Ozone micro-bubble disinfection method for wastewater reuse system

Abstract

Reuse of wastewater is regarded as one important way to deal with the world's shortage of potable water. The authors focused on a disinfection system using micro-bubbles and evaluated its capability for wastewater reuse. This paper reports experimental results from examination of the basic characteristics of micro-bubbles and disinfection of secondary effluent by air or ozone micro-bubbles. The results suggest that when micro-bubbles are applied in an ozonation system it is possible to reduce the reactor size, the amount of ozone decomposition equipment needed and the ozone dose rate.

Removal of residual pesticides in vegetables using ozone microbubbles

“…Thus, in lettuce, both the treatments of the decompression type and the gas-water circulation type removed residual FT effectively, and the decompression type was more effective than the gas-water circulation type. The dissolved O3 in the solutions of OMB treatments generates hydroxyl radicals that are highly effective at decomposing organic molecules like the residual FT (Sumikura et al, 2007;Takahashi et al, 2007b), and hydroxyl radicals are generated by the collapse of OMB in solutions (Chu et al, 2008a). The decompression type would have generated a high enough concentration of dissolved O3 to produce a large amount of hydroxyl radicals.…”

“…The dissolved O3 in the OMB treatment solutions generates hydroxyl radicals that are highly effective at decomposing organic molecules like the residual FT (Sumikura et al, 2007;Takahashi et al, 2007b). Hydroxyl radicals are generated by the collapse of OMB in solution, and so the 1.0 ppm OMB, 2.0 ppm OMB and bubbling OMB solutions would have had a high enough concentration of dissolved O3 to produce a large amount of hydroxyl radicals.…”

“…Microbubbles (MB) are less than 50 μm in diameter and have special properties such as generation of free radicals, self-pressurization and negative charge, and their use in the field of food science and agriculture is attracting attention (Sumikura et al, 2007;Takahashi et al, 2007b). Millibubbles generated by using an air pump are 2-3 mm in diameter, rapidly rise in water and burst at the water surface.…”

“…In addition, reports on disinfecting wastewater using ozone (O3) MB have discussed their strong disinfectant activities and relative long-term durability in water (Sumikura et al, 2007;Chu et al, 2007;Chu et al, 2008a;Chu et al, 2008b).…”

Investigations on fungicide removal from broccoli by various processing methods

“…As in the case of washing with chlorinated water, the lowest reduction for metalaxyl was also observed (Table 5). Such a large reduction may be possible since the dissolved ozone generates hydroxyl radicals that are highly effective at decomposing organic molecules like fungicide residual [19,20].…”