Desalination of brackish water by nanofiltration and reverse osmosis

Brackish groundwater treatment by reverse osmosis in Jordan

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

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.

BackgroundAs an appropriate tool, membrane process is used for desalination of brackish water, in the production of drinking water. The present study aims to investigate desalination processes of brackish water of Qom Province in Iran.MethodsThis study was carried out at the central laboratory of Water and Wastewater Company of the studied area. To this aim, membrane processes, including nanofiltration (NF) and reverse osmosis (RO), separately and also their hybrid process were applied. Moreover, water physical and chemical parameters, including salinity, total dissolved solids (TDS), electric conductivity (EC), Na+1 and Cl−1 were also measured. Afterward, the rejection percent of each parameter was investigated and compared using nanofiltration and reverse osmosis separately and also by their hybrid process. The treatment process was performed by Luna domestic desalination device, which its membrane was replaced by two NF90 and TW30 membranes for nanofiltration and reverse osmosis processes, respectively. All collected brackish water samples were fed through membranes NF90-2540, TW30-1821-100(RO) and Hybrid (NF/RO) which were installed on desalination household scale pilot (Luna water 100GPD). Then, to study the effects of pressure on permeable quality of membranes, the simulation software model ROSA was applied.ResultsResults showed that percent of the salinity rejection was recorded as 50.21%; 72.82 and 78.56% in NF, RO and hybrid processes, respectively. During the study, in order to simulate the performance of nanofiltartion, reverse osmosis and hybrid by pressure drive, reverse osmosis system analysis (ROSA) model was applied. The experiments were conducted at performance three methods of desalination to remove physic-chemical parameters as percentage of rejections in the pilot plant are: in the NF system the salinity 50.21, TDS 43.41, EC 43.62, Cl 21.1, Na 36.15, and in the RO membrane the salinity 72.02, TDS 60.26, EC 60.33, Cl 43.08, Na 54.41. Also in case of the rejection in hybrid system of those parameters and ions included salinity 78.65, TDS 76.52, EC 76.42, Cl 63.95, and Na 70.91.ConclusionsComparing rejection percent in three above-mentioned methods, it could be concluded that, in reverse osmosis process, ions and non-ion parameters rejection ability were rather better than nanofiltration process, and also better in hybrid compared to reverse osmosis process.The results reported in this paper indicate that the integration of membrane nanofiltration with reverse osmosis (hybrid NF/RO) can be completed by each other probably to remove salinity, TDS, EC, Cl, and Na.

The role of desalination in bridging the water gap in Jordan

The production and supply of potable water and the disposal of wastewater are among the major challenges of the 21st century. Inadequate supply of potable water, coupled with increasing water demand in developing countries due to rapid population growth and industrialization are among the major reasons for the worsening water situation (1). Desalination of brackish water by reverse osmosis (RO) and nanofiltration (NF) are the leading technologies used in supplying potable water. Typically, these plants operate at 75% product water recovery so that 25% of RO feed water is wasted as concentrated brine. However, the recovery can be increased by processing the primary RO reject water with the aid of selective membrane processes such as a secondary RO or NF unit. Hybrid RO/NF processes were modeled using the membrane manufacturer's software for various membranes and for two specific brackish waters studied (total dissolved solids, TDS = 1700 and 3700 mg/1). The analyses show that 90% product water recovery is achieved for the low TDS feed water and 88% recovery is achieved for the high TDS feed water using simple, state-of-the-art hybrid membrane systems, and with minimal feed water chemical pre-treatment. It is also shown that the specific energy consumption of the RO system is reduced when it is powered by a stand-alone, on-site fuel cell power plant.

