纳米铁为脱氯菌供电降解三氯乙烯实验研究

采用一种从氯乙烯污染场址土壤中提取的脱氯菌种(Dehalococcoides spp.)进行三氯乙烯(TCE)降解实验,研究纳米铁厌氧腐蚀产氢为该脱氯菌种提供电子的可能性.结果表明,在甲醇做电子供体时,稀释25倍的菌液［（2.0±0.44）×105　cell/mL)］可以在96　h内将20 mg/L TCE完全降解,并在190　h时有2.706　μmol乙烯产生.而在无甲醇做电子供体时,96　h内只有部分TCE转化为顺二氯乙烯(cisDCE),且190　h时几乎无乙烯产生（0.159　μmol）,因此无电子供体时菌液脱氯活动不能维持.但在4　g/L纳米铁腐蚀产氢的情况下,脱氯菌可以利用纳米铁产生的阴极氢维持脱氯活动,在131　h内将20 mg/L TCE完全降解,并且其耦合的脱氯速率高于纳米铁单独降解时的速率.从乙烯的产量分析中可以看出,纳米铁供电时190　h后由脱氯菌产生的乙烯量为1.187　μmol,明显低于甲醇做电子供体时乙烯的产量2.706　μmol,表明纳米铁可能对微生物存在一定的毒性效应.同时反应190　h后乙炔的产量为0.109　μmol,相对低于与纳米铁单独降解TCE时的产量0.161　μmol,说明微生物在无电子供体的情况下,竞争利用了纳米铁与水反应产生的电子导致乙炔的生成量降低.上述结果表明,4　g/L的纳米铁与水反应生成的活性氢可以为脱氯菌提供电子,并维持其脱氯活动,这对纳米铁和脱氯菌耦合应用于地下水的有机氯修复具有重要的实际意义.     

δ-MnO_2降低无机三价砷毒性的研究

文章利用自制的δ-MnO2对剧毒性无机A(sⅢ)进行了氧化吸附过程的实验室研究,考察了反应进程中各形态砷的变化,同时进一步对与高浓度A(sⅢ)反应前后δ-MnO2的结构和形貌进行了X射线衍射(XRD)、扫描电子显微镜(SEM)和拉曼光谱(Raman)鉴定。实验结果表明,δ-MnO2通过氧化和吸附作用对A(sⅢ)的毒性去除效果显著,60 min内溶液中A(sⅢ)消失了72.3%。形态学研究表明,反应前后δ-MnO2的XRD图没有明显变化;而SEM图显示,反应后δ-MnO2的蜂窝状结构其固体孔隙比反应之前明显变小;EDX的数据显示δ-MnO2固体中出现了一定含量的As元素;δ-MnO2反应前后Raman光谱的吸收强峰由649 cm-1处变化到865 cm-1处,也表明出现了一部分可以永久固定在δ-MnO2固体内的A(sV)。该研究认为,δ-MnO2具有较强氧化和吸附活性,可以大大降低三价无机砷的毒性。     

饮用水中9种卤乙酸的同时测定方法

建立了一种能够同时测定饮用水中9种卤乙酸的气相色谱方法.研究了前处理过程中不同实验条件对卤乙酸回收率的影响,通过简化前处理方法,优化色谱操作条件,提高了卤乙酸的回收率,降低了方法检测限,9种目标化合物的线性相关度均在0.99以上,回收率保持在88%-109%之间,能够满足美国环保局和中国生活饮用水卫生标准水质监测分析的...     

Effects of ferrous and manganese ions on anammox process in sequencing batch biofilm reactors

Ferrous and manganese ions, as essential elements, significantly affect the synthesis of Haem-C, which participates in the energy metabolism and proliferation of anammox bacteria. In this study, two identical sequencing batch biofilm reactors were used to investigate the effects of ferrous and manganese ions on nitrogen removal efficiency and the potential of metal ions serving as electron donor/acceptors in the anammox process. Fluorescence in situ hybridization analysis was applied to investigate the microbial growth. Results showed that the nitrogen removal increased at high concentrations of Fe2＋ and Mn2＋ and the maximum removal efficiency was nearly 95% at Fe2＋ 0.08 mmol/L and Mn2＋ 0.05 mmol/L, which is nearly 15% and 8% higher than at the lowest Fe2＋ and Mn2＋ concentrations （0.04 and 0.0125 mmol/L）. The stabilities of the anammox reactor and the anammox bacterial growth were also enhanced with the elevated Fe2＋ and Mn2＋ concentrations. The Fe2＋ and Mn2＋were consumed by anammox bacteria along with the removal of ammonia and nitrite. Stoichiometry analysis showed Fe2＋ could serve as an electron donor for NO3-N in the anammox process. Nitrate could be reduced with Fe2＋ serving as the electron donor in the anammox system, which causes the value of NO~-N/NH4-N to decrease with the increasing of N-removal efficiency.     

