Liu Ying, Lv Wenzhou, Zhang Zhiqiang, Xia Siqing
State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University Shanghai 200092 China
Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092 China.
RSC Adv. 2018 Sep 18;8(56):32172-32177. doi: 10.1039/c8ra06277c. eCollection 2018 Sep 12.
The spatial distribution and adsorption capacity of extracellular polymeric substances (EPS) were systematically investigated for waste activated sludge (WAS) treated by a short-time aerobic digestion (STAD) process. During the STAD process, both the slime and the loosely bound EPS (LB-EPS) increased first and then decreased, while the tightly bound EPS (TB-EPS) gradually increased all the way. The variations of the fluorescence intensities at peaks A and B for the slime, the LB-EPS and the TB-EPS were consistent with the above variation of their concentrations. In the initial stage of the STAD process, aeration scour was mainly responsible for the release of LB-EPS and TB-EPS, which further resulted in the increase of slime and LB-EPS. Meanwhile, newly secreted EPS by microorganisms led to the increase of TB-EPS. In the later stage of the STAD process, the biodegradation of soluble organic matter caused the concentration decrease of both slime and LB-EPS. The Pb adsorption capacity by LB-EPS, TB-EPS and total EPS gradually increased with the increasing of STAD time, suggesting that the LB-EPS and TB-EPS played a key role in the adsorption of Pb and the LB-EPS had a higher adsorption capacity. FTIR results further indicated that STAD could improve the amounts of functional groups, especially for -OH, -COOH and -NH in both LB-EPS and TB-EPS responsible for the binding of heavy metals, resulting in the increased adsorption capacity of EPS. Disclosing the influencing characteristics of the STAD process on the spatial distribution and the adsorption capacity of EPS in WAS for the first time, this work lays a foundation for the application of the STAD process in the reuse of WAS.
针对通过短时好氧消化（STAD）工艺处理的废弃活性污泥（WAS），系统研究了胞外聚合物（EPS）的空间分布和吸附能力。在STAD过程中，黏液和松散结合的EPS（LB-EPS）均先增加后减少，而紧密结合的EPS（TB-EPS）则一直逐渐增加。黏液、LB-EPS和TB-EPS在峰A和峰B处的荧光强度变化与其浓度的上述变化一致。在STAD过程的初始阶段，曝气冲刷主要导致LB-EPS和TB-EPS的释放，进而导致黏液和LB-EPS增加。同时，微生物新分泌的EPS导致TB-EPS增加。在STAD过程的后期，可溶性有机物的生物降解导致黏液和LB-EPS的浓度降低。LB-EPS、TB-EPS和总EPS对Pb的吸附能力随STAD时间的增加而逐渐增加，表明LB-EPS和TB-EPS在Pb的吸附中起关键作用，且LB-EPS具有更高的吸附能力。傅里叶变换红外光谱（FTIR）结果进一步表明，STAD可增加官能团的数量，尤其是LB-EPS和TB-EPS中负责重金属结合的-OH、-COOH和-NH，从而提高EPS的吸附能力。这项工作首次揭示了STAD过程对WAS中EPS的空间分布和吸附能力的影响特征，为STAD工艺在WAS再利用中的应用奠定了基础。
