膜生物反应器中膜污染机理及其防治

通过向一体式膜生物反应器中分别投加聚合铝和粉煤灰改变料液性质,来预防膜污染和提高膜生物反应器对总磷的去除效率,并通过X射线衍射和红外光谱实验分析活性污泥性质的变化,利用扫描电镜分析中空纤维膜表观结构的变化情况,探讨防治膜污染的机理.实验结果表明:聚合铝的投加改变了活性污泥的性质和生物膜的表观结构,可有效地减缓膜污染,且除磷效率达85%以上;而投加粉煤灰并没有明显效果.     

矿区生活污水深度处理后作电厂用水工艺性实验研究

根据生活污水深度处理工艺,对高锰酸钾的厨量和活性炭的种类和投加量进行了实验研究,结果表明高锰酸钾和粉末椰壳活性炭的最佳投加量分别为0．5mg/L和15mg／L。工艺运行后出水水质符合电厂用水要求。     

Fenton氧化膜-生物反应器出水中丙烯腈的实验研究

采用膜-生物反应器和Fenton氧化组合工艺对丙烯腈废水进行处理。从GC/MS测量结果来看,膜-生物反应器出水中主要物质为2,6双（二甲基-乙基）-4-酚、苯二甲酸和硝基苯二甲酸,均为生物难降解有机物,使出水不能达标。后续Fenton氧化工艺处理膜生物反应器出水,可以使COD含量等指标达到所要求的排放标准。经过膜-生物处理与Fenton法结合的优化工艺,COD去除率达到80%~88%,去除率达到98%,出水水质可达排放标准。Fenton氧化工艺的最佳工艺条件为：pH值为3.4,硫酸亚铁的投加量为700mg/L,双氧水的投加量为600mg/L。     

胞外聚合物对膜生物反应器运行性能的影响

膜生物反应器处理污水过程中,依据胞外聚合物(EPS)、蛋白质、多糖、粘度等参数随时间的变化趋势以及对膜通量的影响,求出上述参数及蛋白质/多糖的比值与膜通量间的相关系数分别为0.28、0.57、0.38、0.14、0.70。结果表明:蛋白质/多糖的比值与膜通量的衰减速度两者相关系数最大。     

膜蒸馏处理乳化油废水的实验研究

采用自制的中空纤维膜蒸馏组件对模拟的乳化油废水进行膜蒸馏处理研究, 分析了料液的浓度、流速、温度和处理时间等因素对膜通量及去除率的影响。实验结果表明: 在料液温度为50℃、流速为14 mL /min、乳化油浓度为500 mg/L 的条件下, 运行1 h后乳化油膜通量为21.20 g/m2 ·h, 去除率> 70%; 运行5 h后膜通量下降为5.141 g/m2 ·h, 去除率> 90%。     

SMBR中污染物处理效率随污泥浓度变化的数学模型

以一体式膜生物反应器(SMBR)对生活污水进行处理,研究不同水力停留时间(HRT)条件下污泥浓度对有机物去除率的影响,并对所得试验数据进行曲线拟合,建立有机物去除率与污泥浓度的数学模型。试验结果表明:在溶解氧(DO)浓度为2.0～3.0mg/L的条件下,HRT为3h、2h和1h时,有机物去除率(η)随着污泥浓度的增大而增大,但当污泥浓度增大到6000mg/L时,η增大趋势逐渐减小,并趋于稳定。有机物去除率与污泥浓度的数学模型表明:有机物去除率(η)与水力停留时间(τ)、进水COD浓度(S_o)和污泥负荷率(N_s)等主要运行参数有关,并可以通过调节运行参数τ、S_o和N_s来达到所需要的COD去除率。     

复合生物反应器处理城市污水的试验研究

为了提高城市污水的处理效率、降低运行成本,进行了复合生物反应器处理城市污水的试验研究,从曝气停留时间、有机负荷率、气水比等3个方面研究了试验运行的最佳条件和控制参数.试验结果表明,利用该工艺方法处理城市污水在有机负荷率高达2.44 kgCOD/kgMLSS*d的条件下,停留时间1.5～2 h,气水比(2.5～3)∶1,可使出水COD去除率达80%以上.该方法强化了混合液的物相传质速率.     

