Jihee Han

Experimental comparison of direct contact membrane distillation (DCMD) with vacuum membrane distillation (VMD)

Abstract Membrane distillation (MD) is a thermally driven membrane process using porous hydrophobic membranes. MD has been investigated as an alternative desalination technology due to its advantages over multi-stage flash (MSF) and reverse osmosis (RO). Nevertheless, it is difficult to design and optimize the MD systems under various conditions, because both thermal and hydrodynamic effects play an important role. Therefore, this study focused on performance analysis of MD systems in different configurations. Direct contact MD (DCMD) and vacuum MD (VMD) were experimentally compared using laboratory-scale systems. A simple model was also applied to analyze the difference between two configurations theoretically. Experimental results indicated that permeate flux in DCMD and VMD were sensitive to the operating conditions. Using same membranes, two MD systems showed different flux behaviors. The influences of operating parameters for DCMD and VMD on overall efficiency were also investigated. The model result...

Integration of forward osmosis with membrane distillation: effect of operating conditions

Abstract Hybrid desalination systems combining both thermal and membrane desalination processes are currently considered a viable alternative to conventional desalination plants. Recently, an incorporation of forward osmosis (FO) with membrane distillation (MD) has been considered as a new hybrid desalination technology. Nevertheless, few works have been done to design and optimize these types of new hybrid systems. The focus of this study was to investigate FO–MD hybrid process in which MD is being used to recover draw solutes in product water from FO. Laboratory-scale systems for FO and MD were developed to examine the effect of key operating conditions (draw solute concentration, operation time, temperature, etc.) on flux and solute transport. The results indicated that the efficiency of FO–MD hybrid is affected by the selectivity of draw solute transport through the MD membrane. As decreasing the temperature difference between the feed and distillate in MD, the rate of separation decreases but the sel...

Analysis of reverse osmosis system performance using a genetic programming technique

Reverse osmosis (RO) membrane process has been considered a promising technology for water treatment and desalination. However, it is difficult to predict the performance of pilotor full-scale RO systems because numerous factors are involved in RO performance, including membrane scaling, fouling, and deterioration. This study was intended to develop a practical model for the analysis of pilot-scale RO processes. A genetic programming (GP) technique was applied to correlate key operating parameters and RO permeability statistically. The GP model was trained using a set of experimental data from a RO pilot plant with a capacity of 1,000m 3 /day and then used to predict its performance. The comparison of the GP model calculations with the experiment results revealed that the GP model was a useful tool for predicting the efficiency of pilot-scale RO systems. The GP model also allowed the in-depth analysis of RO system performance even under unsteady conditions.

Design optimization of ultrafiltration membrane module for desalination applications

Ultrafiltration (UF) membrane provides an effective means of removing particles and microbial contaminants by size exclusion with the requirement of smaller footprints with conventional pretreatment processes. Although a few works have been done to optimize UF membrane modules and systems for drinking water treatment and membrane bioreactor (MBR), little information is available on UF design for pretreatment of seawater/brackish water desalination. This study focuses on the design of hollow fiber UF membrane modules for pretreatment processes in desalination plants. A theoretical model was developed and applied to predict the filtration efficiency of hollow fiber UF membranes. Typical conditions for pretreatment of feed solution to reverse osmosis desalination were considered. The effect of module dimensions and fiber packing density on pressure drops was also analyzed using the model. It was found that fiber thickness and module size are important as well as inner diameter and length of the fiber.