School of Environmental Science and Engineering, Tianjin University, Tianjin, 300354, China.
School of Environmental and Safety Engineering, Taiyuan Institute of Technology, Taiyuan, 030008, China.
Environ Res. 2020 Nov;190:110011. doi: 10.1016/j.envres.2020.110011. Epub 2020 Aug 5.
Since the effect of electro-dewatering (EDW) on sludge water holding capacity was unknown, tests were conducted in this study to investigate the water holding capacity of EDW sludge and the potential mechanism related to the sludge physicochemical characteristics, EPS properties and sludge structure. Sludge was dewatered to the average moisture content (AMC) of 80%, 70% and 60% with different applied voltages at 20, 30 and 40V in EDW, respectively. Then the dewatered sludge near the anode and cathode were rewatered. The variation of sludge water holding capacity in EDW process was evaluated in terms of filterability and saturated moisture content (SMC), and the filterability was assessed by the specific resistance to filtration (SRF) of rewatered sludge. The results indicated that SRF of rewatered sludge near the cathode increased greatly. The proteins/polysaccharides (PN/PS) of loosely bound extracellular polymeric substances (LB-EPS) was significantly positively correlated with SRF (r = 0.891, p < 0.01). Moreover, the exposure of hydrophobic sites or groups in PN near the cathode improved the surface hydrophobicity of sludge, which reduced the filterability. In addition, higher voltage could destroy the sludge structure near the anode at the later stage of EDW process, leading to the decrease of SRF and SMC. These results expanded the knowledge about changes in sludge properties and water holding capacity during EDW process.
由于电脱水（EDW）对污泥持水能力的影响尚不清楚，本研究进行了测试，以研究 EDW 污泥的持水能力以及与污泥物理化学特性、EPS 特性和污泥结构相关的潜在机制。在 EDW 中，分别以 20V、30V 和 40V 的不同外加电压将污泥脱水至平均水分含量（AMC）为 80%、70%和 60%，然后将靠近阳极和阴极的脱水污泥重新加水。通过重新水合污泥的比阻力过滤（SRF）评估 EDW 过程中污泥持水能力的变化，以过滤性和饱和水分含量（SMC）为指标评估过滤性。结果表明，靠近阴极的再水合污泥的 SRF 大大增加。松散结合胞外聚合物物质（LB-EPS）的蛋白质/多糖（PN/PS）与 SRF 呈显著正相关（r=0.891，p<0.01）。此外，阴极附近 PN 中疏水性位点或基团的暴露提高了污泥的表面疏水性，从而降低了过滤性。此外，较高的电压可能会在 EDW 过程的后期破坏靠近阳极的污泥结构，导致 SRF 和 SMC 降低。这些结果扩展了关于 EDW 过程中污泥特性和持水能力变化的知识。
