聚磷生物膜法磷回收研究进展

从污水中回收磷已经成为当前污水全面资源化研究领域的重要研究方向之一,聚磷生物膜法磷回收工艺因其在节省碳源、简化回收流程、提高回收效果、污泥减量化等方面的潜力,成为该领域的重要技术手段和研究热点。本文着重介绍了聚磷生物膜法磷回收的基本原理、功能微生物及其代谢特征;详细梳理了生物膜法磷回收工艺不同模式的回收思路,综合分析了不同工艺模式的技术特征和磷回收效果。此外,对聚磷生物膜系统微生物及其代谢的研究方法与技术进行了整理。文章在综合分析聚磷生物膜法磷回收研究现状的基础上,对该技术的应用前景进行了宏观展望,以期为开展聚磷生物膜法磷回收的基础研究和技术开发提供支撑。     

生物膜型污水脱氮系统中膜结构及微生物生态研究进展

生物膜法污水脱氮系统主要利用生物膜中脱氮功能微生物的代谢活动去除氮素,从而达到净化水质的目的,研究脱氮生物膜的微观结构和微生物生态是揭示生物膜脱氮机理从而提高脱氮效率的重要途径.本文综述了生物膜型污水脱氮系统类型、生物膜微观结构特征及其影响因素、生物膜型污水脱氮系统内氮素传质过程、脱氮机理和生物膜数学模型等方面的研究进展.另外,本文介绍了生物膜型污水脱氮系统内生物膜脱氮功能微生物分布特征,不同生物膜脱氮系统、底物、运行条件和时间对功能微生物群落影响,及新型脱氮功能微生物等方面的研究进展,为生物膜脱氮技术的深入研究提供参考.     

光合细菌在水污染治理中的研究进展

光合细菌以其无毒、繁殖快、适应能力强、易人工培养等优点而在环境治理中受到重视。国内外对光合细菌的研究主要集中在水产养殖业(如净化水质,作饵料添加剂等)和生活及工业重污染水处理中的作用,关于光合细菌在景观微污染水体治理方面的作用研究较少。课题组研究发现光合细菌中的沼泽红假单胞菌对西南大学景观水中氨氮的去除率高达95%,暗示光合细菌能有效治理景观水污染。综述了光合细菌的分类、脱氮除磷原理以及目前光合细菌在治理有机废水、重金属废水和养殖污水方面的应用,并展望了光合细菌在处理景观微污染水体方面的应用前景,以期为进一步研究光合细菌在景观水治理中的作用提供参考。     

细菌生物膜在农田土壤污染修复中的应用研究进展

全球农田土壤污染日趋严重。重金属、农药、微塑料作为常见的土壤污染物,已对农田生态系统与粮食安全造成严重威胁。细菌生物膜(bacterial biofilm,BF)作为分布于细菌表面的多组分聚集体,近年来已被证明在环境保护领域具有较高的应用价值。本文主要介绍了细菌生物膜的组成和功能,并对近年来细菌及其生物膜在重金属、有机物污染土壤修复中的应用及机理进行综述,展望生物膜群落结构在污染土壤中的修复潜力,以期深入理解细菌生物膜的关键作用,为挖掘更多细菌生物膜在环境保护方面的应用潜力提供理论指导。     

蛭弧菌的噬菌特性及其在水污染检测和控制应用中的研究进展

蛭弧菌的噬菌特性及其在水污染检测和控制应用中的研究进展王丽娜,吴联熙（中国预防医学科学院环境卫生与卫生工程研究所北京１０００５０）蛭弧菌（Ｂｄｅｌｌｏｖｉｂｒｉｏ）是Ｓｔｏｌｐ和Ｐｅｔｚｏｌｄ于１９６２年从土壤中分离噬菌体时首次发现的￣［１］,其独特...     

膜层析技术在下游工艺中的应用

随着生物技术尤其是单抗药物的快速发展,我们发现工艺过程中会陆续遇到一些挑战,例如：药物使用剂量的增加需要更加经济稳定的工艺的支撑;在工艺设计之初就要考虑所选择方法的简便性和可放大性;同时法规也就药品中内毒素、残留DNA、HCP与潜在病毒等污染物的检测限度提出了更高的要求。面对这些挑战,需要更多的创新技术来解决相应的问题。在改进工艺的经济性和污染物控制上,大家谈论较多的技术是膜层析技术。     

PVDF膜在电印迹法中的应用

本文介绍的是聚偏二氟乙烯膜（Polyvinylidenedifluoride,PVDF）在电印迹法中的应用,即将蛋白质SDS聚丙烯酰胺凝胶电沪后的条带电转移到PVDF膜上,随着蛋白质的转移,蛋白质在凝胶上的相对位置将在膜上得到相对的反映,然后将膜上所需蛋白质条带切割下来,直接可以用于N－未端序列分析及总氨基酸组成分析。该方法无需做到蛋白质的完全纯化,所以方法简单快速,所需样品量极少。     

