Brackish Water Desalination Plants Research Articles

A design method of the RO system in reverse osmosis brackish water desalination plants (calculations and simulations)

This paper proposes a simple design method of the RO system in RO brackish water desalination plants. This method is based on the application of maximum available recovery without scaling of any of the compounds present in the water as silica, calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, and calcium fluoride, and membrane manufacturer design guidelines, and the plant production. It is a continuation of the paper “A design method of the RO system in reverse osmosis brackish water desalination plants (procedure)” presented at the conference on Membranes in Drinking and Industrial Water Production, Leeuwarden, The Netherlands, 10–12 September 2012. Although the method was originally conceived for application to subterranean brackish waters in the Canary Islands, Spain (principally Gran Canaria, Fuerteventura and Tenerife), it can be extrapolated to other types of region and water treatable with RO systems. The required input data are the chemical composition of the feed water, pH, temperature, SDI, membrane manufacturer design guidelines, and the plant production. The programmed method determines the design of the RO system (arrangement) and the operating pressure so as the quality of the product water for different operating years and different types of the RO elements. The method whose procedure is described graphically and analytically can be used as an aid in design optimization of RO brackish water desalination plants with acid-free pre-treatment processes and by the use of scale inhibitor using spiral wound membranes. Practical applications are presented. Calculations and simulations for different types of feed water and capacities are showed. A comparison between the values obtained by this method and from membranes manufacturer software is shown so as the comparison between these and the real values from different desalination plants.

Evaluation of the first nine years operating data of a RO brackish water desalination plant in Las Palmas, Canary Islands, Spain

The RO brackish water desalination plant described in this paper has been operating from June 2004 without using acid in the pretreatment and only using antiscalants during 75.000 h with the same RO elements. The present research describes the graphical evolution of the operating information of the first nine years. A study of the normalization and standardization of the information about the nine years of evolution of the plant for fixed feedwater conditions, operating pressure, and system recovery are also shown, so that the performance evaluation of the plant can be indicated correctly. From these results it has been deduced the compaction and fouling factor values, and the average ionic permeability coefficients of the RO membrane utilized. Likewise, this paper describes the graphic evolution of the brine Langelier saturation index and Stiff and Davis stability index (actual and theoric values). The conclusions of this study and the operating experience are intended to get a practical and optimum design of RO brackish water desalination plants without using acid in the pretreatment and having a reasonable operating life between 9 and 10 years.

Evaluation of the first seven years operating data of a RO brackish water desalination plant in Las Palmas, Canary Islands, Spain

The present research describes the graphical evolution of the operating information of the first seven years. A study of the normalization and standardization of the information about the seven years of evolution of the plant for fixed feedwater conditions, operating pressure, and system recovery are also shown, so that the performance evaluation of the plan can be indicated correctly. From these results, it has been deduced that the compaction and fouling factor values and the average ionic permeability coefficients of the reverse osmosis (RO) membrane were utilized. Likewise, this paper describes the graphic evolution of the brine Langelier saturation index and Stiff and Davis stability index (actual and theoric values). The conclusions of this work and the operating experience are intended to get a practical and optimum design of RO brackish water desalination plants without using acid in the pretreatment and having a reasonable operating life between 7 and 8 years.

Energy recovery consideration in brackish water desalination

In brackish water RO desalination, the low feed water TDS and relatively low brine flow make the use of energy recovery devices ambiguous. The decision to implement energy recovery device must always be based on the Life Cycle Cost estimation of the plant. Design considerations concerning the energy recovery device selection and field experience in Lahat brackish water desalination plant (40,000m3/day) are presented in this article.Two types of energy recovery device are generally considered in the brackish water RO desalination, turbocharger and isobaric energy recovery devices. Taking into consideration the simplicity of the turbocharger, it was selected for the 1st phase of the Lahat brackish water desalination plant with the design recovery range of 80%–88%. The turbocharger was designed for max recovery and external bypass line was added to operate the plant at low recoveries. For such wide recovery range the turbocharger entire efficiency range of 30%–40% was achieved.Due to the limitation of the turbocharger to operate efficiently at the broad recovery range and Life Cycle Cost benefits of isobaric energy recovery device, the isobaric energy recovery device was selected for the 2nd phase of the Lahat brackish water desalination plant.

