Fouling mechanisms in microfiltration were studied using a specially designed dialysis set-up and scanning electron microscope observations. It has been shown that the pore blocking type of membrane fouling is by far the most predominant. Since backflushing is the most effective method to prevent pore blocking, the process was optimised to reduce the loss of permeate and the operation time. A novel backflushing technique with an effective backflush time of less than 0.1 s and an interval between 1 and 5 s has been developed. It was found that extremely good results could be obtained by combining the technique with the use of reverse asymmetric membranes. A possible mechanism is presented in terms of better control of the fouling and polarisation layers.