Simultaneous decarburization, nitrification and denitrification (SDCND) in coking wastewater treatment using an integrated fluidized-bed reactor

• Published in: Journal of environmental management 2019-12, Vol.252, p.109661-109661, Article 109661
• Main Authors: Li, Kui, Wu, Haizhen, Wei, Jingyue, Qiu, Guanglei, Wei, Chaohai, Cheng, Dangyu, Zhong, Lianwen
• Format: Article
• Language: English
• Subjects: Carbon and nitrogen removal; Coking wastewater; Differential DO distribution; Integrated fluidized-bed reactor; Microbial community
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2019.109661

There are two problems in biological treatment of coking wastewater (CWW): incapability of pre-anaerobic treatment to eliminate the toxicity in wastewater, and the lack of carbon source for subsequent denitrification in pre-aerobic treatment. To achieve simultaneous decarburization, nitrification and denitrification (SDCND) in CWW treatment, biological carrier materials was used to build an integrated fluidized-bed reactor (Reactor B, RB). A conventional fluidized-bed reactor (Reactor A, RA) was used as a control reactor under the same condition. The results showed that RB was more advantageous since its removal efficiencies of COD and TN were 90% and 87%, respectively, which were significantly higher than these in RA (82% and 45%), at a hydraulic retention time (HRT) of 60 h. Microelectrode measurement indicated that oxygen transfer was limited inside the carrier where the formation of a dissolved oxygen (DO) concentration gradient was observed. Microbial community analysis showed that the aerobic and anoxic microenvironments in RB promoted the co-existence of a wider variety of bacteria, thus achieving SDCND. These results indicated the integrated fluidized-bed reactor exhibited promising feasibility for simultaneous carbon and nitrogen removal in CWW treatment under the same aeration driven conditions. The SDCND process realized by fluidized-bed reactor provided a reference for the treatment of toxic industrial wastewater with high carbon to nitrogen ratio. [Display omitted] •Differential distribution of DO was achieved via the addition of carrier.•Efficient SDCND was accomplished in a single reactor.•The TN removal reached 87%, doubled that of the control reactor.•The carrier supported aerobic and anoxic environments for various bacteria.