Startup of a Thermophilic Digester in 30 Days

The City of St. Joseph, MO started up a 2.0 Mgal thermophilic digester in the spring of 2007. The thermophilic digester was constructed to operate as the lead digester of a temperature phased anaerobic digestion system (TPAD) and is followed by four 1 Mgal mesophilic digesters.A TPAD system is an advanced digestion process consisting of a first stage thermophilic digestion process (55 degrees centigrade) followed by second stage mesophilic digestion (35 degrees centigrade). The process has been shown to improve volatile solids destruction, digester gas production, product odors, and pathogen destruction.This paper will discuss the planning of the thermophilic digestion startup and present actual data from the startup. Issues covered in this paper include digester seeding, initial tank heating, and the introduction of raw sludge. Data available from the startup will demonstrate how the process behaved and acclimated during startup. Data will also be presented to illustrate the solutions that the plant and engineers implemented to ensure a successful startup.