陶瓷膜微滤骨架镍催化剂的膜污染机理分析

用孔径为0.2μm的陶瓷膜过滤骨架镍催化剂悬浮液,研究膜污染机理。结果表明,膜污染主要是骨架镍催化剂在膜表面上形成的滤饼层,当操作压力循环变化时滤饼层表现出不可逆性。工业上用过的污染膜和滤饼层的组分分析表明,污染物主要是骨架镍催化剂。应用结果也表明了膜污染原因是骨架镍催化剂在膜表面形成了不可逆性滤饼层。     

膜生物反应器中膜污染滤饼层渗透模型的研究

在膜生物反应器中,活性污泥在膜表面沉积形成滤饼层是造成膜污染的主要因素.采用扫描电镜和自动图像分析技术研究了膜过滤滤饼层的微观结构,并以分形理论和Darcy定律为基础,推导出用于预测膜污染滤饼层渗透性能的数学模型,验证了该渗透模型的可靠性,并利用该渗透模型进行了膜生物反应器中污泥浓度对滤饼层渗透性能影响的研究.结果表明,活性污泥颗粒沉积形成的柔性滤饼层具有明显的多孔结构,并且具有很好的分形特征;膜污染滤饼层的分形维数能够真实反映滤饼层的孔隙率大小;用该渗透模型得到的渗透系数K'可以作为有效预测滤饼层渗透性能的参数;滤饼层渗透系数K'随污泥浓度的增大而递减,污泥浓度低于10000 mg·L-1时,K'的变化趋势较小,污泥浓度达到10000 mg·L-1以上时,K'急剧下降.     

浸没式厌氧双轴旋转膜生物反应器的膜污染特性研究

试验研究了浸没式厌氧双轴旋转膜生物反应器处理啤酒废水时膜的污染特性.试验分析了膜阻力分布和膜污染速率及稳定运行时膜过滤阻力随运行时间变化的阻力模型.结果表明,膜表面滤饼层很薄,膜污染很轻,膜污染速率很小.结果表明系统由膜组件双轴旋转而形成的良好水力学条件,能有效地减小浓差极化和避免污泥颗粒在膜表面的沉积.可有效控制膜污染.     

PAC-UF处理含蛋白质类溶液过程中的膜污染研究

使用粉末活性炭(PAC)-超滤(UF)组合工艺处理牛血清白蛋白(BSA)溶液,研究了不同PAC投量下组合工艺的膜污染情况。结果表明,PAC本身对膜污染无明显贡献,PAC吸附BSA后使得膜通量急剧下降;PAC对改善BSA溶液通过超滤的膜通量和膜污染阻力均有一个最佳投加值;PAC在膜表面形成的滤饼层对膜通量改善作用明显;PAC滤饼层主要形成可逆污染,而水中BSA则是不可逆膜污染。     

地下水除铁除锰-超滤组合工艺的膜污染特性

针对含铁锰地下水采用直接超滤工艺、曝气-超滤工艺和曝气-砂滤-超滤工艺对比研究了除铁除锰效果和膜污染特性。研究结果表明,超滤膜可以有效截留三价铁,但对二价锰的截留效果不佳;曝气-砂滤-超滤组合工艺可以显著提高除铁除锰效果和工艺稳定性,超滤出水铁和锰含量达0.10 mg/L和0.02 mg/L。此外,SEM分析结果发现,预处理工艺对滤饼层形态有显著影响,直接超滤工艺和曝气-超滤工艺的滤饼层较松散,曝气-砂滤-超滤工艺形成的致密滤饼层是造成其运行后期跨膜压差快速增长的重要因素;EDS及XPS分析表明膜表面的滤饼层主要由三价铁颗粒组成,是造成膜污染和跨膜压差的主要成分。     

