Desalination Of Brackish Groundwater Research Articles

Scaling behavior of Si in capacitive deionization (CDI) systems for brackish groundwater desalination

Capacitive deionization (CDI) is a potentially cost-effective method of desalinating brackish groundwaters though the technology has not yet been widely utilised for this particular application. Silicon (Si) is a common element in groundwaters which may cause problems due to its tendency to induce severe fouling of equipment used for water treatment. In this study we focus on the impacts of the presence of Si on the performance of CDI. A systematic evaluation procedure is proposed, which is used to distinguish the “dynamic” and residual Si scaling and the impacts of these types of fouling on desalination performance. Results show that Si has minimal influence on CDI performance within low concentration ranges (<0.5 mM). Sorption of deprotonated silicic acid species is largely avoided in CDI, which contributes to sustaining the removal of major ions and stable operation of the system. However, at high concentrations of Si (>2.0 mM), scaling was observed to form on the electrode surface, leading to noticeable deterioration in CDI electrode performance. The presence of ion exchange membrane in CDI (i.e., membrane CDI or MCDI) can significantly alleviate Si scaling of the desalination system. Results of this study clearly demonstrate the scaling behavior of CDI and its derivatives when dealing with Si-laden water matrices, providing insights into the design and maintenance of CDI systems in practical applications.

Flexible batch electrodialysis for low-cost solar-powered brackish water desalination

Globally, 1.6 billion people in rural regions face water scarcity. Expanding freshwater access via brackish groundwater desalination can provide additional resources to address this challenge. In this study, we have developed a time-variant electrodialysis reversal (EDR) technology that flexibly uses available solar energy for desalination. Our proposed photovoltaic-powered desalination system can vary pumping and EDR power to match the availability of intermittent solar power, maximizing the desalination rate. Our results show improved system performance with the direct use of 77% of available solar energy—91% more than in conventional systems—and a 92% reduction in battery reliance. In a village-scale desalination case study in India, these system improvements lead to a 22% reduction in water cost, making the technology competitive with the currently used on-grid, village-scale reverse osmosis systems that are mainly powered by fossil fuels. Future advances could further reduce costs, providing an improved, sustainable solution to water scarcity in remote areas.

Brackish groundwater desalination by constant current membrane capacitive deionization (MCDI): Results of a long-term field trial in Central Australia

A long-term field trial of membrane capacitive deionization (MCDI) was conducted in a remote community in the Northern Territory of Australia, with the aim of producing safe palatable drinking water from groundwater that contains high concentrations of salt and hardness ions and other contaminants. This trial lasted for 1.5 years, which, to our knowledge, is one of the longest reported studies of pilot-scale MCDI field trials. The 8-module MCDI pilot unit reduced salt concentration to below the Australian Drinking Water Guideline value of 600 mg/L total dissolved solids (TDS) concentration with a relatively high water recovery of 71.6 ± 8.7 %. During continuous constant current operation and electrode discharging at near zero volts, a rapid performance deterioration occurred that was primarily attributed to insufficient desorption of multivalent ions from the porous carbon electrodes. Performance could be temporarily recovered using chemical cleaning and modified operating procedures however these approaches could not fundamentally resolve the issue of insufficient electrode performance regeneration. Constant current discharging of the electrodes to a negative cell cut-off voltage was hence employed to enhance the stability and overall performance of the MCDI unit during the continuous operation. An increase in selectivity of monovalent ions over divalent ions was also attained by implementing negative voltage discharging. The energy consumption of an MCDI system with a capacity of 1000 m3/day was projected to be 0.40∼0.53 kWh/m3, which is comparable to the energy consumption of electrodialysis reversal (EDR) and brackish water reverse osmosis (BWRO) systems of the same capacity. The relatively low maintenance requirements of the MCDI system rendered it the most cost-efficient water treatment technology for deployment in remote locations. The LCOW of an MCDI system with a capacity of 1000 m3/day was projected to be AU$1.059/m3 and AU$1.146/m3 under two operational modes, respectively. Further investigation of particular water-energy trade-offs amongst MCDI performance metrics is required to facilitate broader application of this promising water treatment technology.

