Pharmaceuticals and Their Main Metabolites in Treated Sewage Sludge and Sludge-Amended Soil: Availability and Sorption Behaviour

Abstract

This work evaluated the availability and sorption behaviour of four pharmaceuticals and eight of their metabolites in sewage sludge and sludge-amended soil. Digested sludge and compost were evaluated. The highest levels found in digested sludge corresponded to caffeine (up to 115 ng g−1 dm), ibuprofen (45 ng g−1 dm) and carbamazepine (9.3 ng g−1 dm). The concentrations measured in compost were even lower than in digested sludge. No compound was detected in sludge-amended soils. This fact could be due to the dilution effect after sludge application to soil. Different adsorption capacities in sludge–soil mixtures were measured for the studied compounds at the same spike concentration. In general, except for paraxanthine and 3-hydroxycarbamazepine, the metabolite concentrations measured in the mixtures were almost two-fold lower than those of their parent compounds, which can be explained by their mobility and lixiviation tendency. The log Kd ranged from −1.55 to 1.71 in sludge samples and from −0.29 to 1.18 in soil–sludge mixtures. The log Kd values calculated for compost were higher than those calculated for digested sludge. The obtained results implied that the higher organic carbon content of compost could influence soil contamination when it is applied to soil.

Thermodynamic and Kinetic Investigation of the Adsorption and Desorption of Trimethoprim and Its Main Metabolites in Mediterranean Crop Soils

“…The third step of the model corresponds to the equilibrium phase [ 23 ]. According to previously published papers about the adsorption of TMP [ 1 , 24 , 25 ] and other PhACs and their metabolites [ 17 , 18 , 19 , 20 ] in different soils and following the recommendations of the OECD [ 26 ], kinetic experiments were carried out from 0 to 1440 min (24 h). The studied period was enough to achieve equilibrium; however, the third step (slopes for the Weber–Morris plots ( k ip ) close to cero) was not viewable (these are usually viewable from 24 to several days).…”

“…This shows the need to evaluate the adsorption and desorption of each compound case-by-case in relation to the soil characteristics to know its mobility and the potential influence on its environmental risks. However, despite the fact that the adsorption of several compounds has been previously evaluated (such as polycyclic aromatic hydrocarbons [ 13 , 14 ], pesticides [ 15 , 16 ], and even PhACs [ 17 , 18 , 19 , 20 , 21 ] including TMP), to the best of our knowledge, there are no previous studies about the adsorption or desorption of TMP metabolites in Mediterranean soils. In addition, most of the reported data is focused on the adsorption of PhACs into the soil, while there is a lack of information on their desorption behavior.…”

From Sewage Sludge to the Soil—Transfer of Pharmaceuticals: A Review

“…A very simple classification for risk assessment by RQ divides substances with low (RQ < 0.1), medium (RQ between 0.1–1), and high risk (RQ > 1) environmental effects [ 104 ]. It was also proposed to assess the environmental risk in soil based on pharmaceutical concentrations and PEC soil calculation from the formula of the European Commission Technical Guidance Document on Risk Assessment [ 105 ]: PEC soil = C sludge × APPL sludge /DEPTH soil × RHO soil where C sludge is the concentration of pollutants in the sludge; APPL sludge is the dry sludge application rate (0.5 kg/m 2 year); DEPTH soil is the depth of soil mixing (0.20 m); and RHO soil is the bulk density of wet soil (1700 kg/m 3 ) [ 33 ].…”

Multiresidue method for the determination of critically and highly important classes of antibiotics and their metabolites in agricultural soils and sewage sludge

“…Because of their extended use—and often overuse and misuse—parent compounds and their metabolites are continuously discharged into the environment mainly through effluents from wastewater treatment plants (WWTP). They can also be accumulated onto sewage sludge generated during wastewater treatments [ 1 – 3 ]. This fact is of special concern when sewage sludge is applied onto agricultural soils as fertiliser [ 4 ].…”