Desalination Technology - Health & Environmental Impacts
... Scale inhibitors are then added to improve treated water quality prior to RO process. Table 4 summarises chemicals that are commonly used in the conventional pretreatment process of the source water prior to RO membrane desalination [236]. These chemicals can be categorised into coagulant/flocculant, scale inhibitor, acid, and oxidising agent. ...
... Chemicals used during pretreatment process of membrane desalination process[236]. Dose rates shown as mg of chemical/L of feed water are only indicative. b Site specific. ...
Water scarcity at global level has called for attentions to establish new and innovative technologies that can be tapped to provide sustainable solutions to water crisis. Membrane-based desalination has been acknowledged as one of the promising approaches to resolve the global challenges. Currently, different membrane-based technologies have been deployed worldwide for clean water production. However, despite the great advances made in terms of the permeate flux and rejection, the practical application of membrane for desalination is still limited by the inevitable membrane fouling issue. Membrane fouling is known to be the major culprit to the elevated operating costs due to the deterioration of permeate flux, increasing transmembrane pressure, and frequent chemical cleaning which shorten the membrane's lifespan. This review provides insights into the recent advancement in mitigating membrane desalination fouling. The fouling control strategies which encompass the efforts made in the novel membrane development, feed water pretreatment, and membrane cleaning are highlighted. The advantages and limitations of these techniques are discussed and reviewed based on a substantial number of up-to-date literatures.
... Similarly, no consideration is given to deterioration of the membrane system over time or degradation as a result of fouling. Fouling of the membrane surfaces means an additional resistance to osmotic pressure[23]. To compensate for productivity losses as a consequence of fouling, the feedwater pressure of the membrane system should be raised[23][24][25]. ...
... Fouling of the membrane surfaces means an additional resistance to osmotic pressure[23]. To compensate for productivity losses as a consequence of fouling, the feedwater pressure of the membrane system should be raised[23][24][25]. After defining the acceptable operational limit and selecting the operational strategy (for example: a) constant feed pressure and variable feed seawater flow rate, b) constant feed seawater flow rate and variable feed pressure, c) variable pressure and feed flow rate, such that the permeate recovery rate remains constant, d) variable pressure and feed flow rate, such that the brine flow rate remains constant, etc.), an estimation is made of the power required (supposing a specific efficiency which in the studies is considered constant) by the drive system (high-pressure motor pump)[13]. ...
For the purpose of managing the operation of a small-scale prototype of a sea water reverse osmosis desalination plant installed on the island of Gran Canaria (Spain) and enabling it to function with fluctuating power input, artificial neural network (ANN) models were incorporated into its control system. The ANN models were developed to generate feed flow and operating pressure setpoints (with the restriction of having to maintain the permeate recovery rate within a certain range) after taking into account not only the available electrical power but also the temperature and conductivity of the feedwater.
... The "10% increment above ambient ocean salinity" threshold is a conservative measure of aquatic life tolerance to elevated salinity. The actual salinity tolerance of most marine organisms is usually significantly higher than this level and often exceeds 40 ppt (Cotruvo et al., 2010;Hammond et al., 1998). For example, gobies, which are one of the most common species inhabiting California coastal waters, are tolerant to relatively high salinity concentrations and are well known to inhabit the Salton Sea of California, which currently has an ambient salinity of 45 ppt. ...
... The model selected to identify the boundaries of the desalination plant discharge should be used to define the concentrate plume dissipation boundaries under a variety of outfall and diffuser configurations and operational conditions. Evaluation of the concentrate dispersion and recirculation at large desalination plants usually requires a sophisticated discharge plume analysis and is completed using various computational fluid dynamics software packages tailor-made for a given application (Bleninger and Jirka, 2008;Cotruvo et al., 2010). The models most widely used in salinity plume analysis are CORMIX and Visual Plumes. ...
This work addresses overview of regulatory requirements for discharges from seawater desalination plants.