Evaluation of the five years operating data of a RO brackish water desalination plant in Las Palmas, Canary Islands, Spain: a historic case

The reverse osmosis (RO) brackish water desalination plant described in this article has been operating without acid in the pretreatment and only using two types of antiscalants (this was the first experience of 40,000 operating hours in Canaries). This work describes the graphical evolution of all the daily operating information of the first five years. A study of the normalization and standardization of the information about the five years of the evolution of the plant for fixed feedwater conditions, operating pressure, and system recovery is shown too, so that the performance evaluation of the plant can be indicated correctly. Likewise, this article describes the graphic evolution of thse brine Langelier saturation index (real and theoric values). The conclusions of this study and the operating experience are intended to get a practical and optimum design method of RO brackish water desalination plants.

A design method of the RO system in reverse osmosis brackish water desalination plants (procedure)

This study proposes a simple design method of the Reverse osmosis (RO) system in RO brackish water desalination plants. This method is based on the application of maximum available recovery without scaling of any of the compounds present in the water as silica, calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, and calcium fluoride, and membrane manufacturer design guidelines, and the plant production. Although the method was originally conceived for application to subterranean brackish waters in the Canary Islands, Spain (principally Gran Canaria, Fuerteventura and Tenerife), it can be extrapolated to other types of region and water treatable with RO systems. The required input data are the chemical composition of the feed water, pH, temperature, silt density index membrane manufacturer design guidelines, and the plant production. The programmed method then determines the design of the RO system. The method whose procedure is described graphically and analytically can be used as an aid in design optimization of RO brackish water desalination plants with acid-free pretreatment processes and only the use of scale inhibitor using spiral wound membranes. Practical applications are presented. The final results for different types of feed water and capacities are showed.

Large-scale brackish water desalination plants in Gaza Strip: assessments and improvements

Water scarcity is a serious challenge in the Gaza Strip, a region that is mostly considered to be semi-arid. In this region, the population's options for provision of potable water are limited to desalination of saline groundwater. Six large brackish water desalination plants (BWDPs) and one seawater desalination plant are operating and providing drinking water along with small private plants. The BWDPs were assessed in terms of operational conditions and quality of their feed and permeate with the aim of estimating essential improvements required as well as performance significance. All these plants are reverse osmosis plants and their operational conditions are similar in terms of production, recovery rate, and energy consumption. The quality of the plants’ feed was found not to comply with WHO and Palestinian Standards in most cases, unlike the permeate from all plants. The assessment made through this study assists in better understanding of the current situation of the large-scale desalination plants in Gaza and recommending essential improvements needed to increase water production of these plants without increasing abstraction and feed quantities. In addition, multi-criteria analysis used to evaluate BWDPs performance may assist in prioritizing improvements application.

Assessment of large scale brackish water desalination plants in the Gaza Strip

Desalination practice presented by desalination plants' performance is an attractive area in which researchers investigate and contribute to both plant improvement and desalination research and development fields. Six large BWDPs and one SW desalination plant are operating in Gaza and providing 4% of the total water demand of the Gaza population. Most of the drinking water is produced through small private plants and RO housing units. The six BWDPs were investigated and assessed in terms of operational conditions and feed and permeate quality towards estimating the essential improvements required and their performance significance. The quality of plant feed was found to be noncompliant with WHO and Palestinian Standards Institute in most cases which is in contrast with the permeate of all plants. The assessment made through this study assists in the better understanding of the current situation of these plants in Gaza and recommending the essential improvements needed to increase their water production without increasing abstraction. In addition, the multi criteria analysis used to evaluate BWDP performance may assist in prioritizing the application of improvements.

