樊立萍1,*,温越霄1,2

为提高微生物燃料电池(MFC)的废水处理效果和发电性能,制备了一种海藻酸钠-聚季铵盐11/碳毡(SA-PQ-11/CF)阳极,分别以制药废水和糖蜜废水为阳极液,以碳毡为阴极,构建微生物燃料电池(MFC)实验系统,通过扫描电子显微镜(SEM)、电化学阻抗谱(EIS)、循环伏安特性(CV)、化学需氧量(COD)对其性能进行表征。结果显示,SA-PQ-11/CF阳极具有较大的比表面积,MFC的溶液电阻和电荷转移电阻也得到明显降低。阳极液为制药废水时,采用SA-PQ-11/CF阳极的MFC的稳态输出电压和COD去除率分别约为0.22 V和62%,较常规碳毡阳极时分别提高了100%和130%。阳极液为糖蜜废水时,采用SA-PQ-11/CF阳极的MFC的稳态输出电压和COD去除率分别为0.15 V和43%,分别较采用常规碳毡阳极时提高了275%和95%。基于SA-PQ-11的阳极改性能够有效提高MFC的废水处理效果和产电能力。     

交联壳聚糖/蒙脱土复合膜的制备及性能研究

以壳聚糖（CS）为基质材料，蒙脱土（MMT）为填料，采用戊二醛（GA）交联改性并结合溶液插层法制备了交联壳聚糖/蒙脱土（CS/GA/MMT）复合膜。通过扫描电子显微镜、X射线衍射仪、红外光谱仪及热重分析仪对复合膜的结构进行了表征，考察了MMT用量对复合膜的吸水性能、水蒸气阻隔性能和力学性能的影响。结果表明，交联改性CS可提高CS膜的耐水性，CS/GA膜的吸水率较CS膜降低了9.6 %；MMT可提高复合膜的耐水性、水蒸气阻隔性能、力学性能和热稳定性；当MMT的用量为CS质量的5 %时，复合膜的各项性能较好，吸水率、水蒸气透过率和断裂伸长率较CS膜分别降低了37.3 %、36.7 %和41.9 %，且拉伸强度提高了160.5 %。     

不同来源菌群接种微生物燃料电池处理淀粉废水的研究

以人工模拟淀粉废水为底物运行微生物燃料电池(MFC),分别采用淀粉废水、生活污水和二者的混合液为接种液,考察不同来源菌群接种下,MFC产电能力与废水处理效果。研究结果表明,采用混合液接种时,MFC启动时间相对于淀粉废水和生活污水接种分别缩短了29.6%和26.9%,最大产电功率密度分别提高了156%和6.1%;COD、NH4+-N去除率略有提高。对利用混合液接种的MFC进一步优化,结果表明,当MFC基质pH为9,NaCl质量浓度为1.0 g/L,基质COD为3 100 mg/L,温度为30℃时,MFC的产电能力与废水处理效果最佳,产电功率密度达4.63W/m3,COD去除率为86.3%,NH4+-N去除率为82.6%。     

曝气方式对微生物燃料电池脱氮和产电性能的影响

微生物燃料电池(Microbial fuel cells,MFCs)用于低C/N废水脱氮具有较好的应用前景。研究以模拟尿液为底物,考察了曝气方式与膜材料对双室MFC产电性能和脱氮效果的影响。结果表明,当进水COD浓度为1500 mg/L、C/N为2,两个MFC均具有良好的除氮脱碳效果,COD降解率平均值高于89%,总氮去除率平均值高于72%。产电能力最强的是间歇曝气状态下的MFC2,采用阳离子交换膜,最高输出电压为702.1 mV,最大输出功率密度为365.14 W/m~3;阳离子交换膜有利于提高MFC的产电性能,质子交换膜具有良好的有机物降解和脱氮效果。间歇曝气可为阴极室提供较低浓度的溶解氧,MFC的产电性能和脱氮能力明显优于不曝气方式。     

静电层层自组装改性SPPESK/PWA质子交换膜

运用直接掺杂法制备的磺化聚芳醚砜酮/磷钨酸(SPPESK/PWA)复合质子交换膜存在PWA流失严重的问题,影响了膜的正常使用。为了解决这一问题,以壳聚糖(CS)和PWA为聚阴阳离子电解质对,对复合膜进行静电层层(LBL)自组装改性研究,对膜的吸水率、溶胀度、质子传导率等性能进行了表征,并测试了膜中PWA的稳定性。经测定,SPPESK/PWA/(CS/PWA)₂的质子传导率达到154mS/cm(80℃),高于相应的SPPESK膜(118mS/cm)及SPPESK/PWA膜(147mS/cm);SPPESK/PWA/(CS/PWA)₄在80℃水中浸泡30天后,膜的质量损失率由18.45%降为11.81%,电导率损失率由32.20%降为16.77%。结果表明,该方法不仅提高了复合膜的质子传导率,并且有效抑制了PWA的流失。     

