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Secondary digester mixing and heating project

This project increases the digestion process capacity using the existing digestion tanks by converting the existing unheated and unmixed secondary digesters to mixed mesophilic digesters (i.e., digesters operating at a mesophilic temperature of 98 deg. F).  This will double the mesophilic Solids Retention Time (SRT) at the plant and bring the plant into compliance with the SRT and Volatile Solids (VS) loading requirements of State and Federal regulations.

The Secondary Digester Mixing and Heating project consists of installing four new internal draft tube mixers with integral heat exchangers in each of the two secondary digesters, new pumping and piping systems to connect the heat exchangers to the plant heat reservoir supply system, and recoating and insulating the existing steel floating digester covers.

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