论文总字数：27102字

摘 要

本研究利用土壤天然结构上类似于微生物燃料电池上层好氧、下层厌氧的优势，构建了新型土壤微生物燃料电池（Microbial Fuel Cell，MFC），处理难降解有机农药阿特拉津，实现了降解有机农药同步产电的效果。为了进一步优化土壤MFC系统，本研究主要从电极间距和外接电阻两个方面研究系统对去除阿特拉津同步产电的影响，以提高系统性能，并由土壤MFC内的电子流动机制分析了土壤MFC促进阿特拉津降解作用的原因。

研究表明，不论外接电阻大小，闭路土壤MFC均可比开路对照组获得更高的阿特拉津去除率，且随着外阻值的减小，系统输出电压减小，电流增大，阿特拉津去除率也同时增加，外接电阻为20Ω的土壤MFC电压达到最小值6.3mV，电流达到最大值0.315mA，获得最高去除率95.0%。不同外接电阻的土壤MFC由于本身结构相同，内阻没有显著差异，且外阻接近内阻时可获得最大功率密度。

当电极间距由大变小时，电池内阻逐渐变小，但输出电流和功率密度先增大后减小，在电极间距为8cm时取得最大值，分别为0.240mA和19.4mW/m²，而电极间距为4cm时输出电流和功率密度最小，分别为0.142mA和6.8mW/m²。这是由于电极间距增大增加了电池系统内阻，而电极间距过小又会导致氧气渗入阳极，抑制产电微生物活性，阻碍了土壤MFC产电性能；在实验范围内，电极间距越小，阿特拉津的降解速率和去除率越高，电极间距为4cm、8cm、12cm的土壤MFC阿特拉津降解速率分别为1.38mg/(kg·d)、1.28 mg/(kg·d)、1.07 mg/(kg·d)，9周平均去除率分别为91.7%、84.9%、71.2%。综合考虑产电特性，认为电极间距8cm的土壤MFC具有最佳性能。

阿特拉津的降解反应主要优先发生在阴极和阳极附近区域，而两极间的中间层去除率较低，当两极去除率提高时，中间层的阿特拉津也能逐渐得到更好的去除。阴极与阳极的去除率相当，没有明显差异。由土壤MFC系统的电子流动机制，说明了电极作用下电子分配方式的改变及共基质效应是土壤MFC促进阿特拉津降解的重要原因。

关键词：土壤微生物燃料电池；阿特拉津；产电；电极间距；外阻

A Research on Bioelectrochemistry System’s Efficiency on Purification of Soil Organic Pollutants

ABSTRACT

In this study, a new type of soil Microbial Fuel Cell was constructed by taking advantages of the natural structure of soil similar to microbial fuel cell which is superficial aerobic and inferior anaerobic, to degrade the organic pesticide atrazine and generate electricity synchronously. In order to further optimize the soil microbial fuel cell (soil MFC) system, this study mainly studied the influence of the system on the removal of atrazine from the electrode separation distance and the external resistance in order to improve the system performance. The mechanism of soil MFC promoting the degradation of atrazine was analyzed by the electron flow mechanism.

The results show that, regardless of the external resistance, the closed-loop soil MFC can obtain higher atrazine removal rate than the open control group. With the decrease of the external resistance, the system output voltage decreases and the current increases. The removal rate of atrazine is increased at the same time. The maximum removal rate of 95.0% is reached when the external resistance is 20Ω, meanwhile the current reaches the maximum value of 0.315mA. The soil MFCs with different external resistance have similar internal resistance. The closer external resistance reaches the battery internal resistance, the greater power density can soil MFC get.

When the electrode separation distance reduces, the internal resistance of the battery becomes lower, yet the output current and power density first increase and then decrease. The maximum value of 0.240mA and 19.4mW/m² is obtained when the electrode pitch is 8cm. The minimum value of 0.142mA and 6.8mW/m² is obtained when the electrode pitch is 4cm. The reason is that the increase of the electrode separation distance increases the internal resistance of the MFC system, while the too small electrode separation distance will lead oxygen permeating into the anode, inhibiting the activity of exoelectrogenic microbes, and then hinder the electrongenesis performance of soil MFC. In the experimental range, atrazine attains higher removal rate when the electrode separation distance is smaller. The degradation rate and the atrazine removal rate of the soil MFCs with electrode pitch of 4cm, 8cm, 12cm is 1.38mg/(kg·d), 1.28 mg/(kg·d), 1.07mg/(kg·d) and 91.7%, 84.9%, 71.2%, respectively. Take consideration of the performance of electricity generation, the electrode separation distance of the soil MFC which is 8cm is recognized to have the best performance.

The degradation of atrazine mainly occurs in the regions of cathode and anode, while and the removal rate in the middle layer is low. When the removal rate in the electrode is increased, atrazine in middle layer can be removed better. There is no significant difference in the removal rate between the cathode and the anode. The electronic flow mechanism of the soil MFC system shows that the change of the electron distribution mode and the co - substrate effect under the action of the electrode are the important reasons for the degradation of atrazine by soil MFC.

Key words: soil microbial fuel cells; atrazine; electrogenesis; electrode separation distance; external resistance

目 录

摘 要 I

ABSTRACT III

第一章 绪论 1

1.1土壤污染与难降解有机农药 1

1.2MFC技术 2

1.2.1MFC的工作原理 2

1.2.2MFC处理沉积物中难降解有机物概况 3

1.3研究目的及内容 4

1.3.1研究目的及思路 4

1.3.2研究内容 4

第二章 实验材料及分析方法 5

2.1实验装置 5

2.2实验材料、药品及仪器 6

2.2.1污染土壤的制备 6

2.2.2接种污泥的处理 6

2.2.3实验药品与仪器 6

2.3实验设置 7

2.4测定项目及方法 7

2.4.1电池性能指标 8

2.4.2土壤样品的分析测定方法 9

第三章 土壤MFC系统降解阿特拉津及产电影响因素的研究 12

3.1不同外阻土壤MFC的产电及阿特拉津降解特性 12

3.1.1产电特性 12

3.1.2阿特拉津降解特性 15

3.2不同电极间距土壤MFC的产电及阿特拉津降解特性 18

3.2.1产电特性 19

3.2.2阿特拉津降解特性 22

3.3土壤MFC促进阿特拉津降解作用分析 24

3.4小结 24

第四章 结论与展望 25

4.1研究结论 25

4.2研究展望 25

参考文献 26

致 谢 28

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