负载诱导膜多孔电气石陶瓷的制备及生物相容性的研究

笔者采用浸渍提拉的方法将聚乙烯醇、硅溶胶、海藻酸钙等涂敷于多孔电气石板上对其进行改性,并通过SEM观察改性后对多孔电气石的生物相容性及其处理COD的能力进行测定。实验表明:聚乙烯醇和硅溶胶可以对多孔电气石进行改性,改性后多孔电气石板的生物相容性提高,微生物负载量增大。其处理COD的能力明显提高。负载PVA诱导膜的多孔电气石板的COD的最大去除率达到80%左右,负载硅溶胶诱导膜的多孔电气石板对污水COD的去除率达到79%。     

MFC-MEC耦合系统产电性能及处理含镉重金属废水的研究

以厌氧活性污泥为阳极菌种,乙酸钠为阳极底物,硫酸铜和重铬酸钾溶液为微生物燃料电池（MFC）阴极液,人工模拟含镉重金属废水为微生物电解池（MEC）阴极液,构建MFC-MEC耦合系统,利用MFC的产电驱动MEC运行,在不消耗外部能源的情况下,实现含镉重金属废水中Cd²⁺的去除。实验研究了MFC反应器容积、MFC堆栈、MEC电极材料、MEC阴极液pH对MFC-MEC耦合系统电性能及含镉重金属废水处理效果的影响。结果表明：MFC反应容积的扩大可以提高其产电性能,但与此同时会造成MFC的内阻升高,随着MFC容积的增加,MEC中Cd²⁺去除率逐渐增加,但同时MFC阴极Cr⁶⁺去除率逐渐下降;MFC堆栈可以提高工作组两端电压,串联时最大输出电压为1509 mV,Cd²⁺去除率为69.3%;以钛板作为MEC电极时,微生物能有效附着在阳极表面,MFC阳极COD去除率为85%,MEC中Cd²⁺去除率为51.5%;MEC阴极液pH在3~5时,有利于含镉重金属废水的处理,Cd²⁺去除率80%以上。经XRD分析,MEC阴极还原产物为CdCO₃。     

双极室微生物燃料电池处理不同阳极底物废水的产电研究

为了研究微生物燃料电池(MFC)在不同阳极底物废水条件下的产电效率和废水处理效果。分别以啤酒废水、糖蜜废水和啤酒-糖蜜混合废水作为阳极基质,含银电镀废水作为阴极电子受体,构建了双极室微生物燃料电池。结果表明,3组以糖蜜废水作为阳极基质的MFC产电量和COD去除率最高,啤酒废水次之,啤酒-糖蜜混合废水最低。糖蜜废水作为阳极基质的MFC最高电压和功率密度可达356 m V和36.21 m W/m~2,第3周期时COD去除率达到最高的69.29%,实验结束时阴极Ag~+的质量浓度最低至304 mg/L。不同阳极基质对MFC产电效率和废水处理效果有影响。     

NCC/改性纳米SiO2/PVA共混膜的制备及表征

采用共混法制备了纳米纤维素(NCC)/改性纳米二氧化硅(SiO2)/聚乙烯醇(PVA)共混膜。傅里叶变换红外(FTIR)光谱分析结果表明NCC/改性纳米SiO2/PVA共混膜的共混模式为存在氢键作用力的简单物理共混。力学性能分析结果表明NCC/改性纳米SiO2/PVA共混膜较PVA膜具有较高的拉伸强度,其拉伸强度平均值为128.41 MPa。热学性能分析结果表明NCC/改性纳米SiO2/PVA共混膜较PVA膜具有较好的热稳定性,其最大热失重温度为238℃。扫描电子显微镜(SEM)图分析结果表明NCC/改性纳米SiO2/PVA共混膜样品的表面和断面形貌较规整。     

尿素/甲酰胺增塑PVA的性能研究

采用流延成膜法制备了以尿素/甲酰胺为复配增塑剂改性的聚乙烯醇(PVA)改性薄膜。采用FTIR研究了复配增塑剂尿素/甲酰胺和PVA之间的相互作用,采用XRD、DSC、TGA和拉伸性能测定对改性后的PVA膜性能进行了测试表征。结果表明,尿素/甲酰胺能与PVA形成氢键作用,破坏PVA的结晶结构,降低PVA膜的结晶度。尿素/甲酰胺的加入降低了PVA的熔点,提高了PVA的热分解温度。改性后的PVA膜的拉伸强度降低,断裂伸长率提高。     

Facile modification of thin-film composite nanofiltration membrane with silver nanoparticles for anti-biofouling

