超声在陶瓷膜处理乳化含油废水中的作用研究

Ultrasonic field was applied in the treatment of oil emulsification wastewater by ZrO2 ceramic mem-brane. The permeate flux, rejection ratio in the filtration process and recovery ratio of flux in the membrane cleaning process were measured. Great improvement in the permeate flux and rejection ratio have been observed for the membrane process enhanced by the ultrasonic field. The permeate flux of water through the membrane was about 210L.m^-2.h^-1 and the oil rejection ratio was over 99.9% under the optimal ultrasonic treatment conditions, which were 8W of ultrasonic power, 7cm of ultrasonic probe length introduced into the membrane channel and the same ultrasonic radiation direction as the wastewater flow. The resistance of the membrane process was compared between the cases with and without ultrasound, and the total resistance was reduced 68% by the use of ultrasound, Four methods including water cleaning, water cleaning under sonication, chemical cleaning and chemical cleaning under sonication were used to recover membrane flux. It was found that the flux recovery ratio increased with the increase of ultrasonic cleaning power. In addition, the use of chemical agents combining with ultrasonic irradiation showed a synergistic effect, which resulted in the highest cleaning efficiency and the shorter cleaning time.     

Optimization of backflushing conditions for ceramic ultrafiltration membrane of disperse dye solutions

In the ultrafiltration (UF) of disperse dye solutions using ceramic membrane, backflushing is necessary to minimize the formation of fouling by disperse dye, and to enhance the permeate flux. In this work, the effects of backflushing on the ultrafiltration performance and decolorization were investigated. In the optimum backflushing condition, the permeate flux increased slightly and the filtration performance was stable during filtration process.     

往复旋转管式陶瓷膜超滤脱脂奶水溶液的研究

往复旋转管式陶瓷膜过滤系统通过膜组件往复旋转在膜表面反复产生高剪切率,达到减缓膜污染的效果。在相同操作条件下,与单向旋转过滤和死端过滤相比较,往复旋转过滤具有更好的减缓膜污染的作用。本实验利用往复旋转膜过滤装置超滤脱脂奶水溶液,考察了各种参数对该膜系统过滤特性的影响。实验结果表明,料液浓度增大,膜通量减小;过高的操作压差将会抑制膜通量增加;旋转速度增大,膜表面剪切强化作用增强,膜通量相应增大;膜稳态通量随往复旋转周期增大呈现先增大后减小的趋势。当料液速度达到膜组件转速时,瞬时反方向旋转膜组件,膜表面产生最大的剪切率,膜稳态通量也达到最大值。能耗分析表明,往复旋转过滤较单向旋转过滤单位通量能耗低。     

Tubular Membrane Filtration with A Side Stream and its Intermittent Backwash Operation

The tubular membrane filtration system is widely applied to solid-liquid separation processes. Any improvements to the filtration module would increase separation efficiency, thus reducing operating costs. In this experiment, PMMA powder with an average particle diameter of 0.8 µm was filtered by a ceramic tubular membrane with an average pore size of 0.2 µm, and the impacts of the operating variables, such as suspension concentration, the filtration pressure, and the crossflow velocity on the permeate flux were discussed. In order to understand the increased permeate flux, the proposed module is comparable to the tubular membrane filtration module, but with an additional side stream under the same filtration mass flow rate. In addition, variations of shear force on the membrane surface are analyzed by CFD simulation, and the influence of backwash operations on the permeate flux is discussed. The results show that the side stream membrane filtration increased the shear force on the membrane surface, reduced fouling on the membrane surface, and increased the permeate flux. Furthermore, a backwash operation with a side stream flow channel could effectively clean the particles deposited in the module, thus, increasing the permeate flux.     

