反渗透海水淡化预处理工艺

对不同海水预处理工艺进行了研究,对比分析了不同工艺产水浊度、化学需氧量（COD_Mn）、污染密度指数（SDI₁₅）等参数及不同预处理工艺对超滤膜膜比通量的影响。混凝-沉淀或气浮处理能够有效降低海水浊度,配合砂滤或纤维过滤,浊度可以降低到0.3NTU左右。当超滤处理海水时,无论采用何种预处理方法,其产水浊度和SDI₁₅都可以满足反渗透进水要求。直接超滤时,COD_Mn去除效果较差,超滤结合混凝-沉淀或气浮处理时,COD_Mn去除率有了较大的提高。预处理方法对超滤膜膜比通量影响较大,直接采用超滤进行处理时,超滤膜膜比通量衰减较快,经混凝-沉淀或气浮处理后,膜比通量衰减有所减缓,进一步经砂滤或纤维过滤后,膜比通量的衰减得到了较好的控制。采用混凝-沉淀/纤维过滤预处理工艺时超滤膜膜比通量衰减最低。     

混凝超滤作为海水淡化预处理工艺中试研究

对海水淡化反渗透预处理工艺--混凝澄清和超滤组合工艺进行了中试研究.在水质、水温差别较大的两个海域进行了海水混凝澄清和超滤组合工艺的试验,考察了海水混凝澄清效果与絮凝剂种类、用量的关系,比较了3种超滤膜的处理效果及其差异,同时,提出了超滤膜通量优化的简便方法.结果表明:该工艺对海水水质变化具有较强的适应性,产水满足反渗透进水要求;海水絮凝剂宜选铁盐,投加量和海水中胶硅含量成正比.     

铝系混凝剂减缓膜污染的红外光谱-多变量曲线分辨分析

超滤是一种高效的水处理技术，近年来被广泛应用于工业废水处理、生活污水回用、海水淡化预处理等领域。然而，超滤长期运行会造成膜污染。本文采用了在线混凝结合超滤工艺，使用不同形态的铝系混凝剂（硫酸铝、氯化铝或聚合氯化铝），处理含有不同溶解性有机质组分（腐殖酸、牛血清白蛋白和高岭土）的模拟原水，研究不同铝形态、不同组分及其相互作用对超滤膜污染过程的影响。本研究建立了流量衰减模型模拟膜污染过程，结合衰减全反射红外光谱（IR-ATR）和多变量曲线分辨-交替最小二乘法（MCR-ALS）的数据处理方法对膜上的多种污染物进行定性和定量分析。结果表明硫酸铝和氯化铝混凝剂均可明显提高膜比通量，减缓膜污染。该工艺混凝剂投加量低于常规处理工艺即可明显减缓膜污染。混凝剂投加量为0.4mg/L时，氯化铝混凝效果较好，混凝剂投加量为2.4mg/L时，硫酸铝混凝效果较好。低投加量（0.2mg/L、0.4mg/L）下，PAC对缓解膜污染程度不明显，反而加重膜污染。牛血清白蛋白对超滤膜的污染比腐殖酸严重。因为牛血清白蛋白的存在大大降低了混凝的效果，阻碍疏松滤饼层的形成。向原水中投加硫酸铝混凝剂，膜污染主要发生在过滤前期，即膜孔窄化、堵塞。过滤后期，膜表面形成疏松滤饼层，对膜通量影响不大，膜污染减缓。     

超滤膜处理水库水研究

超滤膜过滤哈尔滨附近B水库水研究显示,超滤膜通量下降受膜进水浊度影响很大。利用混凝作为超滤的预处理能提高膜通量,并且能减缓膜通量的下降,混凝／超滤工艺所需混凝剂量比自来水厂常规工艺少．并且出水水质好。对于B水库水质量分数0．1％的柠檬酸溶液是较好的膜清洗剂。     

沉淀-超滤工艺膜反洗水的回收处理

在处理以地表水为水源的沉淀池出水时,超滤技术存在产水率较低的问题,反洗水的回收可以有效地提高系统的产水率和降低运行成本。试验设计了两套小试微滤膜系统,将膜反洗水经过预处理后按1∶9比例与滦河水混合作为一套小试膜系统进水,另外一套小试膜系统处理滦河水。试验考察了两种预处理方式对于混配水膜系统的出水水质及膜污染的影响。结果表明,在膜反洗水中投加混凝剂和粉末活性炭（PAC）后,相对仅投加混凝剂的预处理方式,混配水系统的出水水质得到改善,UV₂₅₄和COD_Mn的去除率分别提高了9%和6.3%,预处理方式对于混配水系统出水浊度没有影响,比通量衰减速率降低了16.6%。在反洗水经混凝和PAC吸附后,混配水和滦河水系统出水水质与膜污染状况未见显著差异。     