陶瓷膜过滤细微颗粒悬浮体系的数学模拟

通过对陶瓷膜过滤悬浮液过程中单颗粒的受力分析,获得了可沉积颗粒临界粒径(xcrit)的计算公式.计算的xcrit值与实验测定的沉积层内的粒径分布一致:随颗粒粒径的增大, xcrit呈先增大后减小的趋势. 在讨论xcrit与颗粒粒径(dp)、膜孔径(dm)关系的基础上,将微滤过程按dp/dm的比值分为三种类型:dp/dm≤1, 颗粒迅速阻塞膜孔;1＜dp/dm≤10 ,颗粒在膜表面形成连续滤饼;dp/dm》10,颗粒对膜孔口覆盖,在膜表面形成不连续滤饼.并以此为基础建立了预测陶瓷膜过滤不同粒径和粒径分布的颗粒悬浮液渗透通量的数学模型.计算结果与实验结果的比较表明:本模型对文献模型的改进之处是适用范围从1＜dp/dm≤10扩展到0.48≤dp/dm≤120;在操作压力对渗透通量的影响计算中,假设滤饼层孔隙率不变的计算结果与实验结果一致,说明此体系的滤饼是不可压缩的;在错流速率对渗透通量的影响计算中,假定滤饼层孔隙率随错流速率成指数变化的计算结果比假定沉积层孔隙率随错流速率不变的计算结果好,说明错流速率的变化同时影响滤饼层内颗粒的粒径分布和其形成的滤饼层的结构.     

基于小孔径PVDF内衬膜A/O-MBR膜污染分析

为研究膜生物反应器膜污染问题,在缺氧-好氧一体式膜生物反应器中,对模拟生活污水的处理效果进行考察,考察了4种不同孔径聚偏氟乙烯(PVDF)内衬膜对膜污染的影响规律。结果表明,基于小孔径PVDF膜的MBR工艺对模拟生活污水中COD、NH3-N的去除率分别达到96%、90%,出水浊度在0.35 NTU以下;在操作条件固定的情况下,随着膜孔径增加,临界通量逐渐降低;孔径越小,跨膜压差上升越缓慢,膜污染较轻。膜污染模型分析结果显示:无论何种孔径的膜,在MBR系统中,滤饼层和凝胶层污染所占的比例都最大(>80%),因此,在使用过程中减缓滤饼层及凝胶层的形成至关重要。     

膜生物反应器膜面滤饼层数学模型建立及表征方法研究进展

论述了膜生物反应器滤饼层形成机理,阐述了滤饼层数学模型的研究概况。最后,指出了滤饼层微观研究对于探究膜污染问题的重要性。     

电极超滤膜生物反应器处理阴离子表面活性剂废水

化妆品生产过程中产生大量的阴离子表面活性剂废水,具有有机物浓度高和易产生泡沫的特点,影响普通超滤膜生物反应器（UMBR）的处理效果和稳定运行。采用自制的电极超滤膜生物反应器（EMBR）处理阴离子表面活性剂废水,考察电流强度对EMBR污染物处理效果和活性污泥性质的影响,探索膜污染的机理。结果表明：与UMBR相比,在电场能的作用下,EMBR滤饼层的有机物含量较低,跨膜压差（TMP）降低50%左右,膜污染较轻。当电流强度为10 mA时,COD去除率和微生物活性最高,分别为97.92%和41.6 mg/（g TSS·h）;滤饼层有机物含量最低,PN、PS和HA的浓度分别为5.6、8.02、0.85 mg/L。较低的电流强度即可促进微生物活性和污染物去除率的提高,有效控制膜污染。     

电极超滤膜生物反应器处理阴离子表面活性剂废水

化妆品生产过程中产生大量的阴离子表面活性剂废水,具有有机物浓度高和易产生泡沫的特点,影响普通超滤膜生物反应器（UMBR）的处理效果和稳定运行。采用自制的电极超滤膜生物反应器（EMBR）处理阴离子表面活性剂废水,考察电流强度对EMBR污染物处理效果和活性污泥性质的影响,探索膜污染的机理。结果表明：与UMBR相比,在电场能的作用下,EMBR滤饼层的有机物含量较低,跨膜压差（TMP）降低50%左右,膜污染较轻。当电流强度为10 mA时,COD去除率和微生物活性最高,分别为97.92%和41.6 mg/（g TSS·h）;滤饼层有机物含量最低,PN、PS和HA的浓度分别为5.6、8.02、0.85 mg/L。较低的电流强度即可促进微生物活性和污染物去除率的提高,有效控制膜污染。     

