Fate and risk of pesticides, pharmaceuticals, illicit drugs, and personal care products in the Iberian river basins of Ebro and Llobregat: Challenges and solutions using advanced treatment technologies in a European context

Occurrence of emerging contaminants in environmental waters is directly related to their removal in wastewater treatment plants (WWTPs) and the flow rate of the receiving waters. Conventional WWTPs were not designed to remove some organic compounds such as emerging pollutants. A wide array of micropollutants are usually found in WWTP efluents, so there is a need to develop and evaluate alternative treatments which could be efficient for their elimination.Advanced treatment technologies such membrane bioreactors (MBR) and photocatalytic processes could improve the removal of many emerging pollutants and thereby diminish their presence in surface waters. Mediterranean rivers are characterized by important fluctuations in the flow rates and heavy contamination pressures from extensive urban, industrial and agricultural activities. This translates in contamination levels most often higher than in other European basins. For instance, the Llobregat river basin (Catalonia, NE Spain) suffers from extreme and frequent flow fluctuations (1–100 m3 s-1) and receives the effluent discharges of more than 55 WWTPs, and at some points, especially in drought periods, the effluents may represent almost 100% of the total flow of the river. Thus, it is not strange to find considerably high levels of organic contaminants along the river and increasing concentrations when moving downstream due to the also increasing number of WWTPs and population pressure. Besides conventional contaminants such as pesticides, Hg, organochlorine compounds, polycyclic aromatic hydrocarbons (PAHs), alkylphenols and polybrominated diphenyl ethers (PBDEs), emerging contaminants such as pharmaceuticals and personal care products and illicit drugs represent an overgrowing portion of trace organic contaminants of concern in two studied Iberian rivers (Ebro and Llobregat). This presentation summarizes the findings of several studies and monitoring programs conducted with the aim of getting a better insight about the sources and fate of pesticides, pharmaceuticals, illicit drugs and personal care products in the aquatic environment in Spain. The occurrence of these contaminants is discussed in relationship to their removal in WWTPs, influence of hydrological conditions in the receiving river waters, sediments and dilution factors. The removal of some of them (e.g., acetaminophen, diclofenac, ibuprofen, carbamazepine and atenolol as well as the illicit drugs cocaine and methadone) with advanced water treatments and the study ofthe formed transformation products and their toxicity is also presented. In addition, the risk posed by these emerging contaminants in both surface and effluent wastewaters was assessed towards different aquatic organisms (algae, daphnids and fish) by determining hazard indexes.These indexes are further correlated with some biological descriptors characterizing both the structure and functioning of the receiving aquatic ecosystems such as biofilms or the macroinvertebrate community. The study completes with an analysis of the strategies under discussion within the European Countries in order to reduce the environmental risk posed by the occurrence of the most critical emerging contaminants in surface waters. In particular the recent European directive 2013/39/UE as regards priority substances in the field of water policy and the Swiss Micropoll Strategy are presented and their main issues discussed in terms of relevant compounds to monitor regularly, priority actions to reduce their occurrence, best techniques to adopt in upgrading existing wastewater treatment plants.