[Biological nitrogen removal with excess nitrogen uptake by microorganisms].

The performance of nitrogen removal with sequencing batch reactors were investigated in different pH conditions using simulated municipal wastewater. The experimental results showed that ammonium and nitrate as well as nitrite in R2 (pH controlled at 8.0 +/- 0.2) were 0-1 mg x L(-1) and 8-10 mg x L(-1) respectively, while ammonium and nitrate as well as nitrite in R1 (pH controlled at 7.0 +/- 0.2) were 0-5 mg x L(-1) and 1-2 mg x L(-1) respectively under the operational process of 4-hour aeration --> 4-hour settle/idle phase, which indicated the removal rates of TIN (TIN = NH4+ -N + NO3- -N + NO2- -N) in R1 and R2 were above 85% and about 70% respectively, when the COD and ammonium concentrations in influent were 250-300 mg x L(-11), 30-40 mg x L(-1), respectively. Total nitrogen in sludge was at a high level and increased in the aeration after decreasing in the first hour aeration, the content of total nitrogen in sludge was 214 mg x g(-1) at the beginning of aerobic phase, 210 mg x g(-1) in the first aeration and 215 mg x g(-1) at the end. The researches indicated that high efficiency of nitrogen removal could be obtained in sequencing batch reactor and nitrogen removal in this study was not realized by traditional nitrification/denitrification approach but by the discharge of rich-nitrogen sludge.