Environmental and Economic Assessment of Membrane Capacitive Deionization (MCDI) and Low-Pressure Reverse Osmosis (LPRO) for Sustainable Irrigation in the Mediterranean Region

Ensuring the sustainability of a product or a system requires a thorough evaluation of its environmental and socioeconomic impacts. In this context, one of the objectives of the EU-PRIMA SmaCuMed project is to evaluate the socioeconomic and environmental impacts of the Smart Cube system. The Smart Cube was developed for the PV-powered desalination of brackish groundwater with membrane capacitive deionization (MCDI) and low-pressure reverse osmosis (LPRO); it additionally uses smart sensors for controlled irrigation in remote agricultural areas in Morocco, as an example for the North African region. Based on the Life Cycle Sustainability Assessment approach, this paper aims to assess the environmental and economic impacts of the Smart Cube, using Life Cycle Costing (LCC) and Life Cycle Assessment (LCA) analyses for environmental evaluation. Various scenarios have been defined for both environmental and economic assessments. Based on 1 m3 of produced desalinated water, the LCC results showed that, when using the desalination technologies directly connected to the grid, the prices are lower than those obtained when it was supplied by the PV system. This is only due to the very low energy prices from the Moroccan grid (EUR 0.10/kWh). The LCC results showed that LPRO is a more cost-effective option for producing desalinated water, with a lower total cost compared to MCDI. However, LCA results indicated that LPRO has a higher environmental impact compared to MCDI. If higher water production capacity is a priority, MCDI connected to PV is the best choice, with lower carbon emission but higher overall water costs.

Desalination by batch reverse osmosis (RO) of brackish groundwater containing sparingly soluble salts

Batch RO desalination is a new approach to high-recovery, energy-efficient desalination. So far, however, batch RO has been tested mostly with pure sodium chloride solutions. An important application of batch RO is desalination of brackish groundwater which, besides sodium chloride, contains sparingly soluble salts. In this experimental study of a batch RO system, we used simulated groundwater (with total dissolved solids ranging from 1180 to 3637 mg/L) following compositions of samples taken from a location in Egypt and a location in India. The groundwater contained high levels of salts which could be expected to cause scaling on the RO membrane surface. For example, the Langelier Saturation Index (LSI) for calcite reached 2.6 in the brine. Nonetheless, the system resisted scaling throughout >100 h of operation. Membrane permeability remained almost unchanged, as demonstrated by tests conducted before and after the experiments. Induction time calculations showed that salinity cycling did not fully explain the scaling inhibition. Other anti-scaling mechanisms – such as periodic flushing, osmotic backwash, and feed flow reversal – were also likely contributors. At recovery of 0.8, hydraulic specific energy consumption (SEC) was <0.5 kWh/m3 and close to that obtained with sodium chloride solution at equivalent osmotic pressure.

Comparison of Pilot-Scale Capacitive Deionization (MCDI) and Low-Pressure Reverse Osmosis (LPRO) for PV-Powered Brackish Water Desalination in Morocco for Irrigation of Argan Trees.

The use of saline water resources in agriculture is becoming a common practice in semi-arid and arid regions such as the Mediterranean. In the SmaCuMed project, the desalination of brackish groundwater (TDS = 2.8 g/L) for the irrigation of Argan trees in Essaouira, Morocco, to 2 g/L and 1 g/L (33% and 66% salt removal, respectively) using low-pressure reverse osmosis (LPRO) (p < 6 bar) and membrane capacitive deionization (MCDI) was tested at pilot scale. MCDI showed 40-70% lower specific energy consumption (SEC) and 10-20% higher water recovery; however, the throughput of LPRO (2.9 m3/h) was up to 1.5 times higher than that of MCDI. In addition, both technologies were successfully powered by PV solar energy with total water costs ranging from EUR 0.82 to EUR 1.34 per m3. In addition, the water quality in terms of sodium adsorption ratio was slightly higher with LPRO resulting in higher concentrations of Ca2+ and Mg2+, due to blending with feed water. In order to evaluate both technologies, additional criteria such as investment and specific water costs, operability and brine disposal have to be considered.

