Occurrence of pharmaceuticals and their metabolites in sewage sludge and soil: A review on their distribution and environmental risk assessment

The recycling and recovery of organic matter and nutrients from sewage sludge for application in agricultural soils is gaining interest, while the presence of pharmaceutically active compounds (PhACs) in this matrix may have a great impact on the environment and human health. The aim of this review paper is to outline recent research on the occurrence of PhACs and their metabolites in sewage treatment lines. A total of 32 classes of therapeutic groups including 180 PhACs and 45 metabolites have been included. In a first part, a summary of the analytical methods with a critical overview of the extraction and determination techniques, quality control issues and methodological challenges for their determination is included. Subsequently, the study gives a snapshot of the concentration levels and distribution patterns found in primary, secondary, digested (aerobically and anaerobically), dehydrated and composted sludge. Data have been systematically summarized and categorized according to matrix type, treatment processes available for PhAC degradation in sludge, and geographical areas. Our literature review showed that antimicrobials, antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), antidepressants and antidiabetics were the most abundant PhACs found in sludge matrices.Overall, attenuation of PhACs concentrations occurs during sludge stabilization, in particular during anaerobic digestion and composting. PhAC sorption onto sludge is strongly affected by the physicochemical properties, the sludge matrix and the operating and environmental conditions. Lastly, the paper discusses the impact of PhACs on sludge-amended agricultural land. The potential ecotoxicological risk associated with the presence of PhACs in amended soil is medium-low for most PhACs. The most critical compounds found in sludge-amended soil are ciprofloxacin, 17α-ethinylestradiol, 17β-estradiol, and triclocarban and triclosan.