Distribution and temporal evolution of pharmaceutically active compounds alongside sewage sludge treatment. Risk assessment of sludge application onto soils

In this work, the distribution and the ecotoxicological risk of sixteen pharmaceutically active compounds belonging to seven different therapeutic groups (five anti-inflammatory drugs, two antibiotics, an anti-epileptic drug, a β-blocker, a nervous stimulant, four estrogens and two lipid regulators) have been studied in sewage sludge from wastewater treatment plants. Only three of the sixteen pharmaceutical compounds were never detected in sludge while eleven of the studied pharmaceuticals were still detected in compost. Mean concentration levels of the pharmaceutically active compounds ranged between 24.9 and 4105 μg/kg dm, 14.5–944 μg/kg dm, 3.29–636 μg/kg dm and 9.19–974 μg/kg dm in primary, secondary, digested sludge and compost, respectively. An increase in the concentration levels of most of the pharmaceuticals was observed from summer to winter (mean values in primary and secondary sludge were 304 and 85.1 μg/kg dm in summer and 435 and 175 μg/kg dm in winter, respectively) probably due to an increase of their consumption during the coldest season and a reduction of the microbial activity under colder temperatures. The highest ecotoxicological risk, in digested sludge and compost, was due to the estrogenic compound 17β-estradiol. The ecotoxicological risk significantly decreased after the application of digested sludge or compost to the soils (risk quotient values ranged between 0.04 and 252 in digested sludge and 0.002–37.8 in compost and decreased to 8·10−4–1.92 in digested sludge-amended soil and 1·10−4–0.23 in compost-amended soil).

► The paper deals with the distribution of pharmaceuticals in sewage sludge treatments. ► We examine the temporal evolution of pharmaceuticals in sludge during a one year period. ► Our study evaluates the risks of the application of sewage sludge onto soils due to the pharmaceuticals.