Estimation of the maximum conversion level in reverse osmosis brackish water desalination plants

This paper proposes a simple calculation method to estimate the maximum conversion level in reverse osmosis (RO) brackish water desalination plants. The method is based on the scaling potential of different compounds found in the water to be treated. These compounds include silica, calcium carbonate, calcium sulphate, barium sulphate, strontium sulphate and calcium fluoride. Although the method was originally conceived for application to subterranean brackish waters in the Canary Islands, Spain (principally Gran Canaria, Fuerteventura and Tenerife), it can be extrapolated to other types of region and water treatable with RO systems. The required input data are the chemical composition of the feed water and its pH and temperature. The programmed method then determines the maximum conversion level of the RO system without the risk of scaling of any of the solutes present in the water. The method can be used as an aid in design optimization of RO brackish water desalination plants with acid-free pre-treatment processes and only the use of scale inhibitors.

Thin film composite reverse osmosis membrane development and scale up at CSMCRI, Bhavnagar

Thin film composite (TFC) reverse osmosis membrane containing polyamide active layer on porous polysulfone support was developed at the scale of 1 m width × 100 m long in a batch using semi-automated mechanical casting and coating machines. The polysulfone support was made according to phase inversion method at the rate of 3−6 m/min., and the polyamide active layer on the polysulfone support was prepared by interfacial polymerization method at the rate of 0.3−0.5 m/min under different conditions. Since desalination of brackish water does not require the membrane with very high salt rejection efficiency, emphasis was placed on increase in the flux while maintaining the salt rejection at 94 ± 2%. The membrane preparation conditions and structure−performance relationships were correlated by different techniques like porometry, infrared spectra, scanning electron microscopy and atomic force microscopy. The TFC membranes exhibited 94−96% salt rejection with water flux of 50−65 L/m 2.h when tested with 5000−1500 ppm salt solution at 250 psi. Surface modification of the TFC membrane with polymers containing hydrophilic groups was carried out to impart fouling resistance. Spiral modules of 4040 and 8040 size were made and tested them extensively in the field conditions in 500−2000 LPH brackish and sea water desalination plants.

Hybrid system of nanofiltration, reverse osmosis and evaporation to treat the brine of inland desalination plants

This work is focused on the brine management of brackish water from desalination plants placed in inland areas. In inland areas the aquifers and other water resources present problems of pollu¬tion caused mainly by agricultural activities. In these areas, desalination plants are normally used to produce drinking-water from brackish water. However, the management of the concentrates generated by these plants is a big challenge due to the environmental problems of their disposal in the environment. One possible solution is the combination of membrane processes with low-cost evaporation technologies. This paper presents a theoretical analysis and preliminary experimen¬tal results for an innovative system to manage brines of desalination plants. The system treats sequentially the brine coming from a brackish water desalination plant in a nanofiltration stage (NF) and a natural evaporation process with absorbent surfaces. An osmosis stage (RO) treats the permeate from the NF stage. This hybrid system allows ob...

Adsorptive removal of nitrilotris(methylenephosphonic acid) antiscalant from membrane concentrates by iron-coated waste filtration sand

Iron-coated waste filtration sand was investigated as a low-cost adsorbent for the removal of nitrilotris(methylenephosphonic acid) (NTMP) from membrane concentrates. The adsorption of this phosphonate-based antiscalant on this material was measured and compared with two commercially available anion exchange resins and activated carbon. Comprehensive adsorption experiments were conducted in several synthetic concentrate solutions and in a concentrate collected from a full scale nano-filtration brackish water desalination plant. The effect of pH, ionic strength and the presence of competitive anions on the equilibrium adsorption were investigated. The results showed that, in contrast to the anion exchange resins, the adsorption on coated filtration sand is not suppressed at increasing ionic strength and is much less affected by the competitive anions carbonate and sulphate. The adsorption decreased slightly when the pH was raised from 7.0 to 8.0. The adsorption isotherms in the real nano-filtration concentrate, measured in the concentration interval of 5–50 mg dm −1 NTMP, showed that the maximum adsorption capacity of coated filtration sand was 4.06 mg g −1. The adsorption capacity per unit mass of the adsorbents at low NTMP concentration (12.5 mg dm −3) followed the decreasing order Amberlite IRA-410 > coated filtration sand > Amberlite IRA-900 > Norit SAE Super. This demonstrates that the use of iron-coated waste filtration sand offers a promising means for the removal of NTMP from membrane concentrates.

