Zirconium silicate sand, known as zirconia for application in the ceramics industry, in Valencia, is made by different companies. In one of them, this production is carried out through a milling process, which is made by a dry route and also by a humid route. In humid milling a very fine particle size is obtained, and it is a large-yield process. However, this process is longer than the dry one since it has more factors such as addition and subtraction of water, decanting and addition of polyelectrolytes, and the addition of alumnia (Al2O3) and NaOH, which are used to regulate the process and the quality of the water. The function of polyelectrolytes is fundamental since it forms flocs to make the coagulation, which allows the separation of ZrSiO4 from the water. This work studied the application of membrane technology (basically UF) for the separation of polyelectrolytes from the spill water of this company, with two important purposes: (a) the reusability of the polyelectrolytes in the process of decanting and (b) to reuse the water in the milling process to diminish the amount of spill water. This would produce some environmental and economical benefits: the reuse of the water, the decrease of solids and color (100% transparency) of the water, therefore, better quality of the spill water, saving of polyelectrolytes and a greater yield in the production of zirconia, among others. A proposal for treatment and the results of the pretreatment experiments are presented.