Search Results (7)

The rising global demand for bivalves and declining water quality is placing increasing pressure on depuration facilities to ensure product safety and quality, leading to extended processing times and increased energy consumption. Bacteriophages (phages) offer a low-cost, environmentally friendly, and highly specific approach that may enhance depuration efficiency. In this study, we evaluated a phage cocktail targeting Escherichia coli, Aeromonas hydrophila, Salmonella enterica serovar Typhimurium, and Vibrio parahaemolyticus to improve depuration at laboratory-scale using cockles (Cerastoderma edule). Three depuration experiments of 12 h were performed: (i) cockles artificially contaminated with E. coli or V. parahaemolyticus; (ii) cockles inoculated with all four bacteria; and (iii) naturally contaminated cockles. Phages reduced bacterial loads by 1.62 and 1.61 Log colony forming units per gram (CFU/g) for E. coli and V. parahaemolyticus, respectively. In experiments using the four bacterial strains, reductions of ~1.00 Log CFU/g were observed only at higher doses. This phage dose also caused bacterial reduction in naturally harvested animals by 1.00–1.28 Log CFU/g. Our findings suggest that, under phage selective pressure, bacteria may be released from bivalves, probably as result of phage-induced disruption of biofilms, destabilising bacterial colonisation. Therefore, bivalve exposure to phage doses prior to water disinfection can complement the depuration treatment, increasing decontamination efficiency and enhancing food safety. Full article

The object of this research is the process of water disinfection by means of high-frequency electrical discharge. The study addresses the problem of achieving high biological efficiency while reducing energy consumption and avoiding harmful by-products typical of traditional methods such as chlorination or UV irradiation. As a result, a comprehensive theoretical and experimental investigation was conducted, demonstrating that within 20 s of plasma exposure, E. coli, S. aureus, and P. aeruginosa bacteria were inactivated by 99.2–99.9%. The observed efficiency is explained by the synergistic action of reactive oxygen and nitrogen species (•OH, O₃, H₂O₂, NO₂⁻, NO₃⁻) formed in the plasma–water interface. The distinctive features of the obtained results include the establishment of optimal operating parameters-voltage U = 12–18 kV, frequency f ≈ 35 kHz, and gap distance d = 15 mm—under which the normalized specific energy input (SEI) was 6–9 kWh per cubic meter of water. This value represents the standard normalization used for plasma-based treatment systems, where the electrical energy delivered to the reactor is divided by the treated volume (1.0 L in our setup) and scaled to m³ for comparison with other studies, 30–40% lower than in previously reported plasma systems. The validated physicochemical model (Poisson, Navier–Stokes, and continuity equations) matched experimental data with R² ≥ 0.95, confirming its predictive capability for further scale-up. The practical significance of the results lies in the potential application of this method for decentralized and industrial water treatment systems. The reagent-free, energy-efficient, and environmentally safe nature of the proposed approach makes it suitable for sustainable water purification under real operating conditions. Full article

Ultraviolet-light emitting diodes (UV-LEDs) offer several advantages over conventional mercury-based UV lamps, including wavelength selectivity, compact size, design flexibility, instant on/off, power output adjustment, and mercury-free operation. These features position UV-LEDs as ideal candidates for point-of-use (POU) water disinfection systems, particularly in decentralized or resource-limited environments. In this study, we evaluated the microbial inactivation performance and energy efficiency of a bench-scale flow-through UV-LED POU system using indigenous heterotrophic plate count (HPC) bacteria, E. coli, and MS2 bacteriophage. The system was tested under various flow rates (1–4 L/min) and wavelength configurations (265 nm, 278 nm, and dual-wavelength combinations). MS2 bacteriophage was further used in collimated beam testing to validate UV-fluence-response curves and to estimate delivered doses in the flow-through POU device. HPC inactivation was enhanced under dual-wavelength conditions, suggesting wavelength-specific synergy, while E. coli showed high susceptibility across all wavelength configurations, achieving >2-log inactivation at significantly reduced UV-LED power (1/6 of that required for HPC) even at 4 L/min. Specific energy consumption analysis showed energy demands as low as 0.032–0.053 kWh/m³ for achieving 4-log inactivation of E. coli, with an estimated annual operating cost for UV-LED irradiation below $1.70. These findings demonstrate the potential of UV-LED-based POU devices as safe, energy-efficient, and cost-effective technologies for decentralized water treatment. Full article

Cellulose and chitin are the most abundant natural polymers, and their exploitation paves the way for sustainable materials and products. This work investigates the preparation of composites based on acetylated cellulose and partially deacetylated chitin, i.e., chitosan, using versatile and robust air-assisted solution spraying (AASS), a potential method for preparing materials both in situ and ex situ. These materials, in the form of films, despite being prepared from high-molecular-weight and rigid biopolymers, show high flexibility (Young’s moduli below 1 GPa), outstanding mechanical properties (tensile strengths above 19 MPa and strain at failure higher than 2%), and bioactivity towards E. coli. The unprecedented flexibility, obtained without the use of any plasticizer or by casting with humidity control, is a direct consequence of the specific film morphology, whereby films are constituted from merging droplets. Depending on the solution properties (viscosity, surface tension), various droplet sizes are obtained, thus influencing the roughness and indirectly the wettability. Wettability analysis towards water and oil revealed higher contact angles towards both fluids as the content of chitosan increases in the composite what directly impacts packaging applications by better protecting the food. Besides this, higher chitosan content in the composite (7.5% w/w) enabled bioactivity against E. coli, where colony development was inhibited on the film surface compared with the neat cellulose acetate. This study shows a very high potential for AASS for obtaining uniform thin flexible films for food packaging applications, allowing faster drying and lower energy consumption than other film-forming techniques. Full article

