The effect of organic and hydraulic shock loads on the production of soluble microbial products in anaerobic digesters.

Anaerobic chemostats were used to investigate the effects of organic and hydraulic shock loads on the production of soluble microbial products (SMP). Production of SMP was found to increase during glucose spikes, reaching up 15% of the influent chemical oxygen demand. These SMP appear to be utilization-associated products produced as a result of the temporarily high organic load, and chemical analysis and ultrafiltration experiments revealed that most of these compounds are difficult to identify and that the majority of them are present in the low molecular weight (MW) range. Production of SMP also increased when the hydraulic retention time was reduced from 15 to 3 days, and an increase in DNA concentration in the bulk solution suggested enhanced cell lysis. Although the cause of lysis was not clear, it is believed that most of the SMP produced under such conditions were biomass-associated products following cell death. While the majority of these compounds lay in the low MW range, as much as 35% were found to have MWs greater than 1 kDa. During the period when the anaerobic chemostat was fed no alkalinity and the pH remained lower than 6.5 for more than a week, a slightly higher production of SMP and a shift in the MW distribution towards the production of higher MW SMP was observed.     

辛基酚的好氧生物降解及微生物群落特征

利用典型的活性污泥实验了辛基酚(octylphenol,OP)的生物降解性能。研究了水力停留时间、OP浓度和碳氮比对OP处理效率的影响,通过实时PCR和PCR-DGGE方法分别分析了微生物群落的总体密度和多样性变化。通过30d的启动,OP在序批式活性污泥典型好氧条件下出现有效生物降解。在OP浓度50～150μg/L整个实验过程中,OP去除率(84%～99%)基本保持稳定。在实验范围内,较长的水力停留时间(12 h)和碳氮比(2∶1)有利于OP生物降解。通过实时PCR方法测定得到系统微生物平均密度约为1.22 g/L,但富碳状态下生物密度增长上升。通过DGGE分离到17种优势基因型,包括了α-proteobacteria(6种)、β-proteobacteria(5种)、γ-proteobacteria(2种)、Actinobacteria(2种)和δ-proteobacteria(1种)群落。α-proteobacteria和δ-proteobacteria菌群密度呈现增长,β-proteobacteria和Actinobacteria菌群中的部分种类密度出现减少,OP在活性污泥中的好氧生物降解可能与α-proteobacteria中的特定类别相关。     

Quantification of the inhibitory effect of methyl fluoride on methanogenesis in mesophilic anaerobic granular systems

The inhibitory effect of CH₃F on methanogenesis in mesophilic anaerobic granules was tested at different concentrations (0-10% v/v, in the gas phase) and verified by the stable carbon isotopic signatures of CH₄ and CO₂. The results showed that the inhibitory effect increased with the initial CH₃F concentration up to 5%. The CH₃F concentration causing 50% metabolic inhibition was 0.32%. Complete inhibition of acetoclastic methanogenesis with a 91% reduction in total methanogenic activity was achieved when 5% CH₃F was initially added to the headspace, which resulted in 870 μM dissolved CH₃F in the liquid. It was much higher than that applied in other natural anoxic non-granular systems, indicating that the layered granular structure influenced the inhibitory effect. The obvious increase in hydrogen content indicated that high concentrations of CH₃F (?5%) suppressed hydrogenotrophic methanogenesis as well. The stable inhibition lasted for at least 6 d as the CH₃F concentration decreased slowly with incubation time. These results suggested that CH₃F could be used for investigating methanogenic processes in anaerobic granular systems after the CH₃F concentration and incubation time for specific inhibition of acetoclastic methanogenesis were carefully determined. In the present system, CH₃F concentration of 5% was suggested to be optimal.     

