Wilhelm Gebhardt

In vitro characterization of the effectiveness of enhanced sewage treatment processes to eliminate endocrine activity of hospital effluents

Occurrence of pharmaceuticals in aquatic ecosystems is related to sewage effluents. Due to the possible adverse effects on wildlife and humans, degradation and removal of pharmaceuticals and their metabolites during wastewater treatment is an increasingly important task. The present study was part of a proof of concept study at a medium sized country hospital in western Germany that investigated efficiency of advanced treatment processes to remove toxic potencies from sewage. Specifically, the efficiency of treatment processes such as a membrane bioreactor (MBR) and ozonation to remove endocrine disruptive potentials was assessed. Estrogenic effects were characterized by use of two receptor-mediated in vitro transactivation assays, the Lyticase Yeast Estrogen Screen (LYES) and the Estrogen Receptor mediated Chemical Activated LUciferase gene eXpression (ER CALUX(®)). In addition, the H295R Steroidogenesis Assay (H295R) was utilized to detect potential disruption of steroidogenesis. Raw sewage contained measurable estrogen receptor (ER)-mediated potency as determined by use of the LYES (28.9 ± 8.6 ng/L, 0.33× concentration), which was reduced after treatment by MBR (2.3 ± 0.3 ng/L) and ozone (1.2 ± 0.4 ng/L). Results were confirmed by use of ER CALUX(®) which measured concentrations of estrogen equivalents (EEQs) of 0.2 ± 0.11 ng/L (MBR) and 0.01 ± 0.02 ng/L (ozonation). In contrast, treatment with ozone resulted in greater production of estradiol and aromatase activity at 3× and greater concentrations in H295R cells. It is hypothesized that this is partly due to formation of active oxidized products during ozonation. Substance-specific analyses demonstrated efficient removal of most of the measured compounds by ozonation. A comparison of the ER-mediated responses measured by use of the LYES and ER CALUX(®) with those from the chemical analysis using a mass-balance approach revealed estrone (E1) to be the main compound that caused the estrogenic effects. Overall, treatment of sewage by use of MBR successfully reduced estrogenicity of hospital effluents as well as substances that are able to alter sex steroid production. However, after ozonation, effluents should undergo further investigations regarding the formation of endocrine active metabolites. The results obtained as part of this study demonstrated applicability of in vitro assays for monitoring of endocrine-modulating potency of treated sewage.

Detection and identification of degradation products of sulfamethoxazole by means of LC/MS and -MSn after ozone treatment.

The ozonation of the antibiotic sulfamethoxazole has been studied, in order to elucidate the structures of some of the degradation products generated throughout the process. Under the conditions applied, a complete destruction of sulfamethoxazole was achieved after 10 minutes of reaction. The biodegradability of the resulting solution has been also determined, and this parameter undergoes a gradual increase along during the reaction time. The acute toxicity of the reaction mixture, on the contrary, is only decreased during the first 5 minutes of reaction while it increases subsequently. Some of the intermediates resulting during ozonation seem to be more toxic to Daphnia magna than the untreated sulfamethoxazole. The structures of selected degradation products found in the solution are determined and identified. Ozone predominantly attacks sulfamethoxazole via the amine group of the aniline ring in some cases giving rise to nitro-aromatic compounds.

Physicochemical and Advanced Oxidation Processes – A Comparison of Elimination Results of Antibiotic Compounds Following an MBR Treatment

The occurrence of pharmaceuticals in the environment has become a subject of concern in recent years. A vast number of these compounds have been detected in sewage treatment plants (STP) effluents, surface waters and, less frequently, in ground and drinking water all over the world. Adverse effects caused by pharmaceuticals include aquatic toxicity, resistance development in pathogenic bacteria, genotoxicity and endocrine disruption. Nowadays, it is widely accepted that the main source of pharmaceutical pollution in the aquatic environment are STPs effluents. Therefore, the discharge of pharmaceutical residues with the effluents of STPs should be minimized as far as possible. Degradation of persistent organic pollutants such as pharmaceuticals in water and wastewater can be achieved using advanced treatment technologies such as membrane bioreactors (MBRs) in combination with advanced oxidation processes (AOPS). This paper evaluates the treatment of three antibiotics of large consumption rates worldwide (roxithromycin, sulfamethoxazole and trimethoprim) by MBR followed by different AOP-steps. The identification and quantification of the precursor compounds and degradation products observable during the different treatment steps applied were performed with liquid chromatography coupled with high resolution mass spectrometry (LC-MS)

Identification of degradation products of erythromycin a arising from ozone and advanced oxidation process treatment.