汞在微生物中的跨膜运输机制研究进展

甲基汞是一种强亲脂性、高神经毒性的有机汞化合物,可以通过生物富集或生物放大造成人类甲基汞暴露。环境中甲基汞的产生主要是厌氧微生物所调控的无机汞的甲基化。主流观点认为厌氧微生物对汞的甲基化是一种细胞内反应,因此,甲基汞的产生速率不仅与环境中具有汞甲基化能力的厌氧微生物的存在与活性相关,同时也与无机汞在微生物细胞中的跨膜运输过程有着重要联系。要明确无机汞经微生物甲基化的机制,就必须了解无机汞被微生物细胞生物吸收的过程,即无机汞在微生物中的跨膜运输路径。目前研究认为该过程主要有Mer抗汞操纵子转运体系、被动扩散、促进扩散和主动运输4种路径。本综述主要围绕无机汞被微生物细胞生物吸收的这4种路径展开,将系统介绍科学界对这4种路径的最新研究进展,并对相关研究进行展望,指出无机汞经促进扩散或主动运输进入到微生物细胞内将是未来研究的重点。     

微生物技术在医疗废水处理中的应用

医院污水含有多种病菌、病毒及寄生虫,其直接危害和潜在危害都是显而易见的,因此,进行医疗废水治理,已成为当务之急。微生物处理主要是通过采用活性污泥法、生物接触氧化法、膜生物反应器、曝气生物滤池法等对污水进行处理,从而有效去除水中的有机物,破坏病原微生物赖以生存的物质基础和保障消毒效果。不同的处理工艺各有优缺,适合于不同规模的医院。     

自控闪光动力学光谱仪及其在紫膜光化循环研究中的应用

在对紫膜光化循环过程的研究中,为了了解光化循环过程中间产物的性质,需要测量其瞬态光吸收的变化。动力学光谱仪就是为此目的设计的。根据脉冲光能动力学测量原理和国内外类似仪器的特点,我们研制成用于测量紫膜光循环中具有毫秒级寿命的中间产物变化的闪光动力学光谱仪。本文对该装置和软件作一简单介绍。     

Multivariate statistical modelling of mass transfer in a membrane-supported biofilm reactor

The main objective of this work is to develop an overall mass transfer model applicable to a particular case of membrane supported biofilm, the ion-exchange membrane bioreactor (IEMB). A multivariate projection to latent structures (PLS) model of the anionic membrane transport in an IEMB was developed and analyzed to establish the mass transfer limiting variables for the removal of anionic pollutants (nitrate and perchlorate) from drinking water. The proposed PLS model accounts for the biological contribution to the mass transfer and predicts the anionic fluxes across the ion-exchange membrane with a prediction improvement of at least 50% when compared with a simplified mechanistic Donnan dialysis-based transport model. The PLS model allowed for predicting the transport of target anions using only operational physicochemical data, therefore, the use of several assumptions as in mechanistic model building was avoided as well as the need for biofilm characterization. To decrease the model complexity, several techniques which select the most informative predictors were also successfully used. The analyses of important predictors to each anionic transport model show that transport driving force related variables were the most important. Moreover, at least 30% of the model information is related with biocompartment bulk variables.     

Biodegradation of acetonitrile by adapted biofilm in a membrane-aerated biofilm reactor

A membrane-aerated biofilm reactor (MABR) was developed to degrade acetonitrile (ACN) in aqueous solutions. The reactor was seeded with an adapted activated sludge consortium as the inoculum and operated under step increases in ACN loading rate through increasing ACN concentrations in the influent. Initially, the MABR started at a moderate selection pressure, with a hydraulic retention time of 16 h, a recirculation rate of 8 cm/s and a starting ACN concentration of 250 mg/l to boost the growth of the biofilm mass on the membrane and to avoid its loss by hydraulic washout. The step increase in the influent ACN concentration was implemented once ACN concentration in the effluent showed almost complete removal in each stage. The specific ACN degradation rate achieved the highest at the loading rate of 101.1 mg ACN/g-VSS h (VSS, volatile suspended solids) and then declined with the further increases in the influent ACN concentration, attributed to the substrate inhibition effect. The adapted membrane-aerated biofilm was capable of completely removing ACN at the removal capacity of up to 21.1 g ACN/m² day, and generated negligible amount of suspended sludge in the effluent. Batch incubation experiments also demonstrated that the ACN-degrading biofilm can degrade other organonitriles, such as acrylonitrile and benzonitrile as well. Denaturing gradient gel electrophoresis studies showed that the ACN-degrading biofilms contained a stable microbial population with a low diversity of sequence of community 16S rRNA gene fragments. Specific oxygen utilization rates were found to increase with the increases in the biofilm thickness, suggesting that the biofilm formation process can enhance the metabolic degradation efficiency towards ACN in the MABR. The study contributes to a better understanding in microbial adaptation in a MABR for biodegradation of ACN. It also highlights the potential benefits in using MABRs for biodegradation of organonitrile contaminants in industrial wastewater.     

