In the oil industry, it may be necessary to pump the residues from the grinding of olives (vegetation waters). In many oil mills there is currently a tendency to consider the use of residues as fuel in biomass boilers or to feed anaerobic fermentation processes for the production of biogas, in combination with other fermentable residues. We offer solutions with open impeller to avoid clogging of the pump in case of viscous liquids or with solid particles.