NanoparticlesIt’ll All Come Out in the Wash…?

Background Info

A “nanoparticle” is generally accepted to be between 1 and

100 nanometers (nm) in diameter. For reference, a

human hair is about 75,000 nm in diameter.

Nanoparticles have been used by humans for centuries, but modern

science is responsible for uncovering a multitude of new uses for nanoparticles

in medicine, clothing, and other industries.

Some products that use nanoparticles:

-stain-resistant khakis -some sunscreens

-odor-trapping socks -scratchproof eyeglasses -crack-resistant paints

Nanotechnology has caused concern in the scientific

community because some believe that not enough

research is being done on possible dangers of the

particles (toxicity, environmental impact, etc.)

(Nanoparticle)

One particular NP that could pose a problem for wastewater

treatment facilities is silver (Ag), which is found in (among other things) odor-resistant socks and

some new washing machines.

Some research indicates that Ag NPs, Ag+ ions, and AgCl

colloids all significantly inhibit microbial growth and

respiration of autotrophic nitrifying organisms.

Testing has proven that the socks lose NP content over

time. Some brands released almost all of their silver

content after only 4 washings.

*Note: Individual socks were tested and found to have as much as 31 mg of

silver per sock

(Organism)

*cough

Ag+ ions inhibit function by attaching to the negatively charged wall of bacterial cells, deactivating cellular enzymes, disrupting membrane permeability, and ultimately

leading to cell lysis and death.

Nanosilver particles also pose a threat. They have the ability to pass straight through cell membranes and can lead to cell malfunction. In addition, they are highly catalytic and can

generate reactive oxygen species.

(Ag+ ions)(Bacteria Cell)

Other NPs to Look For

Aluminum Oxide NPs, commonly found in sunscreen, can stunt root growth in plants (in very high concentrations,

>2 mg/ml water)

Titanium dioxide NPs, found in some types of toothpaste,

cheese, plastic, chocolate and other products have already been

discovered in wastewater biosolids in states across the U.S.

The Good Newsor “The Silver NP Lining”

Nanotechnology has the potential to greatly aid and improve the

wastewater industry!

Nanotechnology is already being used to

detect or remove some of the following materials

from wastewater:

Cadmium, copper, lead, mercury, nickel, zinc,nutrients (e.g. Phosphate, ammonia, nitrate and

nitrite), cyanide, organics, algae (e.g. cyanobacterial toxins), viruses, bacteria, parasites and antibiotics.

Silicon dioxide NPs, currently used in anti-fogging coatings and

potentially as DNA carriers, actually promoted root

growth in plants.

Some iron and aluminum NPs are being used to create more benign

and more stable ceramic membranes for water desalination. The NP membranes decrease energy

consumption for desalination and improve salt rejection properties.

As of June 2008, the EPA does not require

wastewater treatment facilities to treat nanomaterials.

Regulations & Monitoring

The EPA has spent millions of dollars researching the

positive and negative effects of nanoparticles on the

environment, but regulations are still few and far between.

As of 2006, companies that make products containing

silver NPs for the purpose of killing bacteria are required

by the EPA to prove that they pose no environmental

health risk. However, testing methods are only in

developmental stages.

There is additional debate on whether or not to consider NPs such as silver as “pesticides”, since they are now used to kill pests (bacteria). As of 2007,

the EPA does claim silver NPs to be pesticides, which requires

their regulation under the Federal insecticide, fungicide and rodenticide act (FIFRA).

WERF’s Contributions

The 2006 Paul L. Busch award was given to Dr. Paul Westerhoff of Arizona State University, to continue his team’s

research on the fate of commercial nanomaterials in drinking water and

wastewater treatment plants, and their potential human toxicity.

WERF is also funding Dr. Zhiquang Hu of the University of Missouri to research

the impact of silver nanoparticles on wastewater treatment.

(Both of these projects and their preliminary findings and results were referenced in the preparation this presentation)

Discussion:

Strategies or plans of action for wastewater

treatment plants to prepare for possible issues with NPs

in the near future

Made by:Andrew Reyno

Sources:Okkyoung Choia, Kathy Kanjun Dengb, Nam-Jung Kimc, Louis Ross Jr.d, Rao Y. Surampallie, Zhiqiang Hu.

The inhibitory effects of silver nanoparticles, silver ions, and silver chloride colloids on microbial growth. Water Research, Vol. 42, 2008. pp. 3066-3074.

Dhermendra K. Tiwari, J. Behari and Prasenjit Sen. Application of Nanoparticles in Waste Water Treatment. World Applies Sciences Journal, Vol. 3, 2008. pp. 417-433.

Anonymous. Nanoparticle Impact on Plants. United Press International, 2005. Physorg.com

Melissa Crytzer Fry. Too small to see: the environmental impact of nanoparticles. Arizona State University, 2008.

Summer Intern, Holland BPW