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This study evaluates the effectiveness of a pilot-scale high-rate algae-bacteria pond (HRAP) to remove pharmaceutical compounds (PhACs) from municipal centrate. The studied PhACs belonged to different classes of synthetic active compounds: antihypertensives, antiepileptics, antidepressants, neuroprotectors, and anti-inflammatory drugs. The HRAP, growing a mixed microalgal consortium made of Chlorella spp. and Scenedesmus spp., was operated in continuous mode (6 days hydraulic retention time) from May to November 2021. Removal efficiencies were high (>85 %) for Sulfamethoxazole and Lamotrigine, promising (65-70 %) for Metoprolol, Fluoxetine, and Diclofenac but low (30-40 %) for Amisulpride, Ofloxacin, Carbamazepine, and Clarithromycin. Propyphenazone and Irbesartan were not removed, and their concentrations increased after the treatment. The combination of abiotic and biotic drivers (mostly global radiation and the synergy between microalgae and bacteria metabolisms) fostered photo and biodegradation processes. Overall, results suggest that microalgae-based systems can be a valuable solution to remove PhACs from wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Metal-based flocculants are commonly used for biomass harvesting in microalgae-based bio-refineries. Besides the high separation efficiency, additional aspects should be considered, related to the toxicity of metals for the algal biomass. Partitioning tests for commonly used flocculants (i.e., FeCl 3 and Al 2 (SO 4 ) 3 ) showed that metals were mostly transferred to the solid phase with more than 95% of dosed metal ending up into the biomass, and low metal concentrations in the liquid effluent (lower than 0.4 mg L -1 for both metals), thus allowing for water reuse. Photosynthesis inhibition was tested on microalgae and microalgae-bacteria cultures, using a standardized photo-respirometry protocol in which typical concentrations used during coagulation-flocculation were assessed. Modelling dose-response curves, concentrations corresponding to 50% inhibition (IC 50 ) were obtained, describing short-term effects. The obtained IC 50 ranged from 13.7 to 28.3 mg Al L -1 for Al, and from 127.9 to 195.8 mg Fe L -1 for Fe, showing a higher toxicity for the Al-based flocculant. The recovery of photosynthesis inhibition was also quantified, to evaluate the possibility of reusing/recycling the harvested biomass. The results highlighted that the residual photosynthetic activities, evaluated after 1 h and 24 h of exposure to metals were partially recovered, especially for Al, passing from 67.3% to 94.6% activity, respectively, while long-term Fe effects were stronger (passing from 64.9% to 77.6% activity). A non-toxic flocculant (cationic starch) was finally tested, excluding potential effects due to biomass aggregation, as the reduction of photosynthetic activity only reached 3.4%, compared to control. Relevant modifications to the light availability and the optical properties of algal suspensions were assessed, identifying a strong effect of iron which caused an increase of the light absorbance up to approximately 40% at high Fe concentrations. Possible implications of dosing metallic flocculants in MBWWT processes are discussed, and suggestions are given to perform inhibition tests on flocculating chemicals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Tetraselmis suecica was cultivated in a semi-continuously operated tubular photobioreactor fed on aquaculture wastewater (AW) testing two hydraulic retention times (HRT): 10 and 7 days (RUN&#95;1 and RUN&#95;2, respectively). The integrated mechanistic model BIO&#95;ALGAE was validated with experimental data in order to simulate the biomass production and nutrient uptake of T. suecica. Moreover, AW was used as substitute synthetic cultivation medium to test the production of lipids, proteins, and carbohydrates in the microalgal biomass. Preliminary photo-respirometric tests were carried out on the AW suspension containing microalgae and bacteria. Dissolved Inorganic Nitrogen (DIN) and Dissolved Inorganic Phosphorus (DIP) were analyzed for the two RUNs, and no significant difference was highlighted (p > 0.05). On the contrary, the productivity of the Total suspended solids (TSS) was significantly higher (p < 0.05) for RUN&#95;1 (900 mg TSS/L) than for RUN&#95;2 (550 mg TSS/L). The analysis of the biochemical composition of biomass has demonstrated a higher content of proteins than of lipids and carbohydrates for the two RUNs. BIO&#95;ALGAE model was validated by comparing simulated results to experimental data. The model was able to reproduce the pattern of these experimental data quite well, for both nutrient uptake and biomass production. The simulated curve follows the same pattern as the experimental data for both RUNs. The wavelike trend indicates the good accuracy of the simulated curves to reproduce the microalgae growth and nutrient uptake that occurring during daytime and at night. With this study, BIO&#95;ALGAE Model was demonstrated to be useful to simulate bioremediation and microalgae production in aquaculture wastewater in a semi-continuous system with different environmental factors. The photo-respirometric outputs were compared with the process rates affecting dissolved oxygen dynamics computed by the mathematical model., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

This study aims at demonstrating the feasibility of using microalgae-bacteria consortia for the treatment of the sidestream flow of the supernatant from blackwater dewatering (centrate) in an urban wastewater treatment plant in Northern Italy. A 1200 L raceway reactor was used for the outdoor cultivation of a diverse community of Chlorella spp., Scenedesmus spp. and Chlamydomonas spp. in continuous operation mode with 10 days hydraulic retention time. During the trial, an average daily areal productivity of 5.5 ± 7.4 g TSS m -2  day -1 was achieved while average nutrient removal efficiencies were 86% ± 7% and 71% ± 10% for NH 4 -N and PO 4 -P, respectively. The microalgal nitrogen assimilation accounted for 10% of the nitrogen in the centrate while 34% was oxidized to nitrite and nitrate. The oxygen produced by microalgae fully covert the oxygen demand for nitrification. This suggests that the proposed process would reduce the aeration demand for nitrification in the water line of the plant, while producing algal biomass to be further valorized for energy or material recovery., Competing Interests: Declaration of competing interest The following authors have affiliations with organizations with direct or indirect financial interest in the subject matter discussed in the manuscript: Marco Mantovani: Università degli Studi di Milano – Bicocca (Italy); Francesca Marazzi: Università degli Studi di Milano – Bicocca (Italy); Riccardo Fornaroli: Università degli Studi di Milano – Bicocca (Italy); Micol Bellucci: Politecnico di Milano (Italy); Elena Ficara: Politecnico di Milano (Italy); Valeria Mezzanotte: Università degli Studi di Milano – Bicocca (Italy)., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Treatment wetlands (TWs) have shown good capacity in dye removal from textile wastewater. However, the high hydraulic retention times (HRTs) required by these solutions and the connected high area requirements, remain a big drawback towards the application of TWs for dye treatment at full scale. Aerated TWs are interesting intensified solutions that attempt to reduce the TW required area. Therefore, an aerated CW pilot plant, composed of a 20 m 2 horizontal subsurface flow TW (HF) and a 21 m 2 Free Water System (FWS), equipped with aeration pipelines, was built and monitored to investigate the potential reduction of required area for dye removal from the effluent wastewater of a centralized wastewater treatment plant (WWTP). During a 8 months long study, experimenting with different hydraulic retention times (HRTs - 1.2, 2.6 and 3.5 days) and aeration modes (intermittent and continuous), the pilot plant has shown a normal biological degradation for organic matter and nutrients, while the residual dye removal has been very low, as demonstrated by the absorbance measure at three wavelengths: at 426 nm (blue) the removal varies from -55% at influent absorbance of 0.010 to 41% at 0.060; at 558 nm (yellow) the removal is negative at 0.005 (-58%) and high at higher influent concentrations (72% at 0.035 of absorbance for the inlet); at 660 nm (red) -82% of removal efficiency was obtained at influent absorbance of 0.002 and 74% at 0.010. These results are a consequence of the biological oxidation processes taking place in the WWTP, so that the residual dye seems to be resistant to further aerobic degradation. Therefore, TWs enhanced by aeration can provide only a buffer effect on peak dye concentrations., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The toxic effects of five Quaternary Ammonium Compounds (QACs) that are widely used as active ingredients in personal care products were assessed using the bioluminescent bacterium Aliivibrio fischeri (formerly Vibrio fischeri) (Microtox® test system). The experimental results showed a relevant toxicity for almost all of the single QACs, with IC 50 values lower than 1mgL -1 . Analysis of the mode of action through the application of the Quantitative Structure-Activity Relationship (QSAR) models indicated an a-specific reactivity for most of the QACs toward A. fischeri. Only hexadecyl trimethyl ammonium chloride (ATMAC-16) behaved as a polar-narcotic, with a low reactivity toward the bacterial cell membrane. The concentration response curves of the different binary and multicomponent mixtures of QACs were also evaluated with respect to the predictions from the Concentration Addition (CA) and Independent Action (IA) models. For almost all of the binary and multicomponent mixtures (7 out of 11 mixtures tested), an agreement between the experimental and predicted IC x was observed and confirmed via application of the Model Deviation Ratio (MDR). In four cases, some deviations from the expected behaviour were observed (potential antagonistic and synergistic interactions) at concentrations on the order of hundreds of µgL -1 , which could be of environmental concern, especially in the case of synergistic effects. The analysis of aquatic ecotoxicity data and the few available values of the measured environmental concentrations (MECs) from the literature for wastewaters and receiving waterbodies suggest that a potential risk toward aquatic life cannot be excluded., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The correct definition of ecosystem needs is essential in order to guide policy and management strategies to optimize the increasing use of freshwater by human activities. Commonly, the assessment of the optimal or minimum flow rates needed to preserve ecosystem functionality has been done by habitat-based models that define a relationship between in-stream flow and habitat availability for various species of fish. We propose a new approach for the identification of optimal flows using the limiting factor approach and the evaluation of basic ecological relationships, considering the appropriate spatial scale for different organisms. We developed density-environment relationships for three different life stages of brown trout that show the limiting effects of hydromorphological variables at habitat scale. In our analyses, we found that the factors limiting the densities of trout were water velocity, substrate characteristics and refugia availability. For all the life stages, the selected models considered simultaneously two variables and implied that higher velocities provided a less suitable habitat, regardless of other physical characteristics and with different patterns. We used these relationships within habitat based models in order to select a range of flows that preserve most of the physical habitat for all the life stages. We also estimated the effect of varying discharge flows on macroinvertebrate biomass and used the obtained results to identify an optimal flow maximizing habitat and prey availability., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Dreissena polymorpha is a widespread filter-feeder species, resistant to a broad range of environmental conditions and different types of pollutants,which has recently colonized Italian freshwaters. Although widely used to monitor pollution in freshwater environments, this species is also an important food source for some fish and water birds. It can also be used to concentrate or remove particulate organic matter to interrupt avian-to-human transmission of pollutants and control health risks for animals and humans. In this study, the accumulation/inactivation in D. polymorpha of human health-related spiked enteric viruses was described. The removal of endogenous Escherichia coli, the classical indicator of fecal contamination,was tested as well.Our preliminary lab-scale results demonstrate that zebra mussels can reduce significantly poliovirus titer after 24 h and rotavirus titer after 8 h. E. coli counts were also reduced in the presence of zebra mussels by about 1.5 log after 4 h and nearly completely after 24 h. The fate of the two enteric viruses after concentration by zebra mussels was also investigated after mechanical disruption of the tissues. To our knowledge, the accumulation from water and inactivation of human health-related enteric viruses by zebra mussels has never been reported.