Improved water quality as a source of nutrient water by nanobubble engineering of various gases: Preliminary study for potato aeroponic systems

Bacterial wilt (Ralstonia solanacearum, RS) is a major constraint in aeroponic potato (Solanum tuberosum L.) seed production. While hydrogen peroxide (H2O2) is a common low-cost sterilizer in aeroponic, nanobubbles (NB) offer a superior alternative by simultaneously sterilizing and enhancing its physicochemical water quality. This study aimed to test the use of NB to produce high-quality nutrient solutions for aeroponics. The first stage tested three water types, namely distilled water, water contaminated with RS at 104 CFU mL-1 (RS4) and at 108 CFU mL-1 (RS8), with and without H2O2. The second stage tested four water types, namely distilled water, garden water, RS4, and RS8, as controls and after NB treatment using air, O2, or O3 for 10, 20, or 30 min. The observed variables were RS population, temperature, pH, dissolved oxygen (DO), salinity, conductivity, particle size, and zeta potential. Data were analyzed using ANOVA, orthogonal contrast, Duncan test, Pearson correlation, and principal component analysis (PCA). The results showed five clusters, with PCA 1 and 2 representing 69.9% of total variation. The NB-O2 not only inhibited RS growth effectively but also improved water quality by increasing DO to 18.77-22.58 μmol mol-1 and reducing particle size, while maintaining suitable pH and temperature closer to the range required for potato nutrient water. Therefore NB-O2 is a promising preliminary source-water treatment, but validation in aeroponic system with potato plants is still required.