BIO-P IMPLEMENTATION AT MCES? METROPOLITAN W TANKAGE

摘要

The Metropolitan Council Environmental Services (MCES) in St. Paul, Minnesota hasrnrecently converted one-quarter of its existing 950,000 m3/d (250-mgd) MetropolitanrnWastewater Treatment Plant (Metro Plant) from a nitrifying activated sludge (NAS)rnstep feed secondary treatment system to a biological phosphorus (Bio-P) removalrnprocess. This modification is the first phase of a series of upgrades that will convertrnthe entire Metro Plant to a Bio-P system and enable the plant to achieve a treatedrneffluent total phosphorus limit of 1.0 mg/L annual average, coupled with a seasonalrnnitrification requirement. To accommodate these effluent requirements, previousrnplanning efforts suggested that either additional tankage would be required, or that arnsignificant capacity derating (17-percent or more) of the plant was necessary. Thisrnpaper presents the significant findings and conclusions of the recent investigations atrnthe Metro Plant, which have included wastewater characterization and bench scalerntesting, process modeling, a one-year full-scale process proving program, andrncapacity rating activities associated with this Bio-P program.