不同原料生物炭对水土环境修复的研究

发布时间：2018-05-16 01:46

本文选题：污泥 + 垫料　；参考：《扬州大学》2017年硕士论文

【摘要】：近年来,随着污水处理的普及,污泥产量剧增;同时随着发酵床养殖技术的应用与推广产生了大量的废弃垫料,如何发挥这些废弃物的内在价值,将其变废为宝已成为当前研究的热点。热解能够将有毒有害成分高效降解和稳定化,是目前较有发展潜力的一种生物质废弃物的处置方式。生物炭(biochar)是由废弃生物质在厌氧或限氧环境下,热解得到的一类稳定的、高度芳香化的多孔状富碳固型材料。由于生物炭含有丰富的表面含氧官能团、发达的孔隙结构及丰富的元素组成,其在固碳、温室气体减排、土壤改良和作物增产等多个方面具有良好的应用前景并受到广泛关注。本文以生活污泥和废弃垫料为原料,在不同温度的氮气保护无氧气氛下热解制备生物炭(记为W500、W600、W700和D500、D600、D700,其中W代表污泥,D代表垫料,所跟数字代表炭化温度),利用元素分析仪、场发射扫描电子显微镜(SEM)、BET比表面积仪、傅立叶变换红外光谱仪(FT-IR)等方法分析其元素组成、表面形貌及其比表面积,分析了热解温度对生物炭特性的影响;采用批量吸附实验研究了吸附时间和溶液平衡浓度对生物炭吸附水溶液中Pb2+的效果;采用土壤培养实验通过BCR分级提取方法研究生物炭对污染土壤中重金属形态和微量元素形态变化影响;并采用盆栽实验研究生物炭对植株生物量和地上部重金属含量累积的影响,结合生物炭特性,分析Pb、Cd化学形态随时间的变化规律,揭示生物炭对土壤改良的效应,以期为生物炭修复污染土壤提供理论支持。主要结论如下:(1)随着制备温度的升高,原料结构都被逐步破坏,污泥与垫料生物炭的产率逐渐下降,pH值和灰分含量逐渐升高,含氧官能团含量减少,CH2、C=C、C=O等基团逐渐减少。(2)两类生物炭对Pb2+的吸附均在24h后可达到表观平衡。生物炭对Pb2+的吸附能力高低次序为:D500D600D700W600W700W500,其中吸附能力最佳的D500对Pb2+的饱和吸附量为97.96mg·g-1。生物炭对Pb2+的吸附过程更符合准二级动力学模型,其中W600和W700对Pb2+的吸附可用Freundlich等温方程较好的拟合,而W500和垫料生物炭则更符合Langmuir模型。(3)添加生物炭后,污染土壤pH值不同程度地升高,并且随平衡时间的延长而显著升高。生物炭对重金属都有很好的固定效果,且对Pb的固定效果优于Cd。同时,Pb在复合污染中的固定效果优于单一污染,而Cd的固定效果与此相反。(4)添加生物炭能提高苏州青地上部的生物量,并降低植株内Pb、Cd含量,与W600相比D500有更好的效果;与对照组相比,在单一污染土壤中,小青菜中Pb、Cd含量的降幅达到显著水平,在复合污染土壤中尚未达到显著水平。(5)生物炭对污染土壤中不同微量元素的影响不相同;综合来说垫料生物炭比污泥生物炭更适合钝化修复重金属Pb、Cd的污染土壤。
[Abstract]:In recent years, with the popularization of sewage treatment, sludge production has increased dramatically. At the same time, with the application and popularization of fermentation bed culture technology, a large number of waste pads have been produced, so how to play the inherent value of these wastes, Turning it into a treasure has become the focus of current research. Pyrolysis can effectively degrade and stabilize toxic and harmful components, which is a potential disposal method of biomass waste. Biochar is a kind of stable, highly aromatized porous carbon-rich solid material obtained from the pyrolysis of waste biomass in anaerobic or oxygen-limited environment. Because of its abundant surface oxygen functional groups, well developed pore structure and abundant element composition, biochar has a good application prospect in carbon sequestration, greenhouse gas emission reduction, soil improvement and crop production. In this paper, biochar was prepared by pyrolysis of living sludge and waste gasket in anaerobic atmosphere of nitrogen protection at different temperatures (W500U W600 W700 and D500 D600 D600 D700, where W represented sludge D as gasket, followed by figures representing carbonization temperature and temperature), and element analyzer was used. Field emission scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the element composition, surface morphology and specific surface area. The effect of pyrolysis temperature on the properties of biochar was analyzed. The effects of adsorption time and solution equilibrium concentration on adsorption of Pb2 in aqueous solution of biochar were studied by batch adsorption experiments. The effects of biochar on the speciation of heavy metals and trace elements in contaminated soil were studied by BCR method. The effects of biochar on plant biomass and accumulation of heavy metals in aboveground were studied by pot experiment. In combination with the characteristics of biochar, the changes of chemical forms of Pb, CD with time were analyzed, and the effects of biochar on soil improvement were revealed. In order to provide theoretical support for biochar remediation of contaminated soil. The main conclusions are as follows: (1) with the increase of preparation temperature, the structure of raw material is destroyed gradually, the yield of sludge and biochar decreases gradually and the pH value and ash content increase gradually. The content of oxygen functional groups decreased and the groups such as Ch _ 2H _ 2C _ (C _ (C) C _ (C) C _ (C) O) gradually decreased. (2) the adsorption of Pb2 by two kinds of biochar could reach the apparent equilibrium after 24 hours. The adsorption ability of biochar to Pb2 was in the order of: D500D600D700W600W500. among them, the saturated adsorption capacity of D500 to Pb2 was 97.96mg g-1. The adsorption process of biochar on Pb2 is more in line with the quasi-second-order kinetic model. The adsorption of W600 and W700 on Pb2 can be fitted well by Freundlich isothermal equation, while W500 and biochar on the pad accord with Langmuir model. 3) after adding biochar, the adsorption of W600 and W700 on Pb2 can be fitted well by Freundlich isothermal equation. The pH value of contaminated soil increased in varying degrees and increased significantly with the increase of equilibrium time. Biochar has a good fixation effect on heavy metals, and the fixation effect on Pb is better than that on CD. At the same time, the fixation effect of Pb in compound pollution was better than that of single pollution, whereas CD fixation effect was opposite. The addition of biochar could increase the aboveground biomass and reduce the content of Pb and CD in the plant. Compared with W600, D500 had a better effect. Compared with the control group, in the single polluted soil, the content of Pb ~ (2 +) CD in green vegetables decreased significantly, but in the compound polluted soil, it did not reach the significant level. (5) the effect of biochar on different trace elements in polluted soil was different. Generally speaking, biochar is more suitable than sludge biochar for passivation and remediation of heavy metal Pb ~ (2 +) CD contaminated soil.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;X703

【参考文献】