... Certain gases and salts in water make it more palatable, while an excess of certain salts may reduce water palatability and/or lead it to become toxic (Sandford, 1996). Scarcity of fresh water has been estimated to affect one in three people globally, especially in the Gulf area (Cotruvo et al., 2010), and, in environments where fresh water is scarce, desalination has been used to provide drinking-water (Qar and Abdel-Monem, 2014). ...
... Although the primary intention of the desalination process is to remove natural ionic contaminants from seawater, some substances are not as well removed as others, such as boron ions, since the process of reverse osmosis is not efficient in removing them. In addition, many chemical treatments have been used to control the desalination process to ensure that the final water does not include unacceptable concentrations of microbial pathogens and compounds (Cotruvo et al., 2010). Desalinated water should, therefore, not be considered as a source of drinking-water production (WHO, 2011). ...
The present study aimed to elucidate the abnormalities in the development of rat brains, livers, kidney and behaviours after drinking desalinated seawater prenatally. Three types of drinking water were employed as an experimental probe (bottled water, filtered desalinated seawater and tap desalinated seawater) to investigate neurobehavioral and morphological changes in the development of pup rats. Female rats from each group were administered water from their birth until gestation and lactation. The 1st and 2nd generation pups were divided into three groups: Group C, mothers and pups administered with bottled drinking water (the control group); Group F, mothers and pups administered with filtered drinking water; Group T, mothers and pups administered with unfiltered desalinated seawater (tap water). Morphological changes (CNS aberration) and neurobehavioral changes were studied. The aberrations recorded in the tissues (brain, liver, kidney and spinal cord) of rats from groups T and F may be due to oxidative stress in these tissues such as reduced glutathione, lipid peroxidation, peroxidase and super oxide dismutase. In conclusion, drinking desalinated seawater for a long time may cause teratogenic effects in the development of New-born rats.
... With population growth and exploitation of available water sources causing scarcity of safe drinking water, mainly in developing countries, public based RO plants and home based RO units are being increasingly used. RO system very effectively removes dissolved solids as well as many microorganisms making water palatable and relatively safe to use [4][5][6]. With increased use of RO processed demineralised water, many adverse health effects are also been increasing identified. ...
... Fisher's exact test was considered for cases where the expected cell frequency was less than 5. Binary Logistic regression analysis was also done to observe the final association between independent variables and vitamin B12 deficiency present or absent. is also been studied [4] and has shown possible association with various health hazards of drinking water low in these microelements [8]. Positive association between Vitamin B12 deficiency and use of RO processed drinking water found in our study suggests possibility of some similar yet unidentified mechanism responsible for development of Vitamin B12 deficiency in individuals drinking RO processed water. ...
Introduction:
Prevalence of Vitamin B12 deficiency has increased in community in recent time. Possibility is raised for new and yet unidentified factors being associated with this increased prevalence. One of these factors frequently questioned is use of Reverse Osmosis (RO) processed water for drinking.
Aim:
We aimed to study association of use of RO processed water for drinking with Vitamin B12 deficiency.
Materials and methods:
This cross-sectional study was done at tertiary care centre of Western India. Total 250 participants were recruited after excluding those participants with known factors responsible for Vitamin B12 deficiency. Information about gender, type of diet, milk intake and duration, dairy product intake, use of RO water and Vitamin B12 level was collected.
Results:
Total 70 (28%) participants out of 250 were having Vitamin B12 deficiency. Forty (50.6%) of 79 participants using RO water were Vitamin B12 deficient against 30 (17.5%) of 171 using other sources. Logistic regression analysis showed independent association between use of RO water and Vitamin B12 deficiency. Although association of male gender, milk quantity of less than 100 ml per day and duration of RO water intake with occurrence of Vitamin B12 deficiency was found statistically significant in univariate analysis, logistic regression analysis did not show significant association.
Conclusion:
Use of RO processed drinking water was associated with Vitamin B12 deficiency. This being cross- sectional study, further longitudinal studies with large sample size and taking confounding factors into consideration, are required to establish this association.
