【作者】 吴希锴；

【导师】 阮敏； 黄兢；

【作者基本信息】 长沙理工大学 ， 动力工程及工程热物理， 2022， 硕士

【摘要】 随着我国高速城市化和农村现代化事业的深入发展,城市污水处理厂的剩余污泥产量逐年增长,迫切需要对其进行安全有效的处理。好氧堆肥工艺被广泛应用于剩余污泥处理处置中。然而,在传统剩余污泥堆肥过程中经常存在发酵温度低、物料腐殖化程度低、固氮效果差等不足之处。为了解决这类问题,需要加入各类堆肥调理剂来优化堆体结构和改善堆肥条件,进而提高其堆肥效率和堆肥品质。近年来,人工湿地污水处理技术的逐年推广,使每年产生了大量的大型湿地植物,这些湿地植物应该如何解决成为了一个新的难题。同时,生物表面活性剂茶皂素被证实在提高微生物活性、促进木质纤维素降解和治理污染物方面具有一定应用潜力。因此,将大型湿地植物和茶皂素作为调理剂和剩余污泥进行联合好氧堆肥,不仅为大型湿地植物与剩余污泥的处理处置提供了一个可持续管理的解决方法,而且为进一步提高剩余污泥堆肥效率和改良堆肥品质提供了新的途径。本研究依次进行两批实验,分别研究了大型湿地植物和表面活性剂茶皂素作为调理剂时对剩余污泥好氧堆肥的影响。在剩余污泥-南荻堆肥体系中,以湿地植物南荻作为调理剂,南荻粒径作为变量,测定了堆肥过程参数、物料参数以及重金属总量和形态在堆肥过程中的变化,并通过光谱和热分析对堆肥物料的腐殖质和官能团进行表征。最后,通过冗余分析来评价堆体中环境参数和重金属形态变化之间的关系。结果表明:随着南荻粒径减小,堆体的保温能力增强、最高温度升高、嗜热阶段时间延长,堆体内的最高温度区域向堆体下层转移。同时,粒径减小促进了污泥堆肥过程中有机质降解、物料腐熟度和固氮效果。堆肥对于剩余污泥中的重金属的钝化效果较好,特别是Cd、Cu和Pb。对Cd和Cu的钝化效果是FM>CM>MM,对Pb的钝化效果是CM>FM>MM。通过傅里叶红外光谱、三维荧光光谱和热重分析的证实了在堆肥结束时FM中芳香结构和腐殖质类物质的含量最高。通过冗余分析表明,MM有利于提高污泥堆肥过程中的内部均匀性。在剩余污泥-芦苇-茶皂素堆肥体系中,以湿地植物芦苇和茶皂素(Tea saponin,TS)作为调理剂,茶皂素投加量作为变量,旨在研究TS对污泥堆肥过程中理化参数、有机质降解和微生物群落结构的影响。结果表明:与空白组相比,TS的添加延长了堆肥的嗜热阶段,并促进了总有机碳和可溶性有机碳的降解。在木质纤维素降解方面,TS的加入显著提高了半纤维素和纤维素的降解率,其中添加5%TS的效果最好。三维荧光光谱的结果表明,TS的添加提高了堆肥产品的腐殖化程度。此外,TS的添加明显改变了堆肥过程中细菌和真菌群落结构变化。在嗜热阶段,TS处理组中厚壁菌门的相对丰度均高于CK,而子囊菌门的相对丰度均低于CK。在成熟阶段,空白组中拟杆菌门更为丰富,而子囊菌门均低于TS处理组。冗余分析表明,添加TS显著影响了堆肥过程中细菌群落结构(主要是厚壁菌门)。这些结果表明,TS的加入为改善剩余污泥堆肥过程、提高堆肥效率提供了一种可行的策略。更多还原

【Abstract】 With the development of China’s high-speed urbanization and rural modernization,the total amount of excess sludge is increasing year by year.It is urgent to treat excess sludge safely and effectively.Aerobic composting is widely used in the treatment and disposal of excess sludge.However,in the traditional excess sludge composting process,there were often shortcomings such as low fermentation temperature,low degree of material humification,and poor nitrogen fixation effect.In order to solve these problems,it was necessary to add various compost conditioners to optimize the compost structure and improve the compost conditions,thereby improving compost efficiency and quality.In recent years,the promotion of sewage treatment technology in constructed wetlands has produced a large number of large wetland plants every year.How to solve these wetland plants has become a new problem.At the same time,the biosurfactant tea saponin has been confirmed to have certain application potential in improving microbial activity,promoting lignocellulose degradation and controlling pollutants.Therefore,the combined aerobic composting of large wetland plants and tea saponin as conditioners and excess sludge not only provides a sustainable management solution for the treatment and disposal of large wetland plants and excess sludge,but also provides a new way to further improve the efficiency and quality of excess sludge composting.In this study,two experiments were conducted to explore the effects of large wetland plants and the biosurfactant tea saponin(TS)as conditioners on excess sludge composting.To explore the effects of particle size of Triarrhena lutarioriparia on excess sludge composting,the changes of composting process parameters,material parameters and total and form of heavy metals were measured,and the humus and functional groups of the compost materials were characterized by spectral and thermal analysis.Then,the relationship between environmental parameters and heavy metal speciation was evaluated by redundancy analysis.The results showed that with the decrease of the particle size,the thermal insulation capacity of the pile increased,the maximum temperature increased,the time of thermophilic stage prolonged,and the maximum temperature area in the pile transferred to the lower layer.Meanwhile,the reduction of particle size promoted the degradation of organic matter,material maturity and nitrogen fixation effect in sludge composting process.Compost had a good effect on the passivation of heavy metals in excess sludge,especially Cd,Cu and Pb.The passivation effect of Cd and Cu was FM>CM>MM,and that of Pb was CM>FM>MM.The results of FTIR,EEMs and TGA confirmed that the content of aromatic structure and humus of FM was the highest at the end of composting.The redundancy analysis showed that MM was beneficial to improve the internal uniformity of pile.To explore the effects of tea saponin(TS)on excess sludge composting,the changes of physicochemical parameters,organic matter degradation and microbial community structure were measured.The results showed that compared with CK,the addition of TS prolonged the thermophilic stage of compost,and promoted the degradation of TOC and DOC.In terms of lignocellulosic degradation,the addition of TS significantly increased the degradation rates of hemicellulose and cellulose.The results of EEMs showed that the addition of TS improved the humification degree of compost products,and the TS addition of 5%had the best effect.In addition,the addition of TS significantly changed the community structure of bacteria and fungi during composting.In the thermophilic stage,the relative abundance of Firmicutes in TS treatments was higher than that in CK,while the relative abundance of Ascomycota was lower than that in CK.In the mature stage,Bacteroidetes were more abundant in CK,while Ascomycota were lower than those in the TS treatments.Redundancy analysis showed that adding TS significantly affected the bacterial community structure(mainly Firmicutes)in the composting process.These results suggested that the addition of TS provides a feasible strategy for improving excess sludge composting process and efficiency.更多还原