Disinfection of urines using an electro-ozonizer

Superior water disinfection via ozone micro-bubble aeration: Performance and mechanism

Ozone has been widely applied in water disinfection because of its high oxidation potential (2.07 V). However, slow ozone gas-liquid mass transfer results in high ozone requirements and operating costs. Micro-bubble aeration can effectively increase the ozone mass transfer efficiency while reducing ozone dose. Here, we used a ceramic ultrafiltration membrane for ozone micro-bubble aeration. The disinfection performance and mechanism of ozone micro-bubble aeration towards pathogenic microorganisms were studied. Micro-bubble aeration reduced the total ozone dose by > 60 % for 6-log inactivation of Escherichia coli and MS2 coliphage. It also improved the disinfection efficiencies for Gram-positive bacteria by 3-log. Both ozone and •OH oxidation was enhanced via micro-bubble aeration because of efficient gas-liquid transfer. The equilibrium aquatic ozone concentration increased by 1.38 times and the •OH yield increased by 2.40 times compared with those with milli-bubble aeration. Consequently, ozone micro-bubble aeration caused severe membrane damage to bacterial cells and fragmented the bacterial DNA, which caused a rapid decrease in the bacterial metabolic activity (> 80 %). This study demonstrates that ozone micro-bubble aeration can boost broad spectrum disinfection and effectively reduce the ozone dose, which will facilitate the application of ozonation with a lower cost and reduced environmental impact.

Ozone disinfection of waterborne pathogens: A review of mechanisms, applications, and challenges

Water serves as a critical vector for the transmission of pathogenic microorganisms, playing a pivotal role in the emergence and propagation of numerous diseases. Ozone (O3) disinfection technology offers promising potential for mitigating the spread of these pathogens in aquatic environments. However, previous studies have only focused on the inactivated effect of O3 on a single pathogenic microorganism, lacking a comprehensive comparative analysis of various influencing factors and different types of pathogens, while the cost-effectiveness of O3 technology has not been mentioned. This review synthesized the migration characteristics of various pathogenic microorganisms in water bodies and examined the properties, mechanisms, and influencing factors of O3 inactivation. It evaluated the efficacy of O3 against diverse pathogens, namely bacteria, viruses, protozoa, and fungi, and provided a comparative analysis of their sensitivities to O3. The formation and impact of harmful disinfection by-products (DBPs) during the O3 inactivation process were assessed, alongside an analysis of the cost-effectiveness of this method. Additionally, potential synergistic treatment processes involving O3 were proposed. Based on these findings, recommendations were made for optimizing the utilization of O3 in water inactivation in order to formulate better inactivation strategies in the post-pandemic eras.

Treatment of hospital wastewater by electron beam technology: Removal of COD, pathogenic bacteria and viruses

The effective treatment of hospital sewage is crucial to human health and eco-environment, especially during the pandemic of COVID-19. In this study, a demonstration project of actual hospital sewage using electron beam technology was established as advanced treatment process during the outbreak of COVID-19 pandemic in Hubei, China in July 2020. The results indicated that electron beam radiation could effectively remove COD, pathogenic bacteria and viruses in hospital sewage. The continuous monitoring date showed that the effluent COD concentration after electron beam treatment was stably below 30 mg/L, and the concentration of fecal Escherichia coli was below 50 MPN/L, when the absorbed dose was 4 kGy. Electron beam radiation was also an effective method for inactivating viruses. Compared to the inactivation of fecal Escherichia coli, higher absorbed dose was required for the inactivation of virus. Absorbed dose had different effect on the removal of virus. When the absorbed dose ranged from 30 to 50 kGy, Hepatitis A virus (HAV) and Astrovirus (ASV) could be completely removed by electron beam treatment. For Rotavirus (RV) and Enterovirus (EV) virus, the removal efficiency firstly increased and then decreased. The maximum removal efficiency of RV and EV was 98.90% and 88.49%, respectively. For the Norovirus (NVLII) virus, the maximum removal efficiency was 81.58%. This study firstly reported the performance of electron beam in the removal of COD, fecal Escherichia coli and virus in the actual hospital sewage, which would provide useful information for the application of electron beam technology in the treatment of hospital sewage.

Disinfection of polymicrobial urines by electrochemical oxidation: Removal of antibiotic-resistant bacteria and genes

In this work, data obtained from the University Hospital Complex of Albacete (Spain) were selected as a case study to carry out the disinfection experiments. To do this, different configurations of electrochemical reactors were tested for the disinfection of complex urines. Results showed that 4-6 logs bacterial removal were achieved for every bacterium tested when working with a microfluidic flow-through reactor after 180 min (0.423 Ah dm^-3). The MIKROZON® cell reached a total disinfection after 60 min (1.212 Ah dm^-3), causing severe damages induced in the cell walls observed in SEM images. The concentration profiles of the electrogenerated disinfectants in solution could explain the differences observed. Additionally, a mean decrease in the ARGs concentration ranked as follows: bla_KPC (4.18-logs) > bla_TEM (3.96-logs) > ermB (3.23-logs) using the MIKROZON® cell. This electro-ozonizer could be considered as a suitable alternative to reduce the risk of antibiotic resistance spread. Hence, this study provides an insight into different electrochemical reactors for the disinfection of complex hospital urine matrices and contributes to reduce the spread of antibiotic resistance through the elimination of ARGs. A topic of great importance nowadays that needs to be further studied.

Toward real applicability of electro-ozonizers: Paying attention to the gas phase using actual commercial PEM electrolyzers technology

This work focuses on increasing the TRL of electro-ozonizer technology by evaluating the effect of electrolyte composition and operation conditions on the production of ozone, using an actual commercial cell, CONDIAPURE®, in conditions similar to what could be expected in a real application. Not only is attention paid to the changes in the concentration of ozone in the liquid phase, but also to those observed in the gas phase. The electrolyte and its recirculation flowrate, as well as operation temperatures and pressures are found to have significant influence on production rates. The most efficient way to produce ozone is operating at low temperatures and high pressures. In this work, 0.25 and 0.21 mg O₃/min were obtained operating at 10 A in electrolytes consisting of aqueous solutions of perchloric and sulfuric acid, respectively, in tests carried out at 13 °C and 2 bars of gauge pressure. The negative effect of scavengers that appear electrochemically along the production of ozone is very important and seems to be partially compensated when organics are present in the solution due to the competition between the reaction of these scavengers with ozone or organics.