光照强度对光能自养生物膜去除低污染水体中硝态氮的影响研究

低污染水体存在C/N较低的特征,往往导致水体自净过程中反硝化碳源的不足.提出采用光能自养生物膜去除低污染水体中的硝态氮,研究不同光照强度对光能自养生物膜脱氮能力的影响,并验证了生物膜自行产生的胞外聚合物(EPS)及溶解性微生物产物(SMP)中多糖能否成为反硝化的碳源.结果表明,采用光能自养生物膜去除低污染水体中硝态氮具有良好的效果,光照强度的提高可以有效促进硝态氮的去除,在光暗比为12:12、水力停留时间为72 h时,1 500、3 000、4 500 lx光照强度下系统的硝酸盐去除率分别为37.1％、56.7％、62.5％,且随着光照强度增加硝酸盐去除速率逐渐提高;光照强度的增加可促进光能自养生物膜系统的EPS、SMP中多糖的产生,且光暗交替时EPS、SMP中多糖浓度呈“锯齿形”变化,在有光照时浓度明显上升,而在无光照时浓度下降;光能自养生物膜系统的EPS、SMP中的多糖可作为碳源被反硝化菌利用,而且在无外加碳源条件下,SMP中多糖对碳源的贡献大于EPS中的多糖.     

电极生物膜耦合硫自养强化型人工快渗系统脱氮性能

由于人工快渗(CRI)系统对TN去除率较低,该技术在污水处理领域的应用受到限制。为提高TN去除率,将电极生物膜和硫自养反硝化技术耦合应用于CRI系统,考察了"异养+氢自养+硫自养"反硝化脱氮的可行性,并通过菌群结构解析了电极生物膜耦合硫自养强化脱氮的机理。结果表明,电极生物膜耦合硫自养强化型CRI系统在电流强度为15mA时,TN平均去除率可达73.0%,相比传统CRI系统提高了48.0百分点。从稳定运行的电极生物膜耦合硫自养强化型CRI系统反硝化区共检测出231个已知菌属,其中具有硫自养反硝化功能的产硫酸杆菌属(Thiobacillus)和具有氢自养反硝化功能的噬氢菌属(Hydrogenophaga)相对丰度较高,分别为35.9%、15.7%。硫自养反硝化、氢自养反硝化和异养反硝化的共同作用促进了CRI系统脱氮性能的提高。     

3DBER-S阴极nirS型反硝化菌群的分析

为探究低碳氮比条件下3DBER-S(三维电极生物膜与硫自养耦合脱氮工艺)阴极反硝化菌群特征、强化脱氮机制,在TOC/TN=0.36的进水条件下稳定运行反应器,运用nir S基因克隆文库方法,分析了3DBER-S阴极生物膜反硝化菌群结构。结果表明,在3DBER-S阴极生物膜上反硝化菌中,β变形菌(β-proteobacteria)是优势菌种,占细菌总数的59.22%。其中,所占比例最大的是异养菌,包括与固氮弧菌属(Azoarcus tolulyticus)和趋磁螺菌(Magnetospirillum magneticum)类似的细菌,分别占44.74%和21.05%。能够分别利用硫单质或氢气作为电子供体进行反硝化脱氮的Sulfuricella denitrifican、高氯酸盐降解菌(Dechlorospirillum sp.)和陶厄氏菌属(Thauera)三者所占比例之和达到了17.11%。表明系统中氮的去除是由异养反硝化、氢自养反硝化和硫自养反硝化共同作用的结果,既有效减少了脱氮过程中有机碳源的消耗,又维持了系统酸碱度的平衡,从而能够在低碳氮比条件下维持稳定高效的脱氮效果。     

溶解氧分区控制的一段式自养脱氮工艺的性能及其中微生物的特征

针对一段式自养脱氮工艺普遍存在脱氮性能较差或不稳定的问题,提出了溶解氧分区控制的策略,研发了一种内外分层、溶解氧分区的新型自养脱氮反应器.通过改变反应器的进水氮负荷和调控曝气量,考察其溶解氧分区效果和脱氮性能变化,并探究长期运行过程中微生物群落结构特征.结果表明:在为期250d的连续实验中,新型反应器能实现良好的溶解氧...     