Managed aquifer recharge for agriculture in Australia – History, success factors and future implementation

Managed aquifer recharge (MAR) is the intentional recharge of water to aquifers for subsequent recovery or environmental benefit. MAR can potentially increase security of water in drought more economically than new dams, can augment existing dams with higher efficiency storage (less evaporation), augment brackish groundwater desalination schemes, and facilitate conjunctive use of surface and groundwater resources. In Australia in 2023, there are currently 10 known operational MAR schemes used to increase agricultural activity in varying stages of development, providing a total capacity of ∼ 70 × 106 m3/year. A review of these Australian MAR schemes identified several general principles which are more likely to lead to successful implementation, including: an ongoing demand for water for high value agriculture; availability of water for recharge; a suitable aquifer for storage with the capacity to store water for recovery and use; a suitable location for the MAR scheme typically in areas of low topographic relief; and the organisational capability, institutional arrangements and supportive policies to operate the scheme sustainably and economically. If MAR schemes are to be developed to support agricultural activity in Australia, site identification, project design, economic viability, and community and regulator consultation within an investment prospectus will be required. Operational demonstration schemes in a variety of agricultural settings will encourage wider adoption. Supportive policy development is required to ensure sustainable and equitable ongoing operation of MAR to support irrigated agriculture and for drought resilience.

Desalination of brackish groundwater using self-regeneration hybrid ion exchange and reverse osmosis system (HSIX-RO)

The United Nations International Decade for Action on Water for Sustainable Development (2018–2028) recognized the importance of water to sustainable development and the eradication of poverty and hunger. It voiced alarm over the worsening of issues such as access to clean water, water scarcity, and wastewater as a result of increasing populations and altered climates. One of the most promising solutions to the water shortage is desalination, which can increase the available water supply beyond the currently possible limit. In this study, we analyze the performance of a unique hybrid self-regeneration ion exchange and reverse osmosis (HSIX-RO) system for the desalination of brackish groundwater. In the pretreatment step for protecting RO membrane fouling, the traditional homogenized strong acid cation exchanger (Purolite C100) and shallow shell structured strong acid cation exchanger (Purolite SSTC65) were compared for their efficiency in removing hardness cations from brackish groundwater. The fixed-bed column study concluded that C100 and SSTC65 can treat brackish water containing 250 mg L−1 Ca2+ and 10,000 mg L−1 NaCl at approximately 80 and 76 bed volumes (BVs), respectively. Studying the efficiency of RO system, it has % RO recovery of >70 % at an optimized pressure of 120 psi. An upscale self-regeneration ion exchange and RO system, i.e., HSIX-RO, that can be applied for a pilot-scale study was proposed. This proposed study suggested that HSIX-RO can be suited for the desalination of brackish groundwater with minimum use of an additional salt and can be self-sustained using an automated control. It was noted that the HSIX-RO system cannot be effectively applied to groundwater (TDS < 5000 mg L−1) nor seawater (TDS > 30,000 mg L−1) contained high Ca2+ and Mg2+ due to low regeneration efficiency and short length service runs, respectively.

Feasibility assessment of a BWRO desalination plant powered by renewable energy sources

This paper investigated the technical, economic, and environmental aspects of using six different power plant configurations powered by renewable energy sources (RES), namely photovoltaic (PV) and wind to provide electricity to operate a reverse osmosis brackish groundwater desalination plant (BWRO) with a capacity of 2 m3/hr, and load power of 6.5 kW. The BWRO plant is located at the Libyan Center for Solar Energy Research and Studies (LCSERS) in the city of Tajura. The six proposed power plants, backed-up with/out batteries and diesel generator were modeled and simulated using HOMER software. Optimal design configurations resulting from the simulation were then selected based on levelized cost of energy (LCOE) and net present cost (NPC) appropriate to the operating conditions at the site. The study showed that the Grid-Connected photovoltaic power plant (PVGC) yielded the lowest levelized cost of water (LCOW), a direct consequence of its lower cost of energy.

Floodwater harvesting within Wadi Billi, Egypt

ABSTRACT Water scarcity is a major feature in Egypt. However, events of heavy rain occur increasingly, leading to repetitive flash floods. Wadi Billi is a poorly gauged drainage basin in the Eastern Desert of Egypt and hosts El-Gouna town in the delta, which depends on the desalination of brackish groundwater as the main source of freshwater. On 9 March 2014, the wadi was exposed to a flash flood event that extended to the Red Sea causing damages to humans and infrastructure. In this paper, a system of infiltration trenches supported with a series of simple surface and subsurface dams has been designed to protect the downstream urban area and recharge the flooded water into shallow aquifers. The rainfall-runoff and sediment transport processes have been modeled using a 1D lumped hydrological model. The susceptible areas for groundwater recharge have been determined using geospatial analysis. The results show that the storm event produced 1,78 million m3 of flooded water carrying 5523 t of sediments. The streams and valleys that penetrate the downstream mountain formation have the highest potentiality for groundwater recharge. Four longitudinal infiltration trenches are needed with an average dimensions of 3,000 m × 25 m × 15 cm. In addition to 37 simple surface dams and 10 sub-surface dams with a total length of 2.7 km and 0.94 km, respectively. The spatial analysis showed almost 27.63 km is potentially suitable to extend the infiltration trenches with a width range of 25–250 m, which have a minimum capacity to recharge more than 4 million m3 for one event. By considering El-Gouna’s water demands, harvesting the flooded water for one flash flood event provides a new source of cheap and high-quality freshwater for 162–261 days. In addition to avoiding the potential damages for infrastructure and human lives.