Climate change, population growth, and increased industrial activities are exacerbating freshwater scarcity and leading to increased interest in desalination of saline water. Brackish water is an attractive alternative to freshwater due to its low salinity and widespread availability in many water-scarce areas. However, partial or total desalination of brackish water is essential to reach the water quality requirements for a variety of applications. Selection of appropriate technology requires knowledge and understanding of the operational principles, capabilities, and limitations of the available desalination processes. Proper combination of feedwater technology improves the energy efficiency of desalination. In this article, we focus on pressure-driven and electro-driven membrane desalination processes. We review the principles, as well as challenges and recent improvements for reverse osmosis (RO), nanofiltration (NF), electrodialysis (ED), and membrane capacitive deionization (MCDI). RO is the dominant membrane process for large-scale desalination of brackish water with higher salinity, while ED and MCDI are energy-efficient for lower salinity ranges. Selective removal of multivalent components makes NF an excellent option for water softening. Brackish water desalination with membrane processes faces a series of challenges. Membrane fouling and scaling are the common issues associated with these processes, resulting in a reduction in their water recovery and energy efficiency. To overcome such adverse effects, many efforts have been dedicated toward development of pre-treatment steps, surface modification of membranes, use of anti-scalant, and modification of operational conditions. However, the effectiveness of these approaches depends on the fouling propensity of the feed water. In addition to the fouling and scaling, each process may face other challenges depending on their state of development and maturity. This review provides recent advances in the material, architecture, and operation of these processes that can assist in the selection and design of technologies for particular applications. The active research directions to improve the performance of these processes are also identified. The review shows that technologies that are tunable and particularly efficient for partial desalination such as ED and MCDI are increasingly competitive with traditional RO processes. Development of cost-effective ion exchange membranes with high chemical and mechanical stability can further improve the economy of desalination with electro-membrane processes and advance their future applications.

Water is the most common substance in the world, however, 97% is seawater and only 3% is fresh water. The availability of water for human consumption is decreasing due to increasing the environmental pollution. According to the World Health Organisation (WHO), about 2.4 billion people do not have access to basic sanitation facilities, and more than one billion people do not have access to safe drinking water (Singh, 2006). Moreover, the world’s population is expected to rise to nine billion from the current six billion in the next 50 years. Chronic water pollution and growing economies are driving municipalities and companies to consider the desalination as a solution to their water supply problems. Generally, desalination processes can be categorized into two major types: 1) phasechange/thermal and 2) membrane process separation. Some of the phase-change processes include multi-stage flash, multiple effect boiling, vapour compression, freezing and solar stills. The pressure driven membrane processes, such as reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF), have found a wide application in water treatment (Charcosset, 2009). The energy required to run desalination plants remains a drawback. The energy limitations of traditional separation processes provided the impetus for the development and the commercialisation of membrane processes. Membrane technologies (simple, homogenous in their basic concepts, flexible in application), might contribute to the solution of most of the existing separation problems. Nowadays, membranes are used for the desalination of seawater and brackish water, potable water production, and for treating industrial effluents. RO membrane separation has been traditionally used for sweater desalination (Charcosset, 2009; Schafer et al., 2005; Singh, 2006). One of the limitations of membrane processes is severe loss of productivity due to concentration polarisation and fouling or scaling (Baker & Dudley, 1998; Schafer et al., 2005). Membrane pretreatment processes are designed to minimise the potential problems of scaling resulting from the precipitation of the slightly soluble ions. Membrane (MF or UF) pretreatment of RO desalinations plants is now a viable options for removing suspended solids, fine particles, colloids, and organic compounds (Banat & Jwaied, 2008; Singh, 2006). NF pretreatment of sweater is also being used to soften RO feed water instead of traditional softening (Schafer et al., 2005). The industrial development of new membrane processes, such as membrane distillation (MD), is now being observed (Banat & Jwaied, 2008; Gryta, 2007). In MD process feed water is heated to increase its vapour pressure, which generates the difference between the partial