Performance evaluation of reverse osmosis desalination plant: A case study of Wadi Ma'in, Zara and Mujib Plant

Reverse osmosis (RO) desalination systems are being increasingly used in the world as an efficient, reliable and cost-effective technology. It is widely used for the production of municipal and industrial grade water treating seawater and brackish water. For instance, RO desalination has been widely and successfully used in Middle Eastern oil-producing countries. However, utilization of membrane plants has been spread throughout every region of the world as a viable economic alternative to traditional water treatment. To date, desalination of either seawater or brackish water in Jordan has been limited. In the case of seawater, Jordan has a very short shoreline on the Gulf of Aqaba and this is very distant from the main centers of population. This is further aggravated by the fact that these centers of population are at high elevations (Amman 1000 m above the mean sea level) and would therefore involve high pumping costs. Jordan does have reserves of brackish water, and a small number of brackish water desalination plants have been built. The Wadi Ma'in, Zara and Mujib desalination plant was officially inaugurated on the 18th of November 2007, the water production started on the 22nd of August 2006. Desalination is carried out using the reverse osmosis techniques. This is a Design-Build-Operate contract. The plant includes desalination of 55 MCM per year of water with a salinity of 1500–2000 mg/l. It shall provide Amman with 38 MCM per year with a TDS of 250 mg/l. This paper describes the performance evaluation of this plant so as to bring out the state of the art of its operation and maintenance. Detailed information on the plant design and engineering, water quality, plant personnel, and cost of operation and maintenance will be collected since commissioning of the plant. The performance of the plant is characterized according to the main parameters: quantity of water produced and quality of water.

Water supply development for a new 17.5 MGD (66,200 m3/d) brackish-water RO facility for the City of Hialeah, Florida

Freshwater supply limitations in Southeast Florida have caused a change in the water supply strategy for the next 30 years. As a result of the move away from the use of fresh groundwater, a 17.5 MGD (66,200 m3/d) brackish-water desalination plant is under design for the City of Hialeah, Florida. Feedwater for this facility will be developed from the upper part of the Floridan Aquifer System at depths ranging from 1,080 to 1,480 ft (329–451 m) below surface. The initial water quality is mildly brackish with a total dissolved solids concentration (TDS) of about 2,300 mg/l. The anticipated volume of raw water required to operate the RO plant will be about 23.3 MGD (88,200 m3/d). The raw water will be obtained from 12 primary production wells and two backup capacity wells. A critical design issue for any RO plant is the maintenance of feedwater quality over the operating life-cycle of the facility. The wellfield water quality is anticipated to change in time because of the upward leakage of greater salinity w...

Upgrading and capacity extension of old brackish water desalination plants

In some cases upgrading and extension of old BWRO plants is far more economic in comparison with the development of new plants. This is especially true at sites where expenses related to the infrastructure are high and increase the cost of new installations. Another aspect is technological - usually the operation in the old systems requires excessive energy due to the old generation membranes that are installed that should anyhow be upgraded to reduce the energy cost. The concept will be demonstrated by describing the upgrading and extension of a 17-year old 10,000 m3/day BWRO system operating in Eilat. The system desalts a source of 6,000 ppm brackish water with high content of calcium-sulphate at 63% product recovery. The redesign of this plant comprises replacement of the 12-year old RO membranes by a set of new high permeability membranes and addition of a second desalination stage. As a result, the capacity increased to 18,000 m3/day at 80% recovery and the specific energy consumption has been reduced from 1.0 kWh to about 0.80 kWh at full capacity operation, and to less than 0.65 kWh, when operating at a partial load of 12,000 m3/day. Due to the existing infrastructure and the increase of the recovery, the required investment in the extension and the old membranes replacement has been relatively low and the pay back time is of less than 4 years.

Market for sea-water desalination plants set for high growth

A technical market research report now available from BCC Research Co of Wellesley, Massachusetts, USA, predicts that the market worldwide for sea-water and brackish water desalination plants is set to grow substantially over the next four years.

