基于低强度超声波激励的短程SND生物膜微环境行为效应及功能菌群响应机制

Treatment of wastewater with high ammonia and low C/N ratio is a hotspot and difficulty of research on water treatment science and technology at home and abroad, Short-cut simultaneous nitrification denitrification (SND) is a high-efficient and low-consumption new technology for biological nitrogen removal to solve above problem. Low intensity ultrasound (LIU) was introduced to biofilm system, using its special biological effect, prompting dominant co-existing of ammonia oxidizing bacteria and denitrifying bacteria while suppressing nitrite oxidizing bacteria. Effect mechanisms and regulation measures of process efficiency enhanced by LIU were interpreted from the perspective of biofilm micro-environment in this project. Using microscopic detection technologies such as CLSM, AFM, MRFM and FCM to analyze the impacts of morphology and structure of biofilm and physicochemical characterization from LIU; Using microelectrode measurement technique, mass transfer pattern and functional partition within the biofilm under the irradiation of LIU to reveal behavior effects of biofilm micro-environment; Using molecular biology technologies including high-throughput sequencing and FISH, microbiology diversity and quantity, distribution and activity of target bacteria were analyzed to explore dynamic response mechanisms of functional nitrogen-removing bacterial groups to LIU and behavior improving of biofilm micro-environment and optimization strategies for natural deployment of functional bacterial groups under LIU-induced condition were proposed. Research results will provide theoretical guidance and scientific basis for process design and operation optimization of short-cut simultaneous nitrogen removal and enrich microbiogy principles for nitrogen removal from wastewater.

高氨低C/N比废水处理是国内外水处理科学和技术研究的热点和难点，短程同步硝化反硝化(SND)是一种解决上述问题的高效低耗生物脱氮新技术。研究将低强度超声波(LIU)引入生物膜系统，利用其特有的生物学效应，促使氨氧化菌和反硝化菌优势共生而对亚硝酸氧化菌形成抑制。项目拟从生物膜微环境角度阐释LIU强化工艺效能的作用机理与调控手段。采用CLSM、AFM、MRFM及FCM等微观检测技术分析LIU对生物膜形态结构和理化性能的影响作用；借助微电极测量技术，明确膜内氧与底物传质规律及功能分区，揭示LIU诱导下生物膜微环境行为效应；采用高通量测序、FISH分子生物学技术研究目标微生物活性及数量分布，探明功能脱氮菌群结构对LIU的动态响应机制，提出基于LIU诱导下生物膜微环境行为改善和功能菌群自然调配的优化策略，为污水短程同步脱氮工艺设计与运行优化提供理论指导和科学依据，丰富了污水脱氮微生物学原理。

高氨低C/N比废水实现经济高效生物脱氮是国内外污水生物处理领域研究的热点和难点。亚硝酸型同步硝化反硝化（SND）作为一种新型生物脱氮技术展现了良好的技术优势和应用前景。生物膜反应器所提供的微环境是SND发生的先决条件。本课题将低强度超声波（LIU）引入生物膜反应器，重点明确了不同超声作用下的短程硝化反硝化发生的生物膜微环境特征，阐明了LIU强化短程SND脱氮机制与调控策略。首先建立了4套平行运行的SBBR反应器，R0不超声，R1、R2、R3分别施加低、中、高三个超声功率。长期运行结果表明：与控制组相比，超声组具有明显的亚硝酸盐积累和短程硝化反硝化效果，低超声功率TN去除率最高，而高超声功率则降低了生物脱氮效率。采用胞外聚合物（EPS）组分分析、3D-EEM技术发现低功率超声促使生物膜分泌更多的多糖物质，同时产生一定量的富里酸类等芳香类蛋白物质；而高功率超声下的生物膜EPS多糖物质较低而蛋白分泌较多，可能影响微生物合成代谢。氧微电极测试明确了超声辐照下生物膜结构变得松散，促进了底物和氧的传递转移，生物膜内具有显著的氧梯度分布和功能分区，通过液相DO控制可促使好氧/缺氧功能微区比例接近以提高短程SND效率。借助FISH技术进一步明确了超声作用下生物膜功能菌群空间分布特征，发现低功率超声有利于对位于生物膜外层NOB进行攻击，而实现AOB优势选择，而过高的超声功率会使生物膜厚度明显减小从而破坏缺氧微环境。高通量测序分析发现不同超声功率下的微生物群落多样性和菌群结构的差异性，低超声功率下的Nitrosomonas占比最高，而硝化螺菌属并未检出，超声功率的升高使反硝化菌属占比降低，因此保持适当低超声功率对于系统实现短程SND至关重要，而过高的超声不仅会抑制NOB生长，而且会对某些反硝化菌属造成不可逆影响。最后通过C/N，DO及进水氨氮等条件控制，提出了超声辅助SBBR系统短程SND工艺运行措施。研究成果丰富了污水生物处理微生物学理论和工艺学原理，为高氨氮低C/N实际废水有效处理提供了可替代的解决方案。