ABSTRACT
The potential of membrane bioreactor (MBR) systems to remove organic micropollutants was investigated at different scales, operational conditions, and locations. The effluent quality of the MBR system was compared with that of a plant combining conventional activated sludge (CAS) followed by ultrafiltration (UF). The MBR and CAS-UF systems were operated and tested in parallel. An MBR pilot plant in Israel was operated for over a year at a mixed liquor suspended solids (MLSS) range of 2.8-10.6 g/L. The MBR achieved removal rates comparable to those of a CAS-UF plant at the Tel-Aviv wastewater treatment plant (WWTP) for macrolide antibiotics such as roxythromycin, clarithromycin, and erythromycin and slightly higher removal rates than the CAS-UF for sulfonamides. A laboratory scale MBR unit in Berlin - at an MLSS of 6-9 g/L - showed better removal rates for macrolide antibiotics, trimethoprim, and 5-tolyltriazole compared to the CAS process of the Ruhleben sewage treatment plant (STP) in Berlin when both were fed with identical quality raw wastewater. The Berlin CAS exhibited significantly better benzotriazole removal and slightly better sulfamethoxazole and 4-tolyltriazole removal than its MBR counterpart. Pilot MBR tests (MLSS of 12 g/L) in Aachen, Germany, showed that operating flux significantly affected the resulting membrane fouling rate, but the removal rates of dissolved organic matter and of bisphenol A were not affected.
Subject(s)
Bioreactors , Environmental Pollutants/isolation & purification , Membranes, Artificial , Organic Chemicals/isolation & purification , Sewage , Ultrafiltration/methods , Waste Management/methods , Anti-Bacterial Agents/isolation & purification , Carbon/chemistry , Cities , Environmental Pollutants/chemistry , Organic Chemicals/chemistry , SolubilityABSTRACT
The mechanism of product formation during ozonation of two widely used antimicrobial agents, macrolide roxithromycin and inhibitor of dihydrofolate reductase (DHFR) trimethoprim was studied in laboratory-scale experiments with two types of matrix: distilled water and secondary wastewater effluent The structures ofthe primary and secondary reaction intermediates were elucidated byquadrupole-time-of-flight (QqToF) instrument, showing that in spite of their high ozone affinity both roxithromycin and trimethoprim oxidation pathway involve to a great degree the *OH radical chain reactions. In total nine ozonation products were detected, whereas two products of roxithromycin exhibited high refractoriness to ozonation, especially in the case of distilled water. Furthermore, the intact tertiary amine moiety of roxithromycin in these products suggests that the antimicrobial activity of the parent compound will be preserved.
Subject(s)
Anti-Bacterial Agents/analysis , Ozone/chemistry , Roxithromycin/analysis , Trimethoprim/analysis , Water Pollutants, Chemical/analysis , Water Purification/methods , Animals , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/toxicity , Daphnia/drug effects , Molecular Structure , Roxithromycin/chemistry , Roxithromycin/toxicity , Trimethoprim/chemistry , Trimethoprim/toxicity , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/toxicityABSTRACT
In this paper, a ceramic open foam is modelled using a two-step procedure. First, a random Laguerre tessellation is fitted to the edge system of the polyurethane foam forming the core of the ceramic foam. In a second phase, a model of the ceramic foam is obtained using dilations with balls of locally varying size. The model fitting is based on geometric characteristics of both polyurethane and ceramic foam estimated from reconstructed tomographic images of these structures.
