Magnetite-Augmented Sulfur-Siderite Autotrophic Denitrification: Deep Nitrogen Removal at Ultra-Low HRT from Lab to Pilot Scale

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research Pub Date : 2025-06-16 DOI:10.1016/j.watres.2025.124034

Jiale Sun, Haoyong Li, He Dong, Lu Liu, Chunyv Zhou, Ziwen Du, Yan Dang, Dawn E. Holmes

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Abstract

Persistent eutrophication and increasingly stringent discharge regulations have intensified the demand for advanced nitrogen removal technologies in wastewater treatment. Sulfur-siderite autotrophic denitrification (SSAD) presents a chemical-free, low-carbon alternative to conventional heterotrophic processes. However, its widespread application is hindered by long hydraulic retention times (HRTs) and frequent nitrite (NO₂^–-N) accumulation. To address these limitations, this study developed a sulfur-siderite-magnetite autotrophic denitrification (SSMAD) system by integrating magnetite into SSAD fillers. Both lab- and pilot-scale experiments confirmed that SSMAD significantly outperformed SSAD in terms of denitrification capacity and stability. The SSMAD system maintained robust performance at HRTs under 3 hours, whereas the SSAD reactor exhibited negligible nitrate removal. In pilot-scale SSMAD reactors treating secondary effluent, total nitrogen in the effluent remained below 11.5 and 12.3 mg/L at ultra-low HRTs of 20 and 15 minutes, respectively. At a 30-minute hydraulic retention times (HRT), the SSMAD system achieved a denitrification load of 0.95 kgN/(m³·d), exceeding those of SSAD and sulfur autotrophic denitrification (SAD) systems by factors of 1.6 and 4.4, respectively. Sulfur served as the primary electron donor, while Fe²⁺ released from siderite provided an additional source of electrons. The microbial community in both SSAD and SSMAD systems was enriched with Thiobacillus and Sulfurimonas, which couple sulfur and iron oxidation with nitrate reduction. Magnetite additions enhanced both sulfur- and iron- driven denitrification and increased the abundance of these key genera. Metatranscriptomic analysis indicated that magnetite facilitated interspecies electron transfer (IET) via sulfur intermediates produced by Sulfurimonas and utilized by Thiobacillus. Additionally, extracellular electron transfer (EET) by Thiobacillus was promoted, evidenced by up-regulated expression of genes coding for extracellular c-type cytochromes. Overall, this study presents a viable strategy for achieving energy-efficient, rapid nitrogen removal at ultra-short HRTs, demonstrating the practical potential of SSMAD for advanced wastewater treatment applications.

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磁铁矿增强硫菱铁矿自养反硝化：从实验室到中试规模的超低HRT深度脱氮

持续的富营养化和日益严格的排放法规加剧了对污水处理中先进脱氮技术的需求。硫菱铁矿自养反硝化（SSAD）提出了一种无化学物质，低碳替代传统异养过程。然而，水力滞留时间长（HRTs）和亚硝酸盐（NO2—N）积累频繁阻碍了其广泛应用。为了解决这些限制，本研究通过将磁铁矿整合到SSAD填料中开发了硫-菱铁矿-磁铁矿自养反硝化（SSMAD）系统。实验室和中试实验均证实，SSMAD在脱氮能力和稳定性方面明显优于SSAD。SSMAD系统在3小时的hrt下保持稳定的性能，而SSAD反应器的硝酸盐去除率可以忽略不计。在处理二级出水的中试SSMAD反应器中，在20和15分钟的超低hrt下，出水总氮分别保持在11.5和12.3 mg/L以下。在30分钟水力停留时间（HRT）下，SSMAD系统的反硝化负荷为0.95 kgN/(m3·d)，分别是SSAD和硫自养反硝化（SAD）系统的1.6倍和4.4倍。硫是主要的电子供体，而从菱铁矿释放的Fe2+提供了额外的电子来源。在SSAD和SSMAD系统中，微生物群落富集了硫杆菌和硫单胞菌，它们将硫和铁氧化与硝酸盐还原结合在一起。磁铁矿的添加增强了硫和铁驱动的反硝化作用，并增加了这些关键属的丰度。亚转录组学分析表明，磁铁矿通过硫单胞菌产生并被硫杆菌利用的硫中间体促进了种间电子转移（IET）。此外，硫杆菌胞外电子转移（EET）被促进，这可以通过上调胞外c型细胞色素编码基因的表达来证明。总的来说，本研究提出了在超短hrt下实现节能、快速脱氮的可行策略，展示了SSMAD在高级废水处理应用中的实际潜力。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.