微生物燃料电池中生物阴极的研究与应用现状

在简要介绍了微生物燃料电池的发展背景、原理和发展趋势的基础上,重点概述了微生物燃料电池阴极的发展现状,特别是生物阴极的研究与应用现状,最后对其目前存在的主要问题进行了分析,并对其今后的发展提出了展望。     

Simultaneous Feammox and anammox process facilitated by activated carbon as an electron shuttle for autotrophic biological nitrogen removal

• The autotrophic nitrogen removal combining Feammox and Anammox was achieved. • Activated carbon can be used as an electron shuttle to enhance Feammox activity. • Fe(III) was reduced to Fe(II) and the secondary Fe(II) mineral (FeOOH) was obtained. • The iron-reducing bacteria and Anammox consortium was enriched simultaneously. Ferric iron reduction coupled with anaerobic ammonium oxidation (Feammox) is a novel ferric-dependent autotrophic process for biological nitrogen removal (BNR) that has attracted increasing attention due to its low organic carbon requirement. However, extracellular electron transfer limits the nitrogen transformation rate. In this study, activated carbon (AC) was used as an electron shuttle and added into an integrated autotrophic BNR system consisting of Feammox and anammox processes. The nitrogen removal performance, nitrogen transformation pathways and microbial communities were investigated during 194 days of operation. During the stable operational period (days 126–194), the total nitrogen (TN) removal efficiency reached 82.9%±6.8% with a nitrogen removal rate of 0.46±0.04 kg-TN/m³/d. The contributions of the Feammox, anammox and heterotrophic denitrification pathways to TN loss accounted for 7.5%, 89.5% and 3.0%, respectively. Batch experiments showed that AC was more effective in accelerating the Feammox rate than the anammox rate. X-ray photoelectron spectroscopy (XPS) analyses showed the presence of ferric iron (Fe(III)) and ferrous iron (Fe(II)) in secondary minerals. X-ray diffraction (XRD) patterns indicated that secondary iron species were formed on the surface of iron-AC carrier (Fe/AC), and Fe(III) was primarily reduced by ammonium in the Feammox process. The phyla Anaerolineaceae (0.542%) and Candidatus Magasanikbacteria (0.147%) might contribute to the Feammox process, and Candidatus Jettenia (2.10%) and Candidatus Brocadia (1.18%) were the dominative anammox phyla in the bioreactor. Overall, the addition of AC provided an effective way to enhance the autotrophic BNR process by integrating Feammox and anammox.     

电子供体刺激下厌氧微生物对1, 2-二氯乙烷的降解效果

通过添加电子供体进行原位生物刺激可有效降解地下水中的氯代烃,目前国内外常采用接种高效微生物的方法强化这一降解过程,鲜见仅利用实际污染场地含水层土著菌开展的生物降解试验.从北京市某氯代烃污染场地采集地下水样品,仅接种场地含水层沉积物,利用微宇宙实验体系,初步探讨了添加不同种类和质量浓度的电子供体对地下水中1,2-二氯乙烷的去除效果影响.结果表明:①同时添加初级生长基质和电子供体对反应体系进行生物刺激可显著降解地下水中的1,2-二氯乙烷.60 d后,添加1 g/L醋酸钠的反应体系中1,2-二氯乙烷的去除率最高,可达93.9%;添加1 g/L的乳酸钠反应体系次之,去除率为82.2%;添加1 g/L的乳酸的反应体系去除率最低,为61.8%.并且添加醋酸钠的试验体系可长时间维持中性pH及较低的氧化还原电位.②相同条件下,对同种电子供体来说,添加量为1 g/L的试验组中1,2-二氯乙烷的降解效果优于添加量为2 g/L的试验组,推测较高质量浓度的电子供体可对微生物的生命活动产生抑制.③对反应体系中间产物进行监测,仅监测到了乙烯的产生,表明在试验周期内无明显毒副产物积累,1,2-二氯乙烷的降解较为彻底.研究显示,醋酸钠为该试验体系中最适电子供体,添加适宜质量浓度醋酸钠对土著菌进行生物刺激可实现对1,2-二氯乙烷的绿色降解.      

堆肥制作中微生物侵染秸秆的环境扫描电镜(ESEM)观察

为了探索堆肥制作中木质纤维素类物质的生物降解过程,在堆肥进程中取不同分解阶段的秸秆样品,利用环境扫描电镜(ESEM)观察微生物的分布情况,并从机械作用的角度探讨了微生物在秸秆分解过程中的作用。结果表明,堆肥制作前新鲜秸秆表面未发现微生物分布,堆肥制作前期微生物开始附着在秸秆表面,随着堆肥进程,秸秆表面微生物密度有所增加,秸秆分解时产生的裂缝中发现也有微生物分布。堆肥制作中,参与秸秆分解的微生物以群落形式分布,从个体形态来看,这些微生物主要由球菌和丝状菌组成,但不同形态微生物个体大小差异较大。分析认为大型丝状菌通过秸秆分解产生的裂缝侵入秸秆内部时所产生的机械作用可促进秸秆的崩解。     

铁盐对活性污泥微生物DHA与ETS活性的影响研究

通过活性污泥脱氢酶活性与电子传递体系活性的测定,对比分析铁盐对活性污泥系统微生物活性影响及其变化规律。研究结果表明:活性污泥TTC-DHA活性与INT-ETS活性之间具有较好的相关性,分批次向活性污泥处理系统投加Fe(OH)3并保持连续运行污水处理系统内的活性污泥含铁质量分数在5%条件下,其活性污泥微生物TTC-DHA与INT-ETS活性可分别达到25～30,275～360μg/(mg.h),其较对比系统提高50%左右,铁盐对活性污泥的微生物活性的影响较为显著。