... Extensive information on desalination for safe drinking-water supply is available in the book Desalination technology: Health and environmental impacts (Cotruvo et al., 2010) and the supporting document Safe drinking-water from desalination (Annex 1). ...
... Many research studies have proved that MED plants are superior than MSF desalination plants because MED processes are characterized by having higher unit capacity, better quality of distilled water, lower production costs, and higher heat efficiency and by being simpler to be integrated with renewable energy. Reviews and studies on different renewable integrated desalination can be found in [22], concentrated solar power and desalination in [23]; environmental issues related to desalination [24]; energy efficient desalination technologies in [25] and challenges of energy recovery systems in [26]. ...
Floating desalination plants are fairly new technologies and are not as common as the traditional land-based desalination plants. Almost none of the proposed nor installed projects' designers indicates that the design is environmentally driven, and only few designs are environmentally assessed. This paper aims to highlight the significant role of the environmental practices to achieve a sustainable design, where most of the environmental impact assessment procedures are performed prior to the design phase. Throughout the research, comparing alternatives and analyzing the baseline provided reliable technical help in the tasks of selecting the proposed project's location, desalination technology, power source and platform configuration. Thus, detailed technical descriptions of different systems are presented. Finally, environmental impacts associated with the operation of the proposed floating desalination plant in the selected location are assessed to give guidance on the monitoring and mitigation processes necessary to enhance the process performance, minimize the adverse environmental impacts and ensure the project's sustainability.
... It is estimated that 40 percent shortfall in freshwater resources by 2030 with rapid population increase has the world careening towards a global water crisis (United Nations 2018). Seawater and high saline brackish water account for more than 97 percent of the earth's water, however, these water sources are either undesirable or unavailable for use without the application of technologies capable of removing large portions of the salinity and dissolved solids (Cotruvo et al. 2011;Bartram 2015). Water desalination refers to a series of processes that separate the fresh water from seawater or other water sources which are too saline for use. ...
In order to address freshwater scarcity, seawater desalination technologies have been widely studied in recent years. However, the disposal of desalination brine which contains an even higher concentration of salts than seawater can potentially damage the surrounding environment. Therefore, alternative approaches aiming to recover valuable resources from desalination brine have been conducted. Three resources that can be recovered have been studied in this paper, which are minerals, freshwater and energy. The techniques to recover minerals can be divided into pressure-driven techniques, thermal-driven techniques, electro-driven techniques and other techniques. The water recovery techniques employ mainly membrane/thermal integrated hybrid processes, while the energy recovery techniques such as pressure retarded osmosis (PRO) and reverse electrodialysis (RED) utilize the salinity gradient energy (SGE) to generate energy. The valuable mineral products have also been reviewed in this paper in terms of recovery methods, performance of processes and product quality. The reviewed products are sodium salts (NaCl, NaOH, Na2SO4), lithium salts (LiCl, Li2CO3), magnesium salts (struvite, Mg(OH)2, MgSO4, MgO), calcium salts (CaSO4, CaCO3) and other minerals (U, Rb, Cs). Based on the cost and revenues of each technique, an economic comparison has been conducted along with the cost analysis of operating desalination plants.
... This method of disposal can be useful if the brine after dilution is safe for the environment. However, this method has disadvantages such as concentration of chemicals, nutrients and salinity along with the increased temperature [17]. Another disposal method is the inland disposal methods that include Deep Well Injection, Spray irrigation and Evaporation Ponds. ...
... Water quality is very critical in influencing the operating efficiency and life of equipment, including pumps, piping systems and wells. Therefore, acidic water with a pH value of less than 6 is a usually corrosive while, alkaline water with pH greater than 8 is less corrosive [9]. ...
