基于微藻营养模式和氮丰度转换处理高氨氮废水技术及机理研究

Treatment of ammonium (NH4+-N) rich wastewater is a world-wide challenge, traditional method of activated sludge removes NH4+-N through nitrification- denitrification process, which has high organic carbon requirements and could generally be satisfied only with addition of external carbon source. Construction and operation of the indispensable aeration equipment further increased the cost of wastewater treatment. Photoautotrophy, mixotrophy, and heterotrophy are the three major trophic modes for microalgae. Most microalgae only grow photoautotrophically, some can grow heterotrophically and/or mixotrophically. Nitrogen (N) is an important element influencing the growth of microalgae, synthesis of N required compounds such as protein, nucleic acid, and chlorophyll are generally impeded under N deprivation, causing the growth of microalgae significantly slowed down or even to a halt. Meanwhile, carbon metabolism pathways would shift from protein synthesis to lipid or starch synthesis, as storage for energy and carbon source. Previous studies only focused on the growth and cell composition of microalgae after N deprivation, growth and NH4+-N uptake after recovering from N deprivation has rarely been researched. Therefore, this thesis studied a three-stage high NH4+-N wastewater treatment process was proposed by using selected high-N tolerant mciroalgae as model, utilizing the advantageous strain’s trophic mode and N sufficiency/deprivation conversion to enhance NH4+-N removal. And various approaches were attempted to optimize the proposed three-stage process, deeper mechanism analysis by using transcriptomics and proteomics were also carried out. All these studies would have great practical significances on improving biomass productivity for biofuel production and offering a new solution for effective ammonium rich wastewater treatment.

高氨氮废水净化是世界范围的一大难题，传统活性污泥法通过硝化-反硝化去除氨氮，需外加有机碳源。曝气设备建设运营、有机碳源的投加均增加了废水处理成本。菌藻系统或单纯微藻系统的引入，有望成为解决传统活性污泥处理高NH4+-N废水局限的新思路。本项目拟以筛选的耐受高NH4+-N废水藻株为对象，将营养模式与氮丰度转换相结合，分三阶段培养微藻，即丰氮异养/混养-氮饥饿异养/混养-高氮自养模式，并对照全阶段自养和无氮饥饿阶段的培养组，明确微藻营养模式和氮丰度转换的高NH4+-N去除潜能与细胞组分变化特征，围绕异养/混养-自养和氮饥饿-丰氮转换过程，研究微藻营养模式和氮丰度转换与微藻利用、吸收高NH4+-N的相互关系和关键优化因素，同时通过比较转录组及蛋白质组学揭示微藻高效吸收氨氮的代谢流变化规律和分子调控机制，为需找合理、经济和高效的基于微藻高NH4+-N废水处理方法奠定理论基础和提供可行的技术新思路。

高氨氮废水净化是世界范围的一大难题，传统活性污泥法通过硝化-反硝化去除氨氮，需外加有机碳源。曝气设备建设运营、有机碳源的投加均增加了废水处理成本。菌藻系统或单纯微藻系统的引入，有望成为解决传统活性污泥处理高NH4+-N废水局限的新思路。本项目拟以筛选的耐受高NH4+-N废水藻株为对象，将营养模式与氮丰度转换相结合，分三阶段培养微藻，明确微藻营养模式和氮丰度转换的高NH4+-N去除潜能与细胞组分变化特征，围绕氮丰度和营养模式转换过程，研究微藻营养模式和氮丰度转换与微藻利用、吸收高NH4+-N的相互关系和关键优化因素，同时通过比较转录组及蛋白质组学揭示微藻高效吸收氨氮的代谢流变化规律和分子调控机制。结果显示筛选获得的三株耐高氨氮淡水藻Chlorella sorokiniana、Scenedesmus sp.、Chlorella vulgaris在同一葡萄糖浓度下，兼养条件下的生物量高于自养、异养生物量之和，即兼养时存在自养与异养的协同效应；其脂质含量差异为C. vulgaris > C. sorokiniana > Scenedesmus sp.，接种生长期对三种微藻自养、异养、兼养生长特性及脂质含量有明显影响。营养模式与氮丰度转换处理显示氮饥饿组UMN266 Chlorella sorokiniana对NH4+-N去除比丰氮组有明显优势，氮丰度相同时异养组的NH4+-N去除普遍高于兼养组；优化实验结果表明提高光照强度并外加无机碳源时，可显著促进UMN266的生长以及对NH4+-N的去除；原种异养流程各组的NH4+-N去除能力不如原种自养流程。从垃圾渗滤液中筛选的藻株显示NCU7藻株具有较强的氨氮耐受性及氮丰度变化适应性，不同营养模式下，NCU7藻株的生长速度关系为兼养＞异养＞自养，氮饥饿处理组微藻对氨氮的去除能力高于丰氮组，而相同的氮饥饿条件下营养模式处理组微藻对NH4+-N的去除能力为兼养组>异养组>自养组；第3阶段转高氮兼养时，再次表明兼养缺氮（M,DN）处理组效果最佳，且氨氮去除率达100%。这表明在实际工程应用中，最后阶段更适合采用兼养培养，实现微藻对氨氮的高效去除，该工作对利用微藻处理高氨氮废水工程化应用提供了理论基础及数据支撑，具有重要意义。