Emerging contaminants (or "contaminants of emerging concern") have long been the subject of attention by the scientific community and, more recently, planning and control bodies, both at European and national level: new substances or classes of substances are progressively identified and added to the lists.
Emerging micropollutants are chemical compounds that are present at very low concentrations (in the order of nanograms per liter, or rather a sugar cube in a pond, for instance)
in urban, agricultural and industrial wastewater as well as in surface water.
Only a few years ago we became able to detect and measure them, after the development of advanced analytical tools.
Some examples of these very numerous compounds are: residues of pharmaceutical products for human and animal consumption, illicit drugs, pesticides, disinfectants, hormones, personal care products.
It is not yet known, for emerging substances, if and what effects they can have on ecosystems and humans, when present in surface water at such low concentrations.
As a matter of fact, these â€śemergingâ€ť substances are yet not regulated.
Why is the knowledge of the effects still limited? Because the data are still few and these â€śtoxicologicalâ€ť studies are extremely complex and must be carried out according to specific protocols recognized and adopted worldwide.
One aspect, however, is already known and confirmed by many research works: traditional wastewater treatment plants have limited capacity to remove many of these emerging micropollutants, essentially because they have been designed to remove other types of pollutants (for example, BOD, ammonia, phosphorus, pathogens, ...), present at concentrations up to a million times greater! So, our weapons to remove these compounds from wastewater before they return to the environment, if and when it is needed, are currently not very effective.
Scientists and researchers are the first to observe and study micropollutants in ecosystems and their possible negative effects.
Thus, organizations responsible for protecting the environment and human health promulgate control limits and strategies
for those compounds for which the harmful effects have been demonstrated and the risk associated to a given level of exposure has been quantified.
For emerging substances whose effects and fate in the environment are still being studied, monitoring and research activities have already been in place for several years, involving a large number of institutions and research centers around the world. In general, a common and characteristic aspect of dangerous substances is their persistence in the environment: it means that they are not naturally degraded or very little, and this leads to their accumulation and potential increase in the harmful effect.
The European Union, through its deputy bodies, has promulgated more than ten years ago the directive 2008/105/CE, which establishes environmental quality standards for water, recognizes some of these compounds as priority and defines maximum limits of admissible concentration in surface water and sediments. In addition to this list of substances, there is another list of chemical compounds, called the watch list, which includes those compounds that are candidates for future regulation, in case their dangerousness is demonstrated by future investigations related to toxicological effects and persistence.
In future years, the Integrated Water Service managers will have to adapt wastewater treatment plants so that
they could also be effective in the removal of emerging micropollutants, in case that these chemical compounds are regulated.
Therefore, the implementation of dedicated technologies and practices will be necessary.
To date, numerous studies have already evidenced the limits of existing technologies and some possible solutions, mainly consisting of additional processes specifically aimed at removing emerging micropollutants. At the current state of development, these technologies have been extensively validated at laboratory scale and under controlled operating conditions, but it is essential to study and validate them even at full scale and under realistic operating conditions.
Within the PerFORM WATER 2030 project, three technological solutions are being studied in relation to the removal of emerging micropollutants from wastewater: adsorption on activated carbon, oxidation with ozone and purification with microalgae.
Many substances where chosen as a subject to investigation within the PerFORM WATER 2030 project; the choice was made through a two-step process that took into account the actual conditions of wastewater in the Metropolitan City of Milan: a first phase of bibliographic research preparatory to the experiments was followed by a second phase of qualitative screening in the waste water treatment plants.
Once the aforementioned preliminary activities have been completed, a detailed analysis has begun on the micropollutants belonging to the identified list of substances: this has only been possible thanks to the innovative specially developed analytical methods adopted, characterized both by a high sensitivity and by a strong specificity for each compound considered.
Web site of the NORMAN network, a network of stakeholders that deal with emerging micropollutants
Web site of the International Panel on Chemical Pollution (IPCP)
Report on emerging micropollutants from the website of the United Nations Environment Programme
Informative video "Dare to Drink? Emerging Pollutants in Our Water" produced by the Ecologic Institute within the European project DEMEAU
Informative video "The Drugs We Wash Away: Pharmaceuticals, Drinking Water and the Environment" produced by the Ecologic Institute within the European project PHARMAS
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