Investigation of bromide removal and bromate minimization of membrane capacitive deionization for drinking water treatment

The ubiquitous bromide (Br-) poses a challenge to current drinking water treatment schemes due to the formation of brominated disinfection by-products, especially bromate (BrO3-). A cost-effective and energy-efficient technology to remove Br- before disinfection is highly desired. In this work, the application of membrane capacitive deionization (MCDI) for the removal of Br- and BrO3- minimization for drinking water treatment was systematically investigated. Results showed that the removal of Br- by MCDI followed the pseudo-second-order kinetics, in which kinetics was faster at lower Br- concentration. Additionally, Br- displayed a preferential electrosorption over Cl- in MCDI despite the relatively smaller amounts. Due to high removal performance of Br-, 99.49% of BrO3- minimization can be achieved. Moreover, the presence of humic acid (HA) had a negative effect on the removal of Br- and BrO3- minimization. However, Br- could be more preferentially removed than Cl- in the presence of HA due to the weak interaction with HA. Finally, by treating an actual surface water sample, it was found that the removal rate of Br- was 91.80%, and 83.97% of BrO3- minimization can be achieved. BrO3- concentration of effluent meets the control standard. Overall, these results prove the feasibility of MCDI for practical drinking water treatment.

Automated summary

The study systematically investigated the application of membrane capacitive deionization (MCDI) for the removal of Br- and BrO3- minimization in drinking water treatment, demonstrating the feasibility of this technology.