生物污泥对染料的吸附及胞外聚合物的作用

Adsorption of a Dye by Sludges and the Roles of Extracellular Polymeric Substances

对比研究了4种生物污泥（包括活性污泥、厌氧污泥、干活性污泥、干厌氧污泥）对染料酸性湖蓝A的吸附，并考察了胞外聚合物（EPS）以及外层溶解性胞外聚合物（SEPS）和内层固着性胞外聚合物（BEPS）在此过程中所起的作用．结果表明，4种污泥吸附量与染料平衡浓度之间均既符合Freundlich模型（R^2为0．921～0．995），又符合Langmuir模型（R^2为0．958～0．993），但不符合BET模型（R^2为0．07～0．863）．干厌氧污泥对染料酸性湖蓝A的吸附性能最好，干活性污泥的吸附性能最差．从Langmuir等温方程来看，干厌氧污泥的最大吸附量最高，为104mg／g，其次为厌氧污泥的吸附（86mg／g）、活性污泥（65mg／g），干活性污泥的最大吸附量最低，仅为20mg／g．EPS的吸附量占整个活性污泥和厌氧污泥的吸附量的比例均大于50％，活性污泥和厌氧污泥对染料酸性湖蓝A的吸附主要是EPS的吸附所贡献．厌氧污泥吸附染料酸性湖蓝A时，BEPS起主要作用；而活性污泥吸附时，SEPS起主要作用．对2种污泥而言，SEPS的单位质量吸附量均远大于BEPS的单位质量吸附量，活性污泥平均为52倍，厌氧污泥为10倍．厌氧污泥BEPS的吸附用Langmuir模型拟合，效果最好（R^2为0．9986）．

This paper investigated the adsorption of a dye, acid turquoise blue A, by four kinds of sludges including activated sludge, anaerobic sludge, dried activated sludge, and dried anaerobic sludge, respectively. The roles of extracellular polymeric substances （EPS） including the soluble EPS （SEPS） and bound EPS （BEPS） for the biosorption of activated sludge and anaerobic sludge were further studied. Results show that the relation between four kinds of sludge adsorption amount and remained concentration of the dye fitted well both Freundlich model （R^2 ： 0.921 - 0.995） and Langmuir model （R^2 ： 0.958 - 0.993）, but not quite fitted BET model （R^2 ： 0.07 -- 0.863）. The adsorption capability of dried anaerobic sludge ranked the highest, and dried activated sludge was the lowest. According to Langmuir isotherm, the maximum adsorption amount of dried anaerobic, anaerobic, activated, and dried activated sludge was 104 mg/g, 86 mg/g, 65 mg/g, 20 mg/g, respectively. The amount of the dye found in EPS for both activated sludge and anaerobic sludge were over 50%, illustrating that EPS adsorption was predominant in adsorption of the dye by sludge. The amount of adsorbed dye by BEPS was greater than that by SEPS for anaerobic sludge, but for activated sludge the result was quite opposite. The amount of adsorbed dye by unit mass SEPS was much higher than the corresponding values of BEPS for both sludges. The average amount of adsorbed dye by unit mass SEPS was 52 times of the corresponding value of BEPS for activated sludge, and 10 times for anaerobic sludge. The relation between adsorption amount of dye by BEPS from anaerobic sludge and remained concentration of the dye in mixed liquor was best fitted to Langmuir model （R^2：0.998 6）.