Sustainable Methods for Decontamination of Microcystin in Water Using Cold Plasma and UV with Reusable TiO2 Nanoparticle Coating

Abstract

Microcystins (MCs) are a family of cyanotoxins and pose detrimental effects on human, animal, and ecological health. Conventional water treatment processes have limited success in removing MCs without producing harmful byproducts. Therefore, there is an urgent need for cost-effective and environmentally-friendly methods for treating MCs. The objective of this study was to develop sustainable and non-chemical-based methods for controlling MCs, such as using cold plasma and ultra violet (UV) light with titanium dioxide (TiO2) coating, which can be applied for diverse scale and settings. MCs, extracted from Microcystis aeruginosa, were treated with cold plasma or UV at irradiance of 1470 μW/cm2 (high) or 180 μW/cm2 (low). To assess synergistic effects, the outside of the UV treatment chamber was coated with nanoparticles (TiO2) prior to irradiation, which can be reused for a long time. The degradation efficiency of UV was enhanced by the reusable TiO2 coating at lower irradiance (70.41% [UV] vs. 79.61% [UV+TiO2], 120 min), but no significant difference was observed at higher irradiance. Cold plasma removed MCs rapidly under experimental conditions (92%, 120 min), indicating that it is a promising candidate for controlling MCs in water without generating harmful disinfection byproducts. It can be also easily and practically used in household settings during emergency situations.

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

“…While hydrogen peroxide presence in control Microcystis culture medium was lower than that produced by HC + plasma in pure mineral growth medium, hydrogen peroxide concentrations in treated Microcystis cultures were high enough to confirm partial destruction of microcystins and fortification of the inhibitory effect of HC + plasma on Microcystis photosynthesis and growth. Our results also suggest that, during a single cycle, HC + plasma produces an equivalent concentration of hydrogen peroxide to that generally added to surface waters for chemical treatment of cyanobacterial biomass [2,3,7,33]. to confirm partial destruction of microcystins and fortification of the inhibitory effect of HC + plasma on Microcystis photosynthesis and growth.…”

“…to confirm partial destruction of microcystins and fortification of the inhibitory effect of HC + plasma on Microcystis photosynthesis and growth. Our results also suggest that, during a single cycle, HC + plasma produces an equivalent concentration of hydrogen peroxide to that generally added to surface waters for chemical treatment of cyanobacterial biomass [2,3,7,33].…”

“…Compared with the 3 µM/L initial concentration in our control cyanobacterial culture, the HC treatment produced around 20 µM/L, while treatment with HC + plasma produced from 65 up to 116 µM/L of hydrogen peroxide, dependent on the number of treatment cycles (see Figure 15). While hydrogen peroxide presence in control Microcystis culture medium was lower than that produced by HC + plasma in pure mineral growth medium, hydrogen peroxide concentrations in treated Microcystis cultures were high enough to confirm partial destruction of microcystins and fortification of the inhibitory effect of HC + plasma In similar experiments, Zhang at al [32] also found discharge plasma oxidation to be a promising technology for removal of microcystin-LR (MC-LR) from aqueous solutions, while Xuewen et al [33] observed that intermediates and end products were non-toxic following microcystin degradation by cold plasma treatment for 120 min. Our own use of combined HC + plasma discharge in continual flow-through mode offers a more practical solution for water treatment technology, because it did not destroy cells and did not release cyanotoxins or other organic compounds and all processes can be completed within seconds in a single treatment, without the need for prolonged or repeated treatments and without the release of potentially dangerous microcystins.…”

“…In similar experiments, Zhang at al [32] also found discharge plasma oxidation to be a promising technology for removal of microcystin-LR (MC-LR) from aqueous solutions, while Xuewen et al [33] observed that intermediates and end products were non-toxic following microcystin degradation by cold plasma treatment for 120 min. Our own use of combined HC + plasma discharge in continual flow-through mode offers a more practical solution for water treatment technology, because it did not destroy cells and did not release cyanotoxins or other organic compounds and all processes can be completed within seconds in a single treatment, without the need for prolonged or repeated treatments and without the release of potentially dangerous microcystins.…”

Potential Applications of Non-thermal Plasma in Animal Husbandry to Improve Infrastructure

“…Another study has found that NTP is a cost-effective, environmentally friendly, sustainable and non-chemical-based promising candidate to destroy microcystins in water which cannot be destroyed by conventional methods. Microcystins are toxins produced by cyanobacteria, and can cause detrimental effects on farm animal health (53). Moreover, DBD-generate -NTP has been shown to inactivate residues of cyanobacteria which cause algal bloom in water (54).…”