采油废水厌氧处理系统的微生物群落特征

为了深入认识石油烃的厌氧降解过程,利用分子生物学技术分析了大庆油田采油废水处理系统厌氧池和进水中的微生物群落特征。基于DGGE和克隆文库的分析结果均表明,厌氧生物膜中存在的古菌源自于采油废水。厌氧生物膜和采油废水中的古菌主要是产甲烷菌,包括嗜甲基的Methanomethylovorans thermophila和利用氢和甲酸的Methanolinea tarda。值得注意的是,氢营养型的M.tarda在厌氧生物膜中得到了富集。进水和厌氧生物膜中的细菌群落结构明显不同。进水中的主要细菌类群为Epsilonproteobacteria,而生物膜中的主要类群为Nitrospira和Deltaproteobacteria。在厌氧生物膜中发现许多与产甲烷古菌(尤其是氢营养型产甲烷菌)协同降解石油烃类物质的细菌相关克隆:其中一个克隆与Syntrophus具有较高的同源性,该类菌是产甲烷菌介导的厌氧烃降解微生物区系中的关键细菌;许多Deltaproteobacteria克隆属于group TA类群,该类群细菌主要参与芳香族化合物产甲烷菌介导的厌氧降解过程。这些结果表明,在大庆油田采油废水厌氧处理系统中已经建立起由产甲烷菌所介导的厌氧石油烃降解的微生物区系。     

Atrazine biodegradation by Arthrobacter strain DAT1: effect of glucose supplementation and change of the soil microbial community

The objective of this study was to investigate the impact of glucose supplementation on the soil microbiota inoculated with the atrazine-degrading Arthrobacter strain DAT1. Soil microcosms with different treatments were constructed for biodegradation tests. The impact of glucose supplementation on atrazine degradation capacity of the strain DAT1 and the strain’s survival and growth were assessed. The densities of the 16S rRNA gene and the atrazine-metabolic trzN gene were determined using quantitative PCR. The growth of the strain DAT1 and the bacterial community structure were characterized using terminal restriction fragment length polymorphism. Glucose supplementation could affect atrazine degradation by the strain DAT1 and the strain’s trzN gene density and growth. The density of the16S rRNA gene decreased during the incubation period. Glucose supplementation could alter the bacterial community structure during the bioaugmentation process. Glucose supplementation could promote the growth of the autochthonous soil degraders that harbored novel functional genes transforming atrazine. Further study will be necessary in order to elucidate the impact of exogenous carbon on autochthonous and inoculated degraders. This study could add some new insights on atrazine bioremediation.     

Effects of ferric hydroxide on methanogenesis from lipids and long-chain fatty acids in anaerobic digestion.

The addition of ferric hydroxide to sludge from a municipal anaerobic digester stimulated the rate of methanogenesis from canola oil when the initial oil concentration was high (4600 mg/L; P < 0.002), but not when it was low (920 mg/L; P > 0.05). Similar trends were observed when oleic acid, a fatty acid that is a major component of canola oil triglycerides, was provided, but the effects were statistically significant only when the initial concentration of ferric hydroxide was also high (18 g/L; P = 0.015). Iron reduction occurred when ferric hydroxide was added to microcosms containing anaerobic digester sludge, but the extent of ferrous iron production was much less in acetate-amended microcosms than in those that were provided with canola oil or oleic acid. Methanogenesis and acetate consumption were completely inhibited when the initial acetate concentration was approximately 5000 mg/L, regardless of the initial ferric hydroxide concentration. The main effect of ferric hydroxide in this system appears to have been a result of stimulation of the rate of fatty acid oxidation.     

