Ultrafiltration based on the use of co-polyelectrolytes bearing carboxyl, sulfonate, and tertiary amino groups was used to investigate removal of divalent ions from aq. solns. The efficiency of metal sepn. was evaluated for model solns. of Cu2+, Zn2+, Mn2+, and CrO42-, and exceeded 99.9% in the runs involving co-polyelectrolytes with carboxyl groups. Industrial wastewater was treated by the suggested technique; its applicability in environmental protection was also demonstrated. [on SciFinder (R)]