Fundamental characteristics of discharge plasma generated in a water cavitation field

Ihara, Satoshi; Sakai, Tomohiro; Yoshida, Yuuki; Nishiyama, Hiroki

doi:10.1016/j.elstat.2018.04.004

Cited by 15 publications

(9 citation statements)

References 25 publications

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“…In principle, the method relies on the formation of vapour cavities in a liquid, with plasma being produced in the bubble cloud that is formed downstream of the reactor nozzle through cavitation. Plasma is produced through the application of high voltage to an electrode pair mounted in the reactor [14]. We modified this method for gentle treatment of cyanobacterial biomass with the aim of reducing cyanobacterial cell photosynthetic activity without cell lysis or release of cyanotoxins.…”

Section: Introductionmentioning

confidence: 99%

Removal of Microcystis aeruginosa through the Combined Effect of Plasma Discharge and Hydrodynamic Cavitation

Maršálek

Maršálková

Odehnalová

et al. 2019

Water

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Cyanobacterial water blooms represent toxicological, ecological and technological problems around the globe. When present in raw water used for drinking water production, one of the best strategies is to remove the cyanobacterial biomass gently before treatment, avoiding cell destruction and cyanotoxins release. This paper presents a new method for the removal of cyanobacterial biomass during drinking water pre-treatment that combines hydrodynamic cavitation with cold plasma discharge. Cavitation produces press stress that causes Microcystis gas vesicles to collapse. The cyanobacteria then sink, allowing for removal by sedimentation. The cyanobacteria showed no signs of revitalisation, even after seven days under optimal conditions with nutrient enrichment, as photosynthetic activity is negatively affected by hydrogen peroxide produced by plasma burnt in the cavitation cloud. Using this method, cyanobacteria can be removed in a single treatment, with no increase in microcystin concentration. This novel technology appears to be highly promising for continual treatment of raw water inflow in drinking water treatment plants and will also be of interest to those wishing to treat surface waters without the use of algaecides.

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Section: Introductionmentioning

confidence: 99%

Removal of Microcystis aeruginosa through the Combined Effect of Plasma Discharge and Hydrodynamic Cavitation

Maršálek

Maršálková

Odehnalová

et al. 2019

Water

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“…The combined effect of hydrodynamic cavitation and discharge plasma led to a single-pass removal of all cyanobacteria with no increase in microcystin concentration in treated water. In actual numbers, 6 L of cyanobacteria contaminated water (5 × 10 5 cells/mL) was disinfected in less than 15 s. This volume efficiency is a remarkable improvement over the known methods of underwater discharge generation (Table 1), even when we compare the HCPJ with a few known works where authors also employed cavitation clouds to sustain the underwater discharge [29,32,33]. Very recently, a plasma-cavitation device for water treatment of throughput similar to ours was presented in [30], but unfortunately no details were given in the article with respect to discharge ignition or energy consumption, so we can not make a qualified comparison to our previous results in [28].…”

Section: Introductionmentioning

confidence: 93%

Mass Production of Plasma Activated Water: Case Studies of Its Biocidal Effect on Algae and Cyanobacteria

Čech

Šťahel

Ráheľ

et al. 2020

Water

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Efficient treatment of contaminated water in industrially viable volumes is still a challenging task. The hydrodynamic cavitation plasma jet (HCPJ) is a promising plasma source for industrial-scale generation of biologically active environments at high flow rates of several m3/h. The combined effect of a hydro-mechanical phenomenon consisting of hydrodynamic cavitation and electrical discharge in cavitation voids was found to be highly efficient for large-volume generation of reactive oxygen species, ultraviolet (UV) radiation, and electro-mechanical stress in a liquid environment. Here, the persistence of biocidal properties of HCPJ-activated water (i.e., plasma-activated water (PAW)) was tested by the study of algae and cyanobacteria inactivation. Algae and cyanobacteria cultivated in media containing PAW (1:1) were completely inactivated after 72 h from first exposure. The test was performed at a total power input of up to 0.5 kWh/m3 at the treated liquid flow rate of 1 m3/h. A beneficial modification of our previous HCPJ design is described and thoroughly characterized with respect to the changes of hydrodynamic flow conditions as well as discharge performance and its optical characteristics. The modification proved to provide high biocidal activity of the resulting PAW, which confirms a strong potential for further design optimization of this promising water (liquid) plasma source.

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“…Treatment of E. coli cells with pulsed discharges with cavitation bubbles leads to the formation of reactive oxygen species (ROS) from the generated plasma, which decreases the viability of the cells and induces DNA damage in E. coli [14] . Ihara et al [15] analyzed the impact of solution conductivity and discharge frequency of discharge plasma formed in HCB on water treatment efficiency. A nozzle-less structure reactor has been developed to increase the efficacy of plasma generated by HCB in water treatment [16] .…”

Section: Introductionmentioning

confidence: 99%

Plasma Generated in Hydrodynamic Cavitation Bubbles for the Preparation of Plasma Activated Water

2023

Mod Plasma Med

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Objective: In recent years, the medical applications of plasma activated water (PAW) have attracted growing interest. PAW can be prepared using plasma generated by hydrodynamic cavitation bubbles (HCB). To facilitate this application, the current study was performed to investigate the efficiency of plasma generation in HCB. Methods:Based on the plasma generated in HCB, an experimental system has been constructed. We measured the characteristics of the cavitating flow, including pressure, temperature, and water flow rate, and estimated the system and cavitation power consumptions. High-speed images of cavitating flow were obtained to examine the evolution of the cavitation zone. Images of discharge emission at various velocities were captured to identify the location of electrodes. In addition, optical emission spectra were examined to determine the type of reactive species. H 2 O 2 concentration and energy efficiency were measured and analyzed. Results:In this experiment, the system power consumption was 1.2W. The highest cavitation power consumption was 50.4W and increased with the elevation of throat velocities. The processing findings of high-speed images revealed that the cavitation characteristic length was essential for plasma generation and was necessary for establishing the location of electrodes. In addition, the UV-Vis emission spectra of the plasma discharge demonstrated that the hydroxyl radical •OH was formed in situ and that cavitation increased the yield of •OH. H 2 O 2 was the principal active component of PAW. Plasma generated in HCB produced H 2 O 2 with a high energy efficiency of 77.0mol/kWh. Conclusion:Plasma generated in HCB may provide a viable and cost-effective alternative method for PAW preparation.

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Fundamental characteristics of discharge plasma generated in a water cavitation field

Cited by 15 publications

References 25 publications

Removal of Microcystis aeruginosa through the Combined Effect of Plasma Discharge and Hydrodynamic Cavitation

Removal of Microcystis aeruginosa through the Combined Effect of Plasma Discharge and Hydrodynamic Cavitation

Mass Production of Plasma Activated Water: Case Studies of Its Biocidal Effect on Algae and Cyanobacteria

Plasma Generated in Hydrodynamic Cavitation Bubbles for the Preparation of Plasma Activated Water

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