厌氧氨氧化工艺的启动及微生物群落结构分析

构建了2个装载不同填料的厌氧污泥床（UASB）反应器（R1：载活性炭的K3填料;R2：普通K3填料）,对比研究了2种厌氧氨氧化系统的启动特征、脱氮性能,分析了R1反应器的微生物群落结构变化规律,并对R1不同高程的基质去除特征和微生物群落组分进行了解析。结果发现,R1在第86天启动成功,短于R2的100 d,长期运行后R1和R2的最大氮容积负荷（NLR）分别为2.156和2.122 g·（L·d）-1,最大氮去除负荷（NRR）分别达到1.855和1.815 g·（L·d）-1。在R1中,内部基质浓度随高度增加而降低,进水NH4+-N浓度较低时（50、100 mg·L-1）和较高时（350、450 mg·L-1）,基质的去除分别集中在反应器高度0~7 cm和17~37 cm处,而且厌氧氨氧化菌含量与氮去除率间呈正相关关系。另外,R1运行过程中厌氧氨氧化优势菌种由Candidatus brocadia（20 d）变为Candidatus Jettenia和Candidatus Kuenenia的混合菌种（134 d）。     

微量NO2对厌氧氨氧化甲烷化反硝化耦合影响的动力学分析

采用批试验方法,研究微量NO2对颗粒污泥厌氧氨氧化、甲烷化和反硝化耦合的影响。基于Haldane模型建立了厌氧氨氧化的NO2强化函数,估计了强化函数中的最大强化系数（30.55）、NO2半饱和常数（1.96 mg/L）、NO2抑制常数（0.0082 mg/L）和基础速率系数（0.0314）。微量NO2对甲烷化和反硝化动力学可用反竞争性抑制动力学方程进行描述。甲烷化的最大比乙酸盐去除速率为0.15 mg COD/（mg VSS·h）,乙酸盐半饱和常数为395 mg COD/L,NO2抑制系数为0.623 mg/L。反硝化的亚硝酸盐氮最大去除速率0.00685 h-1,亚硝酸盐氮半饱和常数 0.214 mg/L,NO2抑制系数为22.4 mg/L。试验中大部分的NOx气体物质出现损失。     

Formation and biodegradation of toluene in the anaerobic sludge digestion process.

The formation of toluene in municipal anaerobic primary and secondary sludge digestion processes was investigated. Experiments were carried out in a large laboratory-scale reactor using sludge from a primary settling tank of a municipal treatment plant. It was found that toluene was produced in the supernatant in relatively large concentrations for almost all cases tested. The concentration of toluene varied and was found to depend on the stage of the anaerobic process. During the acidity phase, which is the first stage of anaerobic digestion, an increase of toluene concentration was observed, while in the transition period, from the acidity phase to methanogenesis, the toluene concentration decreased. It was concluded that biosynthesis of toluene occurs in the acidogenic phase, while biodegradation was prevalent in the methanogenic stage. Depending on the type of experiments, an increase of toluene from a base value of approximately 200 microg/L up to 20,000 and 42,000 microg/L was measured in the first stage of anaerobic digestion. In the subsequent methane-production stage of digestion, the estimated rate of toluene decrease (biodegradation) varied from 400 to 900 microg/L-d.     

Ageing processes and soil microbial community effects on the biodegradation of soil C-2,4-D nonextractable residues

The biodegradation of nonextractable residues (NER) of pesticides in soil is still poorly understood. The aim of this study was to evaluate the influence of NER ageing and fresh soil addition on the microbial communities responsible for their mineralisation. Soil containing either 15 or 90-day-old NER of ¹³C-2,4-D (NER15 and NER90, respectively) was incubated for 90 days with or without fresh soil. The addition of fresh soil had no effect on the mineralisation of NER90 or of SOM, but increased the extent and rate of NER15 mineralisation. The analyses of ¹³C-enriched FAME (fatty acids methyl esters) profiles showed that the fresh soil amendment only influenced the amount and structure of microbial populations responsible for the biodegradation of NER15. By coupling biological and chemical analyses, we gained some insight into the nature and the biodegradability of pesticide NER.     

