Assessment of pharmaceuticals in water systems: sustainable phytoremediation strategies

Abstract

The contamination of aquatic environments with pharmaceuticals has become over the latest years one of the top concerns in Environmental Science and in regard to Public Health and Safety policies. Although reported environmental concentrations of any single pharmaceutical compound are usually too low to induce acute ecotoxicological problems on its own, the prolonged exposure to these pseudo-persistent pollutants (which are originally designed to interfere with biochemical processes) is expected to potentialy cause chronic effects in the long term. In addition, the wide variety of drugs already detected in the environment raises the possibility of cumulative effects of substances with similar modes of action, or even of synergistic effects that may potentiate the harmful effects of some of the compounds. Therefore, the clarification of the current situation in terms of their removal from wastewaters under the currently used wastewater treatment processes, the impacts they may cause or are already causing in ecossytems and to human health, and the prospects for improvements of future wastewater treatment plants design and operation is urgently needed. This chapter presents a review of the current knowledge on the sources, occurrence and fate of a variety of classes of pharmaceuticals in the environment, WWTPs, sewage sludge and/or biosolids and some crop plants and macrophytes. A summary of the most commonly detected pharmaceuticals and typical concentration levels at which they occur is presented, organized by therapeutical class. Wastewater treatment plants, which are the major source of pharmaceuticals in the aquatic environment, are analyzed in some detail, focusing on the efficiencies of pollutant removal that are typical of these conventional means. Ensuingly, alternative or complementary solutions provided by some advanced wastewater treatment technologies are briefly discussed. In this regard, a phytoremediation technology for wastewater treatment is gaining increasing acceptance and widespread use: the constructed wetlands systems, which are discussed in further detail in the final part of the text. The chapter concludes with an overall appreciation of this subject, pointing out some relevant topics that are still scarcely explored and, therefore, may lead to interesting new avenues of research in this field.