细菌的耐盐调控及其在高盐生物脱氮除磷工艺中的应用

生物脱氮除磷(BNR)工艺在氮磷等营养物生物去除过程难免受到盐度变化的冲击,掌握细菌的应对机制,策略性调控系统运行方式,对经济、高效地维持系统的稳定至关重要。本文汇总简述了以下最新研究成果:(1)耐盐微生物能根据环境中盐度的变化,快速地与环境交换水、小分子氨基酸、甘油、多糖类有机物以及钾、钠离子等无机物来平衡细胞渗透压;(2)极端嗜盐菌具有特殊的细胞结构,能够充分利用各类能源(光、电以及化学势比脂肪酸更低的电子供体),促进高能量贮存物(聚糖、聚磷、聚羟基烷酸酯、聚硫)的积累;(3)利用交替厌氧/缺氧/好氧生物膜工艺,接种高盐污泥并同步利用海水驯化生物膜菌群,且借助各种高能物质存储与消耗的偶联反应,可驱动高盐环境中同步硝化/反硝化(除磷)过程的高效运行。最后指出,如何高效地在维持系统稳定性同时设计出合理的工艺与反应器形式,如何通过外源性能源(光、电、化能物质)的输入来调控微生物高盐环境的适应性,是生物脱氮除磷系统的理论研究以及工程实践中亟待解决的问题。

基因编辑鸡制备方法及应用

鸡是研究发育生物学、免疫学以及传染病学的优良模型,同时是满足人们对肉、蛋需求的重要农业经济动物。近年来,随着全球鸡肉产量与消耗量的不断增长,养禽业对禽病防控、保种育种的需求也随之增加。为此,研究人员结合基因编辑技术制备了转基因鸡或基因编辑鸡,从而更加深入地了解鸡生长发育、免疫抗病机制,为产业实践提供了坚实的理论基础。由于鸡独特的生殖生理特点,无法获取单细胞卵子,难以应用哺乳动物的基因编辑方法。文章综述了现有制备基因编辑鸡的方法及优缺点,并指出了基因编辑鸡制备过程存在的问题,为基因编辑鸡的制备提供参考。

RESEARCH ON MEMBRANE BIOREACTOR TREATING DOMESTIC WASTEWATER AND RELATED MECHANISMS

Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With intermittent operation and continuous aeration,the membrane flux was kept steady.The mechanisms of removing COD through membrane,the structure of membrane and filtration resistance were also discussed.

Viable but Non-culturable Bacteria in Bioreactorbased Pharmaceutical Wastewater

We aimed to investigate the composition and phylogenetic rela-tionships of the viable but non-culturable （VBNC） state bacteria in pharmaceutical wastewater. [Method] Soil filter was used for constructing bioreactor. Based on the resuscitation- and growth-promoting function of Resuscitation Promoting Factor （Rpf） for VBNC bacteria, VBNC bacteria were isolated by most probable number （MPN） method and dilution-plating method and 16S rRNA gene phylogenetic analysis was carried out. [Result] In MPN culture system, Rpf could promote the resuscitation and growth of some bacteria. There were VBNC advantage floras that sensitive to Rpf in pharmaceutical wastewater. The culturable VBNC bacteria in pharmaceutical wastewater consisted of high-GC gram-positive actinomycetes including genera Mi-crobacterium, Gordonia and Leucobacter, and gram-negative bacteria including gen-era Candidimonas, Xanthobacter and Aminobacter. Four strains （ZYM1, ZYM3, ZYZR4, ZYXR1） could be potential novel species. [Conclusion] This research re-vealed there were VBNC bacteria in pharmaceutical wastewater. These results could provide important ideas and methods for further studies on VBNC bacteria in the pharmaceutical wastewater, especial y the formation mechanism and recovery mech-anism of VBNC bacteria and the advanced degradation process improvement of pharmaceutical wastewater.