不同环境因素对厌氧甲烷氧化型自养反硝化系统脱氮性能的影响及其微生物群落分析

采用序批实验研究了不同环境因素(甲烷供应、初始硝氮浓度和pH值)对厌氧甲烷氧化型反硝化系统脱氮性能的影响,并采用高通量测序对不同pH下反应器内微生物群落结构进行了分析.结果 表明:当甲烷供给充足时,系统反硝化效果明显;随着初始硝氮浓度的升高,系统平均脱氮率呈现先升高后下降的趋势,表明适当增大硝氮质量浓度(＜30 mg·...     

Influence of particle size distribution on anaerobic degradation of phenol and analysis of methanogenic microbial community

Sludge morphology considerably affects the mechanism underlying microbial anaerobic degradation of phenol. Here, we assessed the phenol degradation rate, specific methanogenic activity, electron transport activity, coenzyme F420 concentration, and microbial community structure of five phenol-degrading sludge of varying particle sizes (i.e., < 20, 20–50, 50–100, 100–200, and > 200 μm). The results indicated an increase in phenol degradation rate and microbial community structure that distinctly correlated with an increase in sludge particle size. Although the sludge with the smallest particle size (< 20 μm) showed the lowest phenol degradation rate (9.3 mg COD·gVSS−1 day−1), its methanogenic activity with propionic acid, butyric acid, and H2/CO2 as substrates was the best, and the concentration of coenzyme F420 was the highest. The small particle size sludge did not contain abundant syntrophic bacteria or hydrogenotrophic methanogens, but contained abundant acetoclastic methanogens. Moreover, the floc sizes of the different sludge varied in important phenol-degrading bacteria and archaea, which may dominate the synergistic mechanism. This study provides a new perspective on the role of sludge floc size on the anaerobic digestion of phenol.     

不同碳氮比对干法厌氧消化产沼气特性及细菌群落多样性的影响

为研究不同初始C/N值的混合物料对甘蔗叶干法厌氧消化过程中理化参数以及产沼气特性的影响及产气最佳的C/N值厌氧消化过程中细菌群落结构多样性,研究采用牛粪与甘蔗叶以及啤酒厂滤泥这3种有机固废物混合并加入自行研究设计的发酵罐里进行厌氧消化,并采用Nested-PCR（巢式PCR）技术扩增消化过程中细菌的16S rDNA V3区域,并通过DGGE方法分析初始C/N值为15.02厌氧消化过程细菌群落的多样性。实验结果表明,初始C/N值为15.02的混合物料产甲烷最佳,最高累计产气量为1 748.63 mL·kg-1,甲烷最高含量为59.26%,最高日产甲烷量为13.58 mL·kg-1;通过研究最佳C/N值为15.02的细菌多样性,可知在厌氧消化过程中细菌数量和群落结构丰富多样,样品间的细菌群落结构差异性相对较大,样品间存在与产沼气相关的共有的优势细菌。     

焦化废水在厌氧反硝化产甲烷体系中降解动力学特征

接种成熟厌氧反硝化产甲烷颗粒污泥,以焦化废水特征污染物苯酚、喹啉、吡啶和吲哚为碳源,研究了不同C/N下,反硝化产甲烷体系有机物降解特征。结果表明,焦化废水为碳源,可以发生反硝化产甲烷反应;在C/N为3、6时,只发生反硝化反应;在C/N为12、50时,同时发生反硝化产甲烷反应;体系中反硝化反应优先于产甲烷反应进行;NOx--N降解过程出现NO2--N积累,C/N比增加,NO2--N最高积累量降低,产甲烷活性恢复时间缩短;反硝化比耗碳速率大于产甲烷比耗碳速率,同时反硝化产甲烷体系有机物去除效率高于单一厌氧产甲烷体系,反硝化反应有助于保持pH值稳定,降低ORP,从而促进产甲烷菌的繁殖。     

