[Removing the nitrogen from the ammonium sulfite method paper mill wastewater by anoxic/aerobic SBR].

The experiment results showed that the best technology of removing the nitrogen was anoxic time to aerobic time of 1:1.5, a cycle of 8 hours; the SRT should be more than 12 d and the loading of NH3-N should be less than 0.063 g/(g.d); when the concentration of CODCr, NH3-N and NOx-N was 1200-1800 mg/L, 135-200 mg/L and 7-10 mg/L respectively, without external carbon sources, the removal rate of NH3-N and TN could respectively achieve 95% and 66%; after adding sodium acetate the removal rate of TN could get to 85%. The addition of sodium acetate at the concentration equivalent to theoretical CODCr values of 125 mg/L appeared to be the most economical and reliable option.