海水微生物菌群去除铵氮和亚硝酸氮研究

研究了筛选的自养和异养微生物菌群的脱氮效果后发现 ,异养微生物无论是生长还是对NH+ 4 N及NO-2 N的去除都明显好于自养微生物。通过研究 ,培养出了具备很强脱氮能力包含自养和异养菌的混合微生物 ,在细胞干重浓度为0 .4 8g/L的情况下 ,在实验 3h和 5h后 ,可将初始浓度 10 6mg/L的NH+ 4 N和初始浓度 4 9.9mg/L的NO-2 N全部去除。     

海水微生物菌群去除铵氮和亚硝酸氮研究

研究了筛选的自养和异养微生物菌群的脱氮效果后发现，异养微生物无论是生长还是对NH4^ -N及NO2-N的去除都明显好于自养微生物。通过研究，培养出了具备很强脱氮能力包含自养和异养菌的混合微生物，在细胞干重浓度为0．48g／L的情况下，在实验3h和5h后，可将初始浓度106mg／L的NH4^ -N和初始浓度49．9mg／L的NO2^--N全部去除。     

基于化学与生物膜耦合深度脱除地下水中硝酸盐氮

我国华北地区超过80%的地下水受到污染,其中硝酸盐氮的污染日益严重,威胁着人类健康。基于单质铁去除地下水中硝酸盐氮,因伴随氨氮的产生而受限制;生物反硝化脱氮因地下水中碳源不足无法满足脱氮要求。采用自制的微电解化学催化固体颗粒与天然生物质构成耦合生物载体,通过自养与异养反硝化耦合深度脱除地下水中硝酸盐氮,并建立了地下水易位好氧、厌氧深度脱氮新工艺。结果表明:好氧反应器在HRT为12 h、DO为2.0～3.0 mg·L-1的条件下,硝酸盐氮平均去除率≥91.24%;厌氧反应器在HRT为14 h的条件下,硝酸盐氮平均去除率≥96.32%;反应器中微电解化学催化固体颗粒可为自养反硝化菌提供电子,生物质可为微生物提供必要的有限碳源,硝酸盐氮的脱除是自制微电解化学催化固体颗粒与生物膜耦合作用的结果。出水均无亚硝酸盐氮和氨氮积累。此技术可为受污染地下水的修复提供理论依据。     

生物同步脱氮除硫工艺研究进展

传统生物脱氮除硫过程中存在着许多问题。近年来,通过对脱氮微生物的深入研究,生物脱氮技术取得了突破性进展,而在生物同步脱氮除硫方面发展相对缓慢。总结了包括反硝化除硫、硫酸盐还原—自养反硝化—硝化、反硝化氨氧化以及硫酸盐型厌氧氨氧化等生物同步脱氮除硫工艺的特点,分析了各自的工艺原理及面临的挑战,并提出了今后的研究方向。     

电极改性对电极生物膜反硝化反应器硝酸盐氮去除性能的影响

探究在碳纤维毡电极上利用恒电压电化学聚合聚吡咯(PPy)的聚合效果,并利用傅里叶变换红外线(FTIR)及扫描电镜(SEM)对其进行表征;将聚吡咯覆膜改性后的碳纤维毡电极应用到自养反硝化的电极生物膜反应器(BER)中,考察电极改性对自养反硝化电极生物膜反应器的硝酸盐氮去除性能影响,并研究电极改性对生物膜附着量及生物膜微生物群落的影响。结果表明,恒电压电化学聚合能够在碳纤维电极表面形成均匀稳定的聚吡咯膜,从而实现聚吡咯在炭纤维毡电极上的覆膜改性。改性后的电极应用到自养反硝化电极生物膜反应器中,可使反应器对NO_3~--N的去除效率由对照反应器的67.3%增加到83.9%,处理效果提高了24.7%。对反应器内电极生物膜进行生物量测定和扫描电镜分析,可以看到R2反应器中改性电极生物膜附着量明显多于R1反应器中未改性电极生物膜的附着量,说明电极改性有利于生物膜的附着。电极生物膜微生物16S rDNA分析中R1反应器电极生物膜菌落组成中优势菌属为Dechloromonas sp.,而R2反应器电极生物膜的优势菌为Hydrogenophaga sp.(噬氢菌属)和Thauera sp.(陶厄氏菌属),两者有明显差别,并且R2反应器比R1反应器生物膜的菌落组成更多样化,这说明电极材料的改性对电极生物膜微生物群落的组成产生了影响。     

