ABSTRACT

The enhancement of phosphorus (P) released from waste activated sludge (WAS) by electrochemical treatment was investigated in this study. Results showed that the concentration of orthophosphate (ortho-P) and organic phosphorus (OP) in liquid both increased after electrochemical treatment. The ortho-P and OP concentration reached a maximum of 5.020 and 1.888 mg/L under the optimal condition respectively (voltage of 4.5 V and time of 60 min), which were 2.86 and 4.93 times higher than that in raw sludge. Meanwhile, the role of extracellular polymeric substances (EPS) in this process was also studied. The variation trends of P-release in tightly bound EPS (TB-EPS) and loosely bound EPS (LB-EPS) were different. In TB-EPS, the concentration of total phosphorus (TP) and ortho-P decreased when the voltage increased. In contrast, the concentration of TP and ortho-P in LB-EPS increased and reached the maximum under the optimal condition. Released metal ions (Ca, Mg, Fe, and Al) had some effects on P-release both in liquid and EPS, which indicated that EPS played an important role. SCOD and TSS revealed that the disintegration of sludge was also enhanced by electrochemical treatment. Additionally, the P fractions in sludge phase suggested that OP was more likely to be released in liquid phase.

摘要

本研究研究了电化学处理对废弃活性污泥 (WAS) 释放的磷 (P) 的增强作用。结果表明，电化学处理后液体中正磷酸盐（ortho-P）和有机磷（OP）的浓度均增加。在最佳条件下（电压4.5 V，时间60 min），邻P和OP浓度分别达到最大值5.020和1.888 mg/L，分别是原污泥的2.86和4.93倍。同时，还研究了胞外聚合物（EPS）在该过程中的作用。紧密结合的EPS（TB-EPS）和松散结合的EPS（LB-EPS）中P-释放的变化趋势不同。在TB-EPS中，随着电压的增加，总磷（TP）和邻磷的浓度降低。相比之下，LB-EPS中TP和ortho-P的浓度增加并在最佳条件下达到最大值。释放的金属离子（Ca、Mg、Fe 和 Al）对液体和 EPS 中的 P 释放有一些影响，这表明 EPS 发挥了重要作用。SCOD 和 TSS 表明，电化学处理也增强了污泥的分解。此外，污泥相中的 P 部分表明 OP 更有可能在液相中释放。