Brackish water is a potential fresh water resource with lower salt content than seawater. Desalination of brackish water is an important option to alleviate the prevalent water crisis around the world. As a membrane technology ranging between UF and RO, NF can achieve the partial desalination via size exclusion and charge exclusion. So, it has been widely concerned and applied in treatment of brackish water during the past several decades. Hereon, an overview of the progress in research on and application of NF technology for brackish water treatment is provided. On the basis of expounding the features of brackish water, the factors affecting NF efficiency, including the feed water characteristics, operating conditions and NF membrane properties, are analyzed. For the ubiquitous membrane fouling problem, three preventive fouling control strategies including feed water pretreatment, optimization of operating conditions and selection of anti-fouling membranes are summarized. In addition, membrane cleaning methods for restoring the fouled membrane are discussed. Furthermore, the combined utilization of NF with other membrane technologies is reviewed. Finally, future research prospects are proposed to deal with the current existing problems. Lessons gained from this review are expected to promote the sustainable development of brackish water treatment with NF technology.

Desalination and disinfection of inland brackish ground water in a capacitive deionization cell using nanoporous activated carbon cloth electrodes

Desalination of seawater and brackish water with reverse osmosis and the disc tube module DT

This article deals with the desalination of seawater and brackish water, which can deal with the problem of water scarcity that threatens certain countries in the world; it is now possible to meet the demand for drinking water. Currently, among the various desalination processes, the reverse osmosis technique is the most used. Electrical energy consumption is the most attractive factor in the cost of operating seawater by reverse osmosis in desalination plants. Desalination of water by solar energy can be considered as a very important drinking water alternative. For determining the electrical energy consumption of a single reverse osmosis module, we used the System Advisor Model (SAM) to determine the technical characteristics and costs of a parabolic cylindrical installation and Reverse Osmosis System Analysis (ROSA) to obtain the electrical power of a single reverse osmosis module. The electrical power of a single module is 4101 KW; this is consistent with the manufacturer's data that this power must be between 3900 kW and 4300 KW. Thus, the energy consumption of the system is 4.92 KWh/m3.Thermal power produced by the solar cylindro-parabolic field during the month of May has the maximum that is 208MWth, and the minimum value during the month of April, which equals 6 MWth. Electrical power produced by the plant varied between 47MWe, and 23.8MWe. The maximum energy was generated during the month of July (1900 MWh) with the maximum energy stored (118 MWh).

Prospects of baromembrane desalination of brackish waters of the south of Ukraine

Analysis of desalination alternates for phosphoric acid plant in Tunisia

In Morocco, water resources are increasingly under threat due to population growth, economic expansion, and climate change. Among the proposed solutions, brackish water desalination using membrane technologies such as nanofiltration (NF) and reverse osmosis (RO) with low‐pressure membranes presents a promising alternative. This study evaluated the impact of salinity on the performance of two nanofiltration membranes (NF270 and NF90) and one reverse osmosis membrane (TM710) using three semisynthetic brackish water samples with salinities of 2, 4, and 6 g L−1. Ion transfer mechanisms, particularly for sodium (Na+) and chloride (Cl−), were analyzed using the Spiegler–Kedem (SK) and Kedem–Katchalsky (KK) mathematical models. Additionally, the effects of salinity on diffusion flux (Jdiff), convection‐induced concentration (Cconv), reflection coefficient (σ), and solute permeability (Ps) were examined. Results indicate that the NF270 membrane exhibits the highest permeate flux, while NF90 and TM710 perform similarly. For all three membranes, permeate flux decreases almost linearly as feed water salinity increases. Regarding total dissolved solids (TDS) rejection, the TM710 membrane achieves the highest removal efficiency, followed by NF90 and then NF270. The NF270 membrane shows greater convective transport than NF90, with both diffusive and convective fluxes increasing with salinity. In contrast, the TM710 membrane operates primarily through diffusion, with TDS having little effect on its diffusion flux. NF90 and TM710 exhibit similar σ and Ps values for sodium and chloride ions, independent of TDS, highlighting the NF90's similarity to a reverse osmosis membrane. In contrast, for NF270, the sodium reflection coefficient (σ) increases with TDS, while solute permeability (Ps) rises for both ions due to a decline in retention efficiency.