Rochester, Minnesota
 The
City of Rochester Wastewater Reclamation Plant (WWRP)
serves the residential, commercial and industrial
residents of the City of Rochester, Minnesota. The
city has a population of approximately 100,000
people, and the plant has the capacity of processing
approximately 24 million gallons per day (MGD) of
sewage and wastewater. The incoming waste stream
(influent) is pumped to a higher elevation with the
plant’s preliminary, primary, secondary, and
advanced treatment processes fed by gravity flow.
The solids handling system utilizes anaerobic
digestion which produces the treated solids that are
trucked from the facility as well as the biogas that
is stored and utilized on-site as fuel for both
heating and electrical generation. The processed
water goes through a final chlorination stage and is
then pumped to a local river.
 This
facility was an early adopter of CHP technologies
installing its first system in 1982. In 2002, a two
phase project was initiated to upgrade the existing
CHP system, and in 2008, the project was completed
when the second original engine was replaced with a
second new 1,000 kW dual fueled engine generator
with heat recovery. The installed capacity of 2,000
kW is more than sufficient to handle the amount of
biogas generated by the digesters today. All the
electricity generated by the CHP system is utilized
onsite to off-set the base load electrical
requirements of the facility. This application is an
excellent example of the flexibility for CHP to
satisfy numerous energy needs: the system provides
adequate facility emergency power; it uses all
treatment process biogas to heat digesters during
extreme temperature conditions; and it maintains a
dual-fuel capability for plant operations.
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