A study of water chemistry in some boreholes in Eket, Nigeria, was conducted to determine the calcium carbonate saturation index, in order to establish the corrosion tendency of the waters towards metal substrates in piping systems, boilers, heat exchangers and submersible pumps. Calcium carbonate saturation index using Langelier system was determined to be more negative (- 4.16 to – 5.2) below the optimum range of – 0.5 to + 0.5 for water that is in equilibrium with calcium carbonate. The water saturation pH (pHs) determined for the waters sampled in the area had values that ranged from 8.82 to 9.55, with a mean value of 9.09. The values were far above the pH values of the waters from all the locations sampled, which ranged from 4.12 to 5.34, with a mean pH of 4.48. The water chemistry was of same characteristic for all the studied locations, indicating that the waters were drawn from same regional aquifer, have same corrosive tendency and the possibility of metal substrates to be attacked by water used for both industrial and domestic purposes in the study area. The more negative the calcium carbonate saturation index, the greater the possibility of the water in its corrosive action especially in oxygenated waters. Therefore, the waters in Eket are likely to exhibit remarkable corrosive tendency against metal substrates. The implication of this finding is that in the study area, there has to be a strategic corrosion control program in piping systems and industrial equipment such as heat exchangers, boilers, domestic water heaters and submersible pumps in tackling corrosion challenges.
... However, this relative comfort in terms of water supply remains questionable in many respects, because: groundwater, due to exploitation beyond its potential, is threatened with exhaustion and subject, as they are coastal, to the phenomenon of marine intrusion; about half the volume of water allocated to the capital comes from superficial resources located in neighboring departments, which are forced to concede part of their water resources to the detriment of their own development (Chikhr Saïdi, 1997). Recurrent droughts greatly affect the contribution of these surface resources, while desalination of seawater cannot be a safe and sustainable solution as regards economical and environmental aspects (Cotruvo, 2011). ...
In Algeria and especially in Algiers the capital city, ensuring inhabitants water requirements remains a critical issue despite huge investments made by the government to secure water supply over the past years. Indeed, in the face of erratic climate conditions with recurrent drought episodes and constantly increasing water demand, due to population growth and economic activity rise, the water supply system is subject to various problems of environmental, economic, technical and managerial nature. This could ultimately affect the water supply of Algiers city. A rigorous and effective management of water resources requires analysis of elements that affect in the long run water resources carrying capacity (WRCC). This latter can be defined as the level of human activity that can be withstood by the available water resources without major degradation of aquatic environments while maintaining an adequate standard of living for the population. Water resources carrying capacity depends mainly onto two major components that are water supply capacity and inhabitants' global water demand. This study aims at proposing key indicators and related thresholds for analysing Algiers water carrying capacity in order to provide a diagnosis tool for policy makers to lay down the foundations of a sustainable water strategy in Algiers city.
... There has been much research on the environmental impacts associated with the disposal of concentrate, which range in geographic scale from local to regional to global. Potential impacts assessed are included in the life's work of Mickley [92][93][94][95][96][97][98][99][100][101][102] and others [8,[103][104][105][106][107][108][109][110][111][112][113][114][115][116][117][118][119][120][121]. The primary environmental impacts associated with discharge of SWRO concentrate include: • increases in the salinity of receiving water bodies, particularly restricted circulation bodies, • local impacts of hypersaline brines on marine benthic communities at and near the point of discharge, • discharge of chemicals used for pretreatment and membrane cleaning, • discharge of metals from corrosion (Cu, Fe, Ni, Mo, Cr), • aesthetic issues (visual impacts), • impacts to aquifers from leaks from brine pipes, • temporary damage during construction, • temporary damage during maintenance, • permanent damage from emplacement of infrastructure (pads, pipelines, etc.). ...