间歇性投加Fe(Ⅱ)协同MBR强化生物脱氮除磷的研究

为考察间歇性投加亚铁(Fe(Ⅱ))对陶瓷膜膜生物反应器(MBR)脱氮除磷效果的影响,以合成废水作为原水,系统考察了当Fe(Ⅱ)的投加量为Fe(Ⅱ)/P=1和2(摩尔比)时,MBR的出水水质、微生物群落结构及相关功能基因拷贝数的变化情况。结果显示,投加Fe(Ⅱ)可有效去除出水总磷(TP)和总氮(TN),与对照组相比,当投加量为Fe(Ⅱ)/P=1和2时,TP的去除率分别提高了14.40%和18.60%,TN的去除率分别提高了2.30%和6.50%。实验进一步研究了Fe(Ⅱ)对优势菌群和相关功能基因的影响,投加Fe(Ⅱ)可以通过提高脱氮(Dechloromonas、Hyphomicrobium、Nitrospira、Zoogloea和Acinetobacter)和除磷(Candidatus Accumulibacter)微生物的相对丰度、脱氮相关功能基因拷贝数(AOB-amoA、narG、nirK/nirS、norB和norZ)强化生物脱氮除磷效能。采用PICRUSt功能预测分析表明,在Fe(Ⅱ)/P=2条件下,Fe(Ⅱ)可以通过促进反硝化过程的酶(NR、NIR、NOR和N2OR)的相对丰度提高脱氮性能。综上,当投加量为Fe(Ⅱ)/P=2时,可通过影响脱氮除磷过程中关键功能基因拷贝数及生物群落结构,强化陶瓷膜MBR系统生物脱氮除磷性能。

不同双酚A废水处理方式对污泥性能的影响

利用序批式生物反应器(SBR)处理双酚A(BPA)废水,其中一个SBR中直接投加进水浓度为40 mg/L的BPA(冲击SBR),另一个SBR经20 mg/L进水BPA驯化成功后提高其浓度至40 mg/L(驯化SBR),探讨了不同BPA废水处理方式对污泥性能的影响。结果表明:驯化SBR出水COD浓度基本维持在50 mg/L左右,出水中未检出BPA的残留,但冲击SBR的污泥活性受到显著抑制,出水COD浓度高达229.6 mg/L,出水BPA浓度高于30 mg/L,但出水COD和BPA浓度随运行时间的延长而逐渐下降。冲击SBR的胞外聚合物(EPS)含量显著高于驯化SBR,但随着运行时间的延长而趋于一致。单个SBR周期中污染物的去除和EPS含量变化证实,冲击SBR的污泥性能在稳定运行后与驯化SBR基本保持一致。

Start-up of anaerobic ammonia oxidation bioreactor with nitrifying activated sludge

The anaerobic ammonia oxidation(Anammox) bioreactor was successfully started up with the nitrifying activated sludge. After anaerobically operated for 105 d, the bioreactor reached a good performance with removal percentage of both ammonia and nitrite higher than 95% and volumetric total nitrogen removal as high as 149.55 mmol/(L·d). The soft padding made an important contribution to the high efficiency and stability because it held a large amount of biomass in the bioreactor.

Effect of leachate recycle and inoculation on microbial characteristics of municipal refuse in landfill bioreactors

Population development of key groups of anaerobic and aerobic bacteria involved in municipal refuse decomposition under laboratory landfill bioreactors with and without leachate recycle and inoculation was measured since modeling municipal refuse was landfilled in bioreactors for about 210 days. Hydrolytic fermentative bacteria (HFB), hydrogen-producing acetogenic bacteria (HPAB), methane-producing bacteria (MPB), sulfate-reducing bacteria (SRB), anaerobic and aerobic cellulolytic bacteria and denitrabacteria were enumerated by the most probable number technique. The results showed that the dominant microorganism groups were the methanogenic bacteria including hydrolytic fermentative, hydrogen-producing acetogenic and methane-producing bacteria. They were present in fresh refuse but at low values and positively affected by leachate recycle and refuse inoculation. The amounts of HFB or HPAB in digesters D4 and D5 operated with inoculation and leachate recycle reached their maximum values of 1010 - 1012 cells/g dry refuse for HFB or 105 - 106 cells/g dry refuse for HPAB on day 60, in digester D3 operated with leachate recycle on day 120 for HFB (109 cells/g dry refuse) or on day 90 for HPAB (105 cells/g dry refuse), and in digesters D1 and D2 on day 210 for HFB (109 cells/g dry refuse) or on day 90 for HPAB (104 - 106 cells/g dry refuse). The population of methane-producing bacteria in digesters D4 and D5 sharply increased on days 60 and 90 respectively, however in digesters D1, D2 and D3 on day 120. Leachate recycle and inoculation changed the cellulolytic microorganisms composition of refuse ecosystem, the higher amounts of anaerobic cellulolytic bacteria were measured in digesters D4 and D5 (107 cells/g dry refuse), followed by digesters D3 (106 cells/g dry refuse), D2 or D1 (104 cells/g dry refuse). However, the amounts of aerobic cellulolytic bacteria were much lower than that of anaerobic cellulolytic bacteria. And it was higher in digesters D3 than those in digesters D1, D2, D4 and D5. The amounts of SRB and denitrabacteria were also higher in digester D5 than those in digesters D1, D2, D3 and D4. Refuse decomposition could be accelerated by leachate recycle and inoculation in the view of microorganism development.