基于SBBR的单级自养脱氮快速启动

以普通活性污泥为接种污泥,采用人工配制无机氨氮废水进行单级自养脱氮工艺快速启动研究。启动过程经历了污泥适应期、部分短程硝化选择期以及单级自养脱氮实现期3个阶段。经过29 d的培养驯化,通过控制游离氨的方法实现了部分短程硝化。当出水中亚硝酸盐积累率达到60%左右时,立即将序批式生物膜反应器(SBBR)由连续曝气改为间歇曝气,间歇曝气使得厌氧氨氧化菌(AAOB)的富集与亚硝酸氧化菌(NOB)的淘汰同时进行,并且避免了高浓度亚硝酸盐对AAOB的抑制作用,从而实现了单级自养脱氮的快速启动。实验仅用50 d成功启动了SBBR单级自养脱氮工艺,总氮容积去除负荷达到0.173 kg N/(m3·d),氨氮的平均去除率达到98.68%,总氮的平均去除率达到80.87%。成功启动之后,反应器内只有少量的悬浮污泥,大部分的污泥都附着在填料上,污泥颜色呈褐色,而反应器内壁及出水管上附着的污泥呈浅砖红色,表明反应器内富集了大量的AAOB。     

Biodegradability of biofilm extracellular polymeric substances

This study discovered that biofilm extracellular polymeric substances (EPS) are biodegradable by their own producers and by other microorganisms when they are starved. The study was performed in a comparative fashion to examine the biodegradability of biofilm EPS by the microorganisms from the original biofilm (its own producers) and from activated sludge (other microorganisms). Four distinctive phases were observed during EPS biodegradation. In the first phase, instantaneous concentration increases of carbohydrate and protein in the test solutions were observed when EPS was added; in the second phase, easily biodegradable EPS from the added EPS was quickly utilized; in the third phase, microorganisms began to produce soluble EPS, using the minimally biodegradable EPS left from the previously added EPS; in the fourth phase, cells consumed the newly produced EPS and microbial activity gradually stopped. This study suggests that EPS can be used as a substrate, and that the EPS carbohydrate can be utilized faster than the EPS protein. The EPS utilization rates (including carbohydrate and protein) in the activated sludge suspension were greater than those in the biofilm suspension. It may take microorganisms longer to get acclimated to a new nutrient environment if they are in a starved state.     

Effects of biofilm growth on flow and transport through a glass parallel plate fracture

The effects of biofilm growth on flow and solute transport through a sandblasted glass parallel plate fracture was investigated. The fracture was inoculated using soil microorganisms. Glucose, oxygen and other nutrients were supplied to support growth. The biomass initially formed discrete clusters attached to the glass surfaces, but over time formed a continuous biofilm. From dye tracer tests conducted during biofilm growth, it was observed that channels and low-permeability zones dominated transport. The hydraulic conductivity of the fracture showed a sigmoidal decrease with time. The hydraulic conductivity was reduced by a factor of 0.033, from 18 to 0.6 cm/s, corresponding to a 72% decrease in the hydraulic aperture, from 500 to 140 microm. In contrast, the mass balance aperture, determined from fluoride tracer tests, remained relatively constant, indicating that the impact of biomass growth on effective fracture porosity was much less than the effect on hydraulic conductivity. Analyses of pre-biofilm tracer tests revealed that both Taylor dispersion and macrodispersion were influencing transport. During biofilm growth, only macrodispersion was dominant. The macrodispersion coefficient alpha(macro) was found to increase logarithmically with hydraulic conductivity reduction.     