Seawater reverse osmosis (SWRO) desalination has some environmental impacts associated with the construction and operation of intake systems and the disposal of concentrate. The primary impact of conventional open-ocean intake systems is the impingement and entrainment of marine organisms. These impacts can be minimized by locating the intake in a geographic position where oceanic productivity is low. Velocity-cap intakes tend to reduce impacts by minimizing the number of fish entrained and some new traveling screens can allow the survival of some marine organisms. Mitigation, such as environmental restoration of habitat or restocking, can provide an acceptable solution to impacts where they are significant. Subsurface intake systems avoid impingement and entrainment impacts, but can cause other, less important impacts (e.g., visual, beach access). Concentrate disposal can locally impact benthic communities, if poorly diluted discharge is allowed to flow across the marine bottom. Impacts to benthic communities from concentrate discharges can be minimized by using properly-designed diffuser systems, designed and located based current and flow modeling.
... The nominal pore size is 0.0001-0.001 mm, so microorganisms including viruses, inorganic ions, and most organics are well removed by intact membrane systems (Cotruvo et al., 2010). Typical reverse osmosis (RO) membrane materials include thin film composite, which uses layers of polyamide and polysulfone and cellulose triacetate. ...
The chapter will address technologies and techniques that are available for home and travelers' use and will relate them to their specific capabilities for managing specific contaminants. Expected performance as well as the used conditions and restrictions and approximate costs of the technique will be described; all costs are given in the US dollars. In addition, the chapter will describe performance standards and certification systems designed to provide reliability and greater confidence for consumers and to induce manufacturers to produce treatment devices with proven performance and claims that do not mislead consumers.
... Toxicity can be caused by naturally occurring fluoride, iodide and silicate compounds, iron, boron, and arsenic, or by industrial and agricultural pollutants such as nitrates, phosphates, sulphates, heavy metals and hydrocarbons [71]. Saline groundwater typically has lower salt concentration than seawater, which can reduce desalination plant energy consumption and operational costs. ...
Over-exploited fresh water resources, fossil-fuel depletion and climate change all highlight need for desalination powered by renewable energy. This study briefly reviews literature on solar desalination technologies and examines economic and environmental feasibility. The maturest technology appears to be reverse osmosis driven by photovoltaics. Many studies refer to apparent spatial coincidences of water scarcity, solar energy abundance and saline water availability, but none examine the phenomenon objectively from a global perspective. This study proposes a method for correlating international data on water scarcity and stress, saline water resources, and insolation levels, to calculate rank scores (0 ≤ R ≤ 1) which identify where solar desalination is most applicable. Low scores (R < 0.125) occur in landlocked nations with limited saline groundwater resources (Nepal, Bolivia, South Sudan) and near polar regions where fresh water is abundant and solar insolation levels are low (Canada, Russia and Scandinavia). High scores (R > 0.422) occur in 30 nations, including Middle Eastern and North African countries where fossil fuelled desalination is commonplace, and solar desalination has obvious applicability. The analysis identifies 28 further countries (including parts of USA, China, India, Indonesia, Australia, and countries throughout Africa, Asia, South America and Europe) where 0.273 < R < 0.422 scores indicate that other, less obvious, solar desalination opportunities exist.
... This waste stream is typically 4-10 times more concentrated than the feed with respect to suspended and dissolved constituents and represents about 15-25% of the total feed flow, although it can exceed 50% or more in some cases. As a result, concentrate disposal is a significant logistical and regulatory concern for utilities and is often a critical factor in the planning and design of an RO facility (78,79). The concentrate streams from RO processes are considered "industrial waste." ...
Recent theoretical progresses in the reverse osmosis (RO) desalination process were reviewed. The long RO channel as commonly used in desalination applications was modeled as a heterogeneous system in which the permeate velocity, crossflow velocity, and salt concentration are all variables along the membrane channel. Concentration polarization and energy consumptions in such a heterogeneous RO channel were rigorously quantified and analyzed. Examples were provided for the demonstrations or illustrations of the theoretical developments.Keywords:reverse osmosis;desalination;modeling;concentration polarization;energy consumption
... As regards unconventional water sources, although large-scale desalination has at least 50 years of existence, there are still many knowledge gaps and uncertainties regarding environmental, socioeconomic, and human health impacts of this water product process (Cotruvo et al., 2011). In addition, costs of desalinated water remain relatively high, compared with those associated with groundwater and surface water withdrawals. ...
