120 research outputs found
Removal of Antibiotics in Biological Wastewater Treatment Systems—A Critical Assessment Using the Activated Sludge Modeling Framework for Xenobiotics (ASM-X)
Many
scientific studies present removal efficiencies for pharmaceuticals
in laboratory-, pilot-, and full-scale wastewater treatment plants,
based on observations that may be impacted by theoretical
and methodological approaches used. In this Critical Review, we evaluated factors influencing observed removal efficiencies of three
antibiotics (sulfamethoxazole, ciprofloxacin, tetracycline) in pilot-
and full-scale biological treatment systems. Factors assessed include
(i) retransformation to parent pharmaceuticals from e.g., conjugated metabolites
and analogues, (ii) solid retention time (SRT), (iii) fractions sorbed
onto solids, and (iv) dynamics in influent and effluent loading. A
recently developed methodology was used, relying on the comparison
of removal efficiency predictions (obtained with the Activated Sludge
Model for Xenobiotics (ASM-X)) with representative measured data
from literature. By applying this methodology, we demonstrated that
(a) the elimination of sulfamethoxazole may be significantly underestimated
when not considering retransformation from conjugated metabolites,
depending on the type (urban or hospital) and size of upstream catchments;
(b) operation at extended SRT may enhance antibiotic removal, as shown
for sulfamethoxazole; (c) not accounting for fractions sorbed in influent
and effluent solids may cause slight underestimation of ciprofloxacin
removal efficiency. Using tetracycline as example substance, we ultimately
evaluated implications of effluent dynamics and retransformation on
environmental exposure and risk prediction
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