The results of an experimental study are presented performed for a non-conventional solid-liquid system where the physical quantities of the liquid are modified by surfactants. The studied surface-active agent was Rokafenol. The solid phase, suspended in water-surfactant systems, was granulated polyethylene. The effect of the solid concentration at constant surfactant concentration on minimal value of rotating speed of a Rushton disc turbine necessary to produce well-dispersed suspension has been estimated. The critical values of the impeller speed obtained experimentally for all water-Rokafenol systems with previous data obtained for Tween-80 in distilled water, have been compared.