膜集成技术处理氯化法钛白后处理废水的研究

氯化法钛白无机包膜处理工序会产生大量中性废水,其中包含少量钛白粉和水溶性盐,现阶段企业多以外排为主。采用膜集成（陶瓷膜+反渗透膜+纳滤膜）技术对氯化法钛白后处理废水的处理进行研究。将氯化法钛白后处理废水用陶瓷膜过滤,分离回收二氧化钛;将陶瓷膜清液用反渗透膜浓缩,清水回收利用;将反渗透浓液用纳滤膜分离硫酸钠和氯化钠。结果表明：利用陶瓷膜处理氯化法钛白后处理废水,平均通量为650 L/（m ²·h）,浓液中钛白粉质量浓度达到90 g/L以上,清液中钛白粉质量浓度低于0.001 g/L;使用反渗透膜截留清液中的硫酸钠和氯化钠,硫酸钠和氯化钠的截留率为99.5%,浓水中的盐质量分数达到4%以上;浓水中的硫酸钠和氯化钠通过纳滤膜分离,纳滤膜对硫酸钠的截留率为97%,硫酸钠质量分数达到14%以上。     

面向过程的陶瓷膜材料设计理论与方法(Ⅰ)膜性能与微观结构关系模型的建立

提出了面向过程的陶瓷膜设计基本研究框架,分析了膜的孔径分布与悬浮液颗粒体系粒径分布对过滤过程的影响,提出采用堵塞因子来表征膜的初始堵塞污染情况,建立了颗粒体系微滤过程中的膜微观结构与性能关系新模型,不仅可以计算膜通量随时间的变化,且能预测陶瓷膜结构参数对膜通量的影响.模拟结果与实验值有较好的一致性.     

面向过程的陶瓷膜材料设计理论与方法(Ⅰ)膜性能与微观结构关系模型的建立

提出了面向过程的陶瓷膜设计基本研究框架 ,分析了膜的孔径分布与悬浮液颗粒体系粒径分布对过滤过程的影响 ,提出采用堵塞因子来表征膜的初始堵塞污染情况 ,建立了颗粒体系微滤过程中的膜微观结构与性能关系新模型 ,不仅可以计算膜通量随时间的变化 ,且能预测陶瓷膜结构参数对膜通量的影响 .模拟结果与实验值有较好的一致性     

纳米TiO_2复合膜光催化和膜分离的耦合作用

以微孔陶瓷管为载体,采用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)辅助的溶胶-凝胶法制备了纳米TiO2复合超滤膜。以1 g/L聚丙烯酰胺(PAM)为料液(目标污染物),以膜截留率及膜通量为实验参数,研究了复合膜的光催化-膜分离耦合作用,耦合时的膜通量较单一膜分离的膜通量提高了60%;以0.5 g/L牛血清白蛋白(BSA)为模拟天然大分子料液,采用无光照料液过膜-紫外光照清水过膜的交替间歇运行方法,膜通量可恢复60%以上。     

Treatment of Oily Wastewaters Using the Microfiltration Process: Effect of Operating Parameters and Membrane Fouling Study

This work focuses on the treatment of oily wastewater using the cross-flow microfiltration (MF) process to determine the effect of different operating parameters such as transmembrane pressure (TMP) and cross-flow velocity on the separation performance and to study the mechanism of membrane fouling during microfiltration of oil in water emulsions. In this regard, the permeation flux and oil rejection of a polyvinylidene fluoride (PVDF) membrane in a flat-frame MF module for separation of 3000 ppm oil/water emulsions were measured. The results indicated that the permeate flux increased by an enhancement in both TMP and cross-flow velocity, while the oil rejection decreased. The analysis of variance (ANOVA) showed that the individual effect of TMP and cross-flow velocity is more important than the interactional effect of these operating parameters on the permeate flux and oil rejection. The results of fouling modeling revealed that the membrane fouling mechanism was affected by the applied TMP. The cake filtration model dominates the fouling mechanism at lower operating pressures. The fouling mechanism was changed from the cake formation to intermediate pore blocking and then to standard pore blocking as the TMP varied from 1 to 3 bar. Finally, a five-step procedure was used for cleaning the oil/water fouled membranes.     

