We use chemicals for everything: personal care products, cleaning products for home, chemical dyes in our clothes, food/industrial preservatives, drugs... Chemicals are part of us and, consequently, part of our water. Water is the footprint of our life style and contents a little part of all the chemicals we use. Specially that chemicals that are not metabolized in our body or degraded in waste water treatment plant.
And… is this bad? Well… in aquifers and rivers from Barcelona cocaine, contraceptives and ibuprofen have been found (e.g. Jurado et al. 2012). Of course, this does not sound well. But they are measured at very small concentrations, normally from micrograms to picograms (10-6 to 10-12 g/L of water). In fact, the emerging organic compounds have been a research issue since analytical chemistry has the tools to analyze them...
So, in most cases we should not worry about that. We normally take drugs much more concentrated, for example 400 mg of ibuprofen in 200mL of water…Nevertheless, as water is the sink of all the chemicals we use, some chemicals that were not designed to be ingested are also found, like industrial components or personal care products… Some of them are endocrine disruptors and can be mutagenic. Of course, this is much more alarming for human health.
Another important issue is the ecosystem. All these products have been designed for human health and human life but not for ecosystem health… for example, contraceptives considers only the women metabolism but not from the other species. Consequently, fish populations with reproductive problems have been found in lot of rivers of Europe.
Finally, another important issue is that when all these chemicals enter in the environment (groundwater, surface water…) they are under very variant conditions and the molecule bonds are slowly broken until get the complete mineralization. Meanwhile, different intermediate compounds, called metabolites, are formed. Of course, some of these metabolites could be more toxic than the parent compounds.
It is obvious that the problem is complex. On the one hand water has thousands of compounds that are increasing the toxicity of water in terms of human and ecosystem health and on the other hand the variant conditions of the environment promote different intermediate compounds that are completely unknown and that can be more dangerous than parent compounds…
To minimize the risk of emerging organic compounds to human and ecosystem health we should understand the fate of these compounds in the subsurface and how the different environmental conditions affect the metabolite formation.
The environment is complex. Conditions (pH, temperature, red-ox potential) change temporally and spatially. In order to understand what is happening with these compounds, we need to work in controlled conditions. For that, experiments under controlled conditions can help to set-up the main processes affecting the fate of organic compounds. In GHS, we have and we are developing different experiments.
Modeling is the perfect tool to verify and understand all the processes that are occurring in a complex system. For that, in GHS we are developing models at different levels:
To understand the mechanism processes of degradation of EOCs:
To understand how mixing influences in the reactivity of benzotriazoles:
In the begining of the 10s, GHS started working with emerging organic compounds at batch scale. We performed different microcosmos experiments and we monitored the fate of emerging organic compounds at controlled environmental conditions. Herewith some results:
INDEMNE project is a Spanish national funded project (CGL2015-69768-R) which aims at improve the understanding of EOCs during managed aquifer project. Concretely, INDEMNE pretends to understand how mixing enhances reactivity of redox processes and, at the same time, improves the degradation of EOCs by direct metabolism or co-metabolism. One of the main tasks is to develop experiments at intermediate scale.
ACWAPUR project is a Water JPI Project which aims at improve the managed aquifer recharge in terms of EOCs degradation by the construction of reactive barriers.