Concord, Massachusetts WWTP - A Low-Cost, 20-Year Solution To Ever-Tightening Phosphorus Limits

Prior to 2007, Concord, Massachusetts wastewater treatment plant operated under a NPDES permit that allowed a seasonal phosphorus limit of 0.7 mg/L. But with the issuance of a new five-year permit with a phosphorus limit of 0.2 mg/L and the probability that future limits could reach as low as 0.05 mg/L, Concord needed a treatment solution that would be reliable and cost-effective today and over the long term.

Choosing Effluent Flexibility, Operating Reliability and a Small Footprint
When compared to dissolved air flotation (DAF), media filtration and sand ballasted technologies, Concord’s consulting engineers recommended the CoMag® System for its:

• Ability to provide effluent TP values from 0.2 mg/L to ≤ 0.05 mg/L simply by adjusting the flocculent dose
• Reliability of operation — conventional flocculation and coagulation coupled with high rate clarification and no filters to clog or backwash
• Capital cost savings given its small clarifiers and footprint