Inactivation of antibiotic-resistant bacteria in hospital wastewater by ozone-based advanced water treatment processes

A critical review of ozone-based electrochemical advanced oxidation processes for water treatment: Fundamentals, stability evaluation, and application

In recent years, electrochemical advanced oxidation processes (EAOPs) combined with ozonation have been widely utilized in water/wastewater treatment due to their excellent synergistic effect, high treatment efficiency, and low energy consumption. A comprehensive summary of these ozone-based EAOPs is still insufficient, though some reviews have covered these topics but either focused on a specific integrated process or provided synopses of EAOPs or ozone-based AOPs. This review presents an overview of the fundamentals of several ozone-based EAOPs, focusing on process optimization, electrode selection, and typical reactor designs. Additionally, the service life of electrodes and improvement strategies for the stability of ozone-based EAOPs that are ignored by previous reviews are discussed. Furthermore, four main application fields are summarized, including disinfection, emerging contaminants treatment, industrial wastewater treatment, and resource recovery. Finally, the summary and perspective on ozone-based EAOPs are proposed. This review provides an overall summary that would help to gain insight into the ozone-based EAOPs to improve their environmental applications.

Ozone therapy in dentistry: An overview of the biological mechanisms involved (Review)

At low medically-relevant concentrations, ozone serves as an oxidant with a wide spectrum of antimicrobial activity and the ability to promote healing and reduce inflammation. Despite providing therapeutic benefits in a range of diseases, certain adverse effects and contraindications of ozone treatment must be considered. These are primarily related to toxicity from inhalation and systemic types of administration and can be avoided by following relevant guidelines and recommendations. Ozone therapy has been implemented in a number of fields of dentistry and the most commonly used formulations for the oral cavity are gaseous ozone, ozonized water and ozonized oil. The biological mechanisms underlying the molecular effects of ozone have been increasingly reported, but currently remain largely unknown. The aim of the present review was to provide an overview of the mechanisms involved in ozone interaction with dental tissues. The present review focused on relevant evidence regarding the effect of ozone on dental tissues, including periodontal structures, dental cells, enamel and dentine, considering in vitro studies in addition to animal and human studies. A variety of biological mechanisms acting through multiple biochemical target pathways were reported to be responsible for the therapeutic effects of ozone. The main beneficial effects of ozone occurred in the following domains: antimicrobial activity, remineralization and microstructural changes of hard dental tissues, immunomodulation and biostimulation of dental and periodontal cells. Additional research could provide further insights into the use of ozone, increase its use for broader clinical applications and assist in the selection of targeted protocols.

Design and Fabrication of Broad-Spectrum Antimicrobial Porous Metallo-Polymeric Microsphere for Water Disinfection

An expedient and efficient approach is used to synthesize a new class of metallo-polymeric microspheres (MPMs) as antimicrobials to succumb the wide range of bacteria from water. Three types of MPMs, that is, poly[Silver (I)-methacrylate-co-methylmethacrylate] (pAgMA), poly[Copper (II)-methacrylate-co-methyl methacrylate] (pCuMA), and poly[Nickel (II)-methacrylate-co-methylmethacrylate] (pNiMA), are prepared via radical suspension polymerization technique in 3D shape with porous texture. The structural and morphological characterization of the prepared microspheres are examined by analytical techniques. The antimicrobial potentialities of prepared MPMs are investigated at the laboratory scale study, revealing that the MPMs exhibit strong antibacterial activity (≈99.9% killing) against Gram-negative and Gram-positive bacteria [Enterobacter hormaechei (EH), Bacillus megatarium (BM), and Bacillus bataviensis (BB)]. The MacConkey agar medium test reveals that MPMs have substantial biocidal efficacy against broad-spectrum Gram-negative bacteria present in tap water. The MPMs exhibit significant antimicrobial efficacy via contact killing owe to the presence of integrated biocidal metal moiety, which represents that the MPMs are safe for water disinfection.

Enhancing pollutants removal in hospital wastewater: Comparative analysis of PAC coagulation vs. bio-contact oxidation, highlighting the impact of outdated treatment plants

While the effectiveness of Poly-Aluminum Chloride (PAC) coagulation for pollutant removal has been documented across various wastewater scenarios, its specific application in hospital wastewater (HWW) treatment to remove conventional pollutants and hazardous genetic pollutants has not been studied. The research compared three hospital wastewater treatment plants (HWTPs) to address a knowledge gap, including the PAC coagulation-sodium hypochlorite disinfection process (PAC-HWTP), the biological contact oxidation-precipitation-sodium hypochlorite process (BCO-HWTP), and a system using outdated equipment with PAC coagulation (ODE-PAC-HWTP). Effluent compliance with national discharge standards is assessed, with BCO-HWTP meeting standards for direct or indirect discharge into natural aquatic environments. ODE-PAC-HWTP exceeds pretreatment standards for COD and BOD5 concentrations. PAC-HWTP effluent largely adheres to national pretreatment standards, enabling release into municipal sewers for further treatment. Metagenomic analysis reveals that PAC-HWTP exhibits higher removal efficiencies for antibiotic resistance genes, metal resistance genes, mobile genetic elements, and pathogens compared to BCO-HWTP and ODE-PAC-HWTP, achieving average removal rates of 45.13%, 57.54%, 80.61%, and 72.17%, respectively. These results suggests that when discharging treated HWW into municipal sewers for further processing, the use of PAC coagulation process is more feasible and cost-effective compared to BCO technologies. The analysis emphasizes the urgent need to upgrade outdated equipment HWTPs.