Potential aquifer mapping for cost-effective groundwater reverse osmosis desalination in arid regions using integration of hydrochemistry, environmental isotopes and GIS techniques

In arid regions, water resources are scarce; therefore, sea and brackish groundwater desalination using reverse osmosis (RO) techniques is commonly used to provide freshwater for potable purposes. El-Moghra Oasis, a case study of an inland depression, represents an arid region in the Western Desert of Egypt. The oasis relies mainly on the brackish groundwater in El-Moghra Aquifer for salt-tolerant crop irrigation and feeding desalination plants. The RO brackish groundwater desalination conserves about 75% of the total cost compared to seawater as feed water. Accordingly, the main target of the present work is to allocate cost-effective sites for constructing desalination plants to solve freshwater shortages. The hydrogeochemical and isotopic techniques have been applied to understand the aquifer recharge mechanism and the main factors that deteriorate the groundwater quality. Additionally, an Analytical Hierarchy Process (AHP) relying on the geographic information systems (GIS) utilized to delineate the promising desalination sites. Four main criteria linked with the cost of RO groundwater desalination were investigated, including aquifer hydraulic parameters, hydrogeochemical characteristics, recharge indicators based on isotopic tracers, and other miscellaneous parameters related to the site accessibility and environmental issues. These four main criteria include fourteen sub-criteria; depth to water (DTW), aquifer saturated thickness (ST), transmissivity (T), total dissolved solids (TDS), iron (Fe), total groundwater hardness (TH), calcium sulfate (CaSO4), silica (SiO2), strontium (Sr), oxygen-18 (δ18O), global solar radiation (GSR), land slope (LS) and distance to roads (D). The final suitability map identifies the most favorable locations for constructing a desalination plant is in the northeast, which comprises 64.5% of the study area. The locations with low appropriateness are concentrated in the west and southwest and account for 35.5% of the area.

Electrothermal hollow fiber membrane for convenient heat management in Joule vacuum membrane distillation

Membrane distillation (MD) for brackish groundwater desalination is a promising approach for alleviating water shortage in rural area. Conventional MD has very low single-pass water recovery leading to high energy consumption for hydraulic circulation. Heating the feed via electrothermal membrane at the interface diminishes the energy consumption for circulation, but the heat loss to the bulk feed and ambient environment critically needs to be managed to achieve higher Joule heat efficiency. An electrothermal hollow fiber membrane was prepared and employed in Joule vacuum membrane distillation (VMD). The narrow inner space of the luminal side of the membrane controlled the amount of feed and limited the heat loss to the bulk feed. The highest Joule heat efficiency of 78.0% was achieved when 0.27 W/cm2 of power was applied. In long-term operation for brackish groundwater desalination, the fluoride was effectively rejected and the single-pass water recovery of ∼70% was achieved, which could critically decrease the energy consumption for circulation. The electrothermal hollow fiber membrane is convenient to conduct heat management in Joule VMD process.

Effective desalination of brackish groundwater using zeolitized diatomite/kaolinite geopolymer as low-cost inorganic membrane; Siwa Oasis in Egypt as a realistic case study