Treatment of oily wastewater using low cost ceramic membrane: Comparative assessment of pore blocking and artificial neural network models

This work addresses the performance and modeling of the separation of oil-in-water (o/w) emulsions using low cost ceramic membrane that was prepared from inorganic precursors such as kaolin, quartz, feldspar, sodium carbonate, boric acid and sodium metasilicate. Synthetic o/w emulsions constituting 125 and 250 mg/L oil concentrations were subjected to microfiltration (MF) using this membrane in batch mode of operation with varying trans-membrane pressure differentials (ΔP) ranging from 68.95 to 275.8 kPa. The membrane exhibited 98.8% oil rejection efficiency and 5.36 × 10⁻⁶ m³/m² s permeate flux after 60 min of experimental run at 68.95 kPa trans-membrane pressure and 250 mg/L initial oil concentration. These experimental investigations confirmed the applicability of the prepared membrane in the treatment of o/w emulsions to yield permeate streams that can meet stricter environmental legislations (<10 mg/L). Subsequently, the experimental flux data has been subjected to modeling study using both conventional pore blocking models as well as back propagation-based multi-layer feed forward artificial neural network (ANN) model. Amongst several pore blocking models, the cake filtration model has been evaluated to be the best to represent the fouling phenomena. ANN has been found to perform better than the cake filtration model for the permeate flux prediction with marginally lower error values.     

Recycling of waste attapulgite to prepare ceramic membranes for efficient oil-in-water emulsion separation

Large-scale application of ceramic membranes is restricted by high cost resulting from raw materials and sintering process. In this study, low-cost ceramic membranes were prepared with waste attapulgite (WAT) and α-Al₂O₃ as starting materials and used for oily wastewater treatment. The optimal membrane sintered at 1100 °C possessed excellent properties, with open porosity of 41.6%, flexural strength of 37.2 MPa and average pore size of 0.40 μm. The membrane also displayed outstanding permeability and chemical stability. The hydrophilicity and underwater oleophobicity were enhanced after surface modification. When used for oil-in-water emulsion filtration, the permeate flux reached 236.8 L m^?2 h^?2 bar^-1 under a low transmembrane pressure of 0.2 bar and the oil rejection exceeded 99%. Membrane cleaning with a simple ultrasonic treatment could easily achieve flux recovery. This study proposed a feasible strategy for both solid waste utilization and oily wastewater treatment.     

陶瓷膜净化溶剂油的实验研究

研究了平均孔径0.2 mm的陶瓷膜对含杂质溶剂油的微滤过程,选用不加水和加0.5%(w)水2种料液,考察了操作时间、跨膜压差、错流速度、温度和铝粉含量对膜通量及铝粉截留率的影响,研究了反冲操作、浓缩和污染膜清洗过程. 结果表明,不加水较加水料液的膜通量明显增大;随操作时间延长,膜通量下降至稳定,铝粉截留率迅速增大至100%;跨膜压差增大或温度升高使稳定通量增大;错流速度增大,稳定通量先升高之后不变;铝粉含量越高,膜通量越低. 适宜的操作参数为跨膜压差0.16 MPa、错流流速3.9 m/s和温度40℃. 反冲操作能有效提高膜通量;浓缩过程中膜通量快速下降至平缓阶段再较快降低,净化溶剂油澄清透明;采用0.15%(w)洗洁精和0.25%(w)硝酸清洗可使通量恢复到新膜通量的94.9%.     

