LOW NITROGEN RECLAIMED WATER ACHIEVED BY AN INTEGRATED SYSTEM OF MBRS AND BNR ACTIVATED SLUDGE SYSTEM

The LOTT Alliance in Olympia WA has created a collection system-wide plan for managing nitrogen emissions by linking a series of satellite reclamation plants (SRPs) to a central, main treatment facility using BNR activated sludge. During a portion of the year, their NPDES permit requires that flow be capped to the main treatment plant and stringent mass-based discharge limits be imposed for nitrogen and BOD. The SRPs are equipped with membrane bioreactors (MBRs) with biological nitrogen control that remove a constant flow from interceptor sewers and provide treatment to meet groundwater recharge criteria. Flow may be distributed between the main treatment plant and the SRPs to off-load the main treatment plant and meet its flow, nitrogen and BOD constraints during these crucial periods of discharge. A simulation tool was developed to allow the management of flow, nitrogen and BOD within this system consistent with optimizing the use of existing capacity at the main treatment plant and minimizing investment in new capital facilities. This paper describes the distributed wastewater management plan, the simulation tool and the initial stages of plan implementation.