电渗透-过硫酸铵协同污泥脱水过程中胞外聚合物的变化

为了研究电渗透-过硫酸盐协同污泥深度脱水的机制,利用自制装置对市政污水处理厂的污泥进行了脱水研究,系统研究了在过硫酸铵投加量、电压梯度、污泥厚度和机械压力的操作条件下,污泥中胞外聚合物的组分（蛋白质和多糖）变化情况及对污泥脱水效果的影响。结果表明,在过硫酸铵投加量为30mg/gDS、电压为25V/cm、污泥厚度为2.0cm、机械压力为23.1kPa条件下,污泥含水率可以降低至57.4%。不同脱水条件均会造成胞外聚合物组分变化,其中过硫酸铵加量和电压是影响胞外聚合物组分以及污泥脱水效果的主要因素。     

Short-term fouling propensity and flux behavior in an osmotic membrane bioreactor for wastewater treatment

The short-term fouling behavior of forward osmosis (FO) membrane in an osmotic membrane bioreactor (OMBR) was investigated, using NaCl or MgCl₂ as the draw solutions. The effect of membrane orientation, mixed liquor suspended solids (MLSS) concentration and draw solution (DS) osmotic pressure on water flux and membrane fouling behaviors was examined, along with the effects of simulated elevated salinity on sludge properties and on membrane fouling. Water flux and membrane fouling were not significantly affected by both MLSS concentration (4.91–12.60 g/L) and osmotic pressure (3.0–15.0 MPa), but were severely affected by elevated salinity, due to changes in activated sludge properties, in particular the increase in extracellular polymeric substances (EPS) and sludge hydrophobicity. MgCl₂ as the DS showed more significant influence on activated sludge properties and membrane fouling than NaCl but gave rise to lower salt accumulation. Analyses of the membrane foulants showed that small sludge floc/particles and EPS (in particular, proteins) were enriched in the fouling layer. UPLC–MS/MS analyses of the proteins showed that hydrophobic proteins were the main cause of membrane fouling.     

Numerical Study on Moisture Transfer in Ultrasound-Assisted Convective Drying Process of Sludge

A coupled heat and moisture transfer model for ultrasound-assisted convective drying process of sludge was established. In this model, the permeable flow caused by acoustic pressure gradient in sludge was considered. The pore structure variety in sludge with ultrasonic irradiation was microscopically studied, and the pore size distribution of sludge was described by fractal geometry. Based on the fractal characterization, the physical properties of sludge including permeability, porosity, and tortuosity factor were determined, and the effective moisture diffusion coefficient of sludge under ultrasonic irradiation was also derived considering the effects of ultrasonic excitation energy and thermal effect on migration rate of water molecule. The effects of ultrasonic energy density and convective air temperature on convective drying process of sludge were numerically analyzed. The results showed that the ultrasonic irradiation changes the pore size distribution in sludge, the sludge flocs are dispersed, and the connectivity of pore structure is improved. Ultrasonic treatment is favorable to accelerating the moisture transport in the convective drying process of sludge, and the ultrasonic influence on moisture transport in sludge intensifies gradually with the increase of acoustic energy density from 0.2 to 0.6 W/ml. Furthermore, it can be also found that the enhancement effect of ultrasound on the average drying rate of sludge is more obvious at the connective air temperature of 65°C than that at 40°C under the uniform acoustic energy density and air velocity of 1.5 m/s.     

