Comparative analysis of physical cleaning operations for fouling control of hollow fiber membranes in drinking water treatment

The combined effect of air scouring, backwashing and relaxation on the fouling reduction of a hollow fiber PVDF ultrafiltration membrane was investigated using factorial designs of experiments. The investigation was carried out to test and compare the efficiency of three physical cleaning operational regimes, specially: air scour, backwashing, and relaxation. Beneficial dependencies between the operations for fouling reduction were identified and examined in this study.The use of a three operation regime under continuous flow conditions was found to be more effective for fouling reduction compared air assisted backwashing and air assisted relaxation with fouling reductions 2.5 and 3 times lower, respectively. While the use of a short backwash duration showed negligible impact on fouling reduction, a longer backwash duration was found to work in synergy with a high air flow rate and a short relaxation duration for the reduction of fouling. The use of a regime involving long backwash duration (20 s), short relaxation duration (5 min.) and high air flow rate (15 LPM) was identified as the optimal regime for fouling reduction while minimizing permeate production losses due to backwash and relaxation operations in this study.

► Comparison of air scouring, backwashing, relaxation.
► An experimental design was employed for comparison of the three effects.
► Air scoring dominated membrane fouling.
► Combination of all three parameters resulted in lowest observed fouling