Development of a High-Throughput Analytical Method for Antimicrobials in Wastewater Using an Automated Pipetting and Solid-Phase Extraction System

Antimicrobial resistance (AMR) has emerged and spread globally. Recent studies have also reported the presence of antimicrobials in a wide variety of aquatic environments. Conducting a nationwide monitoring survey of AMR in the environment to elucidate its status and to assess its impact on ecosystems and human health is of social importance. In this study, we developed a novel high-throughput analysis (HTA) system based on a 96-well plate solid-phase extraction (SPE), using automated pipetting and an SPE pre-treatment system. The effectiveness of the system as an HTA for antimicrobials in environmental water was verified by comparing it with a conventional manual analytical system in a domestic hospital over a period of two years and four months. The results of the manual analysis and HTA using a combination of automated pipetting and SPE systems were generally consistent, and no statistically significant difference was observed (p > 0.05) between the two systems. The agreement ratios between the measured concentrations based on the conventional and HTA methods were positively correlated with a correlation coefficient of r = 0.99. These results indicate that HTA, which combines automated pipetting and an SPE pre-treatment system for rapid, high-volume analysis, can be used as an effective approach for understanding the environmental contamination of antimicrobials at multiple sites. To the best of our knowledge, this is the first report to present the accuracy and agreement between concentrations based on a manual analysis and those measured using HTA in hospital wastewater. These findings contribute to a comprehensive understanding of antimicrobials in aquatic environments and assess the ecological and human health risks associated with antimicrobials and antimicrobial-resistant bacteria to maintain the safety of aquatic environments.

Construction of a three-mode sensor based on gold nanoparticles and carbon quantum dots as probes for the detection of thiosemicarbazone

In this study, ginkgo leaves were used as a carbon source to synthesize carbon quantum dots (CQDs) with uniform particle size, high fluorescence (FL) intensity and strong stability, using a hydrothermal method. FL could be quenched by the FL resonance energy transfer effect between CQDs and gold nanoparticles (AuNPs), an important FL quenching agent. The electrostatic attraction between thiosemicarbazone (TSC) and citrate on the surface of AuNPs and the formation of a stable Au-S bond between TSC and AuNPs led to the aggregation of AuNPs and thus weakened the quenching effect on CQDs and partly recovered the FL. A sensor in FL mode for the detection of TSC was constructed based on the above-mentioned FL "off" and "on" phenomena. The results showed a good linear correlation in the concentration range 0-1.75 μM, and the limit of detection was as low as 0.05 μM. In addition, the aggregation of AuNPs caused by TSC also led to a change in the absorbance curve and color of the solution; colorimetric and chrominance detection modes were also constructed using these two types of changes, with sensitive responses ranging 0-2.25 μM and 0-1.60 μM and the limits of detection of 0.03 μM and 0.08 μM, respectively. More importantly, these three detection modes obtained satisfactory recovery rates in the detection of the TSC content in river water, liquor and wheat samples, and the detection results were mutually verified (95.18% to 104.96%).

Alternations of antibiotic resistance genes and microbial community dynamics on shared bicycles before and after pandemic lockdown

The prevalence of shared bicycles has raised concerns over their potential to transmit pathogens and microbes harboring antibiotic resistance genes (ARGs), which pose significant human health risks. This study investigated the impact of anthropogenic activities on the composition of ARGs and microbial communities on shared bicycles during the COVID-19 pandemic and subsequent lockdown when shared bicycle usage was altered. A total of 600 swab samples from shared bicycle surfaces were collected in Shanghai before and during COVID-19 lockdown periods. Even during lockdown, 12 out of 14 initially detected ARG subtypes persisted, indicating their tenacity in the face of reduced anthropogenic activities. These ARGs displayed significantly higher absolute and relative abundance levels before the lockdown. In addition, the percentage of potential pathogens in the total microbial abundance remained at 0.029 % during the lockdown, which was lower than the pre-lockdown percentage of 0.035 % and suggested that these risks persist within shared bicycle systems. Interestingly, although microbial abundance decreased without the consecutive use of shared bicycles during lockdown, the microbial diversity increased under the impact of restricted anthropogenic activities (p < 0.001). This emphasizes the need for continuous monitoring and research to comprehend microbial community behaviors in various environments. This study uncovered the underlying impacts of the COVID-19 lockdown on the microbial and ARG communities of shared bicycles, providing comprehensive insights into the health management of shared transportation. Although lockdown can decrease the abundance of ARGs and potential pathogens, additional interventions are needed to prevent their continued spread.