Effect of nanobubble concentrations on fouling control capacity in biogas slurry wastewater distribution systems

Nanobubble (NB) represents a promising practice for mitigating fouling in biogas slurry distribution systems. However, its anti -fouling effectiveness and optimal use dosage are unknown. This study investigated the NB antifouling capacity at six concentrations (0 %-100 %, denoting the ratio of maximum NB -infused water; particle concentrations in 0 % and 100 % ratios were 1.08 x 107 and 1.19 x 109 particles mL-1, respectively). Results showed that NB effectively mitigated multiple fouling at 50 %-100 % ratios, whereas low NB concentration exacerbated fouling. NB functioned both as an activator and a bactericide for microorganisms, significantly promoting biofouling at 5 %-25 %, and inhibiting biofouling at 50 %-100 %. Owing to an enhanced biofilm biomineralization ability, low NB concentration aggravated precipitate fouling, whereas high NB doses effectively mitigated precipitates. Additionally, higher NB concentrations demonstrated superior control efficiency against particulate fouling. This study contributes insights into NB effectiveness in controlling various fouling types within wastewater distribution systems.