Wang Shiqin, Chen Hongbo
College of Environment and Resources, Xiangtan University, Xiangtan 411105, China.
College of Environment and Resources, Xiangtan University, Xiangtan 411105, China.
Sci Total Environ. 2023 Dec 10;903:166958. doi: 10.1016/j.scitotenv.2023.166958. Epub 2023 Sep 9.
Lignin-based flocculants are widely used for wastewater purification, but their application in sludge dewatering has not yet been documented. In this study, a novel cationic lignin-based flocculant named LS-g-CPA was prepared by grafting cationic polyacrylamide (CPA) synthesized from methacryloyloxy ethyltrimethyl ammonium chloride (DMC) and acrylamide (AM) onto sodium lignosulfonate (LS), and its roles and underlying mechanisms in sludge conditioning were investigated. The results showed that LS-g-CPA effectively improved the dewaterability of sludge, reducing the filtration resistance and filter cake moisture content of sludge from 0.61 ± 0.05 × 10 m/kg to 0.14 ± 0.02 × 10 m/kg and 85.64 ± 0.25 % to 76.84 ± 0.41 %, respectively. The dewatering performance of LS-g-CPA was positively correlated with the DMC/AM ratio. The quaternary ammonium groups brought by DMC disrupted the reticular structure of extracellular polymeric substances, exposing hydrophobic residues and releasing bound water. Nevertheless, the key to LS-g-CPA for improving sludge dewatering lies more in the amphoteric flocculant properties that enhance sludge flocculation and the octopus-type structure that provides good drainage channels. This study reveals that lignin-based flocculants are effective in improving the dewaterability of sludge, which provides direct evidence for their application in sludge dewatering.
木质素基絮凝剂广泛应用于废水净化，但尚未见其在污泥脱水方面的应用报道。本研究通过将由甲基丙烯酰氧乙基三甲基氯化铵（DMC）和丙烯酰胺（AM）合成的阳离子聚丙烯酰胺（CPA）接枝到木质素磺酸钠（LS）上，制备了一种新型阳离子木质素基絮凝剂LS-g-CPA，并研究了其在污泥调理中的作用及潜在机制。结果表明，LS-g-CPA有效提高了污泥的脱水性能，使污泥的过滤阻力和滤饼含水率分别从0.61±0.05×10 m/kg降至0.14±0.02×10 m/kg，从85.64±0.25%降至76.84±0.41%。LS-g-CPA的脱水性能与DMC/AM比值呈正相关。DMC带来的季铵基团破坏了胞外聚合物的网状结构，暴露出疏水残基并释放出结合水。然而，LS-g-CPA改善污泥脱水的关键更多在于增强污泥絮凝的两性絮凝剂性质以及提供良好排水通道的章鱼型结构。本研究表明木质素基絮凝剂在提高污泥脱水性能方面是有效的，为其在污泥脱水中的应用提供了直接证据。
