Enhanced aerobic granulation by applying the low-intensity direct current electric field via reactive iron anode
2019
Guo, Yuan | Zhang, Bing | Zhang, Zhiqiang | Shi, Wenxin | Zhang, Ruijun | Zheng, Run | Li, Weiguang | Cui, Fuyi
A novel granulation strategy by applying the low-intensity direct current (DC) electric field via reactive iron anode into the aerobic granular sludge (AGS) system was systematically investigated in this study. Three identical sequencing batch reactors (SBRs, namely R1, R2, and R3) were operated for 100 days. Comparatively, the R1 and R3 were continuously subjected to the 1.0 V DC electric field via a reactive Fe anode and an inert Ti-Ir/Rh anode, respectively, while the R2 without DC exposure. The results showed that the sludge granulation processes were accelerated in order as follows: R2<R3<R1, and the properties of mature granules were improved in order as follows: R3<R2<R1. Interestingly, at the end of experiment, total phosphorus (TP) removal efficiency in R1 dramatically increased to 80.52%, which was 2.15 and 1.96 folds than that in R2 and R3, respectively. Further investigations revealed that this novel strategy could simultaneously improve the secretion of EPS and the release of iron ions in R1, which cooperatively enhanced the granulation process. Moreover, in R1, mineral precipitation of phosphate remarkably improved the capability of phosphorus removal. The observed effective and stable performance highlights the feasibility and potential of this novel strategy for the rapid start-up and stable operation of AGS system.
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