Photocatalytic Disinfection Process Research Articles

Effect of humic acid on visible light photocatalytic inactivation of bacteriophage f2 with electrospinning Cu-TiO2 nanofibers: insight into the mechanisms.

Photocatalytic disinfection is a promising technology with low cost and high efficiency. However, most of the current studies on photocatalytic disinfection ignore the widespread presence of natural organic matter (NOM) in water bodies, so the incomplete conclusions obtained may not be applicable. Herein, this paper systematically studied the influence of humic acid (HA), one of the most important components of NOM, on the photocatalytic inactivation of bacteriophage f2 with electrospinning Cu-TiO2 nanofibers. We found that with the addition of HA, the light transmittance of the solution at 550 nm decreased from 94 to 60%, and the band gap of the photocatalyst was increased from 2.96 to 3.05 eV. Compared with reacting without HA, the degradation amount of RNA of f2 decreased by 88.7% after HA was added, and the RNA concentration increased from 1.95 to 4.38 ng·μL-1 after the reaction. Hence, we propose mechanisms of the effect of HA on photocatalytic disinfection: photo-shielding, passivation of photocatalysts, quenching of free radicals, and virus protection. Photo-shielding and photocatalyst passivation lead to the decrease of photocatalyst activity, and the reactive oxygen species (ROSs) (·OH, ·O2-, 1O2, H2O2) are further trapped by HA. The HA in water also can protect the shape of phage f2 and reduce the leakage of protein and the destruction of ribonucleic acid (RNA). This work provides an insight into the mechanisms for the influence of HA in photocatalytic disinfection process and a theoretical basis for its practical application.

Correction: Study of bioaerosol disinfection kinetics and application of nonlinear regression modeling for optimization of TiO2-based photocatalytic disinfection process

Correction: Study of bioaerosol disinfection kinetics and application of nonlinear regression modeling for optimization of TiO2-based photocatalytic disinfection process

Study of bioaerosol disinfection kinetics and application of nonlinear regression modeling for optimization of TiO2-based photocatalytic disinfection process

Study of bioaerosol disinfection kinetics and application of nonlinear regression modeling for optimization of TiO2-based photocatalytic disinfection process

Z-scheme TiO2-Au@CN heterojunction for simultaneous water purification of disinfection and organic pollutant removal by simulated solar light

Simultaneous water purification of multiple hazardous pollutants assisted by photocatalysis technology is regarded as an environmentally friendly and energy-smart strategy under the background of energy and water crisis. Herein, a Z-scheme heterojunction of TiO2-Au@CN nanofibers was constructed. The CB and VB with high potentials were maintained due to the merit of Z-scheme heterojunction. By simultaneous excitement of TiO2 and CN, the TiO2-Au@CN composites presented excellent photocatalytic performance for coinstantaneous 86% inactivation rate against E.coli and 93% RhB removal within 60 min under simulated solar light irradiation. The promoted photocatalytic performance probably resulted from Z-scheme electron transfer mechanism at the interface of the heterojunction assisted by AuNPs as an electron mediator. Moreover, the photocatalytic degradation and disinfection process mainly occurred at surface active sites separately on CB from CN and VB from TiO2, respectively. The constructed Z-scheme heterojunction with efficient light utilization showed great potential in practical water purification under sunlight.

Visible-light-driven photocatalytic inactivation of Escherichia coli by titanium dioxide anchored on natural pyrite

Escherichia coli (E. coli) is a human fecal pathogen and a current serious threat to health. In recent years, photocatalysis has been postulated to be an efficient technology for the disinfection of different types of aqueous matrices. This research focuses on the study of the efficacy of TiO2 anchored in natural pyrite (TiO2NP) in the elimination of E. coli. TiO2NP was successfully prepared and characterized by FTIR, SEM-EDS, and XRD analysis. The effect of operational parameters includes pH, catalyst dosage, catalyst ratio, light intensity, ultraviolet (UV) radiation, aeration, inorganic ions, and organic matter on bacteria inactivation. The result showed that the result showed effective photocatalytic inactivation of E. coli at natural water pH (6.5–8.5). The findings revealed that aeration and UVA accelerate Kmax 0.094 min−1 and 0.139 min−1, respectively. The increase in bacteria density and inorganic matter decreased Kmax 0.14 min−1 and 0.03 min−1, respectively. The inhibiting effect of inorganic ions was obtained as F− > Ca2+ > NO3− > SO42− > Cl−. The effect of the type of catalyst was obtained as TiO2NP > NP > TiO2. However, TiO2 causes •OH generation in the photocatalytic disinfection process, and E. coli inactivation. This study confirmed that TiO2NP is capable of successfully inactivating E. coli in aquatic environments.

