Challenge: Middleburg Municipal Authority’s wastewater treatment plant needed
to be upgraded to meet total nitrogen and phosphorus limits required by the Chesapeake Bay Initiative.

Solution: In order to help the Authority meet its goals, we upgraded the process control to achieve nitrification/denitrification in the aerated lagoons using a programmable logic controller, dissolved oxygen probes, variable speed positive displacement blowers, and automated aeration system valving. Aeration in the lagoons is now cycled on and off to create aerobic and anoxic conditions within the basin. Dissolved oxygen levels in each lagoon are monitored by a submerged DO probe and the process blower speed is altered to maintain the DO within the lagoons. The setpoint can be adjusted by the operator as needed for process control.

Outcome: Total phosphorus removal is achieved through chemical addition using an aluminum sulfate compound. In addition to chemical addition for phosphorus removal, chemical feed systems were provided for a supplemental carbon source and alkalinity addition. The chemical feed systems are located in a new chemical feed building which also provides storage space and an emergency shower.

The project was funded using a combination of PENNVEST low interest loan and PA H2O grant funds. We assisted in the preparation of funding applications and was responsible for administering these funds for the duration of the project.