The effect of triclosan on microbial community structure in three soils

The application of sewage sludge to land can expose soils to a range of associated chemical toxicants. In this paper we explore the effects of the broad spectrum anti-microbial compound triclosan on the phenotypic composition of the microbial communities of three soils of contrasting texture (loamy sand, sandy loam and clay) using phospholipid fatty-acid (PLFA) analysis. Each soil type was dosed and subsequently re-dosed 6 weeks later with triclosan at five nominal concentrations in microcosms (10, 100, 500, 1000 mg kg⁻¹ and a zero-dose control). PLFA profiles were analysed using multivariate statistics focussing on changes in the soil phenotypic community structure. Additionally, ratios of fungal:bacterial PLFA indicators and cyclo:mono-unsaturated PLFAs (a common stress indicator) were calculated. It was hypothesised that triclosan addition would alter the community structure in each soil with a particular effect on the fungal:bacterial ratio, since bacteria are likely to be more susceptible to triclosan than fungi. It was also hypothesised that the PLFA response to re-dosing would be suppressed due to acclimation. Although the microbial community structure changed over the course of the experiment, the response was complex. Soil type and time emerged as the most important explanatory factors. Principal component analysis was used to detect phenotypic responses to different doses of triclosan in each soil. As expected, there was a significant increase in the fungal:bacterial ratio with triclosan dose especially in treatments with the highest nominal concentrations. Furthermore, the PLFA response to re-dosing was negligible in all soils confirming the acclimation hypothesis.     

Enantioselective biodegradation of mecoprop in aerobic and anaerobic microcosms

Natural attenuation of mecoprop has been studied by determining changes in enantiomeric fraction in different redox environments down gradient from a landfill in the Lincolnshire limestone. Such changes could be due to differential metabolism of the enantiomers, or enantiomeric inversion. In order to confirm the processes occurring in the field, microcosm experiments were undertaken using limestone acclimatised in different redox zones. No biodegradation was observed in the methanogenic, sulphate-reducing or iron-reducing microcosms. In the nitrate-reducing microcosm (S)-mecoprop did not degrade but (R)-mecoprop degraded with zero order kinetics at 0.65 mg l(-1)day(-1) to produce a stoichiometric equivalent amount of 4-chloro-2-methylphenol. This metabolite only degraded when the (R)-mecoprop disappeared. In aerobic conditions (S)- and (R)-mecoprop degraded with zero order kinetics at rates of 1.90 and 1.32 mg l(-1)day(-1) respectively. The addition of nitrate to dormant iron-reducing microcosms devoid of nitrate stimulated anaerobic degradation of (R)-mecoprop after a lag period of about 20 days and was associated with the production of 4-chloro-2-methylphenol. Nitrate addition to sulphate-reducing/methanogenic microcosms did not stimulate mecoprop degradation. However, the added nitrate was completely utilised in oxidising sulphide to sulphate. There was no evidence for enantiomeric inversion. The study reveals new evidence for fast enantioselective degradation of (R)-mecoprop under nitrate-reducing conditions.     

光合产电微生物群落构建及光照培养对其产电性能的影响

采用淡水沉积物为接种来源,培养出光合产电微生物群落。将其与藻阴极联用组建了完整的光合作用微生物燃料电池时,功率密度达到(157.5±3.1)mW/m2。采用循环伏安法及电化学阻抗谱对该群落的电化学性能进行了测试。PCR-DGGE及紫外可见吸收光谱分析显示,该群落含有 Ectothiorhodospiraceae科及Chloroflexi门不产氧光合细菌、产电菌Arcobacter butzleri、发酵细菌及其他细菌。对该群落进行长期黑暗培养或长期光照培养时,其产电性能均得到了提高,但功率密度测试显示,光照培养微生物燃料电池最大功率密度为(180.1±8.7)mW/m2,高于黑暗培养的微生物燃料电池(160.7±11.4)mW/m2。电化学测试也显示,光照培养的阳极产电性能优于黑暗培养的阳极。     

Radiolytic decomposition of multi-class surfactants and their biotransformation products in sewage treatment plant effluents