The salinization of the groundwater wells in Siwa oasis, Egypt represents a critical environmental and economic issue. Developing low-cost, effective, and self-supported inorganic membranes were suggested as suitable desalination techniques. Zeolite/geopolymer (Z/GP) membrane was synthesized as a potential low-cost membrane for effective desalination of brackish groundwater in Siwa Oasis, Egypt. The membrane was synthesized by simple geopolymerization for natural kaolinite and diatomite at room temperature. This was followed by hydrothermal growth of zeolite at 100 °C for 24 h to produce zeolitized geopolymer as potential inorganic membrane. After that, the prepared membrane was incorporated in the pervaporation desalination system considering the effect of the membrane thickness and the temperature. The results demonstrated water flux values of 8.34 kg.m−2.h−1, 7.63 kg.m−2.h−1, and 7.05 kg.m−2.h−1 for the tested membrane at thicknesses of 1 mm, 2 mm, and 3 mm, respectively. This associated with significant salt rejection prearranges 95.8% (1 mm), 97.6% (2 mm), and 99.4% (3 mm). Moreover, the high-temperature value (90 °C) is of strong positive impact on the water flux (7.82 kg.m−2.h−1) and a slight impact on the salt rejection (99.6%). The membrane is of significant stability considering the obtained water flux (7.51 kg.m−2.h−1) and salt rejection (99.57%) after 130 h. The reusability properties of the Z/GP membrane demonstrated its suitability to be used in the desalination process for five runs. Therefore, the synthetic Z/GP membrane is a highly recommended product for simple, effective, low cost, and available desalination technique brackish groundwater in Siwa Oasis.

Effectiveness and mechanisms of electromagnetic field on reverse osmosis membrane scaling control during brackish groundwater desalination

This study investigated the effectiveness and mechanisms of electromagnetic field (EMF) on reverse osmosis (RO) membrane scaling control during brackish groundwater desalination. Pilot-scale experiments were conducted with different types of groundwater and two configurations of RO skid operated each for 30 days and 55 days without any other pretreatment. The testing results demonstrated EMF was effective for scaling control under typical RO operating conditions. The EMF significantly enhanced the performance of the RO system by reducing membrane scaling, changing the nature of the formed scales, and decreasing the decline rate of the normalized water permeability. In addition, EMF treatment effectively removed the pre-formed scales and precipitates in water pipelines and tanks but had limited efficacy on removing the pre-formed scales on the RO membranes. Membrane autopsy showed that the scales formed on the membrane surface under the influence of EMF were soft and powdery, being easily removed by water rinsing. The mechanisms of the EMF on RO membrane were discussed, and the dominant mechanism was the magnetohydrodynamic effect. This is the first study that demonstrated the EMF as a chemical-free and effective alternative to control membrane scaling and maintain RO performance during brackish groundwater desalination with discussions on detailed mechanisms and perspectives.

Brackish groundwater and reverse osmosis concentrate influence soil physical and thermal properties and pecan evapotranspiration

AbstractThe use of brackish groundwater (BGW) to supplement irrigation shortfalls has increased because of decreasing surface water availability in the arid areas of the southern United States. Reuse of reverse osmosis (RO) concentrate, a by‐product resulting from desalination of BGW, can increase irrigation portfolio. This 2‐yr greenhouse study aimed to quantify changes in physical and thermal soil properties, and evapotranspiration (ET) rate of pecan [Carya illinoinensis (Wangenh.) K. Koch] irrigated with BGW and RO concentrate. Another objective was to predict soil thermal conductivity (K) using soil electrical conductivity (EC) and soil volumetric water content (VWC) data of 2017–2018. Three irrigation water treatments with four replications were prepared namely, control (EC = 0.8 dS m−1), BGW (EC = 4.0 dS m−1), and RO concentrate (EC = 8.0 dS m−1). Soil physical properties determined were texture, moisture content, bulk density, hydraulic conductivity, and moisture retention. Thermal properties measured were conductivity (K), diffusivity (D), resistivity (ρ), and heat capacity (C). The ET and leaching fractions (LF) were determined using water balance. Pecan irrigated with RO concentrate had the lowest ET among irrigation treatments. Soil thermal conductivities and soil water contents in BGW and RO irrigated pots were higher than the control. However, increases in heat capacity with increasing irrigation water salinity were most pronounced. The new four parameters‐based model using EC and VWC explained 96% of variability of K (average R2 = .96, RMSE = 0.096, normalized RMSE [NRMSE] = 11.14%). The sensitivity analysis showed that the contribution of VWC to K was greater than that of EC. Results indicate that continuous irrigation with RO concentrate can be done for up to 1 yr. A new irrigation scheduling protocol based on optimal LF and soil salinity is needed to sustain pecan production in southern New Mexico.

Is Small Scale Desalination Coupled with Renewable Energy a Cost-Effective Solution?