干化污泥型煤抗压强度的实验研究

利用微波干燥脱水污泥制备型煤粘结剂,与粉煤混合压制成型煤。通过正交试验考察成型压力、干化污泥含水率及添加比例对型煤抗压强度的影响。结果表明：微波干化的污泥型煤较粘土型煤的抗压强度大;成型压力、干化污泥含水率及添加比例均为型煤抗压强度的显著因素,各因素优化范围：成型压力为25～30MPa,干化污泥水分为40％左右,干化污泥添加比例为20％～30％。     

Analysis of Gravity Filtration Behaviors of Waterworks Sludge Based upon Sedimentation Tests

Both gravity filtration experiments under constant pressure conditions and gravity sedimentation experiments were conducted using the municipal waterworks sludge. It was clarified from the theoretical analysis that the effect of sedimentation on the filtration rate was noticeable for the sludge used in this study. The local specific flow resistance at various sludge concentrations was determined by the sedimentation velocity method. The local porosity was related to the local solid compressive pressure by the sedimentation equilibrium method. The decline behaviors in the filtration rate in gravity filtration accompanied by sedimentation were well evaluated only from the sedimentation data based upon the sedimentation velocity method and the sedimentation equilibrium method.     

Effect of Hydraulic Retention Time on Sludge Properties,Cake Layer Structure,and Membrane Fouling in a Thermophilic Submerged Aerobic Membrane Bioreactor

Sludge properties, cake layer structure, and membrane fouling in a membrane bioreactor were studied under various hydraulic retention times (HRT). A decrease in HRT resulted in an increase in extracellular polymeric substance production in bulk sludge and changes in cake layer structure from gel layer to one or two cake layers. Particle size distribution in cake sludge changed with respect to HRT. An evolution in cake layer thickness and porosity was observed with trans-membrane pressure (TMP) jump. The change in cake layer structure might bear more responsibility for the TMP jump than the quantity of cake layer.     

活化污泥基黏结剂制备型煤型焦试验研究

为实现粉煤的综合利用,以城市污泥为黏结剂的基础组分,采用化学方法活化,利用粉煤成型技术制备型煤,对工艺条件进行研究,考查了成型压力、污泥含量、干燥时间对型煤冷压强度和湿压强度的影响,确定了最佳工艺条件。结果表明,污泥含量为12%、成型压力12 MPa、干燥时间8 h时,制得型煤的冷压强度为1 522.5 N,落下强度为97.7%,型煤600℃干馏2 h制得型焦的强度、灰分、挥发分、发热量等主要指标均达到《陕西省地方洁净型煤技术标准》。利用活化污泥可制备出适用于工业生产的洁净型煤。     

Optimization Study of Municipal Sludge Conditioning,Filtering, and Expressing Dewatering by Partial Least Squares Regression

The effect of different conditioner doses and different applied pressures on the dewaterability of municipal sludge during the filtration and expression stage was assessed using a series of experiments referred to as a uniform design. The relative importance of conditioner dose and applied pressure on the dewatering characteristics of municipal sludge was evaluated with a quadratic model using partial least squares (PLS) regression analysis. It was shown that the developed quadratic model was able to accurately predict the dewatering characteristics during the whole process. It was further shown that lime as a physical conditioner had the most significant impact on filtration rate, expression rate, cake dry solids content, net sludge solids yield, and total cycle time. Aluminum polychloride as the inorganic flocculant had a quite complex effect although not as significant as lime. Filtration pressure had only a slight effect on dewaterability of the municipal sludge, though higher feeding pressure was needed in order to enhance the total feeding amount. Furthermore, expression pressure was only of benefit to cake dry solids content and expression rate and failed to improve other dewatering characteristics of the municipal sludge.     

不同混凝剂作用下的污泥性能研究

污泥脱水是依靠过滤介质（多孔性物质）两面的压力差作为推动力,强制水分通过过滤介质,固体颗粒被截留在介质上,以达到脱水的目的。污泥比阻是表示污泥脱水性能的综合性指标,比阻愈大,其脱水性能愈差,反之愈好。添加混凝剂可以使污泥的比阻减小,改善污泥的脱水性质。采用用布氏漏斗试验,以FeCl3和Al（2SO4）3为混凝剂,通过测定污泥滤液滤过介质的速度快慢来确定污泥比阻的大小,并确定混凝剂的最佳添加量。     

优化盐泥压滤工艺 降低氯碱盐泥含盐量

通过采取调整泥水比、用蒸汽预热洗泥水、完善操作规程、加强管理等措施,优化盐泥压滤工艺,盐泥含盐质量浓度由原来的60g／L下降到15g／L左右,取得了较好的环境和经济效益。