膜分离技术处理皂素酸性废水的试验研究

黄姜皂素酸性废水的Cl-、COD高、酸性强,治理难度大,采用纳滤NF(nanofiltration)、反渗透RO(reverse osmosis)过滤组合处理黄姜皂素酸性废水的试验表明:黄姜皂素酸性废水通过石灰中和、MF保安过滤预处理,再进行NF、RO组合处理,其COD可从25 000～50 000 mg/L降至200 mg/L以下,达到国家废水综合排放二级标准,并从废水中回收部分淀粉糖用作工业碳源.同时分析了NF、RO试验过程中膜通量变化的影响因素,为NF、RO组合处理皂素废水的膜运行参数确定提供了依据.     

非对称天然沸石陶瓷膜的制备及其性能表征

利用天然沸石为主要原料,制备出具有过滤功能和重金属离子吸附功能的天然沸石非对称陶瓷膜。非对称膜中支撑体、中间层膜和顶层膜的平均孔径分别为6.6μm、0.6μm和0.1μm。非对称膜单位压力降(1 MPa)下的氮气通量和水通量分别为:24.69×103m3/(m2h)和1.87×103m3/(m2h);对重金属离子(铅离子)吸附交换能力为7.13 mg/g。     

活性炭对浮选废水中黄药的吸附特性研究

通过静态试验研究了粉末活性炭对浮选废水中丁基黄药的吸附性能和影响因素。实验结果表明,粉末活性炭对丁基黄药的吸附过程遵循Lagergren二级动力学模型;粉末活性炭对丁基黄药的等温吸附可用Langmuir等温模型拟合,其相关系数为0.9875(298K);温度从298K上升至313K时,吸附量略有上升,升高温度有利于活性炭对黄药的吸附;pH从7.17上升至12.00时,黄药吸附量下降明显,表明碱性环境对吸附有抑制作用。火法再生实验结果表明粉末活性炭再生性能良好。     

Effect of sludge pretreatment on the performance of anaerobic/ anoxic/ oxic membrane bioreactor treating domestic wastewater

In the present study, two bench-scale anaerobic/ anoxic/ oxic submerged membrane bioreactors were used to study the effect of thermochemical sludge disintegration system on the excess sludge production. Among the two membrane bioreactors, one was named experimental membrane bioreactor and another one was named as control membrane bioreactor, where a part of the mixed liquor was treated with thermo chemical and was returned back to membrane bioreactor. Thermo chemical digestion of sludge was carried out at fixed pH (11) and temperature (75 °C) for 24 % chemical oxygen demand solution. The other one was named control membrane bioreactor and was used as control. The reactors were operated at three different mixed liquor suspended solids range starting from 7500 mg/L to 15000 mg/L. Both of membrane bioreactors were operated at a flux of 17 LMH over a period of 240 days. The designed flux was increased stepwise over a period of one week. During the 240 days of reactor operation, both of membrane bioreactors maintained relatively constant transmembrane pressure. The sludge digestion had no impact on chemical oxygen demand removal efficiency of the reactor. The results based on the study indicated that the proposed process configuration has potential to reduce the excess sludge production as well as it didn’t deteriorate the treated water quality.     

