title: [Effects of COD/TN and HRT(s) on nutrients removal by an alternating anoxic/oxic CAST].
abstract: The effects of different COD/TN and HRT(s) (hydraulic retention time of select) on nutrients removal were investigated by using an alternating anoxic/oxic CAST (cyclic activated sludge technology) fed with municipal wastewater. The results showed that various COD/TN and HRT(s) had a bigger influence on the nitrogen removal efficiency rather than the COD removal efficiency. As the influent C/N ratios were about 2.6 and 3.5, ammonia was removed by 98% and TN removal efficiency was increased from 62.9% to 76.2% and 72.1% to 84.6%, respectively, by increasing the HRT(s) from 1.8 h to 5 h. When the COD/TN ratio was increased to about 4.4, TN removal efficiency was decreased from 86.3% to 58.2% by enlarging the HRT(s), which was due to the incomplete nitrification of ammonia. It was also observed that both of increasing the COD/TN and HRT(s) could improve the phosphorus removal performance of the system. Furthermore, effluent of CAST reached the demanded A of integrated wastewater discharge standards (GB 18918-2002) when the COD/TN and HRT(s) were 4.4 and 1.8 h, respectively.
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing 100124, China. wangli1129@emails.bjut.edu.cn
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Yong-Zhen
authors.initials: YZ
authors.lastname: Peng
authors.forename: Juan
authors.initials: J
authors.lastname: Ma
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Ning-Ping
authors.initials: NP
authors.lastname: Ma
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D002244:Carbon / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry / Q000302:isolation & purification*; D010758:Phosphorus / Q000737:chemistry / Q000302:isolation & purification*; D012722:Sewage / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D012722:Sewage; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen