Ormeci Banu
Department of Civil and Environmental Engineering, Carleton University, 1125 Colonel By Drive, Ottawa ON, Canada K1S 5B6.
Water Res. 2007 Mar;41(6):1243-52. doi: 10.1016/j.watres.2006.12.043. Epub 2007 Feb 15.
Rheology is the science that deals with the flow and deformation of materials, and it has become an important tool in optimizing sludge dewatering. This study presents torque rheology data to illustrate two different methods for polymer optimization. The methods can be used to optimize the polymer dose and mixing intensity, as well as to select the best performing product among a number of candidate polymers. The first method is used for unconditioned sludges, and utilizes the peaks observed after the polymer injection. The second method is used for conditioned sludges and utilizes the entire torque-time rheograms. Both methods were tested at the lab- and full-scale at the Plum Island Water Reclamation Facility (Charleston, SC) using three different polymers. The methods were able to optimize the polymer dose and full-scale mixing, and reduce the polymer consumption by 50% at the treatment plant. This translates into major savings for the utility. Furthermore, the results indicate that the total shear intensity imparted to sludge during full-scale conditioning can be determined using torque rheology, and the jar-tester shear can be matched to the total shear based on the rheological characteristics of sludge. This information is essential to be able to simulate the full-scale mixing using a jar-tester and to precisely determine the optimum polymer dose. The results of this study indicate that well-defined rheological properties of sludge provide a reliable tool for the optimization of conditioning and dewatering operations at wastewater treatment plants.
流变学是一门研究材料流动和变形的科学，它已成为优化污泥脱水的重要工具。本研究展示了扭矩流变学数据，以说明聚合物优化的两种不同方法。这些方法可用于优化聚合物剂量和混合强度，以及在多种候选聚合物中选择性能最佳的产品。第一种方法用于未经处理的污泥，利用注入聚合物后观察到的峰值。第二种方法用于经过处理的污泥，利用整个扭矩-时间流变图。这两种方法均在李子岛水回收设施（南卡罗来纳州查尔斯顿）的实验室规模和全规模条件下，使用三种不同的聚合物进行了测试。这些方法能够优化聚合物剂量和全规模混合，并使处理厂的聚合物消耗量降低50%。这为公用事业带来了重大节省。此外，结果表明，使用扭矩流变学可以确定全规模处理过程中施加给污泥的总剪切强度，并且基于污泥的流变特性，烧杯试验剪切可以与总剪切相匹配。这些信息对于能够使用烧杯试验模拟全规模混合并精确确定最佳聚合物剂量至关重要。本研究结果表明，明确的污泥流变特性为优化污水处理厂的处理和脱水操作提供了可靠的工具。
