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This paper identifies the technologies considered by the City of Bloomington (Indiana) Utilities (CBU) for residuals processing, and presents CBU's approach to residuals management using an innovative process based on proven technologies. CBU has used lagoons and drying beds to dewater and dispose of the sedimentation basin residuals and has returned backwash water to the head of the process at the Monroe Water Treatment Plant for many years. In 1998, after inadvertently discharging solids to Lake Monroe, CBU signed an Agreed Order with the Indiana Department of Environmental Management to implement a residuals management program. After careful consideration, CBU decided to use a pressure filter press with drying, in a single process. This approach to residuals management resulted in lower labor costs as compared to other dewatering technologies and the ability to use the dried solids as cover material at the local landfill instead of waste material. Although this process has been used in wastewater and industrial applications on similar type residuals, this is the first application for water treatment plant residuals. Bench-scale testing indicated that CBU could achieve up to 92 percent solids on their alum residuals. The project goals were to consistently achieve a minimum of 50 percent solids.

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Edition: Vol. - No. Published: 06/16/2002File Size: 1 file , 920 KB