Interactions of multiple factors in micro-nano bubbles coagulation process as explored with Response surface methodology

The micro-nano bubbles (MNBs)-coagulation process developed to meet the needs of cleaning production has attracted the public's attention, but the interactions between multiple factors in this process has not been fully understood. Box-Behnken design (BBD) and response surface methodology were used to explore interactions between factors in the MNBs-coagulation process by taking polymeric aluminium chloride (PACl), micro-nano bubbles intake (Qg), and solution pH as the influencing factors, and humic acid (HA) removal efficiency and the residual Al3+ concentration in the precipitated water as the response variables. The results show that the PACl dosage, Qg and pH could significantly affect the removal efficiency of HA, however, neither the PACl dosage nor the Qg had a significant effect on the Al3+ concentration in the precipitation effluent except pH’s significant influence on the response variable. Compared with the conventional coagulation process, the participation of MNBs in the coagulation process could significantly reduce the residual Al3+ concentration in the precipitated water and improve the utilization efficiency of PACl. Evidently, the MNBs-coagulation process is more suitable for treating pH-neutral raw water, and our study will provide reliable data and theoretical support for the engineering application of the MNBs-coagulation process. © 2024 Chinese Society for Environmental Sciences. All rights reserved.