Since first hypothesizing the existence of nanobubbles (NBs) in 1994, the empirical study of NB properties and commercialization of NB generators have rapidly evolved. NBs are stable spherical packages of gas within liquid and are operationally defined as having diameters less than 1000 nm, though are typically in the range of 100 nm in one dimension. While theories still lack the ability to explain empirical evidence for formation of stable NBs in water, numerous NB applications have emerged in different fields. NBs raise opportunities to improve current or enable new technologies for producing fewer by-products and achieving safer water.<br/>We discuss the potential to exploit the unique properties of NBs for improving water treatment by answering key questions and proposing research opportunities regarding 1) observational versus theoretical existence of NBs, 2) ability of NBs to improve gas transfer into water or influence gas trapped on particle surfaces, 3) ability to produce quasi-stable reactive oxygen species (ROS) on the surface of NBs to oxidize pollutants and pathogens in water, 4) ability to improve particle aggregation through intraparticle NB bridging, and 5) ability to mitigate fouling on surfaces. We conclude with key insights and knowledge gaps requiring research to advance the use of NBs for water purification. Among the highest priorities is to develop techniques that measure NB size and surface properties in complex drinking and wastewater chemistries, which contain salts, organics, and a wide variety of inorganic and organic colloids. In the authors’ opinion, ROS production by NB may hold the greatest promise for usage in water treatment because it allows movement away from chemical-based oxidants that are costly, dangerous to handle, and produce harmful by-products while helping achieve important treatment goals.<br/>

Nanobubble technologies offer opportunities to improve water treatment

2019 Fall National Meeting

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