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A comparison of oxidation and re-flocculation behaviors of Fe2+/PAA and Fe2+/H2O2 treatments for enhancing sludge dewatering: A mechanism study
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DOI：10.1016/j.scitotenv.2022.157690.png)
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Abstract
En 中文
In this study, Fe2+ activated-PAA was developed as a novel technology to enhance sludge dewatering. The result showed that the filterability (CST0/CST) enhanced by 4.20 +/- 0.14 times more than the control, and the SRF and bound water content decreased from 4.58 +/- 0.07 x 10(13) m/kg and 2.11 +/- 0.28 g/g dry sludge to 9.47 +/- 0.05 x 10(12) m/kg and 1.27 +/- 0.18 g/g dry sludge, respectively after the sludge was conditioned by 1.20 mM/g VSS Fe2+ and 1.20 mM/g VSS PAA. The dewatering performance, physicochemical properties, aggregation behaviors, and EPS fractions of sludge were compared before and after Fe2+/PAA and Fe2+/H2O2. conditionings. The results showed that Fe2+/PAA treatment was more competitive in enhancing dewaterability under neutral and alkaline conditions than Fe2+/H2O2 treatment but slightly weaker under acid conditions. Besides, it was found that the oxidation and re-flocculation behaviors were different in those two enhanced dewatering technologies due to the difference in the generated ROS. R-O center dot was the primary radical in the Fe2+/PAA system, while center dot OH was the major one in the Fe2+/H2O2 system. The mechanism analysis found that the Fe2+/PAA process caused harsher disintegration of sludge flocs, meaning more generation of fine particles. However, it exhibited less effect on reducing the energy barrier between sludge particles. Therefore, the Fe2+/PAA treated sludge presented weaker aggregation behaviors. The weaker aggregation was unfavorable for sludge dewatering because the weaker aggregated flocs were more easily fragmented, which hampered the consolidation of sludge cakes and removal of bound water. Moreover, loosely-bound extracellular polymeric substances, particularly tightly-bound extracellular polymeric substances, governed the sludge dewaterability.
Keywords:
Fe2+/PAA pre-treatment
Sludge dewaterability
Radical oxidation and re-flocculation behaviors
Extracellular polymeric substances
Journal
IF:
8
Papers:
7.1W
Citations:
46.4W