Characteristics of RO foulants in a brackish water desalination plant

This study identified the membrane fouling of a two-stage RO process of the Bai-sha brackish water desalination plant facing serious fouling problems. Two membrane modules, one from each stage, were autopsied and diagnosed for the cause for the failure of the RO system. Different morphologies were exhibited on the fouled membrane. Results suggested that the fouling on the first-stage membrane tended to be organic and biological, while that on the second-stage membrane appeared to be scaling. Higher than 85% of the foulants on the first stage membrane were organic substances in opposed to the 5 to 8% of those on the second stage membrane. However, the total organic matter on the second stage membrane was more than that on the first stage one. The thick layer of scalants on the surface of the second-stage membrane was identified to be calcium carbonate of which the crystal was clearly seen in the SEM images. The scaling was thickest at the outlet of the membrane. Huge amount of microbes were found on both membranes. The FTIR results also suggested the existence of extracellular polymeric substance (EPS) on the first stage membrane. This study recommended that the recovery rate, pH and the potential for bio-fouling should be defined at the real operation.

The optimal allocating pumping rate of a multi-well system for a brackish water desalination plant

I applied perspectives on operations research (OR) to propose a non-linear mathematical model, termed the APWs (allocation of pumping wells) model, to address problems associated with allocating pumping rates of a multi-well system for a brackish water reverse osmosis (BWRO) plant. In some arid and inshore regions, feed water mostly preferred to exploit groundwater, owing to its easier desalted characteristic than seawater. However, the operations of most multi-well systems are always arbitrary, and we could not guarantee the strategies of operation might be optimal; additionally, the pumping quantity and quality variation of each well would all induce the unstable quality of feed water, and then lead to the problem of scaling. Though adding acid could treat the problem of scaling, the acidification, on the other hand, means the increasing cost and damage risk of a reverse osmosis (RO) system. Therefore, the overriding objective of this study is to decide the optimal allocating pumping rate among wells for a RO system on the premise of no acid added and under finite groundwater resources, to ensure feed water has no scaling potential and achieve marginal usage of groundwater resources. The APWs model tries to integrate engineering and management aspects to replace subjective operation of a multi-well system. Here, I apply scaling intensity (SI) proposed by literature that considered calcium carbonate (CaCO 3), calcium sulfate (CaSO 4) and silica (SiO 2) as mainly potential scaling compounds in feed water to assess the scaling potential of a RO system. Besides, I present a solving algorithm for achieving the maximal SI with no scaling occurred. Moreover, I apply the proposed model to a case study in Taiwan by considering four-well system, to obtain optimal allocation with retaining the cleanest residual storage of whole groundwater resources, to avoid the waste of water resources. The results shown that through the assistance of OR technique, it could provide helpful information indeed in RO feed water management. In a word, the APWs model proposed in this paper not only could provide referenced guidelines for all RO operators all over the world, but also allow engineers to gain new insights into their field by integrating different disciplines.

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Disposal of brackish water concentrate into depleted oil and gas fields: a texas study

Disposal of concentrate from brackish water desalination plants by deep well injection into oil and gas fields is an attractive option in Texas. Underpressured depleted oil and gas reservoirs cover large areas of the state. Six areas were selected from across Texas for detailed analysis. These sites were characterized by abundant brackish groundwater, a projected shortage of freshwater, depleted oil and gas fields, and shallow injection wells. Information was collected on formation mineralogy, pressure history, geochemical attributes and flow parameters. Numerical modeling using SOLMINEQ, combined with a statistical approach, was used to assess the results of mixing desalination concentrate with formation water. Issues addressed include injection pressures required, the impact of down-hole conditions on mineral precipitation, and mobilisation of formation fines and clays. Numerical modeling found no technical problems outside the range commonly dealt with by the oil and gas industry. In addition, historically, most of the fields have received considerable volume of fresh and/or brackish waters. From a technological standpoint, injection of desalination concentrates into depleted oil or gas fields using existing wells is a highly feasible alternative. A brief look at the economics also suggests that this opportunity is highly advantageous.