Reduction of NO to N2 in an autotrophic up-flow bioreactor with sponge iron bed based Fe(II)EDTA complexation. (15th October 2019)

• Record Type: Journal Article
• Authors: Zhang, Jing; Ren, Lulu; Zhang, Daijun; Li, Jianing; Peng, Shuchan; Han, Xinkuan; Ding, Aqiang; Lu, Peili
• Is Part Of: Fuel. Volume 254(2019)
• Publication Date: 2019-10-15
• Subjects: Anammox -- NAFO -- NO removal -- Fe(II)EDTA regeneration -- Sponge iron; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2019.115631
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: NO was reduced to N2 by a integrated chemical- and biological- system. Efficient regeneration of Fe(II)EDTA by sponge iron. Part of NO reduced to NH4 + by sponge iron and the consumption of exogenous NH4 + decreased. Anammox and NAFO played an important role in this system. Abstract: Integrated Fe(II)EDTA absorption and anaerobic ammonia oxidation process can remove NO from flue gas, but Fe(II)EDTA was easily oxidized to Fe(III)EDTA which is not capable of binding NO. Regeneration of Fe(II)EDTA is the key to this process. A novel autotrophic up-flow bioreactor with sponge iron bed was developed. During 80-day continuous operation of the reactor, NO was almost completely reduced to N2 with the average removal rate of 7.57 mM/d, and N2 O in the off gas was lower than the limit of detection. Since part of NO was chemically reduced to NH4 + by sponge iron, the ratio of NO-N removal to NH4 + -N consumption was up to 5. Sponge iron worked excellently on in-situ regeneration of Fe(II)EDTA, and the average loss rate of Fe 2+ was only 0.190 mM/d. Results of microbial community structure analysis showed that the microbial community diversity decreased gradually as the reactor running. The relative abundance of Candidatus Kuenenia, the dominant anammox genus in seed sludge, changed from 4.48% to 0.78%. The formation of a symbiotic system, in which AnAOB and denitrification bacteria dominated, showed that anammox and nitrate-dependent anaerobic ferrous oxidation (NAFO) played an important role in the biological process of NO reduction. The autotrophic up-flow bioreactor with sponge iron bed can provide a potential process for NO removal from flue gas.