高通量陶瓷膜研制及其除藻性能的初步研究

针对富营养化水中藻细胞的去除,研制了通量大、强度符合使用要求的无机陶瓷膜。所研制的陶瓷膜具有通量大、过滤精度高、易反冲再生等优点。过滤压差为0.08MPa时,清水通量为15.79m^3/（m^2·h）,对水中微型颗粒物的分离精度为0.06μm,且可反冲再生。对富营养化湖水深度处理实验表明,该陶瓷膜可有效去除“混凝-沉淀-砂滤”工艺出水中残存的藻细胞;对水中CODMn、TP也有一定的去除效果。研究结果为富营养化源水中藻细胞的去除提供了新的技术途径。     

光催化协同TiO2动态膜去除水中腐植酸及膜污染特性

针对物理扰动模式控制动态膜污染使涂膜层脱落方面的局限性,提出光催化氧化技术协同动态膜降低膜污染,对比了陶瓷微滤膜、动态膜、光催化协同动态膜处理含腐植酸废水及含腐植酸/TiO₂混合废水过程中的膜通量、污染物去除率及膜污染阻力分布的变化趋势。结果表明:光催化协同作用可有效提高动态膜过滤腐植酸溶液过程中的膜通量、总有机碳(TOC)及UV₂₅₄的去除率,并同时降低可逆污染阻力及不可逆污染阻力,其中可逆污染阻力明显大于其他部分阻力,可逆污染是造成膜通量衰减的主要原因。光催化预处理时间越长,稳态膜通量、TOC及UV₂₅₄去除率增幅越显著,控制膜污染越有效。光催化预处理2h和8h再动态膜过滤时TOC去除率分别可达到80%和90%以上,UV₂₅₄去除率都可达95%以上。     

Insight into fouling behavior of poly(vinylidene fluoride) (PVDF) hollow fiber membranes caused by dextran with different pore size distributions

Membrane fouling is the key problem that occurs in membrane process for water treatment. However, how membrane microstructure influences the fouling behavior is still not clear. In this study, fouling behavior caused by dextran was deeply and systematically investigated by employing four poly(vinylidene fluoride)(PVDF)membranes with different pore sizes, ranging from 24 to 94 nm. The extent of fouling by dextran was accurately characterized by pore reduction, flux decline, and the change of critical flux. The result shows that membrane with the smallest pore size of 24 nm experienced the smallest fouling rate and the lowest fouling extent. As the membrane pore size increased, the critical flux ranges were 105-114, 63-73, 38-44 and 34-43 L·m~(-2)·h~(-1),respectively. The critical flux and fouling resistances indicated that the fouling propensity increases with the increase of membrane pore size. Two pilot membrane modules with mean pore size of 25 nm and 60 nm were applied in membrane filtration of surface water treatment. The results showed that serious irreversible membrane fouling occurred on the membrane with pore size of 60 nm at the permeate flux of40.5 L·m~(-2)·h~(-1).On the other hand, membrane with pore size of 25 nm exhibited much better anti-fouling performance when permeate flux was set to 40.5,48 and 60 L·m~(-2)·h~(-1).     

单通道陶瓷膜管低压透水性能实验分析

无机陶瓷膜作为多孔介质具有分离效率高、耐酸、耐碱等优点,被视为在海水淡化、废水处理、气体分离等领域的研究热点。采用Al₂O₃管式单通道陶瓷膜材料构建膜组件,以燃煤电厂自来水、烟气冷凝水、脱硫废水三种不同水质为例,开展低跨膜压差下的膜组件透水性能实验,研究了膜参数、跨膜压差及水体温度等因素对渗透通量、渗透水质的影响,并对引发膜污染的机理过程进行了探讨分析。实验结果表明：陶瓷膜管的结构参数是关键因素,如孔隙率、孔径及厚度等;低跨膜压差下的渗透通量随压力增大呈线性提高,并未发现浓差极化现象,水体温度变化通过改变黏度进而影响渗透通量,同时水质较差时会导致渗透通量降低;陶瓷膜管的孔径是影响渗透水质的核心要素,微滤与纳滤膜对改善悬浮物含量、浊度及色度效果明显,不同孔径对盐度、电导率影响不同;从SEM图可以看出,污染物在膜表面或膜内部发生的沉积、架桥等现象导致严重的膜污染。充分认识影响陶瓷膜管渗透特性的关键因素及污染物的作用机理,对提高无机陶瓷膜的应用前景具有重要意义。     

