Second life of water and wastewater in the context of circular economy - Do the membrane bioreactor technology and storage reservoirs make the recycled water safe for further use?

Is our winter experience safe? Micropollutant risks for artificial snowing

Artificial snowing is a process that allows ski operators adapt to snow scarcity due to climate change while raising environmental and public health concerns about the role it plays in environmental dissemination of pollutants, but studies addressing this question are still scarce. This study aimed to fill this gap in understanding the role of artificial snowmaking in dissemination of antibiotics, bacterial contaminants, antibiotic resistant bacteria (ARB) and genetic determinants (ARGs) thereof. Technical snow and water used for its production were examined from 11 ski stations located in four river catchments, varying in anthropopressure and the presence/absence of storage reservoirs where water is collected before snowmaking. Culturable E. coli were found in all water intakes with clear reduction/elimination during snowmaking. Fourteen antimicrobial agents were detected using UHPLC/MS/MS. Concentration and prevalence of antimicrobials differed between the catchments; the sites located downstream of long-term stay health centers were most severely contaminated. Two antibiotics of restricted use (vancomycin and linezolid) were detected downstream of hospitals. Antimicrobial resistance of 158 E. coli strains was tested using disk diffusion method. The resistance to penicillins (e.g. ampicillin, amoxicillin/clavulanic acid) was most frequent and in general followed the pattern of antibiotic consumption rather than antibiotic concentration in water. Extended-spectrum beta lactamase (ESBL) genes were detected using PCR tests: 66.46 % (105 out of 158) strains possessed at least one ARG among which blaTEM was most frequent, followed by blaCTX-M and blaSHV. Our study indicates that the major sources of aquatic environment and technical snow contamination with antimicrobial agents are effluents from long-term stay medical centers, while bacterial contamination (including ARB and ARGs) stems from municipal WWTPs, i.e. the main hubs of antimicrobial resistance transfer to the environment. The storage reservoir construction may aid in reducing the transfer rate of pollutants and micropollutants from contaminated water to technical snow.

Biomonitoring emerging hazards of pharmaceuticals in river water using gut microbiome and behavioural Daphnia magna responses

A cost-effective Daphnia magna testing framework was applied to identify emerging hazards such as neurological and cardiovascular defects as well as antibiotic resistant genes (ARGs), related to pharmaceuticals present in waste water treated (WWTP) effluent discharged into rivers. D. magna juveniles were exposed during 48 h to water samples from three rivers in the vicinity of Barcelona (NE Spain), Besós, Llobregat and Onyar, upstream and downstream of WWTP discharging points. The analyses included measuring levels of 80 pharmaceutical residues in water samples by HPLC-MS, determination of the loads of different clinically relevant antibiotic resistant genes (ARGs) in both water samples and exposed animals, and assessment of toxic effects in feeding, heartbeat responses, and behavioural indicators. ARG prevalence in water, but not in gut microbiomes, was associated with the presence of bactericides in water. These results suggest that their levels were high enough to put a selective pressure over river microbial populations, but that Daphnia guts were not easily populated by environmental bacteria. Toxic effects were found in 20-43% of water samples, depending on the river, and related to water quality parameters and to pollutant levels. For example, heartbeats were correlated with salinity, whereas feeding impairment did so with high loads of suspended solids. In contrast, behavioural alterations were associated to the concentration of neuroactive chemicals. Accordingly, we hypothesize that measured neuroactive chemicals have caused the observed effects. If this also applies to local invertebrate populations, the environmental consequences may be severe and unpredictable.

Emerging Issues on Antibiotic-Resistant Bacteria Colonizing Plastic Waste in Aquatic Ecosystems

Antibiotic-resistant bacteria (ARB) adhesion onto plastic substrates is a potential threat to environmental and human health. This current research investigates the prevalence of two relevant human pathogens, Staphylococcus spp. and Klebsiella spp., and their sophisticated equipment of antibiotic-resistant genes (ARGs), retrieved from plastic substrates submerged into an inland water body. The results of microbiological analysis on selective and chromogenic media revealed the presence of colonies with distinctive phenotypes, which were identified using biochemical and molecular methods. 16S rDNA sequencing and BLAST analysis confirmed the presence of Klebsiella spp., while in the case of Staphylococcus spp., 63.6% of strains were found to be members of Lysinibacillus spp., and the remaining 36.3% were identified as Exiguobacterium acetylicum. The Kirby-Bauer disc diffusion assay was performed to test the susceptibility of the isolates to nine commercially available antibiotics, while the genotypic resistant profile was determined for two genes of class 1 integrons and eighteen ARGs belonging to different classes of antibiotics. All isolated bacteria displayed a high prevalence of resistance against all tested antibiotics. These findings provide insights into the emerging risks linked to colonization by potential human opportunistic pathogens on plastic waste commonly found in aquatic ecosystems.