水力空化降解有机废水作用机理研究

With the rapid development of the national economic construction and the society, both the city scale and the population continue to be expanded. The resultant discharge of wastewater containing a large number of harmful chemicals and difficultly degradable organic compounds increases year by year. The traditional wastewater treatment methods cannot meet the new environmental requirements, and therefore it is very urgent to research and develop the new-type wastewater treatment method and technological process. Based on the significant demand for the country's economic construction and social sustainable development, this project keeps up with the international research focus, and systematically studies the degradation mechanism of organic wastewater by hydrodynamic cavitation with the combination of theoretical analysis, numerical simulation and experimental investigation. Through investigating the dynamics of cavitation bubble in wastewater solution and the characteristics of cavitating flow, the intrinsic relationship between the dynamics of cavitation bubble and the degradation reaction will be established, and the microscopic mechanism of hydrodynamic cavitation degraded organic pollutants is also expected to be revealed. By exploring the difference and relation of degradation dynamics between single component and multi-component organic wastewaters, the effect mechanism of wastewater's composition characteristics on the degradation dynamics will be accurately revealed. By means of experimental investigation, the effect law of operational and structural parameters on the degradation process will be grasped. On this basis, the enlarged design criterion of cavitation reactor structure is expected to be established as well as the related optimization design method. The ultimate goal of this project is to lay a solid theoretical foundation and provide an important technical support for the hydrodynamic cavitation technology to be used in wastewater treatment.

随着国家经济建设和社会的快速发展，城市规模与人口数量不断扩大，废水排放量与日俱增，水中有害化学物质和难降解有机物逐年增多，传统水处理方法已无法满足新的环保要求，迫切需要研发新型废水处理方法与技术工艺。本项目立足国家经济建设和社会可持续发展的重大需求，紧跟国际前沿研究热点，采用理论分析、数值模拟与实验研究相结合的方法，对水力空化降解有机废水作用机理进行系统深入研究。通过深入研究废水溶液中空化泡的动力学特性以及废水溶液的空化流动特征，建立空化泡微观动力学特征与降解反应的内在联系，揭示水力空化降解有机污染物微观机理；探索水力空化作用下单组份有机废水与多组份有机废水降解动力学特性的区别与联系，揭示废水成份特征对降解动力学特性的影响机理；掌握系统运行与结构参数对降解过程的影响规律，建立空化反应器结构放大设计准则，发展相关优化设计方法，为水力空化技术用于废水处理奠定坚实的理论基础并提供重要技术支撑。

工业的不断发展，使得水体中人工合成化学物质和难降解大分子有机物逐年增多，迫切要求开发新型水处理方法和技术工艺。水力空化技术作为一种设备简单、无二次污染的高级氧化技术成为国内外学者研究的热点。课题采用理论研究与实验研究相结合的手段，对水力空化技术应用于废水处理领域的若干基础与关键科学问题进行研究。理论研究方面，构建了单空泡动力学模型，再现了空化泡沿流动方向生长、溃灭和反弹的动力学行为过程，揭示了空化降解有机物的微观机理。在此基础上，考虑液体气核半径分布和空化事件发生率，建立了空泡群全生命周期自由基产量计算模型，从运行参数和结构参数影响两方面对模型准确性进行了验证，提出了适合污水处理领域应用的羟基产量计算关连式，用于优化空化反应器结构和系统运行参数，指导空化反应器放大设计。理论研究结果表明，空化泡溃灭瞬间泡内引发了73个可逆化学反应，生成了26种组分，其中强氧化性组分中羟基自由基含量最高，它对有机物的氧化是空化降解的主要机制。实验研究方面，首次提出了对冲空化射流强化有机废水降解的新方法，对单组分罗丹明B和多组分抗生素废水的降解进行了系统研究，提出了适合实际工业应用的多种高级氧化方法结合的水处理系统。实验研究结果表明，降解反应过程符合一阶反应动力学特性，对冲空化射流强化了有机物降解。单独采用对冲空化射流，最优条件下罗丹明降解率可达71.11%。采用对冲空化射流与芬顿法结合的方法，可实现罗丹明B的完全降解，并且可减少过氧化氢用量，降低操作成本，在能量利用率方面比其它空化装置有明显优势。采用对冲空化射流、芬顿法和光催化氧化法等多种高级氧化方法结合的水处理系统，抗生素废水的COD去除率可达到79.92%，且各种高级氧化方法之间具有相互协同的作用。综合考虑降解率和经济性，多种高级氧化技术结合的方法效果最佳。本课题的实施，将为水力空化技术在废水处理领域的实际应用奠定坚实的理论基础并提供重要技术支撑。