Preparation and Performance Verification of a Solid Slow-Release Carbon Source Material for Deep Nitrogen Removal in Urban Tailwater

Zhang Luo; Hongtao Shi; Hanghang Lyu; Hang Shi; Bo Liu

doi:10.3390/molecules29092031

Preparation and Performance Verification of a Solid Slow-Release Carbon Source Material for Deep Nitrogen Removal in Urban Tailwater

Molecules. 2024 Apr 28;29(9):2031. doi: 10.3390/molecules29092031.

Authors

Zhang Luo¹, Hongtao Shi¹, Hanghang Lyu², Hang Shi³, Bo Liu⁴

Affiliations

¹ China Railway Engineering Services Co., Ltd., Chengdu 610083, China.
² China Construction Eighth Engineering Division Co., Ltd., Shanghai 200135, China.
³ Yalong River Hydropower Development Company, Chengdu 610051, China.
⁴ State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, #163, Xianlin Avenue, Nanjing 210023, China.

Abstract

Urban tailwater typically has a low carbon-to-nitrogen ratio and adding external carbon sources can effectively improve the denitrification performance of wastewater. However, it is difficult to determine the dosage of additional carbon sources, leading to insufficient or excessive addition. Therefore, it is necessary to prepare solid slow-release carbon source (SRC) materials to solve the difficulty in determining the dosage of carbon sources. This study selected two SRCs of slow-release carbon source 1 (SRC1) and slow-release carbon source 2 (SRC2), with good slow-release performance after static carbon release and batch experiments. The composition of SRC1 was: hydroxypropyl methylcellulose/disodium fumarate/polyhydroxy alkanoate (HPMC/DF/PHA) at a ratio of 3:2:4, with an Fe₃O₄ mass fraction of 3%. The composition of SRC2 was: HPMC/DF/PHA with a ratio of 1:1:1 and an Fe₃O₄ mass fraction of 3%. The fitted equations of carbon release curves of SRC1 and SRC2 were y = 61.91 + 7190.24e^-0.37t and y = 47.92 + 8770.42e^-0.43t, respectively. The surfaces of SRC1 and SRC2 had a loose and porous morphological structure, which could increase the specific surface area of materials and be more conducive to the adhesion and metabolism of microorganisms. The experimental nitrogen removal by denitrification with SRCs showed that when the initial total nitrogen concentration was 40.00 mg/L, the nitrate nitrogen (NO₃^--N) concentrations of the SRC1 and SRC2 groups on the 10th day were 2.57 and 2.66 mg/L, respectively. On the 20th day, the NO₃^--N concentrations of the SRC1 and SRC2 groups were 1.67 and 2.16 mg/L, respectively, corresponding to removal efficiencies of 95.83% and 94.60%, respectively. The experimental results indicated that SRCs had a good nitrogen removal effect. Developing these kinds of materials can provide a feasible way to overcome the difficulty in determining the dosage of carbon sources in the process of heterotrophic denitrification.

Keywords: denitrification; low carbon-to-nitrogen ratio wastewater; slow-release carbon source; slow-release coefficient.

Abstract

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