In France, the national water authority, ONEMA, is currently conducting a series of consultations in regard to nanoparticles and their effects on both the environment and wastewater treatment plants.
According to recent studies, the cytotoxicity of some nanoparticles seems to have an impact on the activated sludge process: have any of you seen evidence of this or do you have any information about it?
That is a very interesting issue that many water professionals are looking into.
I think it is going to be difficult to quantify the impact of nanoparticles, which have the ability to absorb toxic metals, on bacteria metabolism and potential toxicity because of the very low concentration of these particles in the influent. There are so many other potential toxic pollutants in the wastewater.
In terms of sewage, future processes will focus increasingly on emerging pollutants, e.g., endocrine disrupters that have a bigger impact on health and reproduction.
In terms of research on nanoparticles, these tend to concentrate on the particles' ability to trap toxic metals via adsorption in particular for the treatment of drinking water.
Here is a translated extract from an article in "Environnement & Technique", issue 351 by Dorothée Laperche, specialized correspondent:
“In WWTP, nanoparticles represent a new way of both treating pollutants and possible contaminants. According to Jean-Yves Bottero, Research Director at the Cerege, ‘There are new techniques being developed in metrology, but one of the obstacles to their implementation is that many nanoparticles recombine and transform themselves into other chemical compounds and so are lost.’ (…) In WWTP sludge, work is underway to assess the concentration of frequently used nanoparticles such as titanium dioxide in a range of 370 mg/kg to 2,000 mg/kg, cerium oxide at 10 mg/kg or silver at 2 mg/kg. (…) In light of the estimated quantities, then the question arises about how these compounds interact with other elements in the plant. Nanoparticles could in fact disrupt the effectiveness of secondary biological treatment, clog trickling filters or even interacting with the microorganisms required for processing.”
(…) If nanoparticles are pollutants that have to be eliminated from wastewater treatment, some could however allow for removal of organic compounds such as ethyl chloride, pesticides, herbicides, or even traces of antibiotics.