Discharge of pharmaceuticals from a municipal solid waste transfer station: Overlooked influence on the contamination of pharmaceuticals in surface waters

Effects and mechanisms of aquatic landscape plants on the removal of veterinary antibiotics from hydroponic solutions

Four aquatic landscape plants and three veterinary antibiotics were selected to construct a hydroponic test system to analyze the tolerance, removal effect and mechanism of antibiotics. The results indicated that antibiotic concentrations from 0 to 100 μg·L-1 promoted plant heights and leaf chlorophyll contents, while antibiotics at concentrations > 100 μg·L-1 had inhibitory effects. The ability of different plants to remove antibiotics was Acorus calamus L. > Ceratophyllum demersum L. > Thalia dealbata Fraser > Nuphar pumila (Timm) DC. The plants with the best removal of norfloxacin, sulfadimethoxine and chlortetracycline were Ceratophyllum demersum L., Acorus calamus L. and Acorus calamus L. after 12 d of hydroponic cultivation using 100 μg·L-1 antibiotics, with removal rates of 66.6%, 63.0% and 63.2%, respectively. The accumulation of antibiotics in different plant tissues was root > stem > leaf and the accumulation increased with incubation time. The diversity of plant root biofilm microorganisms decreased with increasing treatment concentrations of antibiotics, while the abundance of dominant genera (Aeromonas, Bacillus, Lysinibacillus, Providencia, and Staphylococcus) showed an increasing trend. The findings imply that the antibiotic uptake by plants and the dynamics of the rhizosphere microbial community combine to promote antibiotic removal.

Profiling emerging micropollutants in urban stormwater runoff using suspect and non-target screening via high-resolution mass spectrometry

Urban surface runoff contains chemicals that can negatively affect water quality. Urban runoff studies have determined the transport dynamics of many legacy pollutants. However, less attention has been paid to determining the first-flush effects (FFE) of emerging micropollutants using suspect and non-target screening (SNTS). Therefore, this study employed suspect and non-target analyses using liquid chromatography-high resolution mass spectrometry to detect emerging pollutants in urban receiving waters during stormwater events. Time-interval sampling was used to determine occurrence trends during stormwater events. Suspect screening tentatively identified 65 substances, then, their occurrence trend was grouped using correlation analysis. Non-target peaks were prioritized through hierarchical cluster analysis, focusing on the first flush-concentrated peaks. This approach revealed 38 substances using in silico identification. Simultaneously, substances identified through homologous series observation were evaluated for their observed trends in individual events using network analysis. The results of SNTS were normalized through internal standards to assess the FFE, and the most of tentatively identified substances showed observed FFE. Our findings suggested that diverse pollutants that could not be covered by target screening alone entered urban water through stormwater runoff during the first flush. This study showcases the applicability of the SNTS in evaluating the FFE of urban pollutants, offering insights for first-flush stormwater monitoring and management.

Simultaneous removal of organics and ammonia using a novel composite magnetic anode in the electro-hybrid ozonation-coagulation (E-HOC) process toward leachate treatment

To achieve simultaneous organics and ammonia (NH₄⁺-N) removal toward leachate treatment, this study designed a composite anode (CA⁺), in which iron powders were attracted to RuO₂-IrO₂/Ti tube surface by an inserted magnet and utilized in electro-hybrid ozonation-coagulation (E-HOC). The E-HOC (CA⁺) resulted in higher chemical oxygen demand (COD) and NH₄⁺-N removal with most content of CO₂/H₂O and gaseous N in product compared with E-HOC (Fe⁺), electrolysis ozonation and single ozonation. Reactive chlorine species (RCS) and coagulants were co-produced by compositing RuO₂-IrO₂/Ti and Fe powders, resulting in multiple reactions including electrocoagulation, ozone oxidation, synergistic between ozone and coagulants (SOC), electrolytic chloride and synergistic oxidation between active chlorine and ozone (SCO) occurred. Hydroxyl radical (•OH) generated through SOC reaction was promoted due the RCS generation in E-HOC. The interaction between •OH and Cl^-/ClO^- also contributed to enhanced Cl•/ClO• production. Consequently, synergy of chlorine, coagulants and ozone enhanced reactive species generation which contributed to favorable organics and NH₄⁺-N removal. Enhanced •OH and RCS are also attributed to conversion of bio-refractory organics like polyphenol, polycyclic aromatics and S-containing to biodegradable ones, e.g., aliphatic compounds and CHO. This study provides an easily operating strategy for leachate treatment with high content organics and NH₄⁺-N.