Hospital-acquired infections (HAIs) remain a major clinical and economic burden, with pathogens such as Escherichia coli contributing to high rates of morbidity and mortality. Traditional manual disinfection methods are often insufficient, particularly in high-risk hospital environments. In this study, we investigated innovative strategies to enhance surface decontamination and reduce infection risk. First, we assessed the efficacy of the SMEG BPW1260 bedpan washer-disinfector, a thermal disinfection system for human waste containers. Our results demonstrated a reduction in Clostridium difficile and Escherichia coli contamination by >99.9% (>3 log reduction), as measured by colony-forming units (CFU) before and after treatment. Molecular techniques, including spectrophotometry, cell counting, and quantitative PCR (qPCR) for DNA quantification, confirmed reduction in bacterial contamination. Specifically, Clostridium difficile showed a reduction of approximately 89% in both optical density (OD) and cell count (cells/mL). In the case of Escherichia coli, a reduction of around 82% in OD was observed, with an even more pronounced decrease in cell count, reaching approximately 99.3%. For both bacteria, DNA quantification by qPCR was below detectable limits. Furthermore, we optimized the energy efficiency of the disinfection cycle, achieving a 45% reduction in power consumption compared to standard protocols without compromising antimicrobial efficacy. Secondly, we developed a sustainable cleaning solution based on methyl ester sulfonate surfactants derived from waste cooking oil. The detergent’s antibacterial activity was tested on contaminated surfaces and further enhanced through the incorporation of nanoassemblies composed of silver, electrostatically bound either to biomimetic magnetic nanoparticles or to conventional magnetic nanoparticles. Washing with the detergent alone effectively eliminated detectable contamination, while the addition of nanoparticles inhibited bacterial regrowth. Antimicrobial testing against E. coli revealed that the nanoparticle-enriched formulations reduced the average MIC values by approximately 50%, with MIC₅₀ values around 0.03–0.06 mg/mL and MIC₉₀ values between 0.06 and 0.12 mg/mL, indicating improved inhibitory efficacy. Finally, recognizing the infection risks associated with intra-hospital transport, we tested the SAFE-HUG Wheelchair Cover, a disposable non-woven barrier designed to reduce patient exposure to contaminated wheelchair surfaces. Use of the cover resulted in a 3.3 log reduction in surface contamination, based on viable cell counts. Optical density and bacterial DNA were undetectable in all covered samples at both 1 and 24 h, confirming the strong barrier effect. Together, these approaches—thermal no-touch disinfection, eco-friendly detergent boosted with nanoparticles, and protective transport barriers—respond to the urgent need for effective, sustainable infection control methods in healthcare settings. Our findings demonstrate the potential of these systems to counteract microbial contamination while minimizing environmental impact, offering promising solutions for the future of infection prevention in healthcare settings. Full article

Pasteurisation was investigated as a process to achieve high microbial quality standards in the recycling of water from unfiltered secondary effluents from a wastewater treatment plants in Melbourne, Australia. The relative heat sensitivity of key bacterial, viral, protozoan and helminth wastewater organisms (Escherichia coli, Enterococcus, FRNA bacteriophage, adenovirus, coxsackievirus, Cryptosporidium, and Ascaris) were determined by laboratory scale tests. The FRNA phage were found to be the most heat resistant, followed by enterococci and E. coli. Pilot scale challenge testing of a 2 ML/day pasteurisation pilot plant using unfiltered municipal wastewater and male specific coliphage (MS2) phage showed that temperatures between 69 °C and 75 °C achieved log reductions values between 0.9 ± 0.1 and 5.0 ± 0.5 respectively in the contact chamber. Fouling of the heat exchangers during operation using unfiltered secondary treated effluent was found to increase the energy consumption of the plant from 2.2 kWh/kL to 5.1 kWh/kL. The economic feasibility of pasteurisation for the current municipal application with high heat exchanger fouling potential can be expected to depend largely on the available waste heat from co-generation and on the efforts required to control fouling of the heat exchangers. Full article

In nutrient-sensitive estuaries, wastewater treatment plants (WWTPs) are required to implement more advanced treatment methods in order to meet increasingly stringent effluent guidelines for organic matter and nutrients. To comply with current and anticipated water quality regulations and to reduce the volume of produced sludge, we have successfully developed a vertical membrane bioreactor (VMBR) that is composed of anoxic (lower layer) and oxic (upper layer) zones in one reactor. Since 2009, the VMBR has been commercialized (Q = 1100–16,000 m³/d) under the trade-name of DMBR^TM for recycling of municipal wastewater in South Korea. In this study, we explore the performance and stability of the full-scale systems. As a result, it was found that the DMBR^TM systems showed excellent removal efficiencies of organic substances, suspended solids (SS) and Escherichia coli (E. coli). Moreover, average removal efficiencies of total nitrogen (TN) and total phosphorus (TP) by the DMBR^TM systems were found to be 79% and 90% at 18 °C, 8.3 h HRT and 41 d SRT. Moreover, transmembrane pressure (TMP) was maintained below 40 kPa at a flux of 18 L/m²/h (LMH) more than 300 days. Average specific energy consumption of the full-scale DMBR^TM systems was found to be 0.94 kWh/m³. Full article