Gold-modified ZnO nanocomposites for photo-Fenton-like catalysis of Escherichia coli disinfection

In this study, gold-modified zinc oxide (Au/ZnO) nanocomposites were fabricated using the solvothermal method. Structure, morphology, and components of Au/ZnO nanomaterials were investigated by XRD, TEM, and XPS analyses, respectively. Results of the UV–Vis analysis manifested a shifting of absorption to light of nanocomposites from visible towards red because of the incorporation of Au and its surface plasmon resonance. In addition, an antibacterial test demonstrated that as compared to pure ZnO and ZnO nanocomposites cooperated with other contents of Au, 1/101 Au/ZnO nanocomposites displayed the highest photocatalysis disinfection activity to Escherichia coli cells. Fenton-like and photo-Fenton-like reactions were executed to further explore the effect of 1/101 Au/ZnO nanocomposites, in which the ESR results revealed the producing of hydroxyl radicals that are considered as one of the dominants to antibacterial activity during photocatalytic disinfection process.

Photocatalytic disinfection of different airborne microorganisms by TiO2/MXene filler: Inactivation efficiency, energy consumption and self-repair phenomenon

Bacteria, fungi and viruses are airborne microorganisms, which can survive and spread in the form of aerosols, posing a serious threat to human health. A dynamic continuous flow photocatalytic reactor containing TiO2/MXene filler was developed to study the inactivation characteristics of four different microorganisms treated by ultraviolet and photocatalysis. By establishing the kinetic fitting model (−lgNpcN0=εAbΦNE1IrtPC+A), it was known that there were differences in the inactivation efficiency of airborne microorganisms with different microstructures. The introduction of catalysis greatly reduced the energy consumption of disinfection. The electrical efficiency per log order (EE/O) of UV254 inactivated E. coli was reduced from 0.012 to 0.015 kW·h·m−3 to 0.0016–0.0040 kW·h·m−3. Furthermore, the self-repair phenomenon was not obvious in a very short time (40 h) under UV irradiation, but the microbial activity continued to decline after photocatalytic treatment. Short wave ultraviolet had stronger penetration than long wave ultraviolet. High radiation intensity can provide more photons and produce more reactive oxygen species (ROS) for photocatalysis, while too high humidity (RH=95%) will inhibit it. Appropriate residence time (4.3 s) can efficiently treat airborne microorganisms with higher concentration (109 CFU·m−3). These external factors affected the photocatalytic disinfection process of different kinds of microorganisms.

Efficient bacterial inactivation with S-doped g-C3N4 nanosheets under visible light irradiation.

The pathogenic bacteria in water that threatens the human health and photocatalytic disinfection have been proven to be a cost-effective and promising green technology. It is significant and necessary to develop efficient, safe, and visible light-driven photocatalysts. In this study, Escherichia coli was used as model bacterium and the disinfection performance of prepared S-doped g-C3N4 nanosheets (S-CNNs) under visible light was investigated. The results showed that the synergistic effects of S doping and the unique 2D structure of S-CNNs enhanced the visible light absorption, enlarged the specific surface area and reduced the recombination of photogenerated charge carriers which is beneficial for promoting the photocatalytic disinfection of the E. coli. Scavenger experiments indicated •O2- and h+ were the predominant reactive species in the photocatalytic disinfection process. In addition, the kinetics of disinfection activity were fitted by the modified Hom model and the k2 value of S-CNNs is 0.0219min-1, which is much higher than that of the bulk g-C3N4 (CN). This work has demonstrated efficient bacterial inactivation with S-CNNs under visible light irradiation.