投加粉末活性炭对超滤膜去除海水中有机物的影响

超滤膜的有机污染问题是膜法海水预处理技术在海水淡化工程应用面临的重要挑战,粉末活性炭吸附是目前常用的膜前预处理手段之一。本文对比分析了直接超滤和投加粉末活性炭后对海水中有机物的截留能力,利用三维荧光光谱分析了投加粉末活性炭对超滤膜截留有机物的影响机制,并考察了海水超滤过程中通量变化及膜污染情况。研究结果表明,投加粉末活性炭能够强化超滤膜对海水浊度和有机物的去除,当粉末活性炭投量为200mg/L时,整个系统对海水中DOC去除率从直接超滤时的55.1%提高到77.6%。利用粉末活性炭的吸附作用及其在超滤膜表面形成的疏松滤饼层能够显著提高超滤系统对海水中腐植酸类有机物的去除能力。与直接超滤相比,粉末活性炭-超滤系统对改善膜通量的作用有限,但粉末活性炭形成的滤饼层能够避免超滤膜与有机物直接接触,可显著减缓超滤膜的不可逆污染。     

混凝-沉淀与混凝-气浮用于海水浸没式膜过滤的对比研究

采用混凝-沉淀-SMF和混凝-气浮-SMF对渤海湾海水进行净化处理,考察了2种工艺作为反渗透海水淡化预处理的净化效果及运行稳定性。结果表明,气浮或沉淀后的海水经SMF处理,出水浊度均小于0.3 NTU,颗粒物去除率在98%以上,总铁质量浓度小于0.1 mg/L,SDI_(15)稳定在1左右,COD_(Mn)小于1 mg/L,达到了反渗透膜的进水水质要求;但是混凝-沉淀-SMF的膜比通量衰减速度明显小于混凝-气浮-SMF,且反洗后膜比通量恢复率较高。从出水水质、运行稳定性和经济性上考虑,混凝-沉淀-SMF优于混凝-气浮-SMF。     

超滤用于海水淡化预处理的应用研究

反渗透系统的性能与预处理效果密切相关,尤其是在水质较差的地区。大量工程案例和测试结果证明,超滤作为反渗透海水淡化的预处理工艺效果显著。然而,超滤预处理工艺并不是一成不变的,为了优化处理效果,系统设计应随操作条件变化。有时,有必要将超滤与传统预处理技术结合使用。为了研究适用于渤海湾地区海水的以超滤为核心的有效预处理工艺,膜天膜公司在该地区开展了三次中试。其中一组试验采用了混凝-超滤集成预处理工艺,其他试验则采用了直接超滤的处理工艺。根据不同的试验条件,如温度、浊度,分为不同的阶段。本文将介绍这些试验的具体过程,并以实际操作经验为基础,对不同的超滤预处理系统进行评估,包括连续膜过滤(CMF)、浸没式膜过滤(SMF),超滤与传统的预处理方法结合或直接超滤系统,同时也验证了一系列有效的膜清洗方式。在本文中,膜性能的主要评价指标包括膜比通量、TMP、产水水质。     

不同超滤组合工艺净水及膜污染的中试研究

采用超滤中试系统处理深圳某水库原水,对比研究了粉末活性炭和混凝2种预处理工艺对超滤净水效果及对超滤膜污染的影响。结果表明,混凝/超滤工艺和粉末活性炭/超滤工艺对浊度、CODMn、UV254、DOC的平均去除率分别为99.6%、34.8%、31.3%、24.9%和99.4%、35.0%、32.4%、29.5%。粉末活性炭/超滤工艺对以CODMn、UV254、DOC表征的有机物的去除效果优于混凝/超滤工艺,而混凝/超滤工艺对有机物的去除效果受原水水质的影响较小,并且出水浊度效果稍好。在原水水质和运行条件相同的情况下,混凝/超滤工艺的跨膜压差的增长速度明显高于粉末活性炭/超滤工艺;但对超滤膜进行化学清洗后,粉末活性炭/超滤工艺膜表面仍有明显的污染物残留。     

陶瓷膜在海水淡化预处理中的应用研究

本研究在天津1000t/d海水淡化示范工程试验基础上,采用砂滤、0.2μm陶瓷膜进行海水淡化预处理,不仅有效保证出水水质满足GB/T19249-2003反渗透膜进水要求,还可有效减缓膜污染,延长膜的使用寿命。该工艺中陶瓷膜具有化学隐定性能好、分离能力强、耐酸碱、抗微生物能力强、机械强度高等优点,实验中膜通量可达600L/m2·h以上,反洗周期为1.5h,反洗效果好且工艺简单,使海水淡化预处理工艺成本低,工艺更为简化,有利于尽快实现大规模海水淡化。     

