纳米零价铁对亚硝化颗粒污泥性能及功能微生物的影响机制

Nanoscale zero-valent iron (nZVI) has been an effective method for treating recalcitrant organics pollutants and heavy metals. It has been used increasingly in evnvironmental remediation and hazardous wastewater treatment. With stringent discharge standard, nZVI should be combined with biological nitrogen removal to deal with ammonia nitrogen in industrial watewater treatment. The "nitrite route" nitrogen removal process is a more sustainable alternative for low energy comsuption and high efficiency. Nitrifying granule has a good partial nitrification capacity and has been the key process of short-cut nitrification. However, the potential influence of nZVI on biological nitrogen removal is still unknown and need to be explored. The overall objective of the proposed project is to develop an understanding of the short-term and long-term impact of nZVI on performance of nitrifying granules. Molecular biogical methods are used to trace the microbial activity and community. It is elucidated to the relation between the effect of nZVI on ammonia oxidation bacteria (AOB), nitrite oxidation bacteria(NOB) and granular sludge performance. Aqueous chemical reaction and interface chemical reaction nZVI are analyzed when nZVI is added to granular sludge system. It is determined the distribution of nZVI in sludge flocs and the interfacial characterizaiton between nZVI and AOB. Such information will contribute to reveal the mechanism of nZVI influence on AOB. The proposed project is expected to provide theoretical basis to nZVI coupling with biological nitrogen removal process for treating industrial wastewater.

纳米零价铁(nZVI)已成为难降解有机物、重金属治理的有效手段，在环境修复、废水治理中的应用不断增加。随着排放标准的日益严格，含氨氮的工业废水，经nZVI去除难降解有机物、重金属后，需耦合生物反应器脱氮。高效低耗的短程硝化工艺是重要的生物脱氮技术。硝化颗粒污泥具有良好的亚硝化性能，已成为短程硝化工艺的基础和关键技术。nZVI对颗粒污泥脱氮性能和功能微生物的潜在影响缺乏研究。本项目探讨nZVI对好氧颗粒污泥硝化性能冲击性影响和长期适应性影响，应用分子生物学手段，分析nZVI对微生物活性和群落结构的影响，构建nZVI胁迫下氨氧化菌、硝化菌群落变化与好氧颗粒污泥性能之间的响应关系。通过研究nZVI水化学反应、nZVI与氨氧化菌作用界面特征、nZVI在颗粒污泥中形态变化与分布，探索nZVI对颗粒污泥中氨氧化菌的影响机理，为nZVI与生物脱氮工艺耦合处理工业废水提供理论依据。

纳米零价铁(nZVI) 作为难降解有机物、重金属等污染物治理的新材料，对污水生物处理系统功能微生物和水体环境的潜在影响尚不清楚。亚硝化颗粒污泥(NGS)是将污泥颗粒化与稳定亚硝化反应相结合的新型生物脱氮技术，是实现亚硝化路线短程脱氮的重要基础和关键，脱氮自养微生物对环境因子比较敏感。本项目在NGS稳定培养的基础上，研究NGS获得稳定亚硝化性能的运行调控机制和关键参数，探索nZVI对NGS性能的影响，颗粒污泥粒径与nZVI投加量之间的响应关系，分析NGS中功能微生物群落特征和动力学速率，建立 nZVI 对亚颗粒污泥中功能微生物氨氧化菌(AOB)和亚硝酸盐氧化菌(NOB)的影响规律。.研究发现，在间歇式反应器实现污泥颗粒化过程中，有机物负荷在3.20 ~4.84 kg•(m3•d)-1时，污泥粒径的增长速率最快。通过协同调控进水碳、氮负荷比值，获得快速稳定的亚硝化自养型颗粒污泥培养方法。低浓度溶解氧(DO)在颗粒污泥中的传质、游离氨（FA）和游离亚硝酸（FNA）对NOB的选择性抑制，是维持稳定、高效亚硝化性能的重要因素。nZVI对NGS性能的影响研究发现，nZVI投加量在10 mg•L-1以内，可显著提高AOB活性，当nZVI在25~500 mg•L-1时，对AOB有抑制作用，当nZVI投加量为700 mg•L-1时，NGS对AOB的抑制率达到46%，此时，nZVI在NGS表面的大量吸附对污泥表面的微生物生态造成了严重破坏。nZVI对亚硝化性能的影响与污泥粒径有关。当nZVI投加量小于100 mg•L-1时，小粒径NGS(Diameter 0.5-0.8mm) 的亚硝化性能有所提高，当nZVI投加量达到900 mg•L-1时，污泥性能才会出现大幅降低。与之相比，投加低浓度nZVI并未对大粒径NGS(Diameter 1.8-2.3mm)的性能起到促进作用。当nZVI投加量大于500 mg•L-1时，大粒径NGS的亚硝化性能将被完全抑制。由Haldane动力学模型可知，nZVI对污泥性能的抑制属于非竞争性抑制。NGS对nZVI的吸附符合Langmuir和Freundlich等温吸附方程。.本研究成果可为纳米铁物化处理与生化技术耦合处理复合型废水提供理论参考和技术参数,有利于提高对纳米零价铁材料的利用率和对生物处理工艺稳定控制水平。