In this paper we report on the performances of full-scale conventional activated sludge
(CAS) treatment and two pilot-scale membrane bioreactors (MBRs) in eliminating various
pharmaceutically active compounds (PhACs) belonging to different therapeutic groups
and with diverse physico-chemical properties. Both aqueous and solid phases were analysed
for the presence of 31 pharmaceuticals included in the analytical method. The most
ubiquitous contaminants in the sewage water were analgesics and anti-inflammatory
drugs ibuprofen (14.6-31.3 microg/L) and acetaminophen (7.1-11.4 microg/L), antibiotic
ofloxacin (0.89-31.7 microg/L), lipid regulators gemfibrozil (2.0-5.9 microg/L) and
bezafibrate (1.9-29.8 microg/L), beta-blocker atenolol (0.84-2.8 microg/L), hypoglycaemic
agent glibenclamide (0.12-15.9 microg/L) and a diuretic hydrochlorothiazide (2.3-4.8
microg/L). Also, several pharmaceuticals such as ibuprofen, ketoprofen, diclofenac,
ofloxacin and azithromycin were detected in sewage sludge at concentrations up to
741.1, 336.3, 380.7, 454.7 and 299.6 ng/g dry weight. Two pilot-scale MBRs exhibited
enhanced elimination of several pharmaceutical residues poorly removed by the CAS
treatment (e.g., mefenamic acid, indomethacin, diclofenac, propyphenazone, pravastatin,
gemfibrozil), whereas in some cases more stable operation of one of the MBR reactors
at prolonged SRT proved to be detrimental for the elimination of some compounds (e.g.,
beta-blockers, ranitidine, famotidine, erythromycin). Moreover, the anti-epileptic
drug carbamazepine and diuretic hydrochlorothiazide by-passed all three treatments
investigated. Furthermore, sorption to sewage sludge in the MBRs as well as in the
entire treatment line of a full-scale WWTP is discussed for the encountered analytes.
Among the pharmaceuticals encountered in sewage sludge, sorption to sludge could be
a relevant removal pathway only for several compounds (i.e., mefenamic acid, propranolol,
and loratidine). Especially in the case of loratidine the experimentally determined
sorption coefficients (Kds) were in the range 2214-3321 L/kg (mean). The results obtained
for the solid phase indicated that MBR wastewater treatment yielding higher biodegradation
rate could reduce the load of pollutants in the sludge. Also, the overall output load
in the aqueous and solid phase of the investigated WWTP was calculated, indicating
that none of the residual pharmaceuticals initially detected in the sewage sludge
were degraded during the anaerobic digestion. Out of the 26 pharmaceutical residues
passing through the WWTP, 20 were ultimately detected in the treated sludge that is
further applied on farmland.