Installation for treating a biological liquid, including a circulation pump (5), a filter element (9), a container for collecting treated liquid, a first circuit section connecting a source of said biological liquid to an inlet orifice of said filter element (9), including a circuit element adapted to cooperate with said circulation pump (5); a second circuit section, connecting an outlet orifice of said filter element (9) to said treated liquid collecting container; characterized in that said treated liquid collecting container, said first circuit section and said second circuit section are disposable and said installation further includes a first cart (1) carrying said pump (5) and a second cart (2) including a housing (14) for said collecting container, separable from the first cart (1) and adapted to be at least partly nested in said first cart (1).