The degradation products of the macrolide antibiotic erythromycin A (ERY) arising from direct ozone attack and hydroxyl radical attack are presented for the first time. Ozone treatment was carried out by spiking ozone stock solutions to solutions containing ERY-ERY:O3 = 1:5 and 1:10 (M:M), while, in parallel, t-BuOH was used as a hydroxyl radical (*OH) scavenger. The advanced oxidation processes (AOPs) O3/UV, O3/H2O2, and UV/H2O2 were carried out to recognize and verify possible differences between their primary degradation products; the initial concentrations were ERY:O3 = 1:5 (M:M), ERY:O3:H202 = 1:5:5 (M:M:M), or ERY:H202 = 1:5 (M:M), respectively. Six degradation products were identified from ozonation-one originates from direct ozone attack on the tertiary amine group, while the others arise from radical ion attack, which might be formed during degradation of O3 in water. Fewer primary degradation products were observed arising from *OH-based treatments (AOP) than from ozonation, possibly because the reaction of *OH radicals is non-selective and typically is diffusion-controlled. Four degradation products were detected by *OH radical attacks; two of them already were observed during ozonation, with one as an oxidized ERY molecule and the other as a non-oxidized fragment of the ERY molecule.

Imazalil Degradation upon Applying Ozone—Transformation Products, Kinetics, and Toxicity of Treated Aqueous Solutions

The elimination of the pesticide imazalil (IMZ) spiked into ultrapure water as well as into wastewater applying ozone (O3) and the identification of transformation products was investigated. O3 under hydroxyl radical suppression conditions reacted rapidly with the aliphatic double bond or the imidazole ring in IMZ, yielding several transformation products by partial oxidation. The structures of four oxidation products not yet described were characterized and identified after liquid chromatography coupled with high resolution, high mass accuracy, mass and tandem mass spectrometry (LC/MS and -MSn) in ultrapure water. For two identified transformation products, generated via direct ozone attack on IMZ, formation pathways were proposed. In wastewater, only two of those transformation products were observed. Kinetics studies for the reaction of IMZ with O3, evaluated by the competition kinetic method, resulted in a second-order rate constant kO3,IMZ ∼ (1.02 ± 0.03) × 105 M−1 s−1 at pH 6.6 ± 0.2, indicating that IMZ is completely transformed during the ozonation process. Tests of acute toxicity were performed applying a solution of IMZ in ultrapure water or treated wastewater to Daphnia magna. In both cases the decrease of toxicity was observed after ozone treatment.

Advanced Oxidation Processes for the Elimination of Drugs Resisting Biological Membrane Treatment

The recalcitrant pharmaceutical compounds carbamazepine, clofibric acid, diazepam, and diclofenac were monitored in municipal wastewater by ESI-LC-MS and -MS-MS in positive and negative mode. Although biological treatment by conventional and membrane bioreactor failed, the advanced oxidation methods using ozone (O3), O3/UV or hydrogen peroxide in combination with UV (H2O2/UV), successfully achieved their complete elimination. Target compounds could be confirmed as permanently present pollutants in Aachen-Soers wastewater in concentrations between 0.006 and 1.9 μg L−1 prior to AOP treatment resulting in a complete elimination.

Identification of New Oxidation Products of Bezafibrate for Better Understanding of Its Toxicity Evolution and Oxidation Mechanisms during Ozonation

Bezafibrate (BF), a frequently detected pharmaceutical in the aquatic environment, could be effectively removed by ozonation. However, the toxicity of treated water increased, suggesting the generation of toxic oxidation products (OPs). In this study, eight OPs of BF ozonation were identified using a LTQ Orbitrap hybrid mass spectrometer coupled with HPLC, and six of them have not been previously reported during BF ozonation. Based on the abundant fragments and high assurance of accurate molar mass, structure elucidation was comprehensively performed and discussed. Hydroxylation, loss of methyl propionic acid group, and Crigée mechanism were observed as the oxidation mechanisms of BF ozonation. The toxicity of identified OPs calculated by quantitative structure activity relationship indicated that three OPs were probably more toxic than the precursor compound BF. This result together with the evolution of identified OPs in the treated solutions, indicated that two OPs, namely N-(3,4-dihydroxyphenethyl)-4-chlorobenzamide and N-(2,4-dihydroxyphenethyl)-4-chlorobenzamide, were the potential toxicity-causing OPs during BF ozonation. To the best of our knowledge, this is the first attempt to identify toxicity-causing OPs during the BF ozonation.