Application of ultrafiltration hybrid membrane processes for reuse of secondary effluent

This study evaluates the factors affecting pretreatment conditions for hybrid UF membrane processes for reuse of secondary effluent from the sewage treatment plant. The experimental results obtained from the ultrafiltration (UF) membrane process showed that the particles of the size range between 0.2 and 1.2 μm caused a significant impact on membrane fouling in all cases even with or without the coagulation process. As pretreatment of UF membrane process, the coagulation significantly improved the permeate flux. Optimal flux improvement was seen at an alum dose of 50 mg/L. In addition, it was found that the permeate flux was least declined under the coagulation condition of charge neutralization (pH 5.0). Also, the powdered activated carbon (PAC) adsorption enhanced the permeate flux. Application of the direct filtration as a pretreatment of UF membrane process was also very effective in reducing the UF membrane fouling.     

混凝耦合多孔陶瓷膜净化河水简

Membrane filtration technology combined with coagulation is widely used to purify river water. In this study, micro filtration （MF） and ultrafiltration （UF） ceramic membranes were combined with coagulation to treat local river water located at Xinghua, Jiangsu province, China. The operation parameters, fouling mechanism and pilot-scale tests were investigated. The results show that the pore size of membrane has small effect on the pseudo-steady flux for dead-end filtration, and the increase of flux in MF process is more than that in UF process for cross-flow filtration with the same increase of cross-flow velocity. The membrane pore size has little influence on the water quality. The analysis on membrane fouling mechanism shows that the cake filtrationhas significant in fluence on the pseudo-steady flux and water quality for the membrane with pore size of 50, 200 and 500 nm. For the membrane with pore size of 200 nm and backwashing employed in our pilot study, a constant flux of 150 L-m^-2-h^-1 was reached during stable operation, with the removal efficiency of turbidity, total organic carbon （TOC） and UV254 higher than 99%, 45% and 48%, respectively. The study demonstrates that coagulation-porous ceramic membrane hybrid process is a reliable method for river water purification.     

凝固浴组成对SMA/CPVC共混超滤膜的结构与性能影响

通过非溶剂致相分离（NIPS）法制备了苯乙烯-马来酸酐共聚物（SMA）/氯化聚氯乙烯（CPVC）共混超滤膜,探讨了凝固浴中不同溶剂（DMAc）含量对其超滤膜表面酸酐基团偏析程度、微观结构、亲水性、水通量、截留率和抗污染的影响。结果表明：凝固浴中溶剂含量的增加抑制了酸酐基团向膜表面的偏析,导致亲水性减弱;同时,铸膜液中溶剂与水分子之间扩散速率的变小引起延迟分相,使得膜表面孔径变小和分布变窄。当溶剂质量分数为3%时,超滤膜对牛血清白蛋白（BSA）截留率提升至98.10%、通量恢复率为96.82%,且不可逆污染率降为3.77%,表明凝固浴中适量的溶剂可进一步提高超滤膜抗污染性能。     

Electrocoagulation pretreatment of seawater prior to ultrafiltration: Bench-scale applications for military water purification systems

The objectives of this research were to investigate the use of in-line electrocoagulation (EC) as a pretreatment for seawater prior to ultrafiltration (UF) at the bench-scale and to compare EC with equivalent doses of ferric chloride. UF membrane performance was evaluated by transmembrane pressure (TMP) and hydraulic resistances at sub- and super-critical fluxes, and by flux recovery after hydraulic and chemical cleanings. Modified Atlantic Ocean seawater was used. Constant flux UF operation (50 to about 350 lmh) was used to evaluate short-term performance at sub- and super-critical fluxes, and constant feed-pressure (15 psi) experiments were used to investigate filter cake stability under high TMP conditions. In-line EC improved UF membrane performance for all coagulation and flux conditions. Compared to no coagulant pretreatment, ferric chloride improved UF membrane performance under short-term, constant flux conditions that resulted in TMP < 8 psi, but produced increased TMP and resistance to filtration at 15 psi. EC always resulted in lower resistance and improved flux recovery after cleaning compared to an equivalent dose of ferric chloride. Overall, EC is a feasible and competitive pretreatment strategy at the bench-scale, but scale-up issues, electrode cleaning requirements, and sustainability during long-term operation need further study.     

