Analysis of desalination alternates for phosphoric acid plant in Tunisia

High recovery rate NF–FO–RO hybrid system for inland brackish water treatment

Solar desalination plant for small size use in remote arid areas of South Algeria for the production of drinking water

A small solar desalination plant for the production of drinking water in remote arid areas of southern Algeria

Review of brackish water reverse osmosis (BWRO) system designs

The desalination of brackish ground water using cascade Rankine cycle is proposed. A pair of a Rankine cycle like steam Rankine cycle (SRC) and organic Rankine cycle (ORC) as a waste heat recovery. The single stage steam turbine for the SRC unit while the scroll expander for ORC unit is selected. Simulation of cascade RO system performance is considered using R245fa as a working fluid for ORC unit. The saturated steam from solar Scheffler disc will expand into steam turbine, where the reject heat from steam turbine will utilize for evaporation of ORC working fluid. The high-pressure RO pumps integrated with SRC and ORC turbines to provide net driving pressure to the RO module. This type of system is well suitable for desalination of brackish water due to moderate working temperature & pressure. Result shows that the pair of Rankine cycle will increase the overall (cascade) efficiency of the system. The basic input parameters are optimised with Taguchi approach. The performance of the system shows a good agreement with variation of mass flow rate of the steam in which the permeate flow rate from RO will increase along with the cycle efficiencies.

Brackish water desalination using reverse osmosis and capacitive deionization at the water-energy nexus

The present study analyzes the economic viability of an Integrated Energy System (IES) that couples a Reverse Osmosis (RO) water desalination facility with a Nuclear Power Plant (NPP). The case study is conducted in collaboration with Arizona Public Service (APS), the operating owner of the Palo Verde Generating Station (PVGS) NPP. A challenge APS is facing is that their cooling water acquisition contract with the Sub Regional Operating Group (SROG) will expire soon and a renewal can only be done for a significantly higher price of the water. Therefore, APS is seeking alternative sources for their cooling water. One opportunity is to pump brackish water from the regional ground water. Although much less expensive than the water from the new SROG contract, the salinity of the brackish water is so high that a blend of brackish and SROG water will need additional treatment to improve its quality for use in the PVGS cooling towers. A study has been conducted in 2018 at Idaho National Laboratory (INL) to investigate the economics of an PVGS onsite RO desalination plant that would reduce the salinity of a SROG and brackish water blend to an acceptable level. One of the main findings of that study was that the overall economics of water desalination can be greatly improved if, in addition to cooling water for PVGS, potable water could also be produced and sold for profit. In fact, the study concluded that only producing cooling water for PVGS via RO desalination is not economically viable compared to buying all needed cooling water from the SROG. The present report investigates the economic impact of a large, regional RO desalination plant that could provide potable water for the region, considering the conclusions from last year’s scoping study. The study looks in particular at the water-market situation in the West Valley of Phoenix; i.e., in the area of the municipalities of Buckeye, Goodyear, Avondale and Tolleson. In addition to providing potable water for the adjacent municipalities, the concentrate from the regional RO plant would be taken and treated by PVGS to provide some cooling water for a (hopefully) lower cost than that of the SROG water. Furthermore, a cost structure could be put in place for the treatment of the concentrate from the regional RO that would offset some of the water acquisition cost for APS. The analysis used the Nuclear-Renewable Hybrid Energy System (N-R HES) software framework, which was developed at INL in 2016. The framework has reached some level of maturity, such that it can be applied to more than simple demonstration cases; i.e., real industry problems. The analysis in this report considers two cases (for various scenarios): First, the Base Case is the most economic one for APS, as no RO is built, i.e. the case for which cooling water acquisition and treatment cost are lowest. The 2018 INL study showed that some brackish water can be blended with the effluent SROG water without having to build the onsite RO. The Base Case is where APS pumps the maximum volume of less-expensive brackish water (limited by water chemistry in the cooling towers), blends it with the effluent from the SROG, and no RO is built. Second, the proposed RO Case includes two RO plants, one onsite at PVGS and another larger, regional one close to the brackish water wells. The regional RO produces potable water that is sold to the regional municipalities, while the PVGS RO onsite treats (part of) the regional ROs' concentrate and brackish water blend. The desalinated water from the PVGS RO is used in the cooling towers at PVGS. The analysis evaluates the difference in economics, using the Net Present Value (NPV) and Internal Rate of Return (IRR), between the cases. By comparing the two cases, in addition to evaluating the economics of the regional RO, we can also assess the impact of the regional RO on PVGS and consequently APS economics. The study shows that (for the Base Case) to offset the treatment cost for the RO concentrate, the cost of concentrate treatment to be paid by the regional RO to APS would be between 5 – 35 $/m3 of concentrate (depending on the regional RO size envisaged). Correspondingly, the Levelized Cost of Potable Water (LCOPW), which is the average or unit cost, for the regional RO is in the 0.55 – 0.6 $/m3 range of potable water. Or, considering the residential water demand model developed for the Phoenix West Valley, the NPV of the regional RO would be between $20 and 100 billion.