固体停留时间对HLB-MR反应器直接回收城市污水中有机物的影响

为优化高负荷生物絮凝-膜反应器（HLB-MR）的工艺参数,提高其资源化城市污水的效能,采用平行对比实验,考察了不同固体停留时间（t_SR）条件下反应器的有机物去除效率、生物絮凝效果、有机物回收效果和膜污染情况。结果表明：在t_SR分别为0.2、0.6、1.0 d时,HLB-MR反应器有机物去除效率均在85%以上,其出水化学需氧量（COD）质量浓度均保持在30 mg/L左右;反应器内的生物絮凝效果随着t_SR的延长而增强,其胶体COD絮凝效率从t_SR为0.2 d时的66%增加到t_SR为1.0 d时的95%,与此同时,有机物的矿化损失率也逐渐增加,从t_SR为0.2 d时的6.9%增加到t_SR为1.0 d时的10.5%,总COD的回收率逐渐降低;反应器内浓缩液的膜污染潜势随着t_SR的延长逐渐缓解,这与较长t_SR条件下反应器内胞外聚合物（EPS）产量较高、生物絮凝效果较好、微细颗粒（0~1 μm）的颗粒浓度较低有关。经过综合对比分析,0.6 d为反应器较优的t_SR参数,在该条件下,胶体COD的絮凝效率高达90%,膜污染程度较轻;总COD的矿化损失率低至7.4%,总COD的回收率（忽略膜清洗时有机物损失）可高达80%以上。     

泥水盾构泥膜形成二维理论分析

在各种复杂环境下采用泥水盾构法修建隧道工程,需要解决在开挖面上如何及时形成安全有效的泥膜支护问题。采用修正的剑桥模型中正常固结黏土各向等压固结曲线规律,建立泥膜固含率与有效应力之间的关系,结合圆球形颗粒孔隙理想模型的渗透率以及泥膜固含率、渗透率和比阻三者之间的关系,确立新的泥膜形成本构关系模型。将泥膜形成一维模型拓展为二维模型,基于增量分析方法分析泥膜的增长规律,给出泥膜滤失量和厚度分别与位置、时间、重度比和盾构直径等因素的关系。结果表明,修正的剑桥模型能够较好地表征泥膜压缩固结特性;对于高压泥浆,泥浆重度对泥膜增长的影响较小,但对超大直径的盾构其影响不可忽略。     

Enhancement of polysulfone membrane with integrated ZnO nanoparticles for the clarification of sweetwater

Clarification is one of the main steps in producing glycerin from glycerin–rich solution (namely sweetwater) in oleo-chemical industry. In this study, ZnO nanoparticles (9–12 nm in diameter) were incorporated into polysulfone (PSf) membranes to improve the membrane antifouling properties toward the fatty acids in sweetwater. The hybrid membranes were fabricated through wet phase inversion method. The modified membranes exhibited better water permeability, membrane surface hydrophilicity (improvement from 82° to 62.1°) and resistance toward fouling by fatty acids. In this study, the best membrane was obtained in the presence of 3% of ZnO nanoparticles, which showed good fouling resistance, high solution flux and a very high rejection of fatty acids (≥80%) in comparison with the pure PSf membranes, at the same experimental conditions. The enhanced membrane performances during the clarification of sweetwater were attributed to the unique properties of ZnO nanoparticles that were uniformly dispersed in the PSf structures.     

Analysis and comparison of mixed finite element and multipoint flux approximation methods for homogeneous media

We consider discretization on quadrilateral grids of an elliptic operator occurring, for example, in the pressure equation for porous-media flow. In a realistic setting – with non-orthogonal grid, and anisotropic, heterogeneous permeability – special discretization techniques are required. Mixed finite element (MFE) and multipoint flux approximation (MPFA) are two methods that can handle such situations. Previously, a framework for analytical comparison of MFE and MPFA in special cases has been suggested. A comparison of MFE and MPFA-O (one of two main variants of MPFA) for isotropic, homogeneous permeability on a uniformly distorted grid was also performed. In the current paper, we utilize the suggested framework in a slightly different manner to analyze and compare MFE, MPFA-O and MPFA-U (the second main variant of MPFA). We reconsider the case previously analyzed. We also consider the case of generally anisotropic, homogeneous permeability on an orthogonal grid.     

