【作者】 李静；

【导师】 王晓慧；

【作者基本信息】 北京化工大学 ， 环境科学与工程， 2016， 硕士

【摘要】 当前我国的环境污染问题十分突出,同时伴随着环境污染而生的能源短缺也同样不容小觑。如果能从污染物中回收资源,或在解决污染的同时产生能源,这将能同时缓解我国的环境污染和能源短缺两大问题。微生物燃料电池(microbial fuel cells,MFC)是一个能将污染转化为能源的先进技术,如果将污染物作为阴极电子受体(如重金属),便可实现两种污染物质同时去除并产生电能,因此可以利用MFC技术处理重金属废水。本文针对改进MFC启动时间长,或因产电不够稳定、处理重金属速率低下等问题,采用串并联的研究手段,研究了串并联的运行模式下MFC的产电性能以及对重金属的去除效率。实验结果如下：(1)通过间歇并联的连接模式成功加速MFC的启动速率。从开始启动时对照组要经过10天后才会产生较低的电压(100 mV以下),但间歇并连运行的MFC,在并联阶段的最大电压可达到467 mV,在解除并联后的第三天电压开始呈现出上升趋势,基本间歇并连15天后实验组的MFC电压趋于稳定,在15天时,不再实施间歇并连,电压仍然能够达到持续稳定在170±3 mV,在本研究中所使用的双室MFC(阴极电子受体不同)使用间歇并联的模式可以将启动时间缩短5-7天左右。(2)通过对同种浓度和pH下的三种化学阴极进行比较筛选(KMnO4、 K3[Fe(CN)6]、K2Cr2O7),KMnO4以其较低的生物毒性和较高的产电效率,成为串联阶段电源补给MFC的阴极电子受体。并进一步对KMnO4阴极运行条件进行优化,pH为3时KMnO4-MFC电压随着KMnO4浓度的增大(浓度依次为0.5,1.0,2.0 g/L)而增加。(3)通过KMnO4-MFC与Cu-MFC串联,前者产生的较高电压为后者提供电压和功率补给,加速处理含铜废水过程并获得额外电能。二者串联能够明显加快Cu-MFC对Cu2+的回收速率,串联时Cu2+的回收率可达98%,24 h回收率可达91.7%,与单独Cu-MFC相比速率提高一倍。二者串联后,在加速铜回收过程的同时还能获得额外的电能,其最高输出功率可达143 mW；(4)通过使用间歇式无功率输出并联模式,加速重金属污水在MFC阴极的去除。阳极在序批式培养模式下,可弥补因电压动力不足造成的重金属去除效率低下的问题,通过间歇并联后的MFC重金属20 h内去除率提高了1.75倍。经过间歇并联后的MFC,恢复串联10 h后的重金属平均去除率便可达到67%,串联时间达到20 h时,Cu2+、Zn2+、Cd2+三种重金属离子的去除效率分别达到91.5%,86.7%,和83.57%,未经并联模式的对照组MFC运行20 h处理效率仅达到52.1%。运行70 h后,重金属平均去除率可达98%及以上。EIS扫描结果显示,与单独的MFC相比,在并联条件下的阳极具有更低的液界电阻,且随着并联时间的增加,阳极的生物电容也随之增加。更多还原

【Abstract】 The current environmental issues in China are obvious, the shortage of resource caused by environmental pollution also cannot be underestimated. If energy could be produced during the process of pollution treatment, this would be two important direction of human future development. As an advanced technology in the mutual transformation between resource and pollution, Microbial Fuel Cells (MFC) could use a lot of materials as cathode electron receptor like heavy metal; therefore MFC could be applied in metal waste-water treatment and produce electric energy.The present study aimed improve the MFC’s start process, and low rate of heavy metals treatment caused by the unstable and low electricity production Different methods were used on MFC reactors. Both of series and parallel research were used to study the electrical properties of MFC production and removal efficiency of heavy metals. The results are as follows:(1) Accelerating the rate of MFC’s start process by connected in intermittent parallel mode. The control group only produced a low voltage (100 mV or less) when started after 10 days. But the MFC run in intermittent parallel mode reached a maximum voltage of 467 mV in parallel stage. The voltage would drop by the lifting of the parallel, but on the third day the voltage showing a rising trend. and even intermittent The voltage of MFC was stabilized at 170 ± 3 mV after 15 days in the experimental group. Using a batch parallel mode can shorten the start-up time of the MFC used in the present study (different cathode electron acceptor) from 5 to 7 days.(2) Screening three chemistry cathode (KMnO4, K3[Fe(CN)6], K2Cr2O7) with different concentrations and pH. KMnO4 has become the cathode electron acceptor of MFC in the series phase because of its low toxicity and high efficiency of electricity generation. Operating conditions of KMnO4 cathode was further optimize, The voltage of KMnO4-MFC increased with concentration of KMnO4 (concentrations were 0.5,1.0,2.0 g/L, respectively) increasing when pH at 3.(3) Accelerating the process of copper containing wastewater treatment and gain additional power by KMnO4-MFC and Cu-MFC connected in series. The high voltage and power generated by the KMnO4-MFC supplied for the Cu-MFC. The recovery efficiency of Cu2+ can significantly accelerate in series which reached up to 98%, and the recovery efficiency in 24 h reached up to 91.7%. KMnO4-MFC acceleration copper recovery process while obtaining additional power, the maximum output power reached up to 143 mW;(4) Improving the performance of microbial fuel cells (MFCs) by using an intermittent connection period without power output. Electric energy was accumulated in two MFCs containing heavy metal ions copper, zinc, and cadmium as electron acceptors by connection in parallel for several hours. This method successfully achieved highly efficient removal of heavy metal ions. Even when the acolyte was run in sequencing batch mode, the insufficient voltage and power needed to recover heavy metals from the cathode of MFCs can be complemented by the developed method. The average removal ratios of heavy metal ions in sequencing batch mode were 67% after 10 h. When the discharge time was 20 h, the removal ratios of zinc, copper and cadmium were 91.5% ,86.7%, and 83.57%, respectively; the average removal ratio of these ions after 20 h was only 52.1% for the control group. Therefore, the average removal efficiency of heavy metal ions increased by 1.75 times using the electrons stored from the bacteria under the open-circuit conditions in parallel mode. Electrochemical impedance data showed that the anode had lower solution resistance and polarization resistance in the parallel stage than as a single MFC, and capacitance increased with the length of time in parallel.更多还原