Self-adaptive dynamic membrane module with a high flux and stable operation for the municipal wastewater treatment

A gradual decline of membrane flux or gradual rise of filtration resistance appeared during the dynamic membrane running processes in previous studies, limiting the acceptance of dynamic membrane bioreactor in a wastewater treatment. In this study, we designed a special tubular membrane module, which can be self-adaptive according to the dynamic membrane filtration process, to gain a sustainable stable flux and enhance the backwashing effect. The comparison among different membrane modules in submerged bioreactor and the performance of the self-adaptive module in recirculated bioreactor were investigated. A pilot scale test lasting for 12 months was conducted to evaluate the long-term applicability of the self-adaptive membrane module. The results demonstrate that the self-adaptive structure had a beneficial effect on the formation and backwashing of the dynamic membrane. The formation time of dynamic membrane was much shorter than the flat module and the average turbidity of effluent was excellent. The self-adaptive membrane module had the longest stable operation time, up to 72.3 h when operated in submerged bioreactor, much larger than other membrane modules. When operated in 60 L/m2 h in recirculated dynamic membrane bioreactor, the stable operation time reached up to 480.3 h, due to the uniform flow field and effective impulse backwashing. The effluent concentrations of COD, TP, NH3-N and SS as well the turbidity in the pilot scale test were similar to or even below the values achieved in the wastewater treatment plants.