Pathways for minimal and zero liquid discharge with enhanced reverse osmosis technologies: Module-scale modeling and techno-economic assessment

Abstract

While mechanical vapor compression is typically applied for the concentration of brine, new approaches that are less costly and less energy intensive are needed to facilitate minimal and zero liquid discharge. Several variations of reverse osmosis for high-salinity desalination and increasing recovery rates beyond the pressure limitation of conventional RO have been proposed in the literature. The promise of these enhanced RO approaches entails a reduction in energy consumption when compared with thermal desalination methods. In this paper, low-salt rejection reverse osmosis (LSRRO), cascading osmotically mediated reverse osmosis (COMRO), and osmotically assisted reverse osmosis (OARO) were comparatively assessed via module-scale, cost optimization models to gain an accurate perspective of the performance differences between each of these configurations. We quantified the optimal levelized cost of water (LCOW) of each technology for the case of desalinating feedwater at 70 g/L at 75% recovery, which would result in a brine concentration near 250 g/L, a level that allows further treatment with crystallizers. For baseline scenarios, LCOW results for LSRRO, COMRO, and OARO were 6.63, 7.90, and 5.14 $/m 3 of product water, respectively, while the corresponding specific energy consumption (SEC) values were 28.9, 12.8, and 10.3 kWh/m 3 . A sensitivity analysis is also presented. KeywordsBrine management Minimal liquid discharge Zero discharge Zero liquid discharge Osmotically assisted reverse osmosis High-salinity desalination

A solar energy desalination analysis tool, sedat, with data and models for selecting technologies and regions

“…These alternative water resources are also represented by location and salinity. The feedwater salinity level, as well as the allowed brine concentration determine the appropriate desalination technology and how it impacts the cost of operating these plants 15 . Input water temperature impacts the energy requirements of the system and thus the cost of producing fresh water.…”

“… Forward Osmosis (FO) The FO model was developed and validated by Trevi Co. 45 ; it was translated into Python and generalized for wide input ranges at Columbia University. Multi-pass Reverse Osmosis (RO), and Osmotically Assisted Reverse Osmosis (OARO) Developed in Matlab and Python at Columbia University 15 , 46 – 48 . The multi-pass RO model was designed for high purity permeate production for electrolyzer and other industrial applications, whereas the OARO model is used in minimal and zero-liquid-discharge pathways, for comparison with thermal desalination technologies.…”

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“…Since the driving force in FO is osmotic pressure gradient, waters with much higher salinity than RO can be used as feed water. When using FO to concentrate feedwater beyond the salinity limit of RO, the osmotic pressure of both feed and draws solution will surpass the bearable pressure limit of RO [11,23,51,52].…”

Comparison of Energy Consumption of Osmotically Assisted Reverse Osmosis and Low-Salt-Rejection Reverse Osmosis for Brine Management

“…For a more detailed and industrially relevant comparison of these two technologies, the levelized cost of water (LCOW) needs to be assessed. , LCOW of a water treatment technology is defined as the cost per unit volume of product water. To estimate LCOW, a techno-economic analysis should be carried out. , We further note that although the process modeling approach is able to evaluate the energy efficiency of the OARO/LSRRO systems, it cannot provide the specific system design parameters (e.g., membrane properties, membrane module sizes, and feed flow rates) that are critical for techno-economic analysis. To acquire these design parameters, future work should carry out detailed module-scale analysis of OARO/LSRRO systems. , …”

“…To estimate LCOW, a techno-economic analysis should be carried out. 44,45 We further note that although the process modeling approach is able to evaluate the energy efficiency of the OARO/LSRRO systems, it cannot provide the specific system design parameters (e.g., membrane properties, membrane module sizes, and feed flow rates) that are critical for techno-economic analysis. To acquire these design parameters, future work should carry out detailed module-scale analysis of OARO/ LSRRO systems.…”