活性炭内嵌MOF对市政污泥恶臭有机物的吸附性能及协同作用机制

The sludge treatment process combining pyrohydrolysis, anaerobic digestion and deep sludge dehydration has received more attention recently in China for the increased biogas emission and sludge minimization in Municipal Wastewater Treatment Plants. However, it greatly rises the release amount of malodorous volatile organic compounds (MVOCs) with more complicated components which result in the disposal difficulty. The understanding of the release law and the development of efficient removal technology are therefore highly significant. This project aims to analyze the composition and concentration of MVOCs and their release law during the sludge treatment process. According to the structure feature of MVOCs such as kinetic diameters, functional groups, et al, corresponding MOFs will be designed in view of pore sizes, specific surface areas, active sites, et al. Then the MOF will be embedded in the mesoporous matrix of activated carbon in-situ and the activated carbon embedded MOF complexes with high efficiency, broad-spectrum absorption and renewability can be obtained. Their adsorption and regeneration properties will be evaluated by single MVOC, simulative MVOCs and practical MVOCs, respectively. The relationships between MVOCs removal efficiencies and the microstructures of activated carbon embedded MOF complexes (activated carbon, MOF, the MOF/activated carbon ratio, et al) will be discussed. The kinetic models will be established and their synergistic mechanism will be revealed. As a result, the absorbents with perfect performance will be obtained by optimizing the structures of complexes repeatedly. The project achievements are expected to promote the treatment level of malodorous gas from sludge in China.

为了提升市政污水处理厂污泥的能源化和减量化效能，污泥“热水解—厌氧消化—深度脱水”处理工艺在我国日益受到关注。然而工艺线的拉长也导致挥发性恶臭有机物（MVOCs）释放量大幅上升，且成分更加复杂，处理难度加大。解析污泥处理过程中MVOCs释放规律和开发高效恶臭控制技术具有重要意义。本项目通过分析污泥各处理单元MVOCs组成和浓度，解析其释放规律，根据MVOCs动力学直径、官能团等特性，从孔径、比表面积、吸附位点等方面进行MOFs结构设计，原位合成高效、广谱、可再生的活性炭内嵌MOF复合吸附材料。通过对单一、模拟和实际污泥MVOCs吸/脱附性能研究，评价吸附材料的吸附特性和再生性能，深入探讨活性炭内嵌MOF（活性炭、MOF及MOF嵌入量等）结构与MVOCs去除之间的构效关系，建立吸附动力学模型，揭示其协同去除机制，通过不断的结构优化获得高效吸附材料。项目成果有望提升我国污泥恶臭污染物治理水平。

污泥“热水解—厌氧消化—深度脱水”处理是实现污泥的能源化和减量化效能的重要工艺。然而工艺线的拉长也导致挥发性恶臭有机物（MVOCs）释放量大幅上升，且成分更加复杂，处理难度加大。解析污泥处理过程中MVOCs释放规律和开发高效恶臭控制技术具有重要意义。本项目分析了污泥在热水解和化学调理（Fenton处理、酸化处理、PAC调理和FeCl3+CaO调理）过程中MVOCs的组成和浓度，结果表明，不同化学调理方式对污泥释放的恶臭气体的组份和浓度有很大影响，H2S、NH3和VOCs的释放量显著增加，其中Fenton调理下H2S和NH3的释放量最大， VOCs中主要成分是苯系物和烃类；热水解过程中产生的恶臭污染物包括硫化氢、甲硫醇、甲硫醚、二甲二硫醚等。 根据MVOCs分子的结构特点，设计合成了的汉麻杆基生物炭、系列MOFs、富含N、S或P的多孔聚合物及MOFs@活性炭等吸附材料，并进行了结构表征。研究了吸附材料对多种污染物如甲硫醚、乙硫醇、乙硫醚、吲哚、盐酸四环素、阳离子染料、阴离子染料、放射性碘等的吸附行为，建立了吸附动力学模型，探讨了吸附剂结构与MVOCs去除之间的构效关系，解释了吸附作用机理。在商业活性炭内嵌入10%的MOF-101，其吸附甲硫醚的穿透容量提高了1.7倍，对乙硫醚、乙硫醇及吲哚等恶臭污染物均具有良好的吸附性能，对甲硫醚、乙硫醇和乙硫醚的穿透硫容分别达到29.05 mg S g-1、29.05 mg S g-1和135.97 mg S g-1，且吸附材料易于再生和重复使用；制备的汉麻杆基生物炭比表面积和孔容分别达到3436 m2∙g-1和1.96 cm3∙g-1，对恶臭污染物、盐酸四环素、染料等均具有良好的吸附行为，吸附容量高，对甲硫醚的动态吸附穿透容量是商业活性炭的3.6倍以上。本项目研究获得的吸附材料在污染物吸附去除方面具有良好的应用前景。