Preparation of PVDF ultrafiltration membranes using PVA as pore surface hydrophilic modification agent with improved antifouling performance

Novel polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes were facilely fabricated using polyvinyl alcohol (PVA) aqueous solution as the coagulation bath through phase inversion method. In the process, PVA was introduced into the pore surfaces of the PVDF membranes via the interdiffusion of the non‐solvent water and the solvent. The effects of PVA content in the coagulation bath on membrane properties were systematically discussed. The results indicated that the increase of PVA content in coagulation bath resulted in the formations of the more sponge‐like structures and the higher surface hydrophilicity. Smaller pore size led to lower water flux and higher bovine serum albumin rejection. Fouling resistance measurement indicated that the membranes made in PVA/water coagulation bath had higher flux recovery ratio (92.1%) than the membrane made in a pure water bath (71.0%). Furthermore, mechanical property test revealed that the resulting membranes had high tensile strength and Young's modulus. In this work, we found that the morphology and the property of the novel PVDF membranes could be determined by the PVA content in the coagulation bath. POLYM. ENG. SCI., 59:E384–E393, 2019. © 2018 Society of Plastics Engineers     

Optimizing the coagulant dose to control membrane fouling in combined coagulation/ultrafiltration systems for textile wastewater reclamation

Optimal coagulation conditions need to be re-examined when coagulation is coupled to membrane filtration for wastewater treatment. This work focused on the optimization of coagulant dosing in order to control membrane fouling in ultrafiltration (UF), following coagulation for the reclamation of textile wastewater. The effects of pore size and coagulant types and dosages on flux decline were investigated using a stirred-cell UF unit. The flux was greatly enhanced for the UF membrane when a coagulant was added, whereas for the microfiltration (MF) membrane the flux decreased. This could be attributed to changes in the size of coagulated particles and their interaction with membrane pores. At a low dosage (e.g., 0.0371 mM as Al), the polyaluminum chloride (PACl) coagulant was found to control the flux decline most effectively for low ionic-strength wastewater. The optimal dose minimized the fouling and cake layer resistances, although it was sharp and dependent on influent composition. The cake layer protected the membrane from fouling, but it provided additional resistance to permeation. Analyses of turbidity, particle size, and membrane surface exhibited the characteristics of coagulated particles and their cake structures that are closely associated with flux behavior.     

Membrane processes for water reuse from the effluent of industrial park wastewater treatment plant: a study on flux and fouling of membrane

Both the relationship between the flux and the fouling mechanism of ultrafiltration (UF) membrane and the effects of pretreatment before reverse osmosis (RO) process on the treatment of the effluent of industrial park wastewater treatment plant (IPWTP) were investigated to examine the application of membrane processes on the water reuse treatment. For the former, the flux data was first fitted to the Hermia model to give the implication of the fouling mechanism. Then, the fouling mechanism was further identified with the aid of the SEM morphology of membrane surfaces. For the latter, the changes of both water characteristics (turbidity, TOC, conductivity, particle size distribution, and organic solute molecular weight) and membrane properties (surface zeta potential and surface morphology) before and after the treatment of membrane processes were measured. It was found that the major blocking mechanisms of UF membrane process at initial and final stage were standard blocking of pore (causing from colloid materials) and cake blocking of pore (causing from suspended particles), respectively. On the other hand, it was concluded that the permeate from 1 μm/UF/RO process was suitable for the reuse of cooling water and low pressure boiler water.     

湿式催化氧化/膜过滤组合工艺膜过滤机理

采用湿式催化氧化/膜过滤组合工艺,以Mo-Zn-Al-O粉末作为催化剂降解阳离子红GTL模拟染料废水,探讨在膜过滤过程中平均孔径为0.1 μm的微滤和0.022 μm的超滤聚偏氟乙烯(PVDF)中空纤维膜的过滤机理。实验结果表明,两种膜过滤组合工艺对染料的降解效果均优于单独湿式催化氧化,0.01 MPa恒压条件下运行120 min后微滤和超滤的膜通量分别衰减了26.63%和16.48%,其原因是粉末催化剂可在微滤膜孔内部沉积形成中间阻塞过滤,后在表面形成滤饼层;而在超滤膜表面仅形成滤饼层。通过实验结果对膜阻力进行计算,可知在相同反应过程后微滤膜产生的不可逆阻力大于超滤膜。在不同反应条件下,催化剂的沉积量与膜阻力呈现线性相关。     

污水深度超滤过程的数学模拟及应用研究

以流体力学理论为基础，从膜结构的角度出发，以膜孔密度和膜孔径为主要参数建立了超滤膜过滤受污染水的膜结构参数模型，并以不同分子量分布的城市污水二级处理水为原水，对模型参数进行了拟合、验证。结果表明：膜结构参数模型能较好地反映深度处理污水的超滤膜污染过程。