The use of membrane technologies for water recycling has increased over the last decades, however, its use is limited due to the fouling of the membranes. This study investigates some different parameters thought to be responsible for membrane fouling. Two different ultrafiltration membranes have been used in this investigation in order to carry out filtrations of feed solutions containing dextran with a molecular weight between 36,000 and 44,000 Da. The influence of some operating conditions such as applied pressure, concentration of dextran, content of calcium and pH of the feed solution on the performance of the filtration has been studied.