Well-designed oxidized Sb/g-C3N4 2D/2D nanosheets heterojunction with enhanced visible-light photocatalytic disinfection activity

2D/2D heterojunction photocatalysts with excellent photocatalytic activity highlight considerable potential in water disinfection. Here, an oxidized Sb/g-C3N4 2D/2D nanosheets heterojunction (Sb-SbOx/CNS) was constructed based on a facile one-step liquid-phase exfoliation method using concentrated sulfuric acid. By doing so, bulk Sb and g-C3N4 were exfoliated simultaneously and then, intercalated each other. Compared with CNS and Sb-SbOx, the obtained Sb-SbOx/CNS demonstrated better photocatalytic disinfection activity towards Escherichia coli K-12 (E. coli K-12) under visible light irradiation. The 5% oxidized Sb/g-C3N4 2D/2D nanosheets heterojunction (5.0% Sb-SbOx/CNS) exhibited the best photocatalytic performance and admirable cycling stability, which was ascribed to the unique structure where the interfacial charge separation was strengthened by the strong coupling effect between Sb-SbOx and CNS. Meanwhile, the fundamental mechanism of photocatalytic disinfection was also proposed. The photogenerated ROS (reactive oxygen species) violently attacked the E. coli K-12 membrane, creating massive and irreparable holes on the cell membrane. The leakage of cations (K+, Na+, Ca2+ and Mg2+), adenosine triphosphate, total soluble sugar and protein accelerated the destruction of E. coli K-12. Trapping experiments suggested that the photocatalytic disinfection process against E. coli K-12 was dominated by h+ generated on 5.0% Sb-SbOx/CNS. This work offers a new promising way to modify the 2D/2D heterojunction featuring efficient photocatalytic disinfection performance.

Synergistic Generation of Reactive Oxygen Species by Visible Light Activated TiO2 and S. Enterica Interaction

Abstract A lot of human activities have negative impact on water quality and sometimes result in the biological water contamination. Currently used chemical (chlorine, ozone, and etc.) and physical (UV) water disinfection methods have strong environmental disadvantages or suffers from limited efficiency. To overcome these problems, scientists suggest to use photocatalyst activated advanced oxidation processes. One of the most studied photocatalysts which attracts a lot of research interest is titanium dioxide. TiO2 application for the disinfection of water, air or surfaces is increasingly encouraged by researchers. However, to unlock its full potential it is highly desirable to make it suitable for the visible light activation. In the current study the effect of visible light assisted photocatalytic treatment to the outer membrane permeability of Salmonella enterica bacteria and how it changes under different titanium dioxide concentrations was analysed. The results from the treatment of relatively complex Salmonella enterica bacteria organism were compared to the visible light activated TiO2 ability to oxidise considerably simpler objects like methylene blue molecules. The efficiency of TiO2 photocatalytic disinfection process was evaluated using spread plate technique. Membrane permeability of the treated Salmonella enterica bacteria was determined by NPN uptake factor assay. Generation of intracellular reactive oxygen species was evaluated by Dichlorodihydrofluorescein diacetate fluorescence measurements. The key finding of this study was that intense wide spectrum visible light irradiation and TiO2 powder synergistically inactivate S. enterica bacteria and halt its potential to form colonies. High amounts of intracellular reactive oxygen species could be seen as the main suspects for the observed inactivation of S. enterica.

TiO2 Application for the Photocatalytical Inactivation of S. enterica, E. coli and M. luteus Bacteria Mixtures

Abstract Water contamination by various bacteria, viruses and other pathogens is a great threat to human health. Amongst other Advanced Oxidation Processes TiO2 photocatalysis is considered as one of the most efficient treatment for the polluted wastewater disinfection. Usually, the wastewater produced by higher risk objects, such as hospitals, implicates diverse contaminants, but efficiency of most of the Advanced Oxidation Processes is tested by using only single pathogens and information on inactivation of bacteria mixtures is still limited. In this study, photocatalytical inactivation of three commonly found bacterial pathogens (gram-positive (Micrococcus luteus) and gram-negative (Salmonella enterica, Escherichia coli)) was investigated. Efficiency of traditional photocatalytic disinfection process using single bacterial pathogens was compared to the one observed for their mixtures. The impact of photocatalytical process parameters and treatment time on bacteria disinfection efficiency was studied. Photocatalytic disinfection efficiency testing with bacteria mixtures revealed, that in the presence of TiO2 photocatalyst and UV irradiation tested gram-positive cells were inactivated slower than gram-negative cells. Another important finding was that an overall photocatalytic disinfection efficiency of bacteria mixtures is not a straight forward sum of inactivation rates of individually tested pathogens but has a strong relationship to the properties of their competitive growth.

