Mitigation of biofouling in water showering system by controlling phosphorus in the feed for HVAC system of...

This work proposed the mitigation of biofilm growth on the water showering system (WSS) in a semiconductor factory through phosphorus limitation. Biofilm development on the WSS was monitored and characterized under simulated systems for >300 days with feed water (P-control, 20 μg/L as PO₄^3--P) and treated water by ion exchange resin (P-Limit, < 2 μg/L as PO₄^3--P). Results from confocal laser scanning microscopy (CLSM) analysis showed that biofilm formation on the WSS was dramatically reduced under the P-Limit, exhibiting a lower volume (13.2 ± 3.7 vs. 26.3 ± 4.7 μm³/μm²) and growth rate (0.0474 vs. 0.0945 μm/day) than under the P-Control, while displaying a more porous and rougher biofilm structure. The mechanical properties of extracellular polymeric substances (EPS), investigated using atomic force microscopy (AFM), revealed a lower EPS cohesion force under the P-Limit (-0.43 nN) than under the P-Control (-0.98 nN). In addition, EPS composition and functional groups measured via Fourier transform infrared (FTIR) spectroscopy showed that phosphorus limitation reduced carbohydrate-associated functional groups related to biofilm cohesion and adhesion, suggesting that carbohydrates are key determinants of EPS cohesion and adhesion. Furthermore, fluorescence excitation-emission matrix (FEEM) coupled with parallel factor analysis (PARAFAC) revealed decreased protein-like and microbial degradation product-associated signals under the P-Limit, which was associated with reduced biofilm development. Overall, our findings suggest that phosphorus limitation effectively controlled biofilm development in the WSS, potentially by weakening EPS mechanical properties and shifting microbial metabolic activity.