Abstract:The biological denitrification effect is inhibited by low temperature, while redox mediator addition can ameliorate the biological denitrification. In this study, the sequencing batch reactors with the same scale were used to investigate the effect of carbon source concentrations(carbon-nitrogen ratios) on biological denitrification with redox mediator addition of 1, 2-naphthquinone-4-sulfonic acid (NQS) at low temperature(10 ℃), the corresponding influent and seeding sludge were synthetic wastewater containing ${\rm{NO}}_3^{-} $ and acclimated activated sludge, respectively. The results showed that the denitrification efficiency increased with the increase of carbon-nitrogen ratio when the carbon source concentrations (in terms of COD) were 150~400 mg·L?1 (carbon-nitrogen ratios: 1.8~4.7). However, the denitrification efficiency decreased with the increase of carbon-nitrogen ratio when the carbon source concentrations were 400~550 mg·L?1 (carbon-nitrogen ratios: 4.7~6.5). The highest total nitrogen removal rate of 64.7% was achieved at the carbon source concentration of 400 mg·L?1 (carbon-nitrogen ratio: 4.7). The denitrification rate with redox mediator addition increased with the increase of carbon-nitrogen ratio. The mechanism for biological denitrification improvement may be due to the redox potential (ORP)reduction with redox mediator addition, which was beneficial to biological denitrification. Key words:low temperature/ carbon source concentration/ carbon-nitrogen ratio/ redox mediator/ biological denitrification.
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1.School of Environmental and Municipal Engineering, Tianjin Chenjian University, Tianjin 300384, China 2.Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin 300384, China Received Date: 2019-02-12 Accepted Date: 2019-04-23 Available Online: 2020-01-20 Keywords:low temperature/ carbon source concentration/ carbon-nitrogen ratio/ redox mediator/ biological denitrification Abstract:The biological denitrification effect is inhibited by low temperature, while redox mediator addition can ameliorate the biological denitrification. In this study, the sequencing batch reactors with the same scale were used to investigate the effect of carbon source concentrations(carbon-nitrogen ratios) on biological denitrification with redox mediator addition of 1, 2-naphthquinone-4-sulfonic acid (NQS) at low temperature(10 ℃), the corresponding influent and seeding sludge were synthetic wastewater containing ${\rm{NO}}_3^{-} $ and acclimated activated sludge, respectively. The results showed that the denitrification efficiency increased with the increase of carbon-nitrogen ratio when the carbon source concentrations (in terms of COD) were 150~400 mg·L?1 (carbon-nitrogen ratios: 1.8~4.7). However, the denitrification efficiency decreased with the increase of carbon-nitrogen ratio when the carbon source concentrations were 400~550 mg·L?1 (carbon-nitrogen ratios: 4.7~6.5). The highest total nitrogen removal rate of 64.7% was achieved at the carbon source concentration of 400 mg·L?1 (carbon-nitrogen ratio: 4.7). The denitrification rate with redox mediator addition increased with the increase of carbon-nitrogen ratio. The mechanism for biological denitrification improvement may be due to the redox potential (ORP)reduction with redox mediator addition, which was beneficial to biological denitrification.
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