Electron beam irradiation (EBI), as one of the most efficient advanced oxidation processes, was applied to the treatment of sewage treatment plant (STP) effluent, with the objective of evaluating the effectiveness of radiolytic decomposition of multi-class surfactants. Target compounds, included several high-volume surfactant groups, such as alkylphenol ethoxylates (APEOs) and their biotransformation products, linear alkylbenzene sulfonates (LAS), alkyl sulfates (AS), alkylether sulfates (AES), coconut diethanol amides (CDEA), alcohol ethoxylates (AEO) and polyethylene glycols (PEGs). EBI treatment of STP effluent (total concentration of APEO-derived compounds 265mugl(-1), being APE(2)C the most abundant by-degradation products) resulted in efficient decomposition of all alkylphenolic compounds; elimination of 94% longer ethoxy chain nonylphenol ethoxylates (NPEO, n(EO)=3-15) was obtained when 3kGy were applied. Slightly less efficient decomposition of short ethoxy chain oligomers (NPEO(1) and NPEO(2)) was observed, resulting in disappearance of about 80% of the initially present compounds. LC-MS analysis of treated wastewater suggested that the mechanism of EBI degradation of APEOs is a combination of two parallel pathways: a progressive shortening and oxidation of the ethoxy chain, which resulted in a formation of short ethoxy chain oligomers and APECs and central fission that resulted in formation of PEGs. Decomposition of APECs at 1kGy initially yielded APs, which were subsequently eliminated applying higher radiation doses. With a radiation dose of 2kGy about 95% of NPE(1)C and 97% of NPE(2)C were decomposed. Similar elimination rates were obtained for octylphenolic compounds. Radiolytic treatment applied was also very effective in removing PEGs formed as by-products from APEO degradation, as well as in decomposing other surfactants, such as linear LAS, AS and AES.     

微量NO2对厌氧氨氧化甲烷化反硝化耦合影响的动力学分析

采用批试验方法,研究微量NO₂对颗粒污泥厌氧氨氧化、甲烷化和反硝化耦合的影响。基于Haldane模型建立了厌氧氨氧化的NO₂强化函数,估计了强化函数中的最大强化系数（30.55）、NO₂半饱和常数（1.96 mg/L）、NO₂抑制常数（0.0082 mg/L）和基础速率系数（0.0314）。微量NO₂对甲烷化和反硝化动力学可用反竞争性抑制动力学方程进行描述。甲烷化的最大比乙酸盐去除速率为0.15 mg COD/（mg VSS·h）,乙酸盐半饱和常数为395 mg COD/L,NO₂抑制系数为0.623 mg/L。反硝化的亚硝酸盐氮最大去除速率0.00685 h^-1,亚硝酸盐氮半饱和常数 0.214 mg/L,NO₂抑制系数为22.4 mg/L。试验中大部分的NOx气体物质出现损失。     

Kinetic study of the anaerobic biodegradation of alkyl polyglucosides and the influence of their structural parameters

This paper reports a study of the anaerobic biodegradation of non-ionic surfactants alkyl polyglucosides applying the method by measurement of the biogas production in digested sludge. Three alkyl polyglucosides with different length alkyl chain and degree of polymerization of the glucose units were tested. The influence of their structural parameters was evaluated, and the characteristics parameters of the anaerobic biodegradation were determined. Results show that alkyl polyglucosides, at the standard initial concentration of 100 mgC L^?1, are not completely biodegradable in anaerobic conditions because they inhibit the biogas production. The alkyl polyglucoside having the shortest alkyl chain showed the fastest biodegradability and reached the higher percentage of final mineralization. The anaerobic process was well adjusted to a pseudo first-order equation using the carbon produced as gas during the test; also, kinetics parameters and a global rate constant for all the involved metabolic process were determined. This modeling is helpful to evaluate the biodegradation or the persistence of alkyl polyglucosides under anaerobic conditions in the environment and in the wastewater treatment.