基于NAIO的地下水硝酸盐污染原位修复新技术及其机理研究

Nitrate contamination of groundwater is an increasingly serious environmental problem around the world, which has shown great threats to human health. Nitrate-dependent anaerobic iron oxidation (NAIO) is a biological process utilizing iron, including zero-valent and ferrous iron, as electron donor to convert nitrate to nitrogen gas under anoxic conditions. NAIO is a significant discovery in the field of microbiology and geology, and several papers have been published in journals of Nature and Science. The in-situ bioremediation of nitrate-contaminated groundwater based on NAIO is an autotrophic biological technology, and takes the wide-spread agent of iron to substitute organic matters as electron donor, which contributes to the safe and practical advantages. So far, however, little information is available on the application NAIO process, especially in the field of in-situ bioremediation of groundwater contaminated by nitrate. It’s necessary to set up a project with aims: 1) to investigate the enrichment method of high-efficient NAIO microorganisms, the device of NAIO system and the NAIO performance to create the novel in-situ bioremediation technology for nitrate-contaminated groundwater. 2) to investigate the device hydraulic properties, the contaminants conversion and migration and microbial growth and metabolism to comprehend the NAIO process characteristics. 3) to investigate the relationships between NAIO kinetics, microbial succession, functional bacteria/gene/enzyme and nitrate removal to reveal the NAIO working mechanisms. Such a project can offer an opportunity to create a novel in-situ bioremediation technology for groundwater contaminated by nitrate, and also help to promote the study of biogeochemical cycles of iron and nitrogen.

硝酸盐污染已严重影响地下水水质，威胁人类饮水安全，污染控制势在必行。以低价铁为电子供体、硝酸盐为电子受体的硝酸盐型厌氧铁氧化（NAIO）是微生物学和地质学领域的重大发现，已有多篇论文发表于Nature和Science上。NAIO原位修复技术是自养生物脱氮技术，以来源大宗的铁素替代碳素（有机物），实用且安全。但迄今为止，基于NAIO的地下水硝酸盐污染原位修复技术鲜见报道。探索高效NAIO菌富集方法、NAIO装置集成方式和NAIO系统运行性能，可创建地下水硝酸盐污染原位修复新技术；探索典型工况下水力流动性状、污染物迁移转化性状和微生物生长代谢性状，可明晰NAIO技术的过程特性；探索基质转化、菌群演替、功能菌/基因/酶动态及其与脱氮效能的关系，可揭示NAIO技术的工作机理。本项目不仅有助于推动地下水硝酸盐污染治理，也有助于丰富氮-铁生物地球化学循环内容，兼具科学意义和实用价值。

硝酸盐污染已严重影响地下水水质，威胁人类饮水安全，污染控制势在必行。以低价铁为电子供体、硝酸盐为电子受体的硝酸盐型厌氧铁氧化（NAIO）是微生物学和地质学领域的重大发现。NAIO原位修复技术是自养生物脱氮技术，以来源大宗的铁素替代碳素（有机物），实用且安全。有鉴于此，本研究研发了基于NAIO的地下水硝酸盐污染原位修复技术。主要结论如下：研发了一种碱度自调控高效铁盐生物脱氮反应器，解决了地下水硝酸盐铁盐修复过程中产物堆积堵塞反应器和出水酸化等问题，并获国家专利授权。建立了基于活性污泥的NAIO技术，稳定阶段工艺硝酸盐去除率为71.56±3.48%，反应器容积去除速率达0.16±0.01 kg-N/(m3·d)，效能达到世界先进水平；建立了基于厌氧颗粒污泥的NAIO技术，稳定阶段工艺硝酸盐去除率可达95.30±2.39 %，反应器容积去除速率为0.20±0.02 kg-N/(m3•d)，效能达到世界先进水平。活性污泥在生物铁氧化脱氮工艺长期运行后，污泥出现团聚现象，粒径增加，铁素含量较接种活性污泥增加5.51倍；而厌氧颗粒污泥在NAIO工艺长期运行后，污泥形貌特征变化不显著，但组成差异显著，其铁素含量较接种污泥增加16.93倍至34.54 ± 3.81%（w%），远高于活性污泥。经过NAIO工艺运行，污泥中的菌群发生演替，其中基于活性污泥的NAIO工艺，其在门水平和属水平的优势菌群分别为Proteobacteria、Chloroflexi、Bacteroidetes、Acidobacteria、Actinobacteria和Nitrosomonadales_unclassified、Geothrix；而基于厌氧颗粒污泥的NAIO工艺，其在门水平和属水平的优势菌群分别为Proteobacteria、Chloroflexi、Bacteroidetes和Nitrosomonadales_unclassified、Desulforhabdus。综合评价表明，相较于活性污泥，厌氧颗粒污泥在运行NAIO技术中具有更好的脱氮性能、更强的稳定性能和更优的经济性能，为优选接种物。本研究结果可为基于铁盐的硝酸盐还原技术应用于地下水硝酸盐污染原位修复提供理论依据和技术支撑。