Carbamazepine and Its Metabolites in Wastewater and in Biosolids in a Municipal Wastewater Treatment Plant

Abstract

Pharmaceutically active compounds (PhACs) are discharged into the environment from domestic wastewater treatment plants (WWTPs). In this study, we determined the distribution of the anti-epileptic drug, carbamazepine (CBZ), and its major metabolites and caffeine in both aqueous and solid phases through different treatment processes of a WWTP. A method was developed to extract samples of biosolids using pressurized liquid extraction (PLE), coupled with cleanup of extracts using solid-phase extraction. Samples of biosolids and wastewater were analyzed for caffeine and CBZ and five of its metabolites, 10,11-dihydro-10,11-epoxycarbamazepine (CBZ-EP), 11-dihydro-10,11-epoxycarbamazepine (CBZ-DiOH), 2-hydroxycarbamazepine (CBZ-20H), 3-hydroxycarbamazepine (CBZ-30H), and 10,11-dihydro-10-hydroxycarbamazepine (CBZ-100H). The analytes were quantified using liquid chromatography-electrospray ionization tandem mass spectrometry. The recoveries of the analytes were 82.1-91.3% from raw biosolids and 80.1-92.4% from treated biosolids, and the limits of detection were 0.06-0.50 and 0.06-0.40 microg/kg on a wet weight basis for raw and treated biosolids, respectively. The behavior of carbamazepine and its metabolites, together with caffeine as a marker of domestic inputs, was investigated in the WWTP for the City of Peterborough, ON, Canada, which utilizes secondary sewage treatment technologies. CBZ, CBZ-2OH, CBZ-30H, and CBZ-DiOH were detected at concentrations of 69.6, 1.9, 1.6, and 7.5 microg/kg (dry weight), respectively, in untreated biosolids and at concentrations of 258.1, 3.4, 4.3, and 15.4 microg/kg (dry weight), respectively, in treated biosolids. However, CBZ-EP and CBZ-100H were not detected in any of the biosolid samples. CBZ and its five metabolites were detected in all wastewater samples collected from four different stages of treatment. The results showed that 29% of the carbamazepine was removed from the aqueous phase during treatment in the WWTP, while the metabolites were not effectively removed. Concentrations of caffeine were reduced by 99.9% in the aqueous phase, which appeared to be due primarily to degradation. Caffeine was also detected at concentrations of 165.8 and 7.6 microg/kg (dry weight) in raw and treated biosolids, respectively. Because of differences in hydrophobicity, CBZ is the primary analyte in biosolids, while CBZ-DiOH is the primary analyte in the aqueous phase of the wastewater. A mass balance calculation showed that the majority of CBZ and its metabolites exist in the aqueous phase (i.e., wastewater), ratherthan in the biosolids, 78 g of CBZ and its metabolites enters the Peterborough WWTP daily, and 91 g is discharged from the WWTP daily in the combined suspended solids and aqueous phases of the wastewater. The calculated daily inputs into the WWTP are somewhat less than the inputs of 192 g estimated from Canadian annual sales data for CBZ.

Treatment of micropollutants in municipal wastewater: Ozone or powdered activated carbon?

“…Indeed, pharmaceutical compounds are usually transformed in the liver or kidney to more polar and hydrophilic metabolites in order to be readily excreted in the urine or bile (Ikehata et al, 2006). For instance, the metabolite 10,11-dihydro-10,11-dihydroxycarbamazepine has a log K ow of 0.13 compared to 2.45 for the parent compound carbamazepine (Miao et al, 2005). Therefore, due to the low hydrophobicity of human metabolites, a lower PAC affinity is expected.…”

Photochemical Fate of Carbamazepine in Surface Freshwaters: Laboratory Measures and Modeling

“…Finally, because of the large overlap between CBZ biotransformation and phototransformation metabolites/intermediates, the same compounds are produced by quite different processes. 1,[27][28][29][30][31] Largely out of this reason, to date there is no indication of which intermediates could be used as reliable markers of CBZ phototransformation in the environment. Therefore, it is presently not possible to distinguish between human metabolism, the (however limited) WWTP processing and photochemistry, as sources of CBZ intermediates in surface waters.…”

Fate and mass balance of contaminants of emerging concern during wastewater treatment determined using the fractionated approach

“…Similarly, removals based on combined loads were obtained for 562 carbamazepine and its two investigated metabolites, CBZ-DiOH and CBZ-EP. A limited number of 563 studies have investigated the removals of carbamazepine and its major metabolites in WWTPs 564 (Hummel et al, 2006;Leclercq et al, 2009;Miao et al, 2005). Only the study by Miao et al (2005) 565 examined the concentrations of carbamazepine and its metabolites at each treatment step of the 566 WWTP and observed a decline in the concentration of carbamazepine and its two metabolites in the 567 primary clarifier and an increase in carbamazepine and CBZ-DiOH concentrations by activated 568 sludge.…”

“…The two metabolites of carbamazepine were not quantified in sludge 588 samples in the present study. However, Miao et al (2005) concluded that these compounds are 589 present at low concentrations in biosolids (<8 ng/g). 590 591 …”