School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China.
School of Environmental and Safety Engineering, Taiyuan Institute of Technology, Taiyuan, 030008, China.
Chemosphere. 2022 Apr;292:133416. doi: 10.1016/j.chemosphere.2021.133416. Epub 2021 Dec 22.
The high moisture content (MC) of activated sludge dewatered by traditional vertical electro-dewatering (VED) is unable to meet the disposal requirements. Therefore, different iron forms (ZVI vs. Fe(II))/peroxydisulfate (PDS) combined VED (ZVI/PDS-VED and Fe(II)/PDS-VED) were employed to enhance the dewaterability of activated sludge. The dewatering behaviors of the two combined dewatering processes and the underlying mechanism related to the sludge characteristics were investigated and compared. Sludge was conditioned using ZVI/PDS and Fe(II)/PDS, respectively, and then dewatered by the VED in the experiment. Experimental results showed that with 0.3 g (g dry solids (DS)) of iron activators, 0.583 g (g DS) of PDS, and 30 V of voltage, the MC of sludge after ZVI/PDS-VED and Fe(II)/PDS-VED reached the minimum values of 50.6 ± 1.2% and 32.1 ± 1.5%, respectively. ZVI/PDS and Fe(II)/PDS conditioning reduced the MC difference of sludge between the anode and the cathode during the VED, facilitating the water homogenization in the sludge cake. ZVI/PDS-VED and Fe(II)/PDS-VED could effectively reduce the bound water and the free water. Free water had high correlations with α-helix (r = 0.999, p < 0.05) and CO (r = 0.998, p < 0.05). Compared with the traditional VED and the ZVI/PDS-VED, the Fe(II)/PDS-VED had a greater improvement of sludge dewaterability due to the more efficient degradation of extracellular polymeric substances and the increase of sludge surface hydrophobicity. This study promoted the development of the new sludge deep-dewatering technology.
传统垂直电脱水（VED）处理的活性污泥水分含量（MC）高，无法满足处置要求。因此，采用不同的铁形态（零价铁（ZVI）与二价铁（Fe(II)））/过一硫酸盐（PDS）组合 VED（ZVI/PDS-VED 和 Fe(II)/PDS-VED）来增强活性污泥的脱水性能。研究并比较了两种组合脱水工艺的脱水行为及其与污泥特性相关的潜在机理。分别用 ZVI/PDS 和 Fe(II)/PDS 调理污泥，然后在实验中用 VED 进行脱水。实验结果表明，在 0.3 g（干固体（DS））铁激活剂、0.583 g（g DS）过一硫酸盐和 30 V 电压条件下，ZVI/PDS-VED 和 Fe(II)/PDS-VED 后污泥的 MC 分别达到 50.6 ± 1.2%和 32.1 ± 1.5%的最小值。ZVI/PDS 和 Fe(II)/PDS 调理降低了 VED 过程中污泥在阳极和阴极之间的 MC 差异，有利于污泥饼中水分的均匀化。ZVI/PDS-VED 和 Fe(II)/PDS-VED 可有效降低束缚水和自由水。自由水与α-螺旋（r = 0.999，p < 0.05）和 CO（r = 0.998，p < 0.05）高度相关。与传统 VED 和 ZVI/PDS-VED 相比，由于细胞外聚合物的更有效降解和污泥表面疏水性的增加，Fe(II)/PDS-VED 对污泥脱水性能的改善更大。本研究促进了新型污泥深度脱水技术的发展。