Online recovery of nisin during fermentation and its effect on nisin production in biofilm reactor

An online removal of nisin by silicic acid coupled with a micro-filter module was proposed as an alternative to reduce detrimental effects caused by adsorption of nisin onto producer, enzymatic degradation by protease, and product inhibition during fermentation. In this study, silicic acid was successfully used to recover nisin from the fermentation broth of Lactococcus lactis subsp. lactis NIZO 22186. The effect of pH (at 6.8 and 3.0) during adsorption process and several eluents (deionized water, 20% ethanol, 1 M NaCl, and 1 M NaCl + 20% ethanol) for desorption were evaluated in a small batch scale. Higher nisin adsorption onto silicic acid was achieved when the adsorption was carried out at pH 6.8 (67% adsorption) than at pH 3.0 (54% adsorption). The maximum recovery was achieved (47% of nisin was harvested) when the adsorption was carried out at pH 6.8 and 1 M NaCl + 20% ethanol was used as an eluent for desorption. Most importantly, nisin production was significantly enhanced (7,445 IU/ml) when compared with the batch fermentation without the online recovery (1,897 IU/ml). This may possibly be attributed to preventing the loss of nisin due the detrimental effects and a higher biomass density achieved during online recovery process, which stimulated production of nisin during fermentation.     

Effective biofilm control in a membrane biofilm reactor using a quenching bacterium (Rhodococcus sp. BH4)

The biofilm thickness in membrane biofilm reactors (MBfRs) is an important factor affecting system performance because excessive biofilm formation on the membrane surface inhibits gas diffusion to the interior of the biofilm, resulting in a significant reduction in the performance of contaminant removal. This study provides innovative insights into the control of biofilm thickness in O₂-based MBfRs by using the quorum quenching (QQ) method. The study was carried out in MBfRs operated at different gas pressures and hydraulic retention times (HRTs) using QQ beads containing Rhodococcus sp. BH4 at different amounts. The highest performance was observed in reactors operated with 0.21 ml QQ bead/cm² membrane surface area, 12 HRTs and 1.40 atm. Over this period, the performance increase in chemical oxygen demand (COD) removal was 25%, while the biofilm thickness on the membrane surface was determined to be 250 μm. Moreover, acetate and equivalent oxygen flux results reached 6080 and 10 640 mg·m⁻²·d⁻¹ maximum values, respectively. The extracellular polymeric substances of the biofilm decreased significantly with the increase of gas pressure and QQ beads amount. Polymerase chain reaction denaturing gradient gel electrophoresis results showed that the microbial community in the MBfR system changed depending on operating conditions and bead amount. The results showed that the QQ method was an effective method to control the biofilm thickness in MBfR and provide insights for future research.     

Developing microbial biofilm as a robust biocatalyst and its challenges

Biocatalysts, such as bacteria, yeast, fungi and the enzymes they produce, have been used for many industrial applications since they function as effective and environmentally friendly tools. Whole cells have also been used in many sophisticated bioprocesses since a number of sequential reactions can be catalyzed within the cells. However, the use of whole cells in suspension in batch, fed-batch and continuous processes has some limitations. For instance, the cultures are non-reusable, they are sometimes sensitive to the toxicity of substrates or products, there can be issues with short-term stability, and each of these issues can impede biocatalyst regeneration, perturbing the downstream process and causing complexity in running large scale continuous culture. Recently, biofilms have emerged as a new generation of biocatalysts to solve these limitations in the production of many bio-based materials, including chemicals, antibiotics, enzymes, bioethanol, biohydrogen, and electricity production via microbial fuel cells. The establishment of industrial processes using biofilms has the potential for high benefit in terms of low-cost cell immobilization without the necessity of added polymers or chemicals. Many small-scale biofilm reactors have been developed for the production of value-added products, and it may be challenging to establish it on an industrial scale.     

