旋流场强化活性污泥释碳机理及其对菌群结构的影响机制

How to effectively and economically remove the nitrogen from sewage with low C/N ratio and reduce sludge yield is the key issue of municipal wastewater treatment in recent years. Hydrocyclone disintegration technology could be used for return activated sludge disintegration to release part organic matters. The organic matters can be used as supplementary carbon sources to promote denitrification and enhance bacteria activity responsible for water pollutants degradation. This technology has the potential in achieving advanced nitrogen removal and in-situ sludge reduction. However, the responding mechanisms of carbon release and microbial community in the hydrocyclone are not fully clear..This project intends to study the effects of operation parameters and geometric structures on sludge disintegration rate and organics release, further obtaining the main factors affecting the carbon release and optimum operation conditions. Microscopic characterization techniques(FT-IR and Roman technique) could be used to investigate the sludge chemical structure and the main migration site of internal carbon sources. Then, fluorescence in situ hybridization technique was used to research the change rule of microbial community structure and activity after long-term hydrocyclone treatment. Numerical simulation technology was used to analyze the whole flow field for sludge-water two-phase fluid flow in the hydrocyclone and hydraulic characteristics. Based on the above, combining fluid dynamics, the relevance between the dynamic characteristics of the flow field and internal carbon sources migration and microbial community structure variation would be founded. The regulatory mechanism of carbon release and bacteria optimization enhanced by the hydrocyclone would be illustrated. The obtained results should be of great benefit for the improvement and practical application of the technology.

如何经济有效地实现废水深度脱氮和污泥减排是当前低C/N比城镇污水处理工程面临的重大难题。旋流破解技术可用于在线释放回流活性污泥内部分有机质以补充反硝化反应所需碳源、同时强化菌群活性用于降解水体污染物，其在高效脱氮和原位污泥减量上具有应用前景。但旋流场中污泥释碳和菌群响应机制尚未明确。.本项目拟系统考察操作参数和几何结构对污泥破解率和内碳源释放的影响，确定主要作用因素和最佳操作工况，并结合红外、拉曼等技术从分子水平上表征污泥化学结构和内碳源迁移主要位点；采用荧光原位杂交技术考察旋流驯化作用下菌群结构和活性的变化规律；同时采用数值模拟技术获取旋流场中泥/水两相流流场全貌和水力特性。在此基础上，结合流体力学理论，建立流场形态与内碳源迁移、菌群结构变化之间的关联，阐明旋流强化活性污泥释碳和菌群结构的调控机制。为该技术的完善和推广建立可靠的理论基础。

低碳氮比城镇废水高效处理是国民经济和社会发展亟待解决的关键问题，旋流破解技术有望实现高效脱氮和原位污泥减量。本项目采用实验和模拟方法系统研究了旋流场作用下污水处理系统回流活性污泥释碳特性和菌群自身结构特征、活性变化规律，揭示旋流驱动活性污泥释碳机理。研究发现，污泥经旋流破解后，污泥粒径变小，污泥沉降性能仍能保持在正常范围内；在强剪切力和湍动作用下污泥细胞内外多糖、核酸等有机质流出，补充了反硝化反应中硝态氮转化为亚硝态氮时所需碳源，可实现内碳源回用；微观表征结果可知，旋流作用后细菌表面的丝状污染物得以脱除，细胞表面光滑，更有利于降解水体污染物；提出耦合旋流释碳器的缺氧/好氧污水处理新工艺，活性污泥活性增强，出水水质改善，实现了深度脱氮和污泥减量；结合模拟和泥粒的受力分析可知，旋流释碳过程主要是以剪切力和自转离心作用为主，以挤压和随机脉动为辅,在剪切流场长期作用下污泥表面得以更新，孔隙得以疏通，从而增加氧气和营养物质的传质速率，提高吸附能力，释放的多糖等有机碳源得以回用。而且，脱除污泥内胞外聚合物有利于强化胞外酶活性，促进胞外蛋白质、胞外多糖和胞外酶由絮体内部向外部转移，提高有机质的降解效率和深度脱氮。研究结果将为耦合旋流破解技术的污水处理优化工艺的工程应用提供基础。