A Review on Applications of Membrane Distillation (MD) Process for Wastewater Treatment

Fouling and wetting in the membrane distillation driven wastewater reclamation process – A review

Membrane processes with outstanding advantages have been developed over the past three decades and could be used for oily wastewater treatment applications, effectively. Nowadays, forward osmosis (FO) and membrane distillation (MD) processes, as two essential membrane processes have received considerable attention, for oily wastewater treatment applications. The excellence of MD and FO processes compared to other membrane processes is their cost-effectiveness and capability to remove smaller oil drops with lower energy consumption. Membrane fouling as a challenge with decreasing separation efficiency has hindered the commercialization of FO and MD processes. Therefore, developing new FO and MD membranes with lower fouling tendency is very important for water treatment applications especially for oily wastewater treatment. In this chapter, after bibliographic analysis, the conventional methods developed for treating various types of oily wastewaters are reviewed, in brief. Then, various membrane processes with particular emphasis on their challenges and advances in oily wastewater treatment applications are presented. Afterward, focusing on FO and MD processes, the current materials used to fabricate proper membranes for FO and MD processes are discussed.

Effect of coagulation pretreatment on membrane distillation process for desalination of recirculating cooling water

Membrane distillation for sustainable wastewater treatment

Feasibility of membrane distillation process for potable water reuse: A barrier for dissolved organic matters and pharmaceuticals

Assessment of atomic force microscopy for characterization of PTFE membranes for membrane distillation (MD) process

ABSTRACTPloy(vinylidene fluoride)–polytetrafluoroethylene nanofibrous membrane fabrication and direct contact membrane distillation (DCMD) process were simulated and optimized by response surface methodology (RSM). Analysis of variance was applied to develop and verify the models that predict the objectives. The three‐dimensional response surfaces of different objectives were obtained. Results showed that the membrane with thickness of 70.7 μm, contact angle of 146.2°, and liquid entry pressure of 53.5 kPa was obtained within investigated experimental range under the optimum electrospinning conditions. Rejection rate of 99.99% and the permeate flux of 67.5 kg m−2 h−1 were gained under the optimum membrane distillation (MD) process parameters. The actual and predicted values show good consistency verifying the accuracy of the models. In addition, an overall investigation of the influence of heat‐press temperature on the morphological and mechanical properties of electrospun membrane was carried out. Results indicated that electrospinning process and MD performance can be enhanced after the corresponding variables were optimized by RSM. This study provides a scientific way to optimize the electrospinning and DCMD parameters. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47125.

Application of fluoroalkylsilanes (FAS) grafted ceramic membranes in membrane distillation process of NaCl solutions

An integrated forward osmosis (FO)-membrane distillation (MD) process is promising for the treatment and resource recovery from municipal wastewater. As higher temperature is applied in MD, it could affect the performance of both FO and MD units. This study aimed to investigate the effects of the type of draw solution (DS) and feed solution (FS) such as ammonium solution or municipal wastewater containing ammonium at higher temperatures on membrane treatment performance. It is found that higher FS and DS temperatures resulted in a higher water flux and a higher RSF with either NaCl or glucose as DS due to the increased diffusivity and reduced viscosity of DS. However, the water flux increased by 23–35% at elevated temperatures with glucose as DS, higher than that with NaCl as DS (8–19%), while the reverse solute flux (RSF) increase rate with NaCl as DS was two times higher than that with glucose as DS. In addition, the use of NaCl as DS at higher temperatures such as 50 and FS at 42 °C resulted in increased forward ammonium permeation from the FS to the DS, whereas ammonium was completely rejected with glucose as DS at all operating temperatures. Reducing pH or lowering the temperature of DS could improve ammonium rejection and minimize ammonia escape to the recovered water, but extra cost or reduced MD performance could be led to. Therefore, the results suggest that in an integrated FO-MD process with DS at higher temperatures such as 50 °C, glucose is better than NaCl as DS. Furthermore, a simplified heat balance estimation suggests that internal heat recovery in the FO-MD system is very necessary for treating municipal wastewater treatment. This study sheds light on the selection of DS in an integrated FO-MD process with elevated temperature of both FS and DS for the treatment of wastewater containing ammonium. In addition, this study highlights the necessity of internal heat recovery in the integrated FO-MD system.

Simulation of Heat and Mass Transfer in Direct Contact Membranedistillation (md): The Effect of Membrane Pore Space Description

The thermal and mechanical stability of different capillary polypropylene (PP) membranes used in the membrane distillation (MD) process were investigated. Membranes differed in storage time from the manufacturing (from 1 to 8 years). Small changes in polymers crystallinity, melting temperature (T m ) and crystallization temperature (T c ) were detected as the storage time of membranes increased. This can be assigned to the crystal growth in amorphous phase of PP. However, independently on the storage time the brand-new membranes were found to be flexible and elastic and capable to bending without fracture. The MD process was carried out either continuously or continuously/periodically. Distilled water and NaCl solutions were used as feeds in MD process. It was found that PP membranes are loosing their flexibility and become brittle during long-term usage in MD modules, and as a consequence, they show susceptibility to cracking and fracture. These effects were more significant when NaCl solutions were used as feeds.

Fertilizer-driven FO and MD integrated process for shale gas produced water treatment: Draw solution evaluation and PAC enhancement

Separation of hydrogen isotopic water by multi-walled carbon nanotube (MWCNT) membrane and graphene oxide (GO)-MWCNT composite membranes

Integration of in situ Fenton-like self-cleaning and photothermal membrane distillation for wastewater treatment via Co-MoS2/CNT catalytic membrane

Membrane distillation (MD) can be used in drinking water treatment, such as seawater desalination, ultra-pure water production, chemical substances concentration, removal or recovery of volatile solutes in an aqueous solution, concentration of fruit juice or liquid food, and wastewater treatment. However, there is still much work to do to determine appropriate industrial implementation. MD processes refer to thermally driven transport of vapor through non-wetted porous hydrophobic membranes, which use the vapor pressure difference between the two sides of the membrane pores as the driving force. Recently, computational fluid dynamics (CFD) simulation has been widely used in MD process analysis, such as MD mechanism and characteristics analysis, membrane module development, preparing novel membranes, etc. A series of related research results have been achieved, including the solutions of temperature/concentration polarization and permeate flux enhancement. In this article, the research of CFD applications in MD progress is reviewed, including the applications of CFD in the mechanism and characteristics analysis of different MD structures, in the design and optimization of membrane modules, and in the preparation and characteristics analysis of novel membranes. The physical phenomena and geometric structures have been greatly simplified in most CFD simulations of MD processes, so there still is much work to do in this field in the future. A great deal of attention has been paid to the hydrodynamics and heat transfer in the channels of MD modules, as well as the optimization of these modules. However, the study of momentum transfer, heat, and mass transfer mechanisms in membrane pores is rarely involved. These projects should be combined with mass transfer, heat transfer and momentum transfer for more comprehensive and in-depth research. In most CFD simulations of MD processes, some physical phenomena, such as surface diffusion, which occur on the membrane surface and have an important guiding significance for the preparation of novel membranes to be further studied, are also ignored. As a result, although CFD simulation has been widely used in MD process modeling already, there are still some problems remaining, which should be studied in the future. It can be predicted that more complex mechanisms, such as permeable wall conditions, fouling dynamics, and multiple ionic component diffusion, will be included in the CFD modeling of MD processes. Furthermore, users’ developed routines for MD processes will also be incorporated into the existing commercial or open source CFD software packages.