Towards More Reliable Dewatering Performance by Optimizing Polymer Dose Decision-making

Blue Plains Advanced wastewater treatment plant (AWWTP) was the first utility in the USA to install Cambi thermal hydrolysis process (THP) together with anaerobic digester (AD) to reduce solids production, increase energy resource recovery and produce class A biosolids. The new facilities were commissioned at the Blue Plains Advanced Wastewater Treatment Plant (AWTP) in 2015. The technology choice provided a major benefit on dewatering process by improving the cake TS, which has a large economic impact on treatment operations by decreasing the hauling costs, and by improving the quality of the "Bloom” biosolids product that is regionally marketed (Li, 2021). Dynamic changes in operational condition of the THP and AD process, sludge characteristics, and seasonal impacts (Li, 2021) result in high variety of cake TS (%) from 24 to 38% TS and filtrate TSS from 50 to 1530 mg TSS/L at the final dewatering belt filter presses. Poor cake TS causes higher hauling costs, while unreliable filtrate TSS significantly impacts the filtrate treatment facility. In addition, the polymer cost also may increase year by year depending on the market price, so picking the right optimal polymer dose range can optimize operational cost. In practice, the polymer dose is set manually by the operator and requires constant attention to minimize polymer dose while maintaining good operational throughput. Polymer dose decision making is thus mainly driven by human factors. Therefore, this study focused on investigating if the polymer dosing decision made by operators is adequate or if there is room to improve dewatering performance, which helps to define research development needs for helping optimizing polymer costs at the plant.