Performance and fouling characterization of a five-bore hollow fiber membrane in a membrane bioreactor for the treatment of printing and dyeing wastewater

Filtration performance and fouling behavior of a five-bore hollow fiber membrane was investigated in a membrane bioreactor (MBR) treating printing and dyeing wastewater. A normal single-bore hollow fiber membrane module was used in the same bioreactor for comparison. During an operation over 30 days, the results of chemical oxygen demand (COD) and color removals demonstrated that the five-bore membrane was favorable for this wastewater treatment. The critical flux (J(c)) of the five-bore membrane and the single-bore membrane was determined at 21 and 15L/(m(2).h), respectively, using a flux-step method. During a steady running at sub-critical flux of 10L/(m(2).h) without cleaning for 50 days, the average increasing rates of trans-membrane pressure (TMP) for five-bore and single-bore membranes were 0.356kPa/d and 0.444kPa/d, respectively, indicating that the five-bore membrane had better fouling resistance. The total resistance values of five-bore membrane and single-bore membrane were 8.68 and 14.1m(-1), respectively. Scanning electron microscope (SEM) and atomic force microscope (AFM) results confirmed the cake layer resistance for five-bore membrane was much lower than single-bore membrane. It was expected that the membrane structure, especially the membrane diameter, influenced the anti-fouling property of five-bore membrane.