Nutrient Removal Treatment Practices Implemented at the City of Los Angeles Upstream Water Reclamation Plants

The principal source of nitrogen compounds in the Los Angeles River is from the City of Los Angeles upstream plants, Donald C. Tillman (DCT) and the Los Angeles-Glendale (LAG) Water Reclamation Plants (WRP's). These WRP's were major contributors, with up to 75% of the total dry weather nitrogen load during dry weather periods. In 2007, the City has completed a nitrogen removal program to reduce the nitrogen mass discharge from its WRP's. As part of the process, a comprehensive research effort was undertaken involving bench, pilot and full scale testing to identify the most effective way to upgrade and optimize the existing WRP's. The combined findings were then used to upgrade WRP's to “full” BNR plants without derating, carbon and alkalinity addition utilizing the MLE (Modified Ludzack Ettinger) process. This paper will focus on the MLE process design and treatment practices successfully implemented at the City's WRP's.