陶瓷膜在反渗透进水预处理中的应用研究

以自来水为原水对砂滤-陶瓷膜装置连续供水,考察了膜通量随时间变化情况。试验结果表明：与传统的预处理方式相比,采用砂滤-陶瓷膜工艺可以长时间在较高膜通量下连续运行,通量为80L/h,并且在去除浊度、总铁、细菌等方面具有较明显的优势,出水浊度低于0.1NTU,总铁的去除率达到90%,细菌的去除率接近100%。因此,采用砂滤-陶瓷膜工艺作为反渗透膜的预处理在技术上是可行的。     

动态膜的形成机理及其水处理性能研究

以陶瓷管为载体,对高岭土动态膜的形成及其污水处理性能进行了详细的研究.实验中采用错流过滤方式涂膜,考查了跨膜压差、涂膜液浓度、错流速度及涂制时间等对动态膜形成的影响.通过对实验数据分析可知,动态膜形成初期10～13 min,膜的形成过程可用标准过滤模型描述,在此期间颗粒堵塞载体膜管孔道,致使渗透液通量急剧减小;之后,膜的形成过程符合滤饼过滤模型,这一阶段颗粒主要在载体膜管内壁面沉积,渗透液通量缓慢下降直至基本稳定.制备的动态膜可用于处理城市污水厂二级出水,动态膜对浊度去除率基本上为100%,对COD也有一定的去除作用.     

Crossflow microfiltration of a primary sewage effluent–solids retention efficiency and flux enhancement

An experimental study was carried out to evaluate flux performance and solids retention efficiency of a ceramic membrane system in the microfiltration (MF) of a primary municipal sewage effluent. The importance of membrane pore size and MF operating conditions on the removal of suspended solids (SS) and reduction of total dissolved solids (TDS) is demonstrated. With properly defined membrane parameters (eg pore size) the MF process was shown as being able to produce a permeate quality better than the required EC regulatory standards concerning urban wastewater treatment for suspended and total solids reduction. The economics of the membrane process depend largely on flux performance which was seriously impeded by severe membrane fouling, especially in‐pore adsorption/deposition of particles. The critical influence of membrane fouling on the flux reduction and change of solids retention characteristics of the membrane system was analysed. Two techniques were employed and evaluated in an endeavour to enhance permeate flux: (i) minimisation of surface particle accumulation by employing a helically wound baffle installed inside the crossflow channel to produce a helical flow pattern and vortices encompassed in secondary flow, and (ii) reduction of in‐pore fouling by employing an automated high frequency backflushing programme. Finally, this paper highlights the relationship between the flux enhancement mechanism and increased soluble solids transmission rate at elevated filtration temperature and when the backflush technique was applied. The increased total dissolved solids concentration in the permeate has profound implications on how the backflush technique should be implemented. © 1999 Society of Chemical Industry     

Experiment and calculation of filtration processes in an external-loop airlift ceramic membrane bioreactor

Air sparging is recognized as an effective way to increase permeate flux in membrane filtration processes. The application of air sparging with an external-loop airlift ceramic membrane bioreactor was studied at different gas flow rates, biomass concentrations and suction pressures. A 180% increase in permeate flux was obtained while filtering a 2 g/L activated sludge wastewater suspension with the airlift cross-flow operation for U_g=0.21 m/s. The mechanism of flux enhancement in the case of slug flow in tubular membrane was discussed. The region near the gas slug was divided into three different zones: falling film zone, wake zone and remaining liquid slug zone. Air sparging significantly lowered cake thickness and consequently cake resistances for the wake region and the falling film region. A novel model combining hydrodynamic of gas-liquid two-phase flow and cake resistance was developed to simulate the process. The model was validated with experimental data with an error of 8.3%.