Effect of sludge retention time on sludge characteristics and membrane fouling of membrane bioreactor

Three identical membrane bioreactors （MBRs） were operated over 2 years at different sludge retention time （SRT） of 10 d, 40 d and no sludge withdrawal （NS）, to elucidate and quantify the effect of SRT on the sludge characteristics and membrane fouling. The hydraulic retention times of these MBRs were controlled at 12 h. With increasing SRT, the sludge concentrations in the MBRs increased, whereas the ratio of volatile suspended solid to the total solid decreased, and the size of sludge granule diminished in the meantime. A higher sludge concentration at long SRT could maintain a better organic removal efficiency, and a longer SRT was propitious to the growth of nitrifiers. The performance of these MBRs for the removal of COD and NH4^＋-N did not change much with different SRTs. However, the bioactivity decreased as SRT increase. The measurement of specific oxygen uptake rates （SOUR） and fluorescence in situ hybridization （FISH） with rRNA-targeted oligonucleotide probes testified that SOUR and the proportion of the bacteria-specific probe EUB338 in all DAPI-stainable bacteria decreased with increasing SRT. The concentrations of total organic carbon, protein, polysaccharides and soluble extracellular polymeric substance （EPS） in the mixed liquor supernatant also decreased with increasing SRT. The membrane fouling rate was higher at shorter SRT, and the highest fouling rate appeared at a SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the relative contribution of the gel layer decreased as SRT increase.

Evaluation of a novel choanoid fluidized bed bioreactor for future bioartificial livers

AIM: To construct and evaluate the functionality of a choanoid-fluidized bed bioreactor (CFBB) based on microencapsulated immortalized human hepatocytes.

Occurrence and removal of organic micropollutants in the treatment of landfill leachate by combined anaerobic-membrane bioreactor technology

Organic micropollutants,with high toxicity and environmental concern,are present in the landfill leachate at much lower levels than total organic constituents (chemical oxygen demand (COD),biochemical oxygen demand (BOD),or total organic carbon (TOC)),and few has been known for their behaviors in different treatment processes.In this study,occurrence and removal of 17 organochlorine pesticides (OCPs),16 polycyclic aromatic hydrocarbons (PAHs),and technical 4-nonylphenol (4-NP) in landfill leachate in a comb...

Zeolite powder addition to improve the performance of submerged gravitation-filtration membrane bioreactor

In this study, the effect of zeolite powder addition on submerged membrane bioreactor （SMBR） on membrane permeability, and the removals for COD, NH3-N, TN were investigated. Through the parallel operation of control and test systems, it was found that the zeolite powder addition could alleviate the ultra-filtration membrane fouling and enhance the membrane permeability. On the basis of experimental investigations, a concept of ＂protection coating layer＂ was proposed to illustrate the phenomenon of UF membrane fouling. In addition, the removal for COD in test system was more stable, a little higher compared to the control system. Due to the combination of nitrification and ion exchange, a more excellent removal for NH3-N in test system was obtained regardless of influent NH3-N loading rate. It was also found that a mean 25% higher TN removal took place in the test system, and ion exchange and simultaneous nitrification and de-nitrification were analyzed to be main factors. During the stable operation period, the SOURs of test zeolite powder added sludge and control activated sludge were measured to be 75 mgO2/（gMLVSS, h） and 24 mgO2/（gMLVSS, h） respectively, it meant that the zeolite powder addition could enhance the microorganism activity significantly.

Effect of powdered activated carbon on Chinese traditional medicine wastewater treatment in submerged membrane bioreactor with electronic control backwashing

Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors （SMBRs） operated in parallel under the same feed, equipped with the same electronic control backwashing device. One was used as the control SMBR （CSMBR） while the other was dosed with powdered activated carbon （PAC） （PAC-amended SMBR, PSMBR）. The backwashing interval was 5 min. One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency. The average flux of CSMBR during a steady periodic state of 24 d （576 h） was 5.87 L/h with average hydraulic residence time （HRT） of 5.97 h and that of PSMBR during a steady periodic state of 30 d （720 h） was 5.85 L/h with average HRT of 5.99 h. The average total chemical oxygen demand （COD） removal efficiency of CSMBR was 89.29% with average organic loading rate （OLR） at 4.16 kg COD/（m^3.d） while that of PSMBR was 89.79% with average OLR at 5.50 kg COD/（m^3.d）. COD concentration in the effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry （300 mg/L）. Hence, SMBR with electronic control backwashing was a viable process for medium-strength Chinese traditional medicine wastewater treatment. Moreover, the increasing rates of preestablished backwashing vacuum, pump frequency, and vacuum and flux loss caused by mixed liquor in PSMBR all lagged compared to those in CSMBR; thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system, and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR.