This study focuses on the modification of a commercial nanofiltration (NF) membrane by an in-situ reaction to load silver nanoparticles (AgNPs) for anti-biofouling. Poly (vinyl alcohol) (PVA) was coated onto the NF membrane firstly, and silver salt was then deposited on the surface of PVA layer. Through thermal reduction, AgNPs with 10–20 nm in diameter were formed and immobilized onto the membrane surface by the interaction between AgNPs and PVA, as confirmed by UV–vis absorption spectrum, SEM and XPS analysis. Compared to the pristine NF90 membrane, the PVA composite membranes (NF90-PVA) and AgNPs (NF90-PVA-AgNPs) modified membranes exhibit lower water flux and slightly higher salt rejection. Release of silver ion experiments were assessed via batch method, and the results indicate silver ion can be released from the AgNPs modified membrane continuously and steadily, which may be responsible for the improved and long-time antibacterial ability of the membrane. Due to the simplicity of the method, the ability to immobilize the AgNPs to avoid leaching out, and the strong antibacterial activity, this NF90-PVA-AgNPs composite membrane displays potential applications in industrial water-treatment.     

Active layer modification of commercial nanofiltration membrane using CuBTC/PVA matrix for improved surface and separation characteristics

The present study proposes a facile route for the modification of commercial nanofiltration (NF) polymeric membrane by embedding metal organic framework (MOF) via dip coating. A mixed membrane matrix comprising of copper benzene-1,3,5-tricarboxylate (CuBTC) and polyvinyl alcohol (PVA) served as the new active layer. The obtained topography, functional group, and surface elemental analysis elucidated the presence of heterogeneous phase and the distribution of the MOF on the membrane. The dip coating well supported the modification through excellent adhesion. The water wettability of the modified membrane displayed a positive correlation with CuBTC loading in the PVA polymer matrix. Permeation and separation characteristics of the resultant membranes were investigated by retaining protein and carbohydrates from synthetic dairy wastewater (SDWW). The permeability rate of modified samples increased to 43% as compared to the commercial NF membrane. A significant improvement in the rejection rate of carbohydrate from 61% to 87% and protein from 88% to 94% was achieved. Membrane Fouling was found to be much lesser for the modified samples. The study highlights the potential of CuBTC as filler material for enhancing the separation characteristic of established NF membrane.     

Performance of the sulfonated poly ether ether ketone proton exchange membrane modified with sulfonated polystyrene and phosphotungstic acid for microbial fuel cell applications

In this research, the preparation of low cost proton exchange membranes (PEMs) based on sulfonated poly ether ether ketone (SPEEK) for application in the microbial fuel cells (MFCs) is studied. Sulfonated polystyrene (SPS) and phosphotungstic acid (PWA) were employed to improve the performance of PEM through the creation of more proton pathways. At first, the sulfonation of PEEK and polystyrene were performed through two modified methods to obtain uniform and high degree of sulfonation (DS) of the polymers and then, the PEMs were prepared through the solution casting method. Accordingly, the formation of uniform skin layer was confirmed by the SEM micrographs. Blending the aforementioned additives to the SPEEK polymer solution significantly enhanced the proton conductivity, water uptake and durability of the modified membranes. The proton conductivities of SPEEK/SPS and SPEEK/PWA membranes at additive/SPEEK weight ratio of 0.15 were 45.3% and 26.2% higher than that of the commercial Nafion117 membrane, respectively. Moreover, the degradation times for the abovementioned modified membranes were 140 and 350 min which indicated satisfactory oxidation stability. Besides, the aforementioned membranes exhibited two times more water uptake compared to the neat SPEEK membrane. Finally, SPEEK/SPS and SPEEK/PWA membranes produced 68% and 36% higher maximum power in the MFC, compared to the commercial Nafion117 membrane. Therefore, the fabricated PEMs are potentially suitable alternatives to be used in the fuel cell applications.     

COD Removal from Concentrated Wastewater Using Membranes

Membranes can be used for wastewater treatment. The selection of the appropriate membrane depends on a number of factors, such as waste characteristics, nature of materials present in the wastewater, concentration, temperature, pH, etc. If the wastewater contains low molecular weight organics, reverse osmosis (RO) is the best treatment process. RO membranes allow solvent (water) to pass and prevent the transport of organics, either completely or partially. In this study, raw wastewater from an alcohol manufacturing plant was treated using a RO process. The chemical oxygen demand (COD) of the wastewater was between 35000-40000 mg/l due to the presence of organic components. Eight polymeric membranes (e.g. FT30, PVD, DSII, DS, BW30, 37100, 3750 and NF45) were used in total. None of the membranes were able to reduce COD to a desirable level (i.e. less than 200 mg/l) in one step. However a two-step process could be designed for wastewater treatment. Based on data obtained for flux and rejection, the NF45 nanofiltration membrane exhibited the best performance. A high volume of fluid can pass through the NF45 membrane because of its high porosity. The flux of this membrane (i.e. 15 kg/m².h) was higher than the reverse osmosis membranes tested. The NF45 membrane decreased COD to a greater extent than the other membranes tested (52%). While the PVD membrane showed better efficiency compared to the other reverse osmosis membranes, probably because of its material of construction and configuration.     

