Effect of DS Concentration on the PRO Performance Using a 5-Inch Scale Cellulose Triacetate-Based Hollow Fiber Membrane Module

Abstract

In this study, pressure-retarded osmosis (PRO) performance of a 5-inch scale cellulose triacetate (CTA)-based hollow fiber (HF) membrane module was evaluated under a wide range of operating conditions (0.0–6.0 MPa of applied pressure, 0.5–2.0 L/min feed solution (FS) inlet flow rate, 1.0–6.0 L/min DS inlet flow rate and 0.1–0.9 M draw solution (DS) concentration) by using a PRO/reverse osmosis (RO) hybrid system. The subsequent RO system for DS regeneration enabled the evaluation of the steady-stated module performance. In the case of pilot-scale module operation, since the DS dilution and the feed solution (FS) up-concentration had occurred and was not negligible, unlike the lab-scale experiment, PRO performance strongly depended on operating conditions such as inlet flow rates of both the DS and FS concentration. To compare the module performance with different configurations, we proposed a converted parameter in which a difference of the packing density between the spiral wound (SW) and the HF module was fairly considered. In the case of HF configuration, because of high packing density, volumetric-based performance was higher than that of SW module, that is, the required number of the module would be less than that of SW module in a full-scale PRO plant.

Comparison of Pressure-Retarded Osmosis Performance between Pilot-Scale Cellulose Triacetate Hollow-Fiber and Polyamide Spiral-Wound Membrane Modules

“…Figure 10 shows the apparent water permeation coefficient as a function of C DS . The of CTA-HF decreased gradually from 1.9 at 0.2 M NaCl to 1.0 [L/m 2 h Pa] at 1.2 M of C DS , which is similar to the decrease of the CTA-HF reported in a previous study [ 43 ] named as M-HF in Table 2 . of PA-SW decreased drastically from 9.0 at 0.3 M of C DS to 3.7 [L/m 2 h Pa] at 1.2 M DS.…”

“…From an industrial point of view, module volume-based PRO performance is vital because the volume-based size and number of required modules are necessary for designing a full-scale PRO plant [ 35 , 43 , 45 ]. The module volume-based gross power density ( ) used in this study is expressed as follows: …”

“…Experiments and simulation studies of PRO performance, using pilot-scale PRO HF modules under various operational conditions, have also been performed [ 35 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. In previous studies [ 35 , 43 ], the module performance with volumetric-based power outputs, as well as membrane-area-based power density, was investigated, to compare the PRO performance between the two different module configurations. However, to the best of the authors’ knowledge, there have been no studies on systematic PRO performance evaluation of pilot-scale SW and HF membrane modules based on experimental data under the same operating conditions, to compare the PRO performance between SW and HF configurations.…”

Role of Operating Conditions in a Pilot Scale Investigation of Hollow Fiber Forward Osmosis Membrane Modules

“…Even more challenging is the testing and comparison of FO membranes in commercial modules. The hydrodynamic limitations of individual module geometries might contribute significantly to the reduction of the performance, thereby rendering comparisons with lab scale membrane coupon testing difficult [28,29].…”

Cellulose Triacetate (CTA) Hollow-Fiber (HF) Membranes for Sustainable Seawater Desalination: A Review

“…Cellulose triacetate (CTA)-based hollow fiber (HF) membrane is therefore one of the commercially successful semipermeable membranes that has a long historical development due to its reliable excellent performances especially for drinking water production from seawater. In addition, recently, because of the versatile demands in energy consumption and environmental concerns about brine discharge as mentioned above, CTA-based HFs have caught attention for the usage of different methods, such as forward osmosis (FO) [ 23 , 24 , 25 , 26 ], pressure-retarded osmosis (PRO) [ 11 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ] and brine concentration (BC) [ 34 , 35 ] for the emerging technologies. Because their applications require optimum characteristics individually, different strategies for designing the membrane and module are required in spite of using the same CTA material.…”