major.  For example, silver can accumulate in soil if sludge from waste water treatment plants is used as , which can result in long-term damage to soil ecosystems."

Utilising sludge as fertilizer in soil is a way to restore phosphorous from waste water to agricultural land. There is a of phosphorous, but if sludge is to be used as fertilizer, contaminated content must remain at a low level.

Rickard Arvidsson conducted a study at Gothenburg's waste water treatment plant in Sweden. The study shows that the effect on sludge, and if sludge is used as fertilizer, is entirely dependent on the amount of silver that manufacturers use in clothing. The silver concentration in the examined clothing varied by a factor of one million – between 0.003 mg/kg and 1400 mg/kg. With the lowest concentration, there would not be an observable effect on sludge and soil even if the utilisation of silver in clothing increased significantly.
 
"With the highest concentration, however, it would suffice if all of the city's residents bought and used one silver nanoparticle-treated sock a year for the silver concentration in waste sludge to double," says Rickard Arvidsson.
 
"Using silver in clothing is a new technology, and it is still difficult to ascertain patterns for how much is being used. However, if the negative is to be avoided, either the silver concentration in clothing or consumption of silver nanoparticle-treated clothing must be limited."

More information about nanosilver

Silver nanoparticles release silver ions, which are toxic to both bacteria and several higher organisms. Usage of as antibacterial agents has increased the past few years in a variety of consumer products such as clothing. The particles are generally quickly washed out of fabrics or are broken down to ions, and the silver can be completely absent after ten washes. The particles enter waste water treatment plants through waste water. The silver cannot be extracted at the plants and therefore it ends up in the or in the watercourses.

Emission of entails several serious problems:

  • It is a long-lived substance that is toxic at low concentrations for many bacteria and aquatic organisms.
  • There is a fear that it causes resistance to antibiotics in bacteria.
  • It can disrupt the biological treatment process at waste water treatment plants.

Explore further: 'Human touch' nanoparticle sensor could improve breast cancer detection

More information: publications.lib.chalmers.se/p… ent-of-nanomaterials

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FMA
1 / 5 (2) Nov 01, 2012
Who would use the sludge from waste water treatment plant as fertilizer? There are a lot of undigested toxic substances, e,g. PCB, in the sludge, they are more toxic the nano silver particles.
ValeriaT
2.5 / 5 (2) Nov 01, 2012
Who would use the sludge from waste water treatment plant as fertilizer?
I see, these Americans.. Welcome back into reality...
Bowler_4007
1 / 5 (2) Nov 01, 2012
delete this post please
Blakut
4 / 5 (1) Nov 02, 2012
Silver is precious! Would it be expensive to extract it back from the sludge?
ValeriaT
1 / 5 (2) Nov 02, 2012
Silver is precious! Would it be expensive to extract it back from the sludge?
Definitely it would cost more, than the production of a new silver. The silver is adsorbed strongly to the particles of organic material - the only option would be to burn them all and extract the ash.
FastEddy
1 / 5 (1) Nov 02, 2012
Blakut:
Silver is precious! Would it be expensive to extract it back from the sludge?
... ValeriaT:
... Definitely it would cost more, than the production of a new silver. The silver is adsorbed strongly to the particles of organic material ...
... There is $$ in this. It might not cost more than "new" Silver. A reasonable, profitable way to isolate or remove the Silver should/could be found. After all, cell phone recyclers get the Gold out.
FMA
1 / 5 (1) Nov 02, 2012
Thanks for the link ValeriaT, I still don't think it is a wise decision to use sludge as a fertilizer, any toxin will enter the food chain from there especially there are so many industrial non-decomposable chemicals!!
antialias_physorg
5 / 5 (1) Nov 04, 2012
Who would use the sludge from waste water treatment plant as fertilizer?

What else would you do with it? There's a LOT of it and nowhere else to put it. Landfill spaces are filling up. And currently it does make pretty good fertilizer (at next to no cost).
The only other alternative is to burn it.

...Or just do what most anyone did thirty years ago: dump the stuff into rivers and lakes. What that looks like, and what kinds of effects it has on health and sanitation you can see in nations where they still do this (India, much of Africa, parts of Asia ... )
christ_jan
1 / 5 (1) Nov 04, 2012
What happened to those mushrooms that can eat plastic?