Pollutants In Spanish Waste Water Evaluated

Scientists at the Centre for Solar Energy Research (CIESOL) at the University of Almeria (UAL) have evaluated the potential environmental impact of certain pollutants on waste water at various urban water treatment plants in Spain, including El Ejido (Almería), Alcalá de Henares (Madrid), El Prat de Llobregat (Barcelona), and Vuelta Ostrera (Cantabria), and have produced a league table of their level of toxicity

"The most problematic pollutants are the so-called "emerging" ones (including various organic chemical compounds) such as pharmaceutical products (which we consume and are excreted by our bodies, ending up in waste water), personal hygiene products (detergents and deodorants), ultraviolet light filters used in sun creams, and synthetic fragrances used in cleaning products," Iván Muñoz, one of the authors of the league table and a researcher at the University of Almeria (UAL), tells SINC.

As ‘emerging' pollutants are not regulated by law, "the treatment plants don't routinely check for them", the experts behind the article published in the journal Chemosphere explain.

The group also analysed "priority" pollutants, in other words those covered by the European Union's Water Framework Directive and classified because of their potential effects on the aquatic environment. These pollutants tend to come from industrial rather than domestic sources, including heavy metals, pesticides and polyaromatic hydrocarbons.

Purified water is less toxic

The researchers analysed 98 pollutants (75 emerging ones and 23 priority ones) over the course of a year at the El Ejido (Almería) treatment plant before and after the water had been purified. They identified the most problematic pollutants and found that "treated water has a lesser impact, in terms of toxicity on aquatic and land-based ecosystems and human health, than unpurified water", according to Muñoz.

The results show that, of the pollutants analysed, 16 have a significant effect on water toxicity, ten being pharmaceutical and personal hygiene products and six being priority contaminants. "The remainder showed very low toxicity, or were present at very low levels, or both," explains the researcher.

In addition, the potential impact of treated water is "notably" reduced, and it is less toxic, if it is released into the water system or re-used in agriculture.

In order to carry out this study, the Almeria-based scientists compiled all available information on the pollutants' physical-chemical characteristics, biodegradability and toxicity. They also evaluated, along with researchers from the Universities of Jaén, Alcalá de Henares and Nijmegen (Holland), how these contaminants tend to disperse in the atmosphere, soil and water, as well as their toxicity levels, using mathematical models similar to those used in Risk Evaluation. The evaluation method used was based on Life Cycle Analysis, a methodology used to evaluate the environmental impacts of products and processes.

The researchers are currently working on the national Treatment and Re-use of Waste Water for Sustainable Management (TRAGUA) project, as part of the Consolider-Ingenio 2010 Programme, in which more than 20 Spanish research groups from various universities are taking part.