Application of zero-valent iron/sulfite system for aerobically digested sludge conditioning

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 420; p. 127650
• Main Authors: Liu, Changgeng, Chen, Dandan, Chen, Xiao'e, Wu, Bin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2021
• Subjects: Advanced oxidation; Aerobically digested sludge; Dewatering performance; Sulfate radical; Sulfite; Zero-valent iron; Sulfite; Sulfate radical; Dewatering performance; Aerobically digested sludge; Advanced oxidation; Zero-valent iron
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.127650

[Display omitted] •ZVI/sulfite was favorable to improve AeDS dewaterability.•Dosages of ZVI and sulfite, reaction time, and pH in ZVI/sulfite were optimized.•S-AOP was the determinant process for the improvement of AeDS dewaterability.•TB-EPS degradation and release of EPS bound water led to improve dewaterability.•Reuse of recovered ZVI for improving AeDS dewaterability was satisfactory. Aerobic digestion is widely used to stabilize and reduce waste activated sludge in the decentralized wastewater treatment plants, but it would deteriorate sludge dewaterability. Thus, improving the dewaterability of aerobically digested sludge (AeDS) is of vital significance for sludge disposal and management. This study investigated the possibility of zero-valent iron (ZVI)/sulfite system for promoting the dewaterability enhancement of AeDS. The results showed that ZVI/sulfite system was favorable to improve the dewaterability of AeDS. The highest reduction of capillary suction time and the lowest value of water content of sludge cake were (81.7 ± 3.6)% and (69.3 ± 1.2)%, respectively, under the optimal experimental conditions (reaction time = 60 min, ZVI = 0.9 mmol/g volatile solids (VS), sulfite = 1.2 mmol/g VS, pH = 6, and purging air). Compared to Fe2+/sulfite and Fe3+/sulfite systems, ZVI/sulfite system was more favorable to improve the dewatering performance of AeDS. The results also demonstrated that the main radical species in ZVI/sulfite system were sulfate radical and hydroxyl radical, which could effectively degrade tightly-bound extracellular polymeric substances and then led to the release of bound water and the increase of zeta potential. Consequently, the dewatering performance of AeDS was obviously enhanced. Additionally, the reusability of recovered ZVI in ZVI/sulfite system for AeDS conditioning was satisfactory.