Addressing Solids Handling Limitations and Stringent Phosphorus Limits through Implementation of a CoMag™ System in Billerica, Massachusetts

The Billerica, Massachusetts WWTF was facing more stringent effluent total phosphorus and aluminum limits. The existing two-point chemical addition phosphorus removal system was not adequate to remove total phosphorus and aluminum to the concentrations required and the facility required major upgrades in order to achieve the new effluent limits. In addition, the facility was plagued by solids processing bottlenecks that were having detrimental effects on the liquid processes and the ability to adequately treat the influent wastewater. A Comprehensive Plant Evaluation was completed to determine the prioritized upgrade and operational needs of the facility. The two highest priority improvements identified included the increase in solids handling capacity and the construction of a new tertiary phosphorus removal system. In addition, operational changes were implemented to reduce solids loading on the secondary clarifiers. The design concepts, operational approaches, operating data and results will be reviewed.