绿色荧光蛋白分子标记在环境微生物学研究中的应用

绿色荧光蛋白(green fluorescent protein,GFP)分子标记是现有遗传标记中最简单方便的一种方法，GFP及GFP突变体在微生物降解污染物、生物膜菌群构架、环境生态学和环境检测生物传感器等研究领域取得了很好的应用效果。     

Combined use of molecular biology taxonomy, Raman spectrometry, and ESEM imaging to study natural biofilms grown on filter materials at waterworks

DNA-based population analysis was applied in combination with Raman spectrometry and Environmental Scanning Electron Microscopy for the characterisation of natural biofilms from sand and activated carbon filters operated for a long term at a municipal waterworks. Whereas the molecular biology polymerase chain reaction combined with denaturing gradient gel electrophoresis approach provides a deeper insight into the bacterial biofilm diversities, Raman spectrometry analyses the chemical composition of the extracellular polymer substances (EPS), microorganisms embedded in EPS as well as other substances inside biofilm (inorganic compounds and humic substances). Microscopy images the spatial distribution of biofilms on the two different filter materials. In addition, bacterial bulk water populations were compared with biofilm consortia using the molecular fingerprint technique mentioned.Population analysis demonstrated the presence of more diverse bacterial species embedded in a matrix of EPS (polysaccharides, peptides, and nucleic acids) on the sand filter materials. In contrast to this, activated carbon granules were colonised by reduced numbers of bacterial species in biofilms. Besides α-, β-, and γ-Proteobacteria, a noticeable specific colonisation with Actinobacteria was found on activated carbon particles. Here, the reduced biofilm formation came along with a decreased EPS synthesis. The taxonomy profiles of the different biofilms revealed up to 60% similarity on the same filter materials and 32% similarity of different materials. Similarity of adherent communities from filter materials and bulk water populations from the filter effluent varied between 36% and 58% in sand filters and 6–40% in granular activated carbon filters.The biofilm investigation protocols are most crucial to subsequent acquisition of knowledge on biofilm dynamics and bacterial contributions to transformation or adsorption processes in waterworks facilities.     

Geosmin degradation by seasonal biofilm from a biological treatment facility

Introduction  

Initial geosmin degradation was closely related to water temperature and natural geosmin concentration of sampling environment. Here, for the first time, we evaluated the biodegradation of geosmin by microorganisms in biofilm from biological treatment unit of actual potable water treatment plant.     

Poly (ε-caprolactone) as substrate for water denitrification

In this paper, poly (ε-caprolactone) (PCL) was used as carbon source and biofilm supporter in a fixed bed bioreactor to biologically remove nitrate from drinking water. The experimental results showed that denitrifying microorganisms could easily adapt to PCL as carbon source and attach to the surface of PCL granules. The fine biofilm could form on the surface of PCL granules within 15 days. Denitrification rate was influenced by temperature greatly and it decreased sharply at low temperature (below 20°C) and it was strongly linearly correlated with influent DO level. The denitrification rate at DO 8.5 mg/L was 47.4% of the value at DO 1.4 mg/L. Fixed-bed bioreactor packed with PCL granules could remove 50 mg/L influent nitrate completely, but the effluent DOC and suspended matter level were high. Accordingly, post-treatment unit are needed to ensure the good quality of effluent. Nitrite level did not accumulate in the whole experiment. Microbial growth was the main reason for reactor clog.     

Investigating the fate of iodinated X-ray contrast media iohexol and diatrizoate during microbial degradation in an MBBR system treating urban wastewater

The capability of a moving bed biofilm reactor (MBBR) to remove the iodinated contrast media (ICM) iohexol (IOX) and diatrizoate (DTZ) from municipal wastewater was studied. A selected number of clones of microorganisms present in the biofilm were identified. Biotransformation products were tentatively identified and the toxicity of the treated effluent was assessed. Microbial samples were DNA-sequenced and subjected to phylogenetic analysis in order to confirm the identity of the microorganisms present and determine the microbial diversity. The analysis demonstrated that the wastewater was populated by a bacterial consortium related to different members of Proteobacteria, Firmicutes, and Nitrisporae. The optimum removal values of the ICM achieved were 79 % for IOX and 73 % for DTZ, whereas 13 biotransformation products for IOX and 14 for DTZ were identified. Their determination was performed using ultra-performance liquid chromatography–tandem mass spectrometry. The toxicity of the treated effluent tested to Daphnia magna showed no statistical difference compared to that without the addition of the two ICM. The MBBR was proven to be a technology able to remove a significant percentage of the two ICM from urban wastewater without the formation of toxic biodegradation products. A large number of biotransformation products was found to be formed. Even though the amount of clones sequenced in this study does not reveal the entire bacterial diversity present, it provides an indication of the predominating phylotypes inhabiting the study site.     