Solar Fecal Coliform Disinfection in a Wastewater Treatment Plant by Oxidation Processes: Kinetic Analysis as a Function of Solar Radiation

The final step in the treatment of municipal wastewater is disinfection, which is required to inactivate microorganisms that have survived after treatment. Chlorine and chloramines are widely used disinfectants in wastewater treatment plants (WWTP); however, the use of chlorine as a disinfectant presents several problems. In the present research, solar disinfection and photocatalytic disinfection processes have been applied to inactivate the fecal coliform microorganisms that are present in municipal wastewater treated by activated sludge in a WWTP. A 2 × 3 × 2 factorial design was applied. The first factor was the process: solar disinfection or photocatalysis; the second was initial pH: 5, 7.5 and 9; the third was the presence or absence of a H2O2 dose of 1 mMol added at the beginning of the process. The data from experimentation were compared to predictions from different inactivation kinetic models (linear, linear + shoulder, linear + tail, Weibull and biphasic). The results show that H2O2 addition plays an important role in the process and that disinfection does not always follow a linear reaction model. When related to radiation, it becomes clear that the accumulated radiation dose, rather than the time, should be considered the most important factor in the solar disinfection process.

Plasmonic Ag decorated graphitic carbon nitride sheets with enhanced visible-light response for photocatalytic water disinfection and organic pollutant removal.

Photocatalytic disinfection with high performance is thought to be a promising way for water purification. Herein, plasmonic Ag doped urea-derived graphitic carbon nitride (g-C3N4) composites were fabricated via in-situ photo-deposition at room temperature as the visible-light photocatalyst. Scan electron microscopy and transmission electron microscopy images showed the uniform dispersion of Ag nanoparticles on the surface of g-C3N4 sheet, which facilitated the synergistic effect of antibacterial performance from Ag and photocatalytic property from Ag/g-C3N4 composites. Photocatalytic water disinfection against Escherichia coli with visible light was performed to demonstrate the improved photocatalytic property with assistance of Ag. The 3-Ag/g-C3N4 exhibited the best bactericidal performance by inactivating all bacteria within 120 min with damaged cell membranes of Escherichia coli observed by scan electron microscopy and transmission electron microscopy images. Photoluminescence spectra, steady-state surface photovoltage spectra, photocurrent response, and electrochemical impedance spectra results revealed that Ag nanoparticles inhibited the recombination of photo-generated e- and h+ pairs and further reinforced the photocatalytic performance of g-C3N4. Scavenger experiments indicated that h+ produced on valence band of g-C3N4 dominated the photocatalytic disinfection process against Escherichia coli. This work further proved Ag/g-C3N4 showed great potential in photocatalytic water disinfection under visible-light irradiation.

Green synthesis of Ag nanoparticles decorated phosphorus doped g-C3N4 with enhanced visible-light-driven bactericidal activity

In this present study, a novel visible-light-driven Ag nanoparticles (Ag NPs) decorated P-doped g-C3N4 (Ag/PCN) composites were successfully fabricated via a facile method combination of one-pot pyrolysis and green reduction. The structure information of as-prepared samples were well characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectroscopy (UV–vis DRS), respectively. The photocatalytic bactericidal activity against representative Gram-negative bacteria of E. coli was employed to evaluate the photocatalytic performance of as-prepared samples. Compared to CN, PCN and Ag/CN, the Ag/PCN composites exhibited the highest visible-light-driven bactericidal activity and could completely inactivate 7.0 log CFU mL−1 of E. coli in 60 min, which were main attributed to the narrowed bandgap, the enhanced visible light response and the accelerated separation rate of photo-generated charges via Ag NPs decorating together with P element doping. Meanwhile, the results of radical trapping experiments revealed that the surface produced superoxide radical (O2−) and photo-generated holes (h+) were the dominant active species during photocatalytic disinfection process, based on which the possible bactericidal mechanism was proposed.

Disinfection mechanism of E. coli by CNT-TiO2 composites: Photocatalytic inactivation vs. physical separation

