A multivariate study of backpulsing for membrane fouling mitigation in produced water treatment

Abstract Produced water contains a large amount of oil droplets and suspended solids that need to be removed before discharge. Research has been focused on membrane technology because it can effectively remove dispersed oil and provide stable effluent of high quality. To mitigate severe membrane fouling in the microfiltration of synthetic produced water, backpulsing with different conditions was investigated in this study. Results showed that backpulsing was efficient to mitigate membrane fouling. However, the cleaning efficiency varied between different backpulsing conditions. The effect of backpulsing parameters (amplitude, duration and frequency) and their interactions on membrane performance were studied by a 23 full factorial design. Final specific flux and net permeate yield were chosen as responses to indicate the situation of membrane fouling and membrane productivity, respectively. Besides, mechanisms of backpulsing on fouling mitigation and membrane productivity were investigated. Within the selected levels all the three backpulsing parameters were important for the two responses. Amplitude was the most crucial variable for fouling removal and final specific flux, while frequency was the most significant one for membrane net yield. The effect of interactions on both responses were significant but performed in a different way. Amplitude and duration showed a trade-off interaction effect on final specific flux, whereas the three parameters showed synergistic interaction effect between each other on net yield.