The Metro Plant treats up to 65% of the wastewater generated in the Twin Cities region and is MCES's largest wastewater treatment plant. The Metro
Plant was constructed in 1938 and has incinerated solids for 80 years with an exceptional track record of environmental compliance. The existing
incinerator system, with three fluidized-bed incinerators, has been operational since 2005.
The fourth incinerator will be designed with state-of-the-art air pollution control equipment that removes 99% of particulates, heavy metals, and other air pollutants. This graph compares emission data from the Metro Plant incinerators, represented as percentage of the corresponding federal standard for new incinerators.
Incineration technology at the Metro Plant has been a key factor in reducing odors from the Metro Plant. The graphic below demonstrates that incineration burns wastewater solids at 1,375 deg F which eliminates odor and disease causing bacteria.
The incineration energy recovery system recovers enough energy to power 800 homes. The energy recovered is used in the plant and saves ratepayers $1.8 million per year. The graphic below is a animation of the steam turbine generator at the Metro Plant.
Incineration reduces the quantity of material to be hauled off-site for disposal by 95-percent. The graphic below shows how 850 tons of wastewater solids (75 trucks per day) are incinerated down to 40 tons of inert ash (2 trucks per day).