A pilot scale anoxic/oxic membrane bioreactor(A/O MBR) for woolen mill dyeing wastewater treatment

A pilot scale(10 m 3/d) anoxic/oxic membrane bioreactor(A/O MBR) was tested for dyeing wastewater treatment of woolen mill without wasting sludge in 125 days operation. Results showed that the effluent quality was excellent, i.e. effluent COD less than 25 mg/L, BOD 5 under 5 mg/L, turbidity lower than 0 65 NTU, and colour less than 30 DT, and met with the reuse water standard of China. The removal rates of COD, BOD 5, colour, and turbidity were 92 4%, 98 4%, 74% and 98 9%, respectively. Constant flux operation mode was carried out in this study, and backwash was effective for reducing membrane fouling and maintaining constant flux. Membrane fouling had heavy impact on energy consumption. More attention should be paid on pipe selection and design for the sidestream MBR system, too.

Engineering stem cell niches in bioreactors

Stem cells, including embryonic stem cells, induced pluripotent stem cells, mesenchymal stem cells and amniotic fluid stem cells have the potential to be expanded and differentiated into various cell types in the body.Efficient differentiation of stem cells with the desired tissue-specific function is critical for stem cell-based cell therapy, tissue engineering, drug discovery and disease modeling. Bioreactors provide a great platform to regulate the stem cell microenvironment, known as "niches",to impact stem cell fate decision. The niche factors include the regulatory factors such as oxygen, extracellular matrix(synthetic and decellularized), paracrine/autocrine signaling and physical forces(i.e., mechanical force, electrical force and flow shear). The use of novel bioreactors with precise control and recapitulation of niche factors through modulating reactor operation parameters can enable efficient stem cell expansion and differentiation. Recently, the development of microfluidic devices and microbioreactors also provides powerful tools to manipulate the stem cell microenvironment by adjusting flow rate and cytokine gradients. In general,bioreactor engineering can be used to better modulate stem cell niches critical for stem cell expansion, differentiation and applications as novel cell-based biomedicines. This paper reviews important factors that can be more precisely controlled in bioreactors and their effects on stem cell engineering.

Three-dimensional Expansion:In Suspension Culture of SD Rat's Osteoblasts in a Rotating Wall Vessel Bioreactor

Objective To study large-scale expansion of SD （Sprague-Dawley） rat＇s osteoblasts in suspension culture in a rotating wall vessel bioreactor （RWVB）. Methods The bioreactor rotation speeds were adjusted in the range of 0 to 20 rpm, which could provide low shear on the rnicrocarriers around 1 dyn/cm^2. The cells were isolated via sequential digestions of neonatal （less than 3 days old） SD rat calvaria. After the primary culture and several passages, the cells were seeded onto the microcarriers and cultivated in T-flask, spinner flask and RWVB respectively. During the culture period, the cells were counted and observed under the inverted microscope for morphology every 12 h. After 7 days, the cells were evaluated with scanning electron microscope （SEM） for histological examination of the aggregates. Also, the hematoxylin-eosin （HE） staining and alkaline phosphatase （ALP） staining were performed. Moreover, von-Kossa staining and Alizarin Red S staining were carded out for mineralized nodule formation. Results The results showed that in RWVB, the cells could be expanded by more than ten times and they presented better morphology and vitality and stronger ability to form bones. Conclusions The developed RWVB can provide the culture environment with a relatively low shear force and necessary three-dimensional （3D） interactions among cells and is suitable for osteopath expansion in vitro.

