Chalcopyrite-activated sodium percarbonate oxidation for sludge dewaterability enhancement: Synergetic roles of •OH and 1O2

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-06, Vol.465, p.142863, Article 142863
• Main Authors: Liang, Jialin, Tan, Zexing, Zhang, Lei, Li, Chengjian, Mo, Zhihua, Ye, Maoyou, Ai, Jing, Huang, Shaosong, Sun, Shuiyu, Liu, Hui
• Format: Article
• Language: English
• Subjects: Natural sulfide mineral; Non-radical 1O2; Sewage sludge dewaterability; SPC-AOPs; Water-holding interfacial affinity reduction
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.142863

[Display omitted] •Sulfur in chalcopyrite facilitated Fe2+/Cu+ regeneration in sludge dewatering.••OH and 1O2 oxidation dominated the enhanced sludge dewaterability.•Natural chalcopyrite + SPC was effective in sludge separation and purification.•The destructed water-holding components promoted sludge-water separation. Efficient dewatering of sewage sludge is an energy- and carbon-saving procedure of sludge treatment in wastewater treatment facilities. Due to the limiting factors of hydrophilic extracellular polymeric substances, it is crucial to weaken the water-holding capacity and hydrophilicity for high-performance sludge-water separation. The current study successfully put forward a combination process of chalcopyrite + sodium percarbonate (SPC) to proficiently facilitate sludge dewaterability. Results showed that after the optimized treatment, the water removal efficiency augmented from 51.3 to 94.9%, while the water content of sludge cake declined from 90.1 to 52.0 wt%. Mechanism investigation demonstrated that the chalcopyrite + SPC system could consecutively generate reactive oxygen species via strong Fe3+/Fe2+ and Cu2+/Cu+ conversion cycles. The dominant reactive radical •OH and non-radical 1O2 could effectively degrade the macromolecular EPS into low-molecular biopolymers, decrease the high-polarity hydrophilic protein secondary structure and amino acids, and further reduce water-holding interfacial affinity. Afterward, the electrostatic force and interfacial free energy were decreased and turned out to enhance self-flocculation and flowability. Accordingly, bound water reduction and sludge-water separation efficiency were promoted. Furthermore, the chalcopyrite + SPC system could be viewed as a surrogate to Fenton/Fenton-like strategies for sludge dewaterability with economic advantage and low environmental risk. These findings inspire the application prospect of the chalcopyrite + SPC conditioning technique, which expects to save energy and reduce carbon emissions.