Utilisation of a packed-bed biofilm reactor for the determination of the potential of biofilm accumulation in water systems

Abstract

An experimental system has been developed that allows the monitoring of biofilm development on supports exposed to water of different characteristics. The system consists of a series of packed-bed reactors filled with glass beads, and by periodically removing biofilm attached to these beads for off-line analyses this provides a means for monitoring biofilm development. Despite its reduced dimensions (6.9 cm long and 1.58 cm in diameter), the experimental system used has a sampling surface of 90.3 cm² (including only the surface of the glass beads). This allows reproducible and representative samples to be taken from different water systems, providing a reliable and economic method for evaluating in situ the formation of biofilms from different environments. The set-up of the entire experimental system was constructed to meet the demands of field experiments in a well-defined hydrodynamic environment and to allow easy removal of samples for biomass quantification and microscopic observation. Data obtained using this device can be used as an indicator of the risk of biofilm formation in different water systems. This indicator, “the biofilm accumulation potential”, represents an effective and representative tool for the monitoring of biofilm development in an integrated antifouling strategy, in order to help keep biofouling, scaling and microbial risks under control. According to the experiments with the packed-bed reactors used with a high flow regime, the ratio TCN/HPC could provide an indication of the state of the biofilm, and lower ratios could indicate a higher biofilm accumulation potential.     

Small-scale domestic wastewater treatment using an alternating pumped sequencing batch biofilm reactor system

An alternating pumped sequencing batch biofilm reactor (APSBBR) system was developed to treat small-scale domestic wastewater. This laboratory system had two reactor tanks, Reactor 1 and Reactor 2, with two identical plastic biofilm modules in each reactor. Reactor 1 of the APSBBR had five operational phases—fill, anoxic, aerobic, settle and draw. In the aerobic phase, the wastewater was circulated between the two reactor tanks with centrifugal pumps and aeration was mainly achieved through oxygen absorption by microorganisms in the biofilms when they were exposed to the air. This paper details the performance of the APSBBR system in treating synthetic domestic wastewater over 18 months. The effluent from the APSBBR system satisfied the European Wastewater Treatment Directive requirements, with respect to COD, ammonium-nitrogen and suspended solids. The biofilm growth in the two reactor tanks was different due to the difference in substrate loadings and growth conditions.     

Kinetics of anaerobic methane oxidation coupled to denitrification in the membrane biofilm reactor

Anaerobic oxidation of methane coupled to denitrification (AOM-D) in a membrane biofilm reactor (MBfR), a platform used for efficiently coupling gas delivery and biofilm development, has attracted attention in recent years due to the low cost and high availability of methane. However, experimental studies have shown that the nitrate-removal flux in the CH₄-based MBfR (<1.0 g N/m²-day) is about one order of magnitude smaller than that in the H₂-based MBfR (1.1–6.7 g N/m²-day). A one-dimensional multispecies biofilm model predicts that the nitrate-removal flux in the CH₄-based MBfR is limited to <1.7 g N/m²-day, consistent with the experimental studies reported in the literature. The model also determines the two major limiting factors for the nitrate-removal flux: The methane half-maximum-rate concentration (K₂) and the specific maximum methane utilization rate of the AOM-D syntrophic consortium (k_max2), with k_max2 being more important. Model simulations show that increasing k_max2 to >3 g chemical oxygen demand (COD)/g cell-day (from its current 1.8 g COD/g cell-day) and developing a new membrane with doubled methane-delivery capacity (D_m) could bring the nitrate-removal flux to ≥4.0 g N/m²-day, which is close to the nitrate-removal flux for the H₂-based MBfR. Further increase of the maximum nitrate-removal flux can be achieved when D_m and k_max2 increase together.     

Simultaneous Bio-reduction of Nitrate,Perchlorate, Selenate,Chromate, Arsenate,and Dibromochloropropane Using a Hydrogen-based Membrane Biofilm Reactor

We tested the hypothesis that the H₂-based membrane biofilm reactor (MBfR) is capable of reducing multiple oxidized contaminants, a common situation for groundwater contamination. We conducted bench-scale experiments with three groundwater samples collected from California’s San Joaquin Valley and on two synthetic groundwaters containing selenate and chromate. The actual groundwater sources had nitrate levels exceeding 10 mg-N l⁻¹ and different combinations of anthropogenic perchlorate + chlorate, arsenate, and dibromochloropropane (DBCP). For all actual groundwaters, the MBfR reduced nitrate to less than 0.01 mg-N l⁻¹. Present in two groundwaters, perchlorate + chlorate was reduced to below the California Notification Level, 6 μg-ClO₄ l⁻¹. As(V) was substantially reduced to As(III) for two groundwaters samples, which had influent As(V) concentrations from 3 to 8.8 μg-As l⁻¹. DBCP, present in one groundwater at 1.4 μg l⁻¹, was reduced to below its detection limit of 0.01 μg l⁻¹, which is well below California’s 0.2 μg l⁻¹ MCL for DBCP. For the synthetic groundwaters, two MBfRs initially reduced Se(VI) or Cr(VI) stably to Se° or Cr(III). When we switched the influent oxidized contaminants, the new oxidized contaminant was reduced immediately, and its reduction soon was approximately the same or greater than it had been reduced in its original MBfR. These results support that the H₂-based MBfR can reduce multiple oxidized contaminants simultaneously.