Keywords: activated sludge, aerobic selector, biosorption, copper, heavy metals, hexavalent chromium, sludge age, metal removal, wastewater treatment
Effect of sludge age on heavy metal biosorption by selector activated sludge
The influence of sludge age on the metal biosorption characteristics of an aerobic selector-activated sludge was investigated. Two bench-scale aerobic-activated sludge systems were operated at sludge ages of 5 days and 15 days for studying biosorption of Cu and Cr(VI). In-vitro batch experiments were performed to compare biosorption characteristics of the sludge samples harvested from the bench-scale systems. Adsorption capacity (k) of the sludge for both of the metals was found to decrease with increasing sludge age from 5 days to 15 days However, percent removals of the metals were variable in relation to sludge age. Although Cr(VI) removal increased from 33% to 68%, Cu removal exhibited a slight decrease from 81% to 74% with increasing sludge age.