预曝气及提取方法对活性污泥胞外聚合物的影响

为了获得更高的胞外聚合物质（EPS）得率及其对污染物的去除效果，比较了活性污泥预曝气时间及2种提取方法（超声法和甲醛+NaOH法）对提取EPS的影响，分析了EPS的荧光组分以及与污染物去除有关的基团差异.结果表明，污泥经过4h预曝气，EPS得率最高；甲醛+NaOH法提取的EPS是超声法的1.5~1.7倍；其中蛋白质、多糖、DNA含量分别是后者的1.4~1.7、0.8~2和2.3~2.7倍.甲醛+NaOH提取法获得的EPS对高岭土的絮凝率和对Cr³⁺的去除率分别高出超声法16%和33%，絮凝率和去除率分别达到了65%和63%.三维荧光光谱分析结果表明，甲醛+NaOH法提取的EPS中芳香蛋白和溶解性微生物代谢产物含量分别是超声法的1.4~1.9倍和1.8~2.4倍；胡敏酸类物质仅大量存在于甲醛+NaOH法提取的EPS中，且腐殖质与Cr³⁺去除率呈显著相关（P<0.01，R²=0.920）.红外光谱分析表明，甲醛+NaOH法提取的EPS中有区别于超声法的特殊基团，其中-OH、-COOH、-NH₂等基团与Cr³⁺发生了配位络合作用.

Effects of pre-aeration and extraction methods on characteristics of extracellular polymeric substances extracted from activated sludge

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.