Progress in bioreactors of bioartificial livers

BACKGROUND: Bioartificial liver support systems are becoming an effective therapy for hepatic failure. Bioreactors, as key devices in these systems, can provide a favorable growth and metabolic environment, mass exchange, and immunological isolation as a platform. Currently, stagnancy in bioreactor research is the main factor restricting the development of bioartificial liver support systems. DATA SOURCES: A PubMed database search of English-language literature was performed to identify relevant articles using the keywords 'bioreactor', 'bioartificial liver', 'hepatocyte', and 'liver failure'. More than 40 articles related to the bioreactors of bioartificial livers were reviewed. RESULTS: Some progress has been made in the improvement of structures, functions, and modified macromolecular materials related to bioreactors in recent years. The current data on the improvement of bioreactor configurations for bioartificial livers or on the potential of the use of certain scaffold materials in bioreactors, combined with the clinical efficacy and safety evaluation of cultured hepatocytes in vitro, indicate that the AMC (Academic Medical Center) BAL bioreactor and MELS (modular extracorporeal liver support) BAL bioreactor system can partly replace the synthetic and metabolic functions of the liver in phase I clinical studies. In addition, it has been indicated that the microfluidic PDMS (polydimethylsiloxane) bioreactor, or SlideBioreactor, and the microfabricated grooved bioreactor are appropriate for hepatocyte culture, which is also promising for bioartificial livers. Similarly, modified scaffolds can promote the adhesion, growth, and function of hepatocytes, and provide reliable materials for bioreactors. CONCLUSIONS: Bioreactors, as key devices in bioartificial livers, play an important role in the therapy for liver failure both now and in the future. Bioreactor configurations are indispensable for the development of bioartificial livers used for liver failure, just as the modified scaffold materials available for bioreactors are favorable to the construction of effective bioartificial livers.

零排放技术在煤化工污水处理中的应用研究

煤化工产出污水中包含了大量的种类繁杂且具有毒性的污染物,随意排放会对环境造成不可逆的破坏。为此,提出一种零排放技术在煤化工污水处理中的应用措施,并探究应用效果。在分析三种煤化工工艺污水产生节点后,确定其中所包含的污染物种类;将零排放技术应用在煤化工污水处理中,通过预处理、生化处理、深度处理、含盐污水处理以及污泥和结晶盐处理等步骤,使污水达到回用标准,无法回收的则转换为固体,实现污水零排放。通过实例分析可知,零排放技术应用后,可使矿区污水达到水平衡,盐类物质含量大幅度减少,避免了水质污染。

Landfill leachate treatment in assisted landfill bioreactor

Landfill is the major disposal route of municipal solid waste（MSW） in most Asian countries. Leachate from landfill presents a strong wastewater that needs intensive treatment before discharge. Direct recycling was proposed as an effective alternative for leachate treatment by taking the landfill as a bioreactor. This process was proved not only considerably reducing the pollution potential of leachate, but also enhancing organic degradation in the landfill. However, as this paper shows, although direct leachate recycling was effective in landfilled MSW with low food waste fraction （3.5%, w/w）, it failed in MSW containing 54% food waste, as normally noted in Asian countries. The initial acid stuck would inhibit methanogenesis to build up, hence strong leachate was yielded from landfill to threaten the quality of receiving water body. We demonstrated the feasibility to use an assisted bioreactor landfill, with a well-decomposed refuse layer as ex-situ anaerobic digester to reducing COD loading in leachate. By doing so, the refuse in simulated landfill column （2.3 m high） could be stabilized in 30 weeks while the COD in leachate reduced by 95%（61000 mg/L to 3000 mg/L）. Meanwhile, the biogas production was considerably enhanced, signaling by the much greater amount and much higher methane content in the biogas.

Improvement of antifouling characteristics in a bioreactor of polypropylene microporous membrane by the adsorption of Tween 20

Surface modification by physical adsorption of Tween 20 was accomplished on polypropylene microporous membranes （PPMMs）. Attenuated total reflection-Fourier transform infrared spectroscopy （ATR/FT-IR） and field emission scanning electron microscope （FE- SEM） were used to characterize the chemical and morphological changes on the membrane surfaces. Water contact angles and relative pure water fluxes were measured. The data showed that the hydrophilic performance for the modified membranes increased with the increase in the adsorption amount of Tween 20 onto the surface or into the pores of polypropylene microporous membranes. To test the antifouling property of the membranes by the adsorption of Tween 20 in a membrane bioreactor （MBR）, filtration for active sludge was performed using synthetic wastewater. With the help of the data of water fluxes and the FE-SEM photos of the modified PPMMs before or after operating in a MBR for about 12 d, the PPMMs with monolayer adsorption of Tween 20 showed higher remained flux and stronger antifouling ability than unmodified membrane and other modification membranes studied.