净水污泥吸附剂的制备及吸附去除废水中氨氮的行为与机制

Drinking water works sludge (DWS) is a waste by-product generated from drinking water treatment plants, with the characteristics of large amount, widely distributed and hazardous. Resource utilization is an effective way to reduce the environmental and social issues generated by DWS. The research of the utilization of DWS focuses on the major components, ways to reuse based on the compositions, as well as the principles and key techniques for implementing these methods. Using the comprehensive analyses of composition of DWS as a basis and also taking adsorbent preparation, structure and property, adsorption capacity and mechanism, absorbent regeneration as the main line, the key points of this research are to expose the effects of the compositions of DWS and preparation methods of DWS adsorbents on their structures and characters for finding out the correlation between component and structure and property. And on this basis, the adsorption behavior and capacity of ammonia nitrogen by DWS will be studied to evaluate its adsorption mechanism on a micro stratum. The desorption and regeneration of ammonia nitrogen adsorbent produced by DWS will be researched, as well as the ammonia removing capacity of DWS after being regenerated. This project aims to make innovative breakthroughs in approaches, principles and key techniques to the resource recycling of DWS, which should provide theoretical and technical support for the utilization of DWS.

净水污泥作为自来水厂产生的废弃物，具有数量多、分布广、有害性的特点，资源化利用是减小其所产生的环境及社会问题的有效途径。净水污泥资源化利用的核心问题是：净水污泥的主要成份构成是什么，基于这种成份构成进行资源化利用的方法，实现这种方法需要解决原理和技术上的科学问题。本项目将在全面分析净水污泥主要成份构成基础上，以净水污泥吸附剂的制备方法-吸附剂的结构特征与性质-吸附剂的吸附效能与吸附机制-饱和状态下吸附剂的解吸再生方法为主线，重点研究净水污泥组成、制备方法对吸附剂结构及性质的影响，探明净水污泥组成与吸附剂结构和性质的相关性；吸附剂对废水中氨氮的吸附行为与吸附效能，在微观层面上阐明吸附剂与氨氮吸附过程的作用机制；吸附饱和状态下吸附剂的解吸再生方法与再生后吸附效能；在净水污泥资源化利用的方法、原理和关键技术方面取得创新性突破，为净水污泥的资源化利用提供理论依据和技术支撑。

作为自来水厂水质净化产生的固体废弃物-净水污泥，因其量大并具有污染性的特点，如何有效进行处置一直是自来水行业比较棘手的问题，而将净水污泥资源化利用则是减小其所产生的环境及社会问题的有效途径。本项目提出利用净水污泥制备吸附剂，并用于吸附去除废水中的氨氮。以净水污泥吸附剂的制备方法-吸附剂的结构特征与性质-吸附剂的吸附效能与吸附机制-饱和状态下吸附剂的解吸再生方法为研究主线，重点研究了净水污泥吸附剂的制备及改性方法、吸附剂的性质及结构分析、净水污泥吸附剂对氨氮的吸附效能和吸附作用机理、吸附剂的解吸再生方法等内容，阐明了净水污泥吸附剂去除氨氮的吸附作用效能和作用机制。对净水污泥的组成进行分析，分析结果表明，净水污泥主要以O、Si、Al、Fe为主，合计占总量的90%以上，为净水污泥制备吸附剂提供了重要依据。以净水污泥复合高岭土或活性炭制备吸附剂，研究结果表明，复合后制备的吸附剂其比表面积均小于原泥制备的吸附剂，但对氨氮的吸附去除效果却好于原泥制备的吸附剂。进一步采用柠檬酸钠和硅酸钠对净水污泥吸附剂进行改性，研究结果表明，改性后的吸附剂其比表面积和对氨氮的吸附去除效果均有所提高。通过吸附动力学模型拟合证实，净水污泥吸附剂对氨氮的吸附符合准二级动力学模型，表明吸附是以化学吸附为主。通过Langmuir和Freundlich等温模型进行拟合，净水污泥吸附剂对氨氮的吸附更符合Langmuir模型。热力学研究结果表明，净水污泥吸附剂对氨氮的吸附为放热且熵增的自发过程。饱和吸附剂的解吸再生研究表明，NaOH溶液对吸附剂的解吸再生具有较好的效果，经过5次对吸附饱和的吸附剂进行解吸再生实验，再生吸附剂对氨氮的去除率仅下降6.53%。