Electrochemical determination of anaerobic microbial decay coefficients

The biokinetics of attached and suspended bacteria are an essential component of activated sludge models, anaerobic digestion models and biofilm models. These parameters are often assumed or “confirmed” based on the goodness-of-fit of the bioprocess models. Using a microbial fuel cell with a baffled reactor chamber, the attached- and mixed-growth microbial decay coefficients were evaluated under anaerobic conditions. The capability for real-time voltage recording allows easy and accurate measurement of the anaerobic microbial decay coefficients (b_L, lysis-regrowth approach), which were determined to be 0.11 ± 0.01 and 0.15 ± 0.01 d⁻¹ for attached (to anode) and mixed (present in the anode chamber) growth microorganisms, respectively. The corresponding half-saturation constants using glucose as a substrate were 204 ± 10 and 123 ± 1 mg COD l⁻¹. Hence, like an oxygen uptake rate-based approach to measure the microbial kinetics under aerobic conditions, the electrochemical recording provides an attractive method to measure anaerobic microbial decay coefficients.     

The effect of a biofilm on solute diffusion in fractured porous media

At sites in fractured rock where contamination has been exposed to the rock matrix for extended periods of time, the amount of contaminant mass residing in the matrix can be considerable. Even though it may be possible to diminish concentrations by the advection of clean water through the fracture features, back diffusion from mass held in the matrix will lead to a continuing source of contamination. In such an event, the development of a biofilm (a thin film of microbial mass) on the wall of the fractures may act to limit or prevent the back diffusion process. The objective of this preliminary study is to explore the influence imparted by the presence of a biofilm on the process of matrix diffusion. The investigation was conducted using radial diffusion cells constructed from rock core in which biofilm growth was stimulated in a central reservoir. Once biofilms were developed, forward diffusion experiments were conducted in which a conservative solute migrated from the central reservoir into the intact rock sample. Diffusion experiments were performed in a total of 11 diffusion cell pairs where biofilm growth was stimulated in one member of the pair and inhibited in the other. The effect of the presence of a biofilm on tracer diffusion was determined by comparison of the diffusion curves produced by each cell pair. A semi-analytical model that accounts for the presence of a biofilm was used to investigate the effect of the biofilm on mass transfer due to changes in the effective porosity, effective diffusion coefficient, and the depth of penetration of the biofilm into the intact rock. The results show that the biofilm acted to plug the rock matrix, rather than forming a discrete layer on the reservoir surface. The reduction in effective porosity due to the biofilm ranged from 6% to 52% with the majority of the samples in the 30% to 50% range. Based on the present results, with more efficient biofilm stimulation, it is reasonable to assume that a more complete plugging of the microcrack porosity might be possible, leaving a much thicker and efficient barrier than could be achieved via a surface biofilm.     

Improved computational model (AQUIFAS) for activated sludge, integrated fixed-film activated sludge, and moving-bed biofilm reactor systems, part II: multilayer biofilm diffusional model

Research was undertaken to develop a diffusional model of the biofilm that can be applied in lieu of a semi-empirical model to upgrade an activated sludge system to an integrated fixed-film activated sludge (IFAS) or moving-bed biofilm reactor (MBBR) system. The model has been developed to operate with up to 12 cells (reactors) in series, with biofilm media incorporated to one or more of the zone cells, except the anaerobic zone cells. The values of the kinetic parameters for the model were measured using pilot-scale activated sludge, IFAS, and MBBR systems. The biofilm is divided into 12 layers and has a stagnant liquid layer. Diffusion and substrate utilization are calculated for each layer. The equations are solved simultaneously using a finite difference technique. The biofilm flux model is then linked to the activated sludge model. Advanced features include the ability to compute the biofilm thickness and the effect of biofilm thickness on performance. The biofilm diffusional model is also used to provide information and create a table of biofilm yields at different substrate concentrations that can be used in the semi-empirical model.