Since independence in 1962, Algiers capital of Algeria has experienced a massive influx of people from other parts of the country. The unrestrained population growth did not take long to induce serious socio-economic and urban issues. Household water supply was one of the problems that arose with acuity. Pressure on water resources was such that the supply could not meet the growing demand. In the mid 90s water shortages were a prevailing phenomenon and the situation worsened with cyclical droughts and continuous population growth. Since 2002, Algerian government has launched major infrastructure projects consisting of dams and desalination plants to expand the water supply system and consequently overcome this deficit. Over the past two years, Algiers household water supply reaches a satisfactory level ensuring 24 hours a day distribution. Nevertheless, such a policy focusing solely on offer may not be sustainable. The demand-side management should be an integral part of a water management policy for the purpose of optimal use of resources. In this paper, we will focus on the analysis of domestic water consumption related to population growth and the means implemented to meet the needs of households since independence to present day. We will then outline the limitations of the pursued supply-oriented policy. We address thereafter the determinants that influence domestic consumption and the levers aiming at reducing Algiers household water demand.
... As regards unconventional water sources, although large-scale desalination has at least 50 years of existence, there are still many knowledge gaps and uncertainties regarding environmental, socioeconomic, and human health impacts of this water product process (Cotruvo et al., 2011). In addition, costs of desalinated water remain relatively high, compared with those associated with groundwater and surface water withdrawals. ...
... As regards unconventional water sources, although large-scale desalination has at least 50 years of existence, there are still many knowledge gaps and uncertainties regarding environmental, socioeconomic, and human health impacts of this water product process (Cotruvo et al., 2011). In addition, costs of desalinated water remain relatively high, compared with those associated with groundwater and surface water withdrawals. ...
... This has led to a significant increase of Algiers water supply. Nonetheless, although large-scale desalination has at least 50 years of existence, there are still many knowledge gaps and uncertainties regarding environmental, socioeconomic, and human health impacts of this water product process (Cotruvo et al., 2011;Lattemann & Höpner, 2008). Moreover, costs of desalinated water remain relatively high, compared with those associated with groundwater and surface water withdrawals. ...
The ever‐increasing amount of batteries used in today's society has led to an increase in the demand of lithium in the last few decades. While mining resources of this element have been steadily exploited and are rapidly depleting, water resources constitute an interesting reservoir just out of reach of current technologies. Several techniques are being explored and novel materials engineered. While evaporation is very time‐consuming and has large footprints, ion sieves and supramolecular systems can be suitably tailored and even integrated into membrane and electrochemical techniques. This review gives a comprehensive overview of the available solutions to recover lithium from water resources both by passive and electrically enhanced techniques. Accordingly, this work aims to provide in a single document a rational comparison of outstanding strategies to remove lithium from aqueous sources. To this end, practical figures of merit of both main groups of techniques are provided. An absence of a common experimental protocol and the resulting variability of data and experimental methods are identified. The need for a shared methodology and a common agreement to report performance metrics are underlined.
This chapter tries to analyze the important issues in dealing with process additives (chemicals) in processing sites. The hydrocarbon processing industry, natural gas industry, and its related utilities were studied. The chemicals used in different areas of a gas plant were identified and the reason for the importance of process additive management was presented properly. The utility processing site was selected as the basis for implementing an effective management of process additives, EMPA, model, or work frame. Important parameters in the operation were identified and how they were affected by chemicals was explained. Several industrial cases and also several operation histories were explained to provide a suitable basis for describing EMPA. The approach of this chapter is the description of events in industrial cases via process analysis. In each of these cases, the impact of chemicals, and other side effects related to them on various operational parameters of the processing site, including corrosion, was investigated. A working model for EMPA was presented. The various activities in this work frame were described in detail, and other operational histories were used to better define the concept of each activity in EMPA.
