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A set of CALUX in vitro bioassays was applied for long-term toxicity monitoring at an advanced wastewater treatment plant comprising ozonation and granular activated carbon filtration for the abatement of contaminants of emerging concern (CEC). During the 13-month monitoring, eight reporter gene assays targeting different modes of action along the cellular toxicity pathway were accessed to evaluate the suitability and robustness of the technologies. Two approaches were followed: on the one hand, signal reduction during advanced treatment was monitored; on the other hand, results were compared to currently available effect-based trigger values (EBTs). A decrease of the corresponding biological equivalent concentrations after the multibarrier system could be observed for all modes of action; while the estrogenic activity decreased below the EBT already during ozonation, the potencies of oxidative stress-like and toxic PAH-like compounds still exceeded the discussed EBT after advanced treatment. Overall, the long-term monitoring confirmed the positive effect of the multibarrier system, commonly evaluated only by CEC abatement based on chemical analysis. It could be demonstrated that advanced WWTPs designed for CEC abatement are suitable to significantly decrease toxicity responses not only in the frame of pilot studies but under real-world conditions as well.

The loading of granular activated carbon (GAC) is influenced by the amount of water treated and the concentrations of adsorbates present in the water matrix. Through extraction experiments, we aimed to investigate the total adsorbed mass of eight organic micropollutants by using ethanol as solvent and the maximum possible concentrations, due to the desorption of organic micropollutants, in water. Three different drying methods and the impact of the contact time, GAC particle size, and GAC/solvent ratio were investigated. Although no significant differences between the drying methods could be observed, the chosen contact time and particle size had a significant impact on the amount of organic micropollutants extracted. Lower GAC/solvent ratios positively affected the extraction yield. The masses extracted in ethanol were compared with the cumulated masses calculated from 72 feed and effluent samples, collected during filter operation, resulting in extraction yields between 0.5% and 30%. The composition of extracted micropollutants in ethanol reflected the concentrations in feed water of the pilot-scale filter. Desorption in water was mostly influenced by the solubility of the investigated micropollutants. The same substances found in the supernatants inf the experiments could also be identified in the backwash water of the filter.

Electrodialysis (ED) is a promising technology suitable for nutrient recovery from a wide variety of liquid waste streams. For optimal operating conditions, the limiting current density (LCD) has to be determined separately for each treated feed and ED equipment. LCD is most frequently assessed in the NaCl solutions. In this paper, five graphical methods available in literature were reviewed for LCD determination in a series of five feed solutions with different levels of complexity in ion and matrix composition. Wastewater from microbial fermentation was included among the feed solutions, containing charged and uncharged particles. The experiments, running in the batch ED with an online conductivity, temperature, and pH monitoring, were conducted to obtain data for the comparison of various LCD determination methods. The results revealed complements and divergences between the applied LCD methods with increasing feed concentrations and composition complexity. The Cowan and Brown method had the most consistent results for all of the feed solutions. Online conductivity monitoring was linearly correlated with the decreasing ion concentration in the feed solution and corresponding LCD. Therefore, the results obtained in this study can be applied as a base for the automatized dynamic control of the operating current density–voltage in the batch ED. Conductivity alone should not be used for the ED control since LCD depends on the ion exchange membranes, feed flow, temperature and concentration, ionic species, their concentration ratios, and uncharged particles of the feed solution.

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