# Micro-Nanobubble Technology in Surface Cleaning and Defouling
## 3 Advanced Applications of NBs in Precision Surface Cleaning
### NBs in Membrane Cleaning
[34] investigated the effects of MNB concentration and size on membrane fouling and filtration performance, with an emphasis on intermittent operation schemes and air-saturated water release pressure optimization (Figure 7). This study found that changing the release pressure from 0.35 MPa to 0.60 MPa significantly decreased membrane fouling by controlling MNB size and concentration. Higher pressures resulted in smaller bubbles and higher concentrations. Improved membrane performance and a 70% decrease in transmembrane pressure were achieved using the ideal release pressure of 0.60 MPa. Furthermore, intermittent release periods of less than 30 min enabled sustainable fouling management and reduced energy consumption, with performance on par with that of continuous release. This study presented a viable and environmentally friendly membrane filtration method by highlighting the significance of bubble size, concentration, and intermittent release for reducing membrane fouling and energy consumption. Study of the efficacy of MNBs against various forms of fouling and additional validation for industrial applications are required. [PERSON] et al. [54] created a novel method for treating reverse osmosis concentration in the iron and steel sector by mixing ozone MNBs with catalytic ceramic membranes coated with active cobalt oxide (Co\({}_{3}\)O\({}_{4}\)). Ozone MNBs significantly improved the breakdown of organic pollutants because they had smaller bubble sizes and twice the dissolved ozone concentration of traditional aeration. Within 45 min, the cobalt-ceramic membrane unit (Co-CMU) catalyst, which contained Co\({}_{3}\)O\({}_{4}\) particles loaded in the inner pores and on the surface of Al\({}_{2}\)O\({}_{3}\) ceramic membranes, achieved a COD removal efficiency of 42.7%, surpassing the 33.3% removal rate of traditional ozonation. *OH and 1O\({}_{2}\) were the primary active species involved. This combined procedure reduced membrane fouling while effectively eliminating soluble microbial metabolites and contaminants resembling humic acid. The Co-CMU catalyst demonstrated excellent stability with minimal cobalt leaching throughout five cycles of reuse, and the operational cost per unit of COD removal was lowered by 2.5 times when compared with conventional ozonation. This method is viable for effectively eliminating harmful and enduring organic contaminants from industrial wastewater. [PERSON] et al. [55] examined how air micro-nanobubbles (AMNBs) can increase the efficiency of the cleaned-in-place (CIP) process for reverse osmosis systems used in the petrochemical industry. A membrane from a desalination unit with different types of fouling was used in the experiment, and its performance was evaluated under four conditions: prior to CIP, following conventional CIP, following AMNB treatment, and following conventional CIP in conjunction with AMNBs. Compared with traditional CIP alone, the results demonstrated that the addition of AMNBs increased the permeate flux and salt rejection. Additionally, SEM and energy-dispersive X-ray spectroscopy tests showed a notable decrease in membrane fouling. This study concluded that using AMNBs in conjunction with CIP prolongs cleaning intervals and boosts RO membrane longevity, which lowers operating costs in desalination facilities. To decrease fouling and enhance CIP performance, this study suggested incorporating an MNB generator into the feed water and CIP processes. [PERSON] et al. [56] investigated the function of MNBs in membrane water treatment processes, emphasizing how well they clean and control fouling. MNBs have unique benefits owing to their high zeta potential, high stability in water, and capacity to produce free radicals, all of which aid in clearing clogged membranes. Particularly in saltwater applications, their mechanisms--turbulence, repulsion, gas bridge effects, and scoring--work together to prevent cake formation, pore clogging, and colloidal fouling.