Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada.
Department of Chemical Engineering, Lakehead University, Thunder Bay, Ontario, Canada.
J Environ Manage. 2023 Jan 1;325(Pt B):116509. doi: 10.1016/j.jenvman.2022.116509. Epub 2022 Oct 27.
In the wastewater treatment plant of pulp and paper mills, biosludge dewatering is needed to reduce the sludge handling and disposal costs. It is usually facilitated by means of the addition of synthetic polymers. There is increasing interest in replacing synthetic polymers with biopolymers derived from low value by-products or industrial residuals to improve the environmental footprint of dewatering. In this study, lignin-based flocculants (LBF) were tested for their ability to improve the biosludge dewaterability based on Capillary Suction Time (CST) and dry cake solids achieved with a Crown Press. The results demonstrate that LBFs alone can significantly enhance dewatering with a decrease in CSTs from 72.7 ± 5.1 s (unconditioned biosludge) to 23.3 ± 0.4 s and an increase in dry cake solids after pressing from 7.1 ± 0.5% to 13.9 ± 1.3% with a relatively high dosage of 7.5% w/w. However, with dual conditioning a LBF and 0.1% w/w anionic polyacrylamide (APAM), the required dosage of LBF was reduced to 3% w/w to achieve a dry cake solids content of 13.8 ± 0.4%, the same as that achieved with Zetag8165, a commercial synthetic polymer. LBF addition lowered the particle surface charge, allowing the particles to agglomerate and enhancing for the biosludge dewaterability. The application of LBFs for sludge dewatering offers novel considerable promise for providing more sustainable approaches by optimizing the use of lignin from different extraction processes, applying various types of lignin modifications in combination with anionic polymers, and exploring different methods of disposal or utilization of the dewatered sludge.
在制浆造纸厂的废水处理厂中，需要对生物污泥进行脱水处理，以降低污泥处理和处置成本。这通常通过添加合成聚合物来实现。人们越来越感兴趣的是用来源于低值副产物或工业废料的生物聚合物代替合成聚合物，以改善脱水的环境足迹。在这项研究中，测试了基于木质素的絮凝剂 (LBF) 改善生物污泥脱水性能的能力，方法是根据毛细抽吸时间 (CST) 和 Crown Press 获得的干饼固体来衡量。结果表明，单独使用 LBF 就可以显著增强脱水性能，使 CST 从 72.7 ± 5.1 s（未经处理的生物污泥）降低到 23.3 ± 0.4 s，并且在压滤后干饼固体的增加从 7.1 ± 0.5%增加到 13.9 ± 1.3%，用量相对较高为 7.5% w/w。然而，通过双重调理（LBF 和 0.1% w/w 阴离子聚丙烯酰胺（APAM）），LBF 的用量减少到 3% w/w，即可达到 13.8 ± 0.4%的干饼固体含量，与商业合成聚合物 Zetag8165 相同。LBF 的添加降低了颗粒表面电荷，使颗粒聚集并增强生物污泥的脱水性能。LBF 用于污泥脱水的应用为提供更可持续的方法提供了很大的希望，方法是优化不同提取工艺中木质素的利用，将各种类型的木质素改性与阴离子聚合物结合使用，并探索脱水污泥的不同处理或利用方法。