Magnetic carbon nanotube (MCNT) composites with titanium dioxide (TiO2) have an enhanced photocatalytic disinfection efficiency (i.e. higher disinfection rate) and better applicability (i.e. solar light applicability and catalyst separation using its magnetic property) than bare TiO2 and/or MCNT. However, the role and mechanism of MCNT in the disinfection process are still unclear. Therefore, this study aimed at investigating the disinfection mechanism of Escherichia coli using MCNT-TiO2 nanocomposites under various conditions (i.e. the presence and absence of light and reactive oxygen species scavengers, and different MCNT-TiO2 ratio) and photocatalytic disinfection models. The results showed that (i) MCNT and its nanocomposites with TiO2 had much higher disinfection efficiencies than bare TiO2, (ii) the physical bacterial capture was the dominant disinfection mechanism, (iii) the higher disinfection rate was found at an optimum MCNT:TiO2 ratio of 5:1 under the tested experimental conditions, (iv) hydroxyl radical (OH) was the influencing reactive oxygen species on the photocatalytic disinfection using MCNT-TiO2, and (v) good correlation between experimental parameters (i.e. carbon contents, surface area and concentration of MCNT-TiO2) and the contribution rate of physical and photocatalysis reactions. The finding from this study and the methods proposed herein are essential for understanding the photocatalytic disinfection processes using TiO2 and its carbonaceous nanocomposites, which can promote the application of photocatalytic disinfection process.

Enhanced photocatalytic disinfection of Escherichia coli K-12 by porous g-C3N4 nanosheets: Combined effect of photo-generated and intracellular ROSs

The porous graphitic carbon nitride nanosheets (PCNSs) with high yields were synthesized by using one–step chemical exfoliation method. PCNSs accelerated separation efficiency of photo-generated electron−hole pairs in comparison to bulk graphitic carbon nitride. The PCNS5 (exfoliation for 5 h) exhibited optimal photocatalytic disinfection capability towards Escherichia coli K-12 under simulated solar light irradiation with complete disinfection of 6.5 log10 cfu/mL of E. coil K-12 within 2 h. The enhanced photocatalytic activity of PCNS5 originated from mesoporous nanosheet structure. The possible mechanism of photocatalytic disinfection has proposed that intracellular reactive oxygen species levels and the activities of antioxidant enzymes (e.g., catalase and superoxide dismutase) were enhanced. Transmission electron microscope images observed during photocatalytic disinfection process suggested that the cell membrane was regarded as the first target for oxidation, resulting in a faster leakage of cytoplasmic content and finally degradation of DNA leading to bacterial death. Furthermore, the trapping experiment showed that superoxide radical (•O2−) and holes (h+) were responsible for E. coli K-12 disinfection by PCNS5.

Fabrication of a double-helical photocatalytic module for disinfection and antibiotics degradation.

A double-helical photocatalytic module was fabricated via an annealing process following an anodic oxidation procedure, and installed into a commercial UV sterilizer to structure continuous-flow photocatalytic device. Benefiting from the superior mass transfer of double-helical structure to common flat plate or corrugated plate, as well as the improved adhesion between Ti support and TiO2 layer, the photocatalytic device displayed potential in practical disinfection and degradation of organics. During photocatalytic disinfection process with 21mJ/cm2 of UV dose, the concentration of Escherichia coli decreased from 1.71×107 CFU/L (typical for municipal wastewater) in influent to 2,720CFU/L in effluent water, which met the wastewater discharged standard of China. Escherichia coli reactivation ratio for the photocatalytic device was only one-tenth of that for UV sterilizer. Furthermore, taking phenol, bisphenol A, and four antibiotics as targets, the device was demonstrated to promote the degradation of photodegradable pollutants via photocatalysis. These results highlight a feasibility of photocatalytic technology as a supporting role in practical wastewater treatment. PRACTITIONER POINTS: TiO2 nanotube array was embedded in the surface of double-helical Ti support to avoid detachment. This double-helical photocatalytic module was installed into a commercial UV sterilizer to structure a continuous-flow device. The continuous-flow device was effective in sterilizing bacteria and decomposing photodegradable organic pollutants in wastewater. Improving the performance of UV technology was proposed as a feasible approach for the practical application of photocatalysis.

Photocatalytic Inactivation of Bacteriophage f2 with Ag3PO4/g-C3N4 Composite under Visible Light Irradiation: Performance and Mechanism

