Fe^(2+)联合NaClO强化污泥脱水性能与作用机理

Performance and Mechanisms of Fe^(2+) Combined with NaClO for Enhanced Sludge Dewatering

为了强化污泥脱水性能,采用亚铁离子(Fe^(2+))活化次氯酸钠(NaClO)氧化工艺改善其脱水效果,考察了Fe^(2+)/NaClO体系中Fe^(2+)和NaClO投加量、初始pH对污泥脱水性能的影响,并探究强化污泥深度脱水的作用机制。研究表明,初始pH为5.0、Fe^(2+)和NaClO投加量(以总悬浮固体计)分别为48.61和39.04 mg·g^(-1)时,污泥的脱水性能最佳,污泥含水率和比阻分别由91.32%和11.81×10^(12)m·kg^(-1)降低至71.74%和1.71×10^(12)m·kg^(-1)。Fe^(2+)/NaClO氧化体系使胞外聚合物(EPS)降解和部分细胞裂解,反应生成的强氧化性的·OH会降解松散附着型EPS (LBEPS)和紧密黏附型EPS (TB-EPS)中的蛋白质和多糖,改变蛋白质二级结构,导致蛋白质结构松散,暴露了更多的疏水位点,同时减少污泥表面的亲水性官能团,释放EPS结合水。Fe^(3+)使污泥絮体颗粒在絮凝形成松散、多孔的絮体结构,有利于胞内结合水的排出,从而改善污泥脱水性能。本研究结果可为有效去除污泥中的结合水和提高污泥的脱水性能提供参考。

The application of ferrous iron(Fe^(2+))-activated sodium hypochlorite(NaClO) could improve the waste-activated sludge dewatering. The impacts of Fe^(2+)dosages, NaClO dosages, and initial pH values on sludge dewatering performance were explored. In addition, the mechanisms of enhancing deep sludge dewatering were investigated. The results indicated that the water content and specific resistance to filtration of sludge decreased from 91.32% and 11.81×10^(12)m·kg^(-1)to 71.74% and 1.71×10^(12)m·kg^(-1), respectively, when Fe^(2+)dosage, NaClO dosage, and initial pH were fixed at, 48.61 mg·g^(-1), 39.04 mg·g^(-1)and 5.0. The oxidation of Fe^(2+)/NaClO system resulted in the destruction of extracellular polymeric substances(EPS) and partial cell lysis. Meanwhile, the strongly oxidizing ·OH degraded the proteins and polysaccharides in TB-EPS/LB-EPS, and altered protein secondary structure, resulting in loosening of protein structure and exposure of additional hydrophobic sites. In addition, this process lowered hydrophilic functional groups on the sludge surface and released EPS-bound water. Simultaneously, Fe^(3+)induced the sludge floc particles to form a loose and porous structure, which aided in the outflow of intracellularly bound water, thus enhancing the dewatering performance of the sludge. This result has developed a novel and cost-effective method for rapidly removing bound water from sludge and enhancing sludge dewatering performance.