Optimization of sludge conditioning and dewatering using sludge network strength and residual polymer concentration

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Dewatering plays a key role in reducing the cost of sludge treatment and final disposal. However, optimization of sludge conditioning and dewatering continues to be a challenge due to continuous changes in sludge characteristics and solids concentration during operation. Ideally, polymer dose should be checked and optimized on a real-time basis but the majority of treatment plants still use operators to manually adjust the polymer dose by checking cake solids. This usually leads to overdosing of polymer typically by 30-40%, which not only increases polymer cost but also decreases cake dryness, and thus disposal costs. In addition, excess polymers discharged to environment have toxic effects on aquatic ecosystems. Therefore, there is a major need for reliable systems that can achieve real-time optimization of polymer dose at wastewater treatment plants. Current technologies typically rely on solids concentration of incoming sludge or turbidity of the effluent, which are not ideal in capturing important sludge characteristics and predicting dewatering performance. An innovative approach to conditioning and dewatering optimization is needed.This proposal presents a completely new and novel approach to dewatering optimization through in-line and real-time monitoring of network strength and residual polymer concentration. Network strength is a holistic parameter that captures the changes in the physical, chemical, and flow characteristics of sludge and is superior to monitoring individual parameters such as sludge solids concentration which current systems rely on. Measurement of residual polymer is a direct way of optimizing the polymer dose based on excess polymer remaining in sludge. The short-term goal of the research is to complete the fundamental research tasks required for the development of a dewatering optimization system that uses network strength for feed-forward control and residual polymer concentration for feed-back control to achieve dewatering optimization. The long-term goal of the research program is to complete the development of a fully integrated dewatering automation system. The research program is expected to lead to important savings for treatment plants, reduce the cost of sludge dewatering and final disposal, decrease the carbon footprint of treatment, and minimize the adverse impact of discharged polymers on aquatic ecosystems. The research will help to train highly qualified personnel in sludge treatment and optimization and automation of treatment systems, which are all high-demand areas. The research has a strong potential to generate new products and systems, and will benefit the Canadian economy.