Full-scale N removal from centrate using a sidestream process with a mainstream carbon source

An innovative approach to treat centrate for rapid nitrogen load discharge reduction was investigated and applied at the Truckee Meadows Water Reclamation Facility (TMWRF) in Reno, NV. This process allowed TMWRF to circumvent an anticipated exceedance of the individual waste load allocation in 2018. Existing infrastructure and equipment were re-purposed in a full-scale suspended growth biological centrate treatment system, attaining simultaneous nitrification, and denitrification with no additional capital investment. Functioning within a few days of start-up, the average ammonia reduction was 81% (1,106 kg/day) and the average total nitrogen reduction in the sidestream was 53% (757 kg/day) using primary effluent as carbon source. Alkalinity and carbon limitations were both anticipated and observed; however, adaptive operations allowed for balancing of nitrification and denitrification processes, providing pH stability and success in meeting treatment goals. Immediately after the sidestream treatment system was placed into service, nitrogen in the mainstream facility was measured at concentrations significantly lower than typical and was sustained at historically low concentrations throughout the operation. This translated into a significant methanol cost savings of $1,500 per day (USD). The system has become a critical supplemental treatment process during upcoming rehabilitation projects to address aging infrastructure of existing nitrogen treatment facilities. PRACTITIONER POINTS: Full scale demonstration of sidestream N removal using a hybrid process. Integration of the sidestream N process to reduce N effluent load without alkalinity or supplementary carbon augmentation. Operational solution to reduce operating costs without new infrastructure.