Design aspects of small-scale photovoltaic brackish water reverse osmosis (PV-BWRO) system

Both brackish water desalination and seawater desalination processes are well established and in common use around the globe to create new water supply sources. The farther the location of the source water from the ocean or seashore, the lower the salinity (TDS) of the water and the lower the osmotic pressure that needs to be overcome when desalinated water is produced. This is one of the major reasons that brackish desalination is often considered less costly than seawater desalination. A number of project considerations, however, indicate that seawater desalination can be beneficial and more cost-effective than brackish water desalination. To make a fair comparison, we need to properly compare all major aspects of both types of projects to define the best and most appropriate desalination technology. While brackish water has less feed water TDS, it is more challenging to dispose of the produced concentrate. Also, although brackish water desalination needs less energy to overcome osmotic pressure, it usually requires more energy to draw the water from the well than it takes to pump seawater from the open ocean intake. Another factor is that the temperature of the brackish well water may be lower than the temperature of ocean water, giving seawater desalination an advantage in energy demand. In comparing brackish to seawater desalination, these major aspects should be evaluated: (1) Locations of seawater and brackish water plants, relative to the major consumers of the desalinated water, (2) Transportation (pumping and disposal) costs of the feed water and produced water, (3) Potential colocation of a seawater plant with a large industrial user (e.g., power plant) of the seawater for cooling or other purposes, (4) Produced quality of brackish water and seawater desalination in terms of major minerals and emerging contaminants, (5) Sustainability of the water source: capacity and depth of the brackish water wells, as well as the type of soil. (6) Technical and economic aspects of produced concentrate disposal, (7) Permitting process costs for brackish and seawater desalination, and (8) The economics of both brackish and seawater desalination treatment processes: capital costs, operational and maintenance (O&M) costs, lifetime water cost, and total water cost (TWC). This paper discusses the major evaluation criteria and considerations involved in properly comparing the economic and technical aspects of brackish and seawater desalination to determine the more favorable desalination technology for a given desalination project.

Side effects of antiscalants on biofouling of reverse osmosis membranes in brackish water desalination

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Pilot study of biofouling occurrence in a brackish water reverse osmosis system using intermittent operation

Enhanced exergy analysis of a full-scale brackish water reverse osmosis desalination plant

A nanofibrous composite reverse osmosis (RO) membrane with a polyamide barrier layer containing interfacial water channels was fabricated on an electrospun nanofibrous substrate via an interfacial polymerization process. The RO membrane was employed for desalination of brackish water and exhibited enhanced permeation flux as well as rejection ratio. Nanocellulose was prepared by sequential oxidations of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and sodium periodate systems and surface grafting with different alkyl groups including octyl, decanyl, dodecanyl, tetradecanyl, cetyl, and octadecanyl groups. The chemical structure of the modified nanocellulose was verified subsequently by Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), and solid NMR measurements. Two monomers, trimesoyl chloride (TMC) and m-phenylenediamine (MPD), were employed to prepare a cross-linked polyamide matrix, i.e., the barrier layer of the RO membrane, which integrated with the alkyl groups-grafted nanocellulose to build up interfacial water channels via interfacial polymerization. The top and cross-sectional morphologies of the composite barrier layer were observed by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) to verify the integration structure of the nanofibrous composite containing water channels. The aggregation and distribution of water molecules in the nanofibrous composite RO membrane verified the existence of water channels, demonstrated by molecular dynamics (MD) simulations. The desalination performance of the nanofibrous composite RO membrane was conducted and compared with that of commercially available RO membranes in the processing of brackish water, where 3 times higher permeation flux and 99.1% rejection ratio against NaCl were accomplished. This indicated that the engineering of interfacial water channels in the barrier layer could substantially increase the permeation flux of the nanofibrous composite membrane while retaining the high rejection ratio as well, i.e., to break through the trade-off between permeation flux and rejection ratio. Antifouling properties, chlorine resistance, and long-term desalination performance were also demonstrated to evaluate the potential applications of the nanofibrous composite RO membrane; remarkable durability and robustness were achieved in addition to 3 times higher permeation flux and a higher rejection ratio against commercial RO membranes in brackish water desalination.

Desalination of brackish water by nanofiltration and reverse osmosis