Influence of filtration conditions on the performance of nanofiltration and reverse osmosis membranes in dairy wastewater treatment

Filtration performance and fouling of nanofiltration (NF) and reverse osmosis (RO) membranes in the treatment of dairy industry wastewater were investigated. Two series of experiments were performed. The first one involved a NF membrane (TFC-S) for treating the chemical-biological treatment plant effluents. The second one used a RO membrane (TFC-HR) for treating the original effluents from the dairy industry. The permeate flux was higher at higher transmembrane pressures and higher feed flowrates. The curves of permeate flux exhibited a slower increase while the feed flowrate decreased and the pressure increased. Membrane fouling resulted in permeate flux decline with increasing the feed COD concentration. Furthermore, the flux decline due to the COD increase was found higher at higher pressures for both NF and RO membranes.     

Preparation, morphology and performance evaluation of polyvinylalcohol (PVA)/polyethersulfone (PES) composite nanofiltration membranes for pulp and paper wastewater treatment

In this study, thin film composite PVA/PES nanofiltration membranes were fabricated for the treatment of pulp and paper industrial wastewater. Phase separation induced by immersion precipitation was used to prepare the PES support membrane. PVA/PES composite nanofiltration membranes were prepared by dipping the support PES membrane in the PVA and cross-linking solutions at different conditions. Maleic acid (MA) was used as cross-linking agent. PVA and MA have concentrations of 0.5?C2 and 0.05?C1 wt%, respectively. Morphological studies were carried out by means of scanning electron microscopy (SEM) as well as atomic force microscopy (AFM) techniques. In addition, the hydrophilicity of membranes was examined by contact angle measurements. Permeability and ability of PVA/PES composite nanofiltration membranes to reduce COD of the wastewater were evaluated by a cross flow filtration system. SEM images indicated that the PVA layer was uniformly formed on the PES support membrane. AFM images showed that the surface roughness, porosity and pore sizes of PES support membrane were reduced after formation of PVA layer on the support surface. Moreover, the hydrophilicity of the membranes was significantly increased. Experimental results demonstrated that the PVA/PES composite nanofiltration membranes were able to reduce the COD of wastewater. Optimum conditions for preparation of PVA/PES composite membrane are consisted of PVA concentration: 1 wt%, MA concentration: 0.5 wt%, cross-linking time: 3?min and curing time: 3?min.     

纳滤/反渗透膜处理重金属废水的性能

The performance of different nanofiltration （NF） and reverse osmosis （RO） membranes was studied in treating the toxic metal effluent from metallurgical industry. The characteristics and filtration behavior of the processes including the wastewater flux, salt rejection and ion rejection versus operating pressure were evaluated. Then the wastewater flux of RO membrane was compared with theoretical calculation using mass transfer models, and good consistency was observed. It was found that a high rejection rate more than 95% of metal ions and a low Chemical Oxygen Demand （COD） value of 10 mg·L^-1 in permeate could be achieved using the RO composite membrane, while the NF rejection of the salt could be up to 78.9% and the COD value in the permeate was 35 mg·L^-1. The results showed that the product water by both NF and RO desalination satisfied the State Reutilization Qualification, but NF would be more suitable for large-scale industrial practice, which offered significantly higher permeate flux at low operating pressure.     

Removal of nitrogen in wastewater by polyvinyl alcohol (PVA)-immobilization of effective microorganisms

To remove nitrogen and carbon simultaneously from municipal wastewater, a mixture of effective microorganisms (EM) was immobilized in polyvinyl alcohol (PVA) hydrogel beads. The modified PVA beads with calcium alginate show characteristic pores and mechanical stability and flexibility. The EM-immobilized PVA system was established in a 3 L sequential batch reactor (SBR) with a synthetic wastewater and operated at an HRT of 12 h with COD loading rate of 0.5–2.4 g COD/L·d. In this system, intermittent aeration is more efficient than continuous aeration, and removal rates of COD and total nitrogen (T-N) were increased as the feed COD/N ratio was increased from 1.9 to 5.6. At an optimal condition, 73% of total nitrogen and 93% of COD were stably removed at a COD loading rate lower than 2.4 g COD/L·d and at 3: 1 ratio of aerobic time to anoxic time.