Wastewater

The COVID-19 pandemic has severely impacted public health and the worldwide economy. Converging evidence from the current pandemic, previous outbreaks and controlled experiments indicates that SARS-CoVs are present in wastewater for several days, leading to potential health risks via waterborne and aerosolized wastewater pathways. Conventional wastewater treatment provides only partial removal of SARS-CoVs, thus safe disposal or reuse will depend on the efficacy of final disinfection. This underscores the need for a risk assessment and management framework tailored to SARS-CoV-2 transmission via wastewater, including new tools for environmental surveillance, ensuring adequate disinfection as a component of overall COVID-19 pandemic containment.

In recent years, several studies have investigated the flux of particulate plastic through municipal waste water treatment plants (WWTP). Challenges related to time consuming analytical methods have limited the number of sampling points and detection limits have hampered quantification of nanoplastic and microplastic fiber fluxes through WWTPs. By synthesizing nanoplastic particles and microplastic fibers labeled with a rare metal (Pd and In, respectively) which can be measured as a proxy for the plastic itself, we have circumvented major analytical pitfalls associated with (micro)plastic measurements. In this study, we spiked the labeled materials to a pilot WWTP mimicking the activated sludge process (nitrification, de-nitrification and secondary clarification). Using a mass flow model for WWTP sludge, we assessed the behavior of particulate plastic in relation to the removal of organic matter. Triplicate samples were collected from the mixed liquor and from the effluent at least twice weekly over the entire experimental run time of 40 d. Our findings show that in discrete grab samples during steady state conditions, at least 98% of particulate plastics were associated with the biosolids. A positive correlation between total suspended solids (TSS) and plastic concentrations was observed in the sludge as well as in the effluent. Because of the strong association between particulate plastic and TSS, TSS removal is likely a good indicator of plastic removal in a full scale WWTP. Therefore, additional process steps in a full-scale WWTP which further reduce the TSS load will likely retain nanoplastic particles and microplastic fibers effectively and consequently increase the removal rates.

Sertraline is one of the most commonly prescribed antidepressants in the last few years. Therefore, it is not surprising that it is regularly detected in wastewaters, surface waters, sediments, biosolids and biota. Effluents from wastewater treatment plants are the main contributors to its presence in the environment. The presented study aims to elucidate the processes involved in its removal, concentrating mainly on sorption and biodegradation during wastewater treatment.
We performed our laboratory scale experiments in two sets of experiments: 1) batch biodegradation and sorption experiments and 2) flow-through laboratory scale pilot wastewater treatment bioreactors. The batch experiments revealed that sorption to activated sludge was the leading removal process, eliminating up to 90% of sertraline present in the batches. Biodegradation was however the secondary removal process, influenced by the presence of alternative easily biodegradable carbon sources. We postulated chemical structures of ten detected biotransformation products. Among these, we propose the previously recognized metabolite norsertraline, sertraline ketone and hydroxy-sertraline. All the remaining biotransformation products are herein reported for the first time.
The removal efficiency of approximately 94% was determined after the treatment in the flow-through bioreactors. To support our findings, we sampled influents and effluents from two wastewater treatment plants and untreated wastewater from a psychiatric hospital. Removal efficiencies of 81% and 77% were determined, and along with the parent compound sertraline, the presence of eight transformation products was confirmed in the actual wastewaters.

Ozonation of secondary wastewater treatment plant effluent for the abatement of organic micropollutants requires an accurate process control, which can be based on monitoring ozone-induced changes in dissolved organic matter (DOM). This study presents a novel automated analytical system for monitoring changes in the electron donating capacity (EDC) and UV absorbance of DOM during ozonation. In a first step, a quantitative photometric EDC assay was developed based on electron-transfer reactions from phenolic moieties in DOM to an added chemical oxidant, the radical cation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS^·+). The assay is highly sensitive (limit of quantification ∼0.5 mg_DOC·L^-1) and EDC values of model DOM isolates determined by this assay were in good agreement with values determined previously by mediated electrochemical oxidation (slope = 1.01 ± 0.07, R² = 0.98). In a second step, the photometric EDC measurement method was transferred onto an automated fluidic system coupled to a photometer (EDC analyzer). The EDC analyzer was then used to monitor changes in EDC and UV absorbance of secondary wastewater effluent treated with ozone. While both parameters exhibited a dose-dependent decrease, a more pronounced decrease in EDC as compared to UV absorbance was observed at specific ozone doses up to 0.4 mg_O3·g_DOC^-1. The concentration of 17α-ethinylestradiol, a phenolic micropollutant with a high ozone reactivity, decreased proportionally to the EDC decrease. In contrast, abatement of less ozone-reactive micropollutants and bromate formation started only after a pronounced initial decrease in EDC. The on-line EDC analyzer presented herein will enable a comprehensive assessment of the combination of EDC and UV absorbance as control parameters for full-scale ozonation.

In this work, emissions of active pharmaceutical ingredients (APIs) from formulating pharmaceutical industries (FPIs) were investigated for the first time based on detailed production information and compared to overall API emissions in wastewater treatment plant (WWTP) effluents. At two municipal WWTPs, both receiving wastewater from several FPIs, two months' daily effluent samples were collected and measured using liquid chromatography high-resolution mass spectrometry (LC-HRMS). Thirty-three APIs formulated during the sampling period as well as >120 organic contaminants commonly present in WWTP effluents were quantified. On the basis of their time patterns and manufacturing data, industrial contributions were found for 22 of 26 APIs (85%) detected in the samples and processed by the FPIs. API emissions from FPIs led to daily concentration increases of up to 300-fold, despite pretreatment of the industrial wastewater. However, emissions from FPIs seemed to depend on the type of formulating activity, with granulation and mixing being most prone to API losses. Losses from FPIs were responsible for the highest concentrations and for up to 60% of the daily total API emissions measured. Furthermore, screening for suspects in LC-HRMS data resulted in the detection of unexpected emissions from FPIs, demonstrating the value of these data to comprehensively assess industrial API losses. Overall, this study showed that FPIs were relevant contributors of APIs emitted in the WWTP effluents, although only a minor fraction (<1%) of the total processed API quantity was lost to the wastewater, and despite the small percentage (<5%) of FPI wastewater compared to the total wastewater flow.