Maximize Polymer Value for Improved Sludge Treatment Dr. Yong Kim
Dr. Yong Kim is the Technical Director for UGSI Solutions, Vineland NJ. His research/technical interest includes fluid mixing in turbulence, solid-liquid separation oxidation and reduction and water disinfection. As a PhD Chemical Engineer from Kansas State University, he has authored a book called “Coagulants and Flocculants: Theory and Practice” and published over 30 technical papers. During 28 years’ professional career in the water industry, five US patents have been issued to his credit.
Operating an efficient polymer mixing system has become more important than ever because the cost of polymer is frequently the third largest operating expense at many wastewater treatment plants. This presentation illustrates how to maximize the value of polymer by utilizing the knowledge of fluid dynamics and polymer chemistry. It includes an extensive review of papers on the relevant subject. Results of various laboratory testing are followed regarding the effect of dilution water chemistry and different mixing technologies on the effectiveness of polymer solution.
Unlike other chemicals used in water and wastewater industries, polymer has a unique long-chain molecular structure which requires a very different approach in designing mixing equipment. While higher molecular weight is required to achieve more efficient flocculation, it also presents technical challenges in the preparation of polymer solutions. The benefit of utilizing two-stage mixing, very high initial mixing energy followed by low and uniform mixing energy, is demonstrated by theoretical considerations as well as experimental data (G-values, polymer solution viscosity, etc.). Since it is becoming a common practice to use treated effluent from the wastewater plants for polymer mixing, the effect of residual chlorine in polymer mixing is also discussed.
Field evaluation at a wastewater treatment plant (Fairfield, CA) showed that a well-designed polymer mixing system can improve the performance of screw press and gravity belt thickener. It was also observed that the polymer consumption was reduced by 22% and 31% for dewatering and thickening processes, respectively.