Fe2+-PDS调理-水平电场脱水工艺对疏浚底泥脱水性能的影响

针对高含水率疏浚底泥限制其后续处置的问题，应用Fe²⁺-过二硫酸盐（PDS）调理-水平电场脱水（HED）工艺处理底泥样品，研究响应曲面法对Fe²⁺-PDS调理-HED工艺操作参数（Fe²⁺及PDS的投加量、电压、通电时间）的优化，分析调理过程底泥形貌及性质的变化以及工艺各阶段（调理、重力沉降、电脱水）底泥水分及有机组分的沿程变化。结果表明：1）Fe²⁺和PDS调理底泥时，最佳投加量分别为4和10 mg/g（以TSS计），HED阶段最佳通电时间为80 min，最佳电压为45 V，在上述参数下，脱水底泥含水率由原泥的88.55%降至55.15%。2）在调理阶段，底泥结合水含量由0.44 g/g（以干固体计，全文同）降至0.28 g/g，胞外聚合物（EPS）中蛋白质和多糖总量增加，黏液层（Slime）中蛋白质类物质和可溶性微生物副产物荧光强度降低，紧密附着层（TB-EPS）中总荧光强度增至12.40×10⁷ AU·nm²；在HED阶段，电场作用导致底泥有机物的进一步释放从阴极流出，阴极区EPS各层中的可溶性微生物副产物荧光强度显著增加。3）调理过程产生的硫酸根自由基（SO₄ ⁻·）能够氧化破解底泥中的微生物细胞并将内含物释放至EPS中，同时改变底泥的水分分布与EPS组分特征，原位产生的Fe（Ⅲ）通过絮凝作用改变了底泥的絮体结构，从而有利于底泥脱水性能的提升。

Effect of Fe2+-PDS conditioning-horizontal electro-dewatering process on dewatering performance of dredged sediment

Aiming at the problem of restricting the subsequent disposal of dredged sediment with high water content, Fe2+-perdisulfate (PDS) conditioning - horizontal electro-dewatering (HED) process was used to treat sediment samples. The operating parameters (Fe2+ and PDS dosage, voltage, power-on time) of Fe2+-PDS conditioning - HED process were optimized through the response surface method (RSM), and the variations in the morphology and properties of the sediment at the conditioning stage, as well as the changes in the water content and organic components of the sediment at various stages of the process (conditioning, gravity settling, HED) were analyzed. The results showed as follows: 1) The optimal dosage of Fe2+ and PDS for the conditioning stage was 4 mg/g (TSS) and 10 mg/g (TSS), respectively. The optimal power-on time and voltage of the HED stage were 80 min and 45 V, respectively. Under the above parameters, the water content of dredged sediment decreased from 88.55% to 55.15%. 2) At the conditioning stage, the bound water content of sediment decreased from 0.44 g/g (DS) to 0.28 g/g, the total amounts of proteins and polysaccharides in extracellular polymeric substances (EPS) increased, while the fluorescence intensity of protein-like substances and soluble microbial byproduct-like materials (SMBP) in Slime layer decreased. The total fluorescence intensity in the tightly bound EPS (TB-EPS) increased to 12.40×107 AU·nm2. At the HED stage, the effect of electric field led to further release of the organic matters in the sediment around the cathode region, and the fluorescence intensity of SMBP in each layer of EPS around the cathode region increased significantly. 3) SO4 −· produced at the conditioning stage could oxidize and crack the microbial cells in the sediment and release the intracellular contents into EPS, and the simultaneous changes in water distribution and EPS components of the sediment occurred. Fe(Ⅲ) produced in situ altered the floc structure of the sediment through coagulation, thus contributing to the improvement of the dewatering performance of the sediment. The research showed that Fe2+-PDS conditioning-HED process could effectively reduce the water content of the dredged sediment, so as to provide technical support for the treatment of dredged sediment.