The American Council of Engineering Companies (ACEC) of Massachusetts has awarded Tighe & Bond its Gold Award for its work at the Town of Sturbridge, MA wastewater treatment plant using an innovative combination of Siemens Water Technologies BioMag® and CoMag® Systems.
ACEC recognized Tighe & Bond for having demonstrated "the highest degree of merit, ingenuity, complexity and client satisfaction," according to Treatment Plant Operator Magazine. The implementation of Siemens BioMag and CoMag water treatment systems "increased wastewater treatment efficiency, improved water quality and reduced costs and overall environmental impact."
According to Ian Catlow, Tighe & Bond senior project manager, it was an honor to receive this recognition and to also have exceeded performance and compliance requirements for the Town while delivering the project substantially below the estimated cost of a conventional treatment system.
Sturbridge originally planned to install a membrane bioreactor (MBR) to meet the need for additional wastewater treatment capacity in a highly constricted footprint, coupled with tighter permit limits for biochemical oxygen demand (BOD), total suspended solids (TSS), total nitrogen and phosphorus. However, after evaluating the high capital and operating costs of the MBR, the town and Tighe & Bond agreed to pilot test the Siemens BioMag System. By using magnetite to ballast biological floc, allowing an increase in mixed liquor concentration as high as 12,000 mg/l, the BioMag system proved to be a cost-effective alternative to MBR technology while expanding capacity from 2.84 MLD (0.75 MGD) to 6.06 MLD (1.62 MGD).
Next to comply with anticipated lower phosphorus discharge limits and a desire for a reliable tertiary treatment process to follow the BioMag System, the Town and Tighe & Bond initially planned to expand its conventional media filtration system. Once again, after a demonstration proved that the installed cost of the larger sand filter would be greater than the smaller and higher performing CoMag System, the town chose the Siemens solution. Since implementing the CoMag System, the plant has experienced no loss of productivity due to clogging, plugging or backwashing and the Town received a process guarantee providing <0.05 mg/L of effluent phosphorus.