基于吸附-结晶法去除与回收常规生物处理尾水氮磷的方法研究

Currently, the sewage treatment plants across the country are popularly upgrading and rebuilding for adding removal of nitrogen and phosphorus units on the base of conventional biological treatment process, it aiming at removing and reducing the nitrogen and phosphorus concentration of the effluent. However, as the role of plant nutrient and the resources, nitrogen and phosphorus are facing the problem of resource shortage, especially the phosphate rock resources are almost exhausted. The municipal sewage collects all kinds of waste from production and life pollutant discharge, the concentration of nitrogen and phosphorus in the municipal sewage are only lower than the concentration of organic pollutants. The conventional biological sewage treatment process is mainly aiming at the removal of organic pollutant, however the removal of nitrogen and phosphorus are just for satisfying the need of microbial growth, so the effluent have still been remaining some nitrogen and phosphorus (TN 15-60mg/L, give priority to with ammonia nitrogen, TP 3-10mg/L). This study will be targeting at the removing and recycling of nitrogen and phosphorus simultaneously, which is differing from other correlative studies including the removal technologies of nitrogen and phosphorus for municipal sewage and the recycling method of phosphorus for rich phosphorus wastewater. The project will discuss the feasibility of removal and recycling nitrogen and phosphorus by adsorption method from the effluent of conventional biological treatment process. By optimizing and modifying the nitrogen and phosphorus adsorbent, and analyzing the mechanism of adsorption, desorption and regeneration, as well as studying nitrogen and phosphorus recycling method and technology, the program will put forward the methods and technologies of adsorption-crystallization process for the removing and recycling of nitrogen and phosphorus simultaneously based on effluent from conventional biological sewage treatment process. It will be the revolution and innovation on the concept of sewage disposal technology in the light of recycling the resources and simplifying the removal technology for nitrogen and phosphorus of municipal sewage. So it will have some scientific significance and application trend.

当前全国各地污水处理厂正在普遍进行升级改造，其目的是在常规生物处理工艺基础上增加脱氮除磷环节，降低外排水氮磷含量。然而，氮磷作为植物营养元素和生产资源，正面临着资源短缺问题，特别是磷矿资源几近枯竭。城市污水汇集了生产、生活排放的各类废弃物，其中氮磷含量仅次于有机物。常规污水生物处理主要针对有机物去除，氮、磷去除仅是满足微生物生长所需，故出水中仍含有一定浓度氮磷（TN15-60mg/L,氨态氮为主,TP3-10mg/L）。区别于脱氮除磷和富磷污废水磷回收研究，本研究从氮磷去除并同时回收角度，探讨吸附-结晶法回收常规生物处理尾水中氮磷可行性，通过对氮、磷吸附剂优化改性、吸附解吸再生机理、回收方法及其工艺技术研究，提出基于吸附-结晶法去除并回收常规生物处理尾水氮磷的方法与工艺技术。本研究从氮磷回收和简化脱氮除磷工艺角度考虑，是对污水处理技术的变革创新，具有科学意义和应用前景。

针对污水传统生物处理工艺氮磷去除率低，生物脱氮除磷技术存在工艺复杂、处理效果不稳定、且不能回收氮磷问题，基于传统生物处理尾水中铵磷存在形态与低浓度特征，选择对NH4+、磷酸根具有吸附选择性的几类吸附剂（天然沸石、人工合成分子筛、水滑石等），通过优化制备条件和改性处理，考察了吸附剂结构变化与吸附性能改善之间的响应关系，确定了各种吸附剂制备方法及其脱氮除磷作用机制。在此基础上，进一步考察了饱和吸附剂再生利用方法与吸附性能恢复机制，建立了基于铵/磷回收的饱和吸附剂在线解吸再生方法。构建了套筒式机械搅拌磷酸镁铵（MAP）结晶-斜板强化沉淀反应器用于饱和铵/磷吸附剂解吸液回收利用，通过对其内部结构优化与流态模拟，提出了满足混合、结晶、沉淀、分离不同流态要求的反应器流态调控策略与模拟方法，可为不同流态要求的反应器结构设计与流态调控提供针对性解决方案。为探讨吸附剂工程应用可行性，考察了尾水基体和共存离子对吸附剂脱铵除磷的干扰影响，明晰了主要干扰因子以及减少干扰的措施。基于各类吸附剂制备技术及其吸附/再生性能对比分析，提出了适宜传统生物处理尾水吸附脱铵除磷深度处理与铵/磷回收的技术路线。.本研究阐明了高效铵磷吸附剂吸附/再生理论，明确提出采用适宜成分的天然沸石原料经碱溶-纯化法合成的低硅型分子筛是吸附法深度脱铵的首选吸附剂，该吸附剂具有吸附容量高、吸附速率快，容易实现原位解吸再生的特点。Mg/Al水滑石、镧改性合成滤渣均具有较强的吸附磷酸根性能，从饱和吸附剂原位解吸再生角度考虑，镧改性合成滤渣吸附除磷更具有工程应用价值。采用上述吸附剂脱氮除磷去除率均可达90%以上，铵/磷解吸液回收合成MAP的氨氮、TP回收率分别达76.00%、97.00%以上。上述研究成果拓展了吸附法在污水深度处理与资源回收技术领域的应用潜力，具有一定的理论与技术创新性，可为传统生物处理尾水深度脱氮除磷与氮磷回收提供理论指导和技术参考。