# Micro-Nanobubble Technology in Surface Cleaning and Defouling
## 4 Biofouling Mitigation and Advanced Cleaning Technologies
### Fouling Mitigation and Biofilm Control  
Biofilm generation and fouling are recurring problems in many industrial and environmental processes, particularly in food production, medical device applications, and water treatment [85]. As NB technologies can improve cleaning effectiveness, postpone material degradation, and disturb microbial communities, they have demonstrated great promise for reducing fouling and managing biofilms [86]. The use of NBs in various contexts has recently been investigated, including boosting the effectiveness of antimicrobial agents against biofilms and increasing membrane cleaning in water filtration systems [87]. Researchers are finding novel solutions to fouling-related problems by utilizing cutting-edge methods, such as surface-modified materials, biofilm reactor systems, and ultrasound-targeted MB destruction [88]. In various sectors, these methods have demonstrated the adaptability and efficiency of NBs as environmentally friendly and sustainable biofilm control options [89]. [PERSON] et al. discussed how well micro- and NBs improved cleaning and managed membrane fouling in the nanofiltration process for direct drinking water treatment [90]. Compared with conventional scale inhibitors, the introduction of MNBs increased the membrane flow by 6.3%, indicating their capacity to efficiently control fouling while reducing the effects on membrane surface functional groups. The membrane flow decreased by 33% after four cleaning cycles, suggesting inadequate cleaning efficacy. However, washing with MNBs did not change the membrane's chemical or physical characteristics, thus delaying the aging process. The findings demonstrated that the continuous introduction of MNBs was superior to intermittent introduction in preserving membrane performance. Characterization investigations showed that although MNBs might lessen membrane fouling, they had a limited capacity for cleaning. However, they helped preserve membrane integrity and postpone deterioration. According to the study, the nanofiltration procedure maintained the effluent quality below legal limits and, under ideal circumstances, achieved over 90% removal efficiency for a variety of contaminants, including turbidity and hardness. Overall, this study demonstrated how MNB technologies can improve the sustainability and effectiveness of nanofiltration systems in water treatment applications, particularly in terms of biofilm-related fouling issues. [PERSON] et al. examined, using computational and experimental approaches, the dynamics of a bubble colliding with and gliding over a tilted surface [91]. To interact with solid substrates at wall angles ranging from 0\({}^{\circ}\) to 40\({}^{\circ}\), an air bubble with a radius of roughly 550 \(\upmu\)m and a rising speed of 30 cm/s was employed. According to the results, the shear stress increased with the wall inclination, reaching up to 300 Pa during the bouncing stage and approximately 45 Pa during the sliding stage. These shear forces were sufficiently high to eliminate microorganisms from the surface. The pressure distribution found in numerical models of the thin liquid film that developed between the bubble and wall matched the findings of the experiments. The shear tension (approximately 307 Pa) produced during the bouncing step was sufficient to separate common foodborne bacteria from surfaces. This study also discussed issues related to the surface curvature and bubble cleanliness, indicating that the results can be used to clean agricultural products such as tomatoes with bubbles in real-world settings. [PERSON] et al. [92] studied the impact of hypochlorite (HOCI) and oxygen (O\({}_{2}\)-) NB water (NBW) on the human salivary microbiome of 16 male patients (Figure 13). No discernible alterations in the diversity of oral microbiota were found using 165 rRNA gene sequencing. HOCI-NBW treatment did not upset the equilibrium of the oral microbiome, as evidenced by the discovery of two subclusters in the microbiota by Principal Coordinate Analysis.