Commercially available adsorption systems use conventional adsorbent materials such as silica gel and zeolite that suffer from lower hydrophilicity and high regeneration temperature of the later. To avoid these problems aluminium fumarate metal-organic framework has been used in this study as a new adsorbent material with high water uptake. This study experimentally investigates the effect of bed modules configuration (2, 4, 6, 8 modules) on specific desalinated water production (SDWP) from a fixed volume two bed adsorption system. Results showed that as the number of bed modules increases, the SDWP decreases significantly up to six modules. The further increase in the number of modules made no effect on the water production.
The degree of hardness of drinking-water is important for aesthetic acceptability by consumers and for economic and operational considerations. Many hard waters are softened for those reasons using several applicable technologies, and the mineral composition will be significantly affected. Present study deals with analysis of few physicochemical parameters of water samples from different sites of Dongargaon village, Mulshi Pimpri Chinchwad Corporation area, District Pune, Maharashtra, India was conducted for their few parameters viz. Temperature, pH , Acidity/ Alkalinity , Conductivity, Total Dissolved Solids(TDS) , Chlorine and Hardness. Acidity/ Alkalinity was tested by pH paper and pH meter also. Conductivity was measured by Conductivity meter. TDS of water sample is measured by the TDS meter. Presence of Chlorine was tested by chemical methods. Hardness of water sample is measured by titrimetric/ Volumetric method. The portability and other uses of Sewage Water of Chemistry laboratory, Bore Water, Sangavi, Bore Water from Pimpale Nilakh, River water from Dongargoan, Swimming Tank Water, Pimpale Saudagar PCMC area. It is necessary to check more parameters of waters for its portability for human being and animals. With two thirds of the earth and 39% surface covered by water and the human body consisting of 75 percent of it, it is evidently clear that water is one of the prime elements responsible for life on earth. Water circulates through the land just as it does through the human body, transporting, dissolving replenishing nutrients and organic matter, while carrying away waste material. Further in the body, it regulates the activities of fluids, tissues, cells, lymph, blood and glandular secretions.
The evaporating process is very important in the system concerned with liquid foods, seawater distillation and wastewater treatment, which is to concentrate the aqueous solution by evaporating the pure water usually at a vacuum state. In general, the liquid concentration is performed through the membrane, electro-dialysis, and evaporation; the former are separation process and the latter is the phase change process. In this study, only the thermal process was treated for evaluating the specific energy consumption by changing the operating conditions of an existing MSF (multi-stage flashing) desalination plant, which is still dominant for a large scale distillation plant. This study shows the quantitative energy saving strategy in sweater distillation process and, additionally, indicates that the performance of the multi-stage evaporating system can be increased with the elevation of a TBT (top brine temperature). The calculated results were based on the operating data of the currently installed plants and suggests the alternative to improve the performance of the MSF desalination plant, which means that the energy saving can be achieved only by changing the operating conditions of the existing MSF plants.
Globally, modifications to the landscape have drastically transformed social and ecological communities. The implication of global climate change for small islands and small island communities is especially troublesome. Socially, small islands have a limited resource base, deal with varying degrees of insularity, generally have little political power, and have limited economic opportunities. The physical attributes of small islands also increase their vulnerability to global climate change, including limited land area, limited fresh water supplies, and greater distances to resources. The focus of this research project is to document place-specific human-environmental interactions from a political ecology perspective as a means to address local concerns and possible consequences of global environmental change. The place in which these interactions are examined is the barrier island and village of Ocracoke, NC. I focus on the specific historical-geography of land and water management on Ocracoke as a means to examine relationships between local human-environmental interactions and environmental change. I provide an account of technological changes in potable water procurement and the paralleling development of island growth (i.e. people, buildings, tourism). Then, relying on interviews with island residents, I consider how advancements in local water infrastructure, specifically the installation of an additional reverse osmosis unit, are hinged on anticipated future economic development. Lastly the social dimensions of change are discussed with specific focus on the increase in housing density and overburdened septic drainage fields in relation to changing hydrologic processes with an examination of how all of these factors affect local vulnerability.
