Micro- and nanobubbles (MNBs) are microscopic gas bodies sized at micro (<100 μm) and nanoscale (<1 μm), that have a long lifetime in aqueous solutions and large specific surface area due to their small size.

Antimony (Sb) is considered to be a toxic metalloid of increasing prevalence in the environment. Although several phytoremediation studies have been conducted, research regarding the mechanisms of Sb accumulation and translocation within plants remains limited. In this study, soil from a shooting range was collected and spiked with an initial Sb(III) concentration of 50 mg/kg. A pot experiment was conducted to investigate whether Nerium oleander could accumulate Sb in the root and further translocate it to the aboveground tissue. Biostimulation of the soil was performed by the addition of organic acids (OAs), consisting of citric, ascorbic, and oxalic acid at low (7 mmol/kg) or high (70 mmol/kg) concentrations. The impact of irrigation with water supplemented with oxygen nanobubbles (O2NBs) was also investigated. The results demonstrate that there was a loss in plant growth in all treatments and the presence of OAs and O2NBs assisted the plant to maintain the water content at the level close to the control. The plant was not affected with regards to chlorophyll content in all treatments, while the antioxidant enzyme activity of guaiacol peroxidase (GPOD) in the roots was found to be significantly higher in the presence of Sb. Results revealed that Sb accumulation was greater in the treatment with the highest OAs concentration, with a bioconcentration factor greater than 1.0. The translocation of Sb for every treatment was very low, confirming that N. oleander plant cannot transfer Sb from the root to the shoots. A higher amount of Sb was accumulated in the plants that were irrigated with the O2NBs, although the translocation of Sb was not increased. The present study provides evidence for the phytoremediation capacity of N. oleander to bioaccumulate Sb when assisted by biostimulation with OAs.

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BACKGROUNDThe uncontrolled discharge of untreated ballast water, which is essential for a ship's optimal operation, is one of the major causes of sea environmental pollution by shipping. Among the disinfection methods available for ballast water treatment, ozonation is a commonly used method, but its performance is limited by the rapid ozone auto‐decomposition rate. Nanobubbles (NBs) technology has attracted much scientific interest as it is characterized by a long residence time in the aqueous phase and a high surface area; therefore, ozone nanobubbles (OzNBs) are expected to enhance disinfection capacity and residual activity. The present study was designed to provide further insight into the inactivation of heterotrophic bacteria in saline water and to examine the use of OzNBs for disinfection of saline water.RESULTSThe survival rate of Escherichia coli (E. coli), which was used as indicator microorganism, along with the ozone consumption at different salinities (1.5, 4, 8 and 15 PSU) and bacterial concentrations (107, 106, and 105 CFU mL−1) with and without supplementation of OzNBs were investigated. The results indicated a statistical difference in the residual concentration of total residual oxidants (TRO) with the presence of OzNBs at salinity level 1.5 PSU and at 4 PSU only at the lowest bacterial content. At a low salinity and high bacterial concentration, the concentration of TRO was 6‐fold higher in the presence of OzNBs.CONCLUSIONThe salinity of water has a strong impact on the residual concentration of ozone. When salinity is increased, ozone reacts more rapidly with the bromide and chloride ions. The use of OzNBs exhibited a greater disinfection performance and higher residual activity. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).