The aim of this work was to examine the fouling of a polypropylene filter fabric, which had been used in a silica filtration process. According to the EDAX-elemental analysis, the fouled multi/monofilament fabric contained sodium, magnesium, aluminium, silicon, phosphorous, sulphur, chlorine, potassium and calcium. The inlet slurry's main components were sodium, silicon and sulphur and some aluminium. Thus, the fouling mineral compounds originated from the water used in the fabric cleaning. The fabric did not clog evenly over the width of the filter; a higher degree of fouling occurred on the feed side than on the filtrate side. Modifying the fabric with Teflon did not improve results. An ultrasonic cleaning technique (frequency 40 Hz), using a variety of chemicals was examined, along with both mechanical cleaning and cleaning with pressurised water. According to the results from the study, it is advisable to add ultrasonic cleaning equipment to the process. Further, with the aid of mechanical cleaning, the air permeability of the cleaned fabric can be returned to the same level seen with new fabric. Cleaning with pressurised water was not effective, possibly because the pressure of the water was too low.