TEvaporator is key component in food, seawater distillation and waste water treatment system, which is basically to concentrate the raw liquid by evaporating the pure water under vacuum condition. The liquid concentration is performed through the membrane, electro-dialysis and evaporation. In this study, only the evaporating type was treated for evaluating the economic analysis with the various operating conditions. The results of this study showed that the performance of the OT-MSF desalination system is increased with decreasing the temperature difference between the neighboring evaporators, which means that the number of evaporators is increased, under the determined design conditions.
The core design technology for the multi-effect desalination plant using the thermo compressor (MED-TVC) was investigated by the performance test of multi effect desalination plant in this paper. The final G.O.R (gain of output ratio) of MED-TVC type desalination plant is strongly affected by the performance of thermo-vapor compressor. The present experiments for the desalinating capacity and G.O.R were obtained for the range of the motive steam pressure, 266.0, 250.0, 230.0 and 200.0 kPa. And as a practical problem, to investigate the influence of the sea water temperature to the G.O.R, the inlet steam temperature of the suction water vapor was changed in the range of K in the present experiment. Through the experiments, the maximum value of G.O.R was 8.5 at the condition of the motive steam pressure, 136.0 kPa and the minimum value of G.O.R was 8.1 at the condition of the motive steam pressure, 266.0 kPa. And it was confirmed that the range of desalination capacity was ton/day in the normal operation condition.
If reverse osmosis is to be used for pathogen removal, quality control measures are necessary.
A bench‐scale study was conducted to evaluate MS‐2 virus rejection by reverse osmosis membranes. Viruses were recovered in permeate passing through some of the membrane structures. Thus, if reverse osmosis is to be used for pathogen removal, quality control measures on reverse osmosis membrane manufacturing are necessary to ensure that the required level of removals are achieved consistently.
Professor Menachem Elimelech and his graduate researchers Robert McGinnis and Jeffrey McCutcheon have developed a new technology (forward osmosis desalination) for removing the salt from seawater. In the forward osmosis system, salt water sits on one side of the membrane and the freshwater on the opposite side is transformed into a high-concentration solution by adding NH3 and CO2. Water naturally flows from the salt water to what is now the "draw solution". The diluted draw solution is then heated to - 58°C to evaporate off the CO2 and NH3 for reuse, leaving behind freshwater. The solute separation process consumes very little energy: 1 kw-hr/1000 gal for electricity and 1200 MJ/1000 gal for heat.
A novel post-treatment approach for desalinated water, aimed at supplying a balanced concentration of alkalinity, Ca(2+), Mg(2+) and SO(4)(2-), is introduced. The process is based on replacing excess Ca(2+) ions generated in the common H(2)SO(4)-based calcite dissolution post-treatment process with Mg(2+) ions originating from seawater. In the first step, Mg(2+) ions are separated from seawater by means of a specific ion exchange resin that has high affinity toward divalent cations (Mg(2+) and Ca(2+)) and an extremely low affinity toward monovalent cations (namely Na(+) and K(+)). In the second step, the Mg(2+)-loaded resin is contacted with the effluent of the calcite dissolution reactor and Mg(2+) and Ca(2+) are exchanged. Consequently, the excess Ca(2+) concentration in the water decreases while the Mg(2+) concentration increases. The process is stopped at a predetermined Ca(2+) to Mg(2+) ratio. All water streams used in the process are internal and form a part of the desalination plant sequence, regardless of the additional ion exchange component. The proposed process allows for the supply of cheap Mg(2+) ions, while at the same time enables the application of the cheap H(2)SO(4)-based calcite dissolution process, thus resulting in higher quality water at a cost-effective price. A case study is presented in which additional cost of supplying a Mg(2+) concentration of 12mg/L using the process is estimated at $0.004/m(3) product water.
Damage to crops after irrigation with extremely pure water from the world's largest reverse-osmosis desalination plant reveals
a need for revised treatment standards.