Key Laboratory of Urban Stormwater System and Water Environment, Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing 100044, China.
Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
J Environ Sci (China). 2023 Mar;125:223-233. doi: 10.1016/j.jes.2021.11.022. Epub 2022 Feb 11.
Citrate (Ct) was chosen as a typical chelator used in the Fe-peroxydisulfate (PDS) process to improve sludge dewaterability. The PDS-Fe-Ct process exhibited better performance in sludge dewatering than PDS-Fe. Specifically, with a PDS dosage of 1.2 mmol/g VS, the molar ratio of PDS/Fe and Ct/Fe were 4:5 and 1:4, respectively, the capillary suction time decreased from 155.8 to 24.8sec, and the sludge cake water content decreased from 82.62% to 64.11% (-0.06MPa). The oxidation led to a reduced negative charge and a decrease in particle size. The enhanced sludge dewaterability and changes of sludge properties were attributed to the decomposition of extracellular polymeric substances, and it was explored by protein, polysaccharide, 3D-EEMs, and FT-IR. Additionally, the quenching experiments of radical species demonstrated that SO• played a more important role than •OH, and its productivity was improved with the addition of Ct. Moreover, the reasons for the improved productivity of radicals with the addition of Ct were discussed. The results of this study could serve as a basis for improving sludge dewatering using the PDS-Fe-Ct process and suggest that the addition of Ct may improve the productivity of SO• in the activation of PDS via Fe.
柠檬酸（Ct）被选为过一硫酸氢盐（PDS）-铁体系中改善污泥脱水性能的典型螯合剂。PDS-Fe-Ct 工艺在污泥脱水方面的性能优于 PDS-Fe。具体而言，当 PDS 用量为 1.2mmol/gVS，PDS/Fe 和 Ct/Fe 的摩尔比分别为 4:5 和 1:4 时，毛细吸水时间从 155.8s 降至 24.8s，污泥饼含水率从 82.62%降至 64.11%（-0.06MPa）。氧化作用导致带负电荷减少和粒径减小。污泥脱水性能的提高和污泥性质的变化归因于细胞外聚合物的分解，并通过蛋白质、多糖、三维荧光光谱和傅里叶变换红外光谱进行了探讨。此外，自由基淬灭实验表明，SO•比•OH 更重要，而 Ct 的加入提高了其生成率。此外，还讨论了 Ct 存在时提高自由基生成率的原因。本研究结果可为利用 PDS-Fe-Ct 工艺改善污泥脱水提供依据，并表明 Ct 的加入可能通过 Fe 促进 PDS 中 SO•的生成。
