Abstract：Extracellular polymeric substances (EPS) extracted from activated sludge can be applied to remove suspended solids or heavy metal ions in water. In order to obtain higher EPS yield and pollutant removal, different pre-aeration time and extraction methods (ultrasonic and formaldehyde+NaOH) were compared to investigate their influence on the EPS yield, fluorescent components and the functional groups associated with removal of contaminants.. The results showed that the highest EPS yield was obtained when the activated sludge was pre-aerated for 4h. The yield of EPS extracted by the method of formaldehyde+ NaOH (FDNH) was 1.5~1.7 times of that by ultrasonic (USC), in which the content of protein, polysaccharide and DNA were 1.4~1.7, 0.8~2 and 2.3~2.7 times of the latter, respectively. The flocculating rate to kaolin and the removal efficiency of Cr3+ by EPS extracted through FDNH were 16% and 33% higher than that by USC reaching a removal rate of 65% and 63%, respectively. 3D-EEM analysis indicated that the content of aromatic protein and soluble microbial metabolites in the EPS extracted by FDNH was 1.4~1.9 times and 1.8~2.4 times of that by USC. Humic acids were only present in the EPS extracted by FDNH and the removal efficiencies of Cr3+ were significantly correlated (P<0.01, R2=0.920) with humus contents. Infrared spectroscopy analysis revealed some special groups existed in the EPS extracted by FDNH in which -OH, -COOH and -NH2 interacted with Cr3+ by complexation.
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