超声强化晶种滤池的结晶除磷特性及其水质协同净化机制研究

Phosphorus removal from wastewater by crystallization arouse wide concern recently, but there are still some restrictions, such as insufficient supersaturation, slow crystal reaction rate, long crystallization time, ionic impurity and poor phosphorus removal efficiency, delayed the development of this technology, especially in low concentration phosphorus wastewater. Therefore, in this project, the power ultrasound is introduced to the seed crystal media filter to develop a novel technology for phosphorus removal and recovery. Firstly, the influence of power ultrasound on the phosphate crystallization in the solution and the bed of seed crystal media is considered to reveal the mechanism and characteristics of phosphate crystallization, which mainly focus on the magnesium ammonium phosphate (MAP) and calcium phosphate (CP). Secondly, a hybrid system of ultrasound -seed crystal filter is designed as well as the air aeration is introduced. Then, the mutual effects of sonic field, seed crystal, aeration and ionic condition on the phosphate crystallization with different influent quality are investigated to reveal the characteristics of the micro-interface phosphate crystallization reaction, and then, to expound the collaborative purification mechanism of wastewater treatment, in the air-solid-liquid heterogeneous system (seed crystal filter) combined with an ultrasound field. Finally, a novel process and technology consideration is put forward based on the operation results of the hybrid sonic field- seed crystal media filtration system for the treating of domestic wastewater.

针对目前废水结晶除磷过程，尤其是中低浓度含磷废水结晶除磷处理过程中面临的过饱和度条件差、结晶反应速率低、晶化时间长、杂质干扰和除磷不彻底等问题，本项目拟将功率超声引入晶种滤料过滤除磷过程，以磷酸铵镁和磷酸钙结晶除磷过程为主要研究对象，分别探讨功率超声对饱和溶液与晶种滤料结晶床（晶种滤池）磷结晶反应的强化效能，研究探讨其作用机制和作用规律；以超声-晶种滤池废水处理模型反应器为研究载体，系统考察不同水质条件下，声场、晶种、曝气和离子条件等物质相互作用对结晶除磷的协同强化效应，揭示超声作用条件下晶种滤池气、固、液非均相介质体系微界面的结晶除磷反应特性，阐明其微界面协同水质净化机制；在系统考察超声-晶种滤池处理生活污水工艺运行特性的基础上，提出基于声能-结晶过滤耦合作用的强化除磷废水处理工艺设计新思路和调控技术方法，为研究开发新型高效复合除磷技术提供科学依据和技术参考。

设计开发了磷酸铵镁（Magnesium Ammonium Phosphate，MAP）结晶反应测试装置，研究得出了溶液体系MAP结晶反应基本特性，阐明了功率超声对MAP结晶的介稳区宽度、反应诱导期和产物特征的影响作用规律，考察了超声作用时间和频率对MAP结晶反应除磷效果、活性污泥（生物膜）生物相、细菌总数以及代谢活性的影响；为探讨MAP结晶法处理含磷废水的工艺可行性，系统揭示了pH值、搅拌强度、镁磷比和氮磷比等条件对含磷废水MAP结晶除磷的影响作用规律，优化了含磷废水MAP结晶除磷反应条件。.在此基础上，利用前期研究制备的具有较强碱度和离子缓释效能的晶种滤料为过滤载体，构建了多套超声强化-A/O交替晶种滤料生物滤池含磷废水处理工艺系统，利用XRD、SEM、EDS和PCR-DGGE技术，研究考察了不同电子受体（亚硝酸盐和硝酸盐）对A/O交替运行晶种滤池脱氮除磷效果的影响作用规律，分析表征了超声/非超声条件下晶种生物滤池微生物种群结构特征与种群演替规律，对比考察了前置和中置超声装置强化MAP结晶-A/O交替晶种滤料生物滤池对城市污水中污染物的处理效能，在磷浓度9.5-12mg/L、氨氮浓度32-42 mg/L、COD浓度270-350 mg/L、pH值8.5-9.0的进水水质条件下，超声强化-A/O交替晶种滤料生物滤池系统的出水COD和氨氮均达到《城镇污水处理厂污染物排放标准》（GB18918-2002）的一级A标准，并且中置超声强化MAP结晶-A/O交替晶种滤料生物滤池具有更稳定的污染物去除效能和磷回收潜力。.在首次系统阐明MAP结晶基本特性的基础上，项目研究揭示了超声强化对晶种滤料-溶液反应体系结晶除磷特性的影响规律及协同强化结晶除磷效应，提出了超声强化与晶种滤池耦合工艺的设计思路及优化运行方法，为丰富磷回收工艺研究提供了理论和技术参考。