title: Effect of reflux ratio on COD and nitrogen removals from coke plant wastewaters.
abstract: A laboratory-scale anaerobic-anoxic-aerobic-moving bed biofilm reactor (A1-A2-O-MBBR) system was undertaken to treat coke plant wastewaters from two different factories (wastewater A and B). Wastewater B had higher BOD5/COD ratio and COD/TN ratio than wastewater A. The effects of reflux ratios on COD, TN and NH3-N removals were studied. Results indicated that, with the reflux ratio increased from 2 to 5, COD removals of wastewater A and wastewater B increased from 57.4% to 72.6% and 78.2% to 88.6%, respectively. Meanwhile, TN removals were also increased accompanying reflux ratio rise, from 53.1% to 74.4% for wastewater A and 64.2% to 83.5% for wastewater B. At the same reflux ratio, compared with wastewater A, higher COD and TN removal efficiencies were observed in wastewater B, which had higher BOD5/COD and COD/TN ratio. Reflux ratio had no significant influence on NH3-N removal; 99.0% of the overall NH3-N removal efficiency was achieved by the system for both coke plant wastewaters at any tested reflux ratio. MBBR was effective in NH3-N removal, and about 95% of the NH3-N was removed in the MBBR.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, Jiangsu, People's Republic of China. xiaols_121@163.com
authors.forename: X L
authors.initials: XL
authors.lastname: Shi
authors.forename: X B
authors.initials: XB
authors.lastname: Hu
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: L L
authors.initials: LL
authors.lastname: Ding
authors.forename: H Q
authors.initials: HQ
authors.lastname: Ren
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D018441:Biofilms; D019149:Bioreactors; D003077:Coke / Q000032:analysis*; D004787:Environmental Pollution / Q000517:prevention & control; D009584:Nitrogen / Q000302:isolation & purification*; D010100:Oxygen / Q000032:analysis; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods
chemical_list: D003077:Coke; D012722:Sewage; D009584:Nitrogen; D010100:Oxygen