[Recovery and reuse of SDS by ultrafiltration with acid or chelator].

The retentate stream containing Cd2+ was chosen for the investigation. Effects of acid reagent, chelator, pH and operation mode on separation of Cd2+ and recovery of SDS, as well as efficiency of reclaimed SDS were investigated. The optimum conditions in acidification were obtained: H2SO4 as acid reagent, pH = 1.0, operation mode of batch. Under these conditions, separation of Cd2+ and recovery of SDS are 98.0% and 58.1%, respectively. And the efficiency of reclaimed SDS for removing Cd2+ is 80.2%. In chelation, the optimum conditions were investigated: EDTA as chelator, uncontrolled pH (pH = 4.4) and operation mode of batch. Under these conditions, separation of Cd2+ and recovery of SDS are 90.1% and 60.5%, respectively. And the efficiency of reclaimed SDS for removing Cd2+ is 79.4%.