title: Excess nitrogen accumulation in activated sludge in sequencing batch reactor with a single-stage oxic process.
abstract: It was occasionally found that a significant nitrogen loss in solution under neutral pH value in a sequencing batch reactor with a single-stage oxic process using synthetic wastewater, and then further studies were to verify the phenomenon of nitrogen loss and to investigate the pathway of nitrogen removal. The result showed that good performance of nitrogen removal was obtained in system. 0-7.28 mg L(-1) ammonia, 0.08-0.38 mg L(-1) nitrite and 0.94-2.12 mg L(-1) nitrate were determined in effluent, respectively, when 29.85-35.65 mg L(-1) ammonia was feeding as the sole nitrogen source in influent. Furthermore, a substantial nitrogen loss in solution (95% of nitrogen influent) coupled with a little gaseous nitrogen increase in off-gas (7% of nitrogen influent) was determined during a typical aerobic phase. In addition, about 322 mg nitrogen accumulation (84% of nitrogen influent) was detected in activated sludge. Based on nitrogen mass balance calculation, the unaccounted nitrogen fraction and the ratio of nitrogen accumulation in sludge/nitrogen loss in solution were 14.6 mg (3.7% of nitrogen influent) and 0.89, respectively. The facts indicated that the essential pathway of nitrogen loss in solution in this study was excess nitrogen accumulation in activated sludge.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha, People's Republic China. wwyy44339745@yahoo.com.cn
authors.forename: Xiao-ming
authors.initials: XM
authors.lastname: Li
authors.forename: Dong-bo
authors.initials: DB
authors.lastname: Wang
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.forename: Jian-bin
authors.initials: JB
authors.lastname: Cao
authors.forename: Xiu
authors.initials: X
authors.lastname: Yue
authors.forename: Ting-ting
authors.initials: TT
authors.lastname: Shen
authors.forename: Guang-ming
authors.initials: GM
authors.lastname: Zeng
authors.forename: Jiu-hua
authors.initials: JH
authors.lastname: Deng
mesh_terms: D000332:Aerobiosis; D019149:Bioreactors; D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis; D012722:Sewage; D012996:Solutions; D013997:Time Factors; D014835:Volatilization; D014865:Waste Disposal, Fluid
chemical_list: D012722:Sewage; D012996:Solutions; D009584:Nitrogen; D010100:Oxygen