Water-borne virus pollution has caused great harm and attracted widespread attention in many countries. Visible-light-driven photocatalysis is considered as a promising process for disinfection. In this study, Ag3PO4/g-C3N4 (AgCN) composites were synthesized by hydrothermal method. The photocatalytic disinfection was investigated using bacteriophage f2 as the model virus. Moreover, the effects of pH and humic acid on photocatalytic disinfection were studied. Meanwhile, the mechanism of enhanced disinfection by Ag3PO4/g-C3N4 was systematically investigated by radical scavenger experiments. The results show that Ag3PO4 particles were uniformly distributed on g-C3N4 sheets. By means of photoluminescence spectrometer analysis, it is confirmed that a lower carrier recombination rate for Ag3PO4/g-C3N4 was achieved compared with Ag3PO3 and g-C3N4. Meanwhile, complete inactivation of f2 with concentration of 3 × 106 PFU/mL was reached within 80 min in the presence of Ag3PO4/g-C3N4 composite. The pH had little effect on removal efficiency overall, while the existence of humic acid resulted in a significant negative effect on the inactivation of f2 due to the optical shielding and absorption of humic acid. Recycling tests of Ag3PO4/g-C3N4 confirmed that Ag3PO4/g-C3N4 presented superior stability. The results from radical scavenger experiments indicated that holes (h+) and hydroxyl radicals (·OH) played important roles in photocatalytic disinfection process.

Fabrication of visible-light-driven silver iodide modified iodine-deficient bismuth oxyiodides Z-scheme heterojunctions with enhanced photocatalytic activity for Escherichia coli inactivation and tetracycline degradation

At present, various organic pollutants and pathogenic microorganisms presented in wastewater have severely threatened aquatic ecosystem and human health. Meanwhile, semiconductor photocatalysis technology for water purification has attracted increasingly significant attention. Herein, we successfully constructed a series of novel visible-light-driven (VLD) Bi4O5I2/AgI hybrid photocatalysts with different AgI amounts. Compared with pristine AgI and Bi4O5I2, Bi4O5I2/AgI with the optimal AgI contents exhibited remarkably enhanced photocatalytic performance in probe experiment for Escherichia coli (E. coli) disinfection and tetracycline (TC) degradation. The efficiency for TC degradation and E. coli inactivation reached 82% and 100% in 30 min, respectively. The enhanced electron-hole separation efficiency was responsible for improved photocatalytic activity. In addition, the destruction process of the chemical structure of TC molecules was further investigated by three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs). The activity and crystal phase of the catalysts did not change significantly after four cycles, demonstrating their excellent recyclability and stability of catalysts. The Ag+ ion leaking experiments, radical trapping experiments and ESR tests demonstrated that OH, O2− and h+ were the main active species in photocatalytic disinfection processes. Furthermore, the photocatalytic mechanism of Bi4O5I2/AgI nanomaterials was discussed in detail in conjunction with the energy band structure, and a reasonable Z-scheme interfacial charge transfer mechanism was proposed. This work is expected to provide an efficient water disinfection method.

Doped ZnO nanoparticles impregnated on Kaolinite (Clay): A reusable nanocomposite for photocatalytic disinfection of multidrug resistant Enterobacter sp. under visible light

Water contamination by multidrug resistant (MDR) enteric bacteria can be considered as the foremost cause of gastrointestinal infections and poses a threat to global public health. Therefore, there is an urgent need to pursue unorthodox techniques with potential of community scale applications for purging of water borne pathogenic bacteria. We communicate visible-light assisted photocatalytic disinfection (PCD) of an enteric MDR bacterium; Enterobacter sp. using Fe-doped ZnO nanoparticles impregnated on Kaolinite (Clay) (ZnO/K). ZnO/K was synthesized by co-precipitation technique and was found to be more effective than Fe-doped ZnO (ZnO) and Kaolinite for PCD process. Analysis from fluorescence microscopy and electron microscopy (FESEM) proposed complete bacterial cell death via PCD due to damage of bacterial cell membrane. Experimental evidences indicated that O2− could be acting as the most significant component in disinfection of MDR Enterobacter sp. in visible-light assisted PCD process in presence of ZnO/K. Considering the experimental data of Resazurin assay, it is proposed that reactive oxygen species (ROS) generated during PCD might have impeded the oxido-reductase enzyme system of the bacteria and hence trammeling its metabolic activity. Crystal structure and particle size of ZnO/K was found to be unaltered during the photocatalytic process indicating its potential for reusability. When ZnO/K was exposed to HCT-116 Human Colorectal Carcinoma cell lines, about 79% cell survivability was noticed. The synthesized material was successful in completely disinfecting the target microorganism in Zebra Fish model, without producing any adverse effects on the Fish itself, further reinforcing its biocompatibility factor. High effectiveness of PCD process using ZnO/K under visible light in disinfecting enteric MDR bacteria, might have promising outcome as an alternative water disinfection technology to prevent the spread of infectious and resistant bacteria without producing any adverse effect on non-specific flora and fauna.