Measurement of advective soil gas flux: results of field and laboratory experiments with CO2

A multi-channel, steady-state flow-through (SSFT), soil-CO₂ flux monitoring system was modified to include a larger-diameter vent tube and an array of inexpensive pyroelectric non-dispersive infrared detectors for full-range (0–100 %) coverage of CO₂ concentrations without dilution. Field testing of this system was then conducted from late July to mid-September 2010 at the Zero Emissions Research and Technology project site located in Bozeman, Montana, USA. Subsequently, laboratory testing was conducted at the Pacific Northwest National Laboratory in Richland, WA, USA using a flux bucket filled with dry sand. In the field, an array of 25 SSFT and 3 non-steady-state (NSS) flux chambers was installed in a 10 × 4 m area, the long boundary of which was directly above a shallow (2-m depth) horizontal injection well located 0.5 m below the water table. Two additional chambers (one SSFT and one NSS) were installed 10 m from the well for background measurements. Volumetric soil moisture sensors were installed at each SSFT chamber to measure mean moisture levels in the top 0.15 m of soil. A total flux of 52 kg CO₂ day^?1 was injected into the well for 27 days and the efflux from the soil was monitored by the chambers before, during, and for 27 days after the injection. Overall, the results were consistent with those from previous years, showing a radial efflux pattern centered on a known “hot spot”, rapid responses to changes in injection rate and wind power, evidence for movement of the CO₂ plume during the injection, and nominal flux levels from the SSFT chambers that were up to sevenfold higher than those measured by adjacent NSS chambers. Soil moisture levels varied during the experiment from moderate to near saturation with the highest levels occurring consistently at the hot spot. The effects of wind on measured flux were complex and decreased as soil moisture content increased. In the laboratory, flux-bucket testing with the SSFT chamber showed large measured-flux enhancement due to the Venturi effect on the chamber vent, but an overall decrease in measured flux when wind also reached the sand surface. Flux-bucket tests at a high flux (comparable to that at the hot spot) also showed that the measured flux levels increase linearly with the chamber-flushing rate until the actual level is reached. At the SSFT chamber-flushing rate used in the field experiment, the measured flux in the laboratory was only about a third of the actual flux. The ratio of measured to actual flux increased logarithmically as flux decreased, and reached parity at low levels typical of diffusive-flux systems. Taken together, the results suggest that values for advective CO₂ flux measured by SSFT and NSS chamber systems are likely to be significantly lower than the actual values due to back pressure developed in the chamber that diverts flux from entering the chamber. Chamber designs that counteract the back pressure and also avoid large Venturi effects associated with vent tubes, such as the SSFT with a narrow vent tube operated at a high chamber-flushing rate, are likely to yield flux measurements closer to the true values.     

渤钻低密度固井水泥浆降低煤层气储层伤害的实验

针对煤层气井传统的固井水泥密度较大,在固井过程中产生较大压差,影响半径较大,且滤液成分矿化度较高,持续对储层产生伤害的问题,通过对比渤海钻探所使用的低密度固井水泥浆(统称渤钻浆)和常规固井水泥浆的失水量、滤液性能和稠化时间,并通过分析其滤液成分、电导率、渗透率回复率和计算污染半径,评价了渤钻浆降低煤层气储层伤害的能力。结果表明:渤钻浆失水量比常规固井水泥浆小一半,并且滤液黏度高、矿化度低和电导率低,使渤钻浆污染的煤样渗透率降低为28.97%(常规水泥浆污染的煤样渗透率降低为65.87%),渗透率恢复率为89.81%(常规水泥浆渗透率恢复率为61.18%)。综合来看渤钻浆不仅密度低,形成压差小,保证煤层稳定,还减小污染半径,降低了对煤层气储层的伤害。      

Simulation of advective methane flux and AOM in Shenhu area, the northern South China Sea

Anaerobic oxidation of methane (AOM) occurring in the marine sediment is an important process for methane cycle and methane sequestration. In this work, a one-dimensional numerical model was developed to study the distribution of advective methane flux with the AOM process. The model has been applied to investigate the gas hydrates bearing sediments of Shenhu areas located in the northern South China Sea, where advective methane transport was detected. The modeling results suggest that methane flux will be consumed in the sediment column via dissolution, sorption, and AOM reaction. Only when the methane flux was one order of magnitude higher than current level, then a portion of methane will enter water column and possibly escape to the atmosphere. The numerical simulation also revealed that, due to the lower permeability of the silt–clay sediments, a much thicker sulfate-methane transition zone exists in the Shenhu area, where AOM is able to consume more.