Monitoring the Physicochemical and Chemical Treatment of Textile Wastewater using GC/MS, LC/MS and ‐MS/MS Techniques

Abstract Conventional biological wastewater treatment processes often fail in the elimination of finishing agents contained in textile wastewater such as dyes, surfactants, and softeners. Therefore, discharges from the textile industry are known as a major source of water pollution reaching groundwater and even drinking water treatment. Physicochemical treatment and advanced treatment processes (AOP) were applied to eliminate the pollutants prior to discharge. Ozone (O3), O3/UV, hydrogen peroxide/UV (H2O2/UV), Fentons reagent (Fe2+/H2O2) were applied to eliminate by oxidation while ultrasonication (US) alone, US/UV or powdered activated carbon (PAC) were used for the physicochemical treatment. Elimination was monitored by a conventional sum parameter analyses (COD, BOD, DOC) while gas chromatography/mass spectrometry (GC/MS) and liquid chromatography coupled with MS and tandem mass spectrometry (LC/MS and ‐MS/MS) was applied for follow‐up of pollutants and their degradation products. The application of PAC, Fenton, and O3/UV resulted in the highest dissolved organic carbon elimination. A complete or partial elimination and/or degradation of non‐polar or polar pollutants was observed by GC/MS or flow injection analysis/MS (FIA/MS) respectively. LC/MS and MS/MS analyses confirmed that ethoxylated surfactants (AEO) present in the original wastewater could be oxidized or destroyed resulting in carboxylated AEO and polyethylene glycol (PEG) or even carboxylated PEG.

Ozone Treatment of Tannery Wastewater Monitored by Conventional and Substance Specific Wastewater Analyses

ABSTRACT Ozone is an unstable and highly reactive gas applied in drinking water or wastewater treatment to oxidize and/or mineralize pollutants. Its application in wastewater treatment leads to a destruction of persistent pollutants combined with an improvement of biodegradability. The oxidation of organic and inorganic compounds in tannery wastewater at different pHs applying O3 was studied. Results after O3-treatment were determined by conventional wastewater parameters, e.g., total organic carbon (TOC), biochemical oxygen demand after 5 days (BOD5), and chemical oxygen demand (COD), as well as by substance-specific mass spectrometric analytical techniques, i.e., gas chromatography—mass spectrometry (GC/MS) and liquid chromatography—mass and tandem mass spectrometry (LC/MS and—MSn). In parallel, variations in the toxicity of the tannery wastewater against water organisms before and after O3-treatment were determined by means of biotoxicity testing, i.e., Daphnia magna Straus and Vibrio fischeri bioassays.

Laboratory- and full-scale studies on the removal of pharmaceuticals in an aerated constructed wetland: effects of aeration and hydraulic retention time on the removal efficiency and assessment of the aquatic risk

Pharmaceutical residues in wastewater pose a challenge to wastewater treatment technologies. Constructed wetlands (CWs) are common wastewater treatment systems in rural areas and they discharge often in small water courses in which the ecology can be adversely affected by the discharged pharmaceuticals. Hence, there is a need for studies aiming to improve the removal of pharmaceuticals in CWs. In this study, the performance of a full-scale aerated sub-surface flow hybrid CW treating wastewater from a healthcare facility was studied in terms of common water parameters and pharmaceutical removal. In addition, a preliminary aquatic risk assessment based on hazard quotients was performed to estimate the likelihood of adverse effects on aquatic organisms in the forest creek where this CW discharges. The (combined) effect of aeration and hydraulic retention time (HRT) was evaluated in a laboratory-scale batch experiment. Excellent removal of the targeted pharmaceuticals was obtained in the full-scale CW (>90%) and, as a result, the aquatic risk was estimated low. The removal efficiency of only a few of the targeted pharmaceuticals was found to be dependent on the applied aeration (namely gabapentin, metformin and sotalol). Longer and the HRT increased the removal of carbamazepine, diclofenac and tramadol.