Separate-stage, suspended growth, denitrification is the key for the River Oaks Advanced Wastewater Treatment Plant to achieve an effluent of 2 mg/l BOD5 and TSS, 1.0 mg/l total nitrogen and 0.4 mg/1 total phosphorus. Following combined BOD5 removal and nitrification, the denitrification system uses methanol as the carbon source for nitrogen removal; a final aerobic stabilization step provides for improved solids settling and oxidation of residual methanol. Effluent filtration removes additional TSS and associated particulate nutrients. This process scheme is the only demonstrated system to consistently achieve total nitrogen levels of 1 mg/l. The high degree of nitrogen removal is attributed to the separate stage system’s ability to reduce nitrate and soluble organic nitrogen to very low levels.