Water and energy are two of the most important inputs for a community to thrive. While water is dominant on earth, only 2.5% of the water is fresh water and over 98% of that water is either ground water or locked up in glaciers and ice caps. Therefore, only about 1.2% of all the freshwater is surface water which is able to meet human needs. About 2 billion people currently do not have sufficient access to fresh water. One of the solutions deployed in the last decades for island and coastal areas has been desalination. Desalination of seawater and brackish groundwater is commercially available and still a fast-advancing technology. The decreasing cost of renewable energy coupled with strategies based on renewables for powering populations without access to electricity and policies for complete decarbonization of the economy such as the European Green Deal make the combination of renewables and desalination a really interesting approach. This paper investigates combinations of small-scale RO desalination systems which are able to produce up to a few thousand m3 of desalinated water per day coupled with photovoltaic (PV) and wind energy systems, both in grid-connected, as well as in autonomous scenarios. The results show that RO desalination coupled with renewables can address cost-effectively the current issues in terms of water scarcity, while minimizing the environmental footprint of the process. In this paper, it has been showcased that desalination powered by renewables can be deployed in practically any location on earth having access to sea or a brackish water source. The results show that even for grid-connected systems it is more cost-effective and profitable to include a renewable energy system to power the plant, apart from the corresponding environmental benefits.

Optimization of the Forward‐Osmosis Performance with a Low‐Concentration Draw Solution Using Response Surface Modeling

AbstractForward osmosis (FO) has recently gained interest in wastewater treatment and seawater and brackish groundwater desalination. Response surface methodology (RSM) was used for the prediction and optimization of the FO process using a low‐concentration draw solution (DS). The process variables were the feed solution (FS) temperature, the DS concentration, and the FS concentration. These variables were subjected to regression models and had R2 values &gt; 0.9. The FS temperature had a negative impact on the weight transfer from the DS, while the FS and DS concentrations had a direct correlation with the performance. At an FS temperature of 29 °C, the DS at 13 986 mg L−1 and the FS at 1702 mg L−1 produced the best results, thereby lowering the DS regeneration costs. Under this condition, the models were experimentally validated, confirming the predictive ability of the models.

Climate change and water supply: governance and adaptation planning in Florida

Abstract Florida has been described as ‘ground zero’ for climate change in the United States with coastal communities vulnerable to sea-level rise and water supplies under threat from saline-water intrusion, changes in precipitation amounts and patterns, and temperature-driven increases in demands. Water utilities and regional suppliers are responsible for their own water supply plans and adaptation strategies, which are developed largely by a relatively small group of technical specialists (internal and contracted). Water supply planning is prescribed by the state water governance system and local community planning processes. The degree of engagement of large coastal communities and water utilities and regional water suppliers in Florida with climate change research is generally high. Climate change-induced impacts to water supplies and demands over the common 20-year planning horizon are likely to be small relative to increases in demand caused by projected on-going population growth and normal climatic variation. Water utilities in Florida have been incidentally moving toward more climate-resilient supplies (e.g., brackish groundwater desalination) due to the unavailability of additional permittable, inexpensive fresh groundwater rather than climate change concerns. Climate change will narrow the alternatives for future water-supply development.

Desalination of brackish water using cascade Rankine cycle based reverse osmosis system

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.

Site specific assessment of the viability of membrane Capacitive Deionization (mCDI) in desalination of brackish groundwaters for selected crop watering

Membrane Capacitive Deionization (mCDI) desalination is an emerging technology that can, potentially, be scaled to an appropriate capacity and powered by photovoltaics for farm applications where costs of electrical power provision are prohibitive. In order to assess the critical influences of location and mCDI configuration on profitability, a farm scale economic model was developed to calculate annualized profits, internal rate of return, return period and bore salinity thresholds for farm profitability with mCDI desalination for a 10-year investment period for various crops at selected locations in south eastern Australia with known groundwater quality issues. Results show that the cost of water supply including bore drilling and pumping, mCDI desalination, photovoltaics, brine disposal and water storage is less than AU$1/m3 for typical field applications with salinity removals <2.3 dS/m. We show that application of mCDI improves profitability over irrigation with brackish water of between AU$2500/ha/yr and AU$44,200/ha/yr depending on the crop. By providing a system level cost analysis, the results highlight areas where there is scope for cost improvements in both mCDI desalination and agricultural processes. The operational scale mCDI performance and sizing model presented here can be modified for use in other desalination applications.