proposal for alternative energy applications in the field of desalination

Session 3662

Proposal for Alternative Energy Applications in the Field of Desalination

Saeed D Foroudastan PhD Professor Jared Odom Research Assistant Olivia Dees Research Assistant

Engineering Technology and Industrial Studies Department

Middle Tennessee State University Abstract Many parts of the world are currently suffering from such an intense deficiency in ground and surface water that this life sustaining treasure often makes the ldquoblack goldrdquo of oil resources look unimportant by comparison Whether it is from overuse neglect or lack of sufficient resource development and management demands for potable water continue to grow Water is a crucial factor in the Israeli-Palestinian peace negotiations and itrsquos also extensively addressed in Israelrsquos treaty with Jordan Political problems throughout the Middle East Europe Africa Asia and even North and South America hinge upon this resource and in the coming decades it is conceivable that wars might be fought over water in much the same way they were fought over oil during the 20th century Many countries are currently pursuing a range of desalination procedures in order to cope with this shortage Such procedures may utilize evaporative processes that require inputs of heat to aid in separation of potable water from water sources that have high total dissolved solid concentrations This external heat source can be a costly process and desalination processes are sometimes coupled with power generation plants to increase efficiency by using waste heat from electric generation to aid in the process of water separation Similarly power generation plants are sometimes coupled with solid waste incineration or more recently solar magnification processes in order to use the heat of combustion or intensified solar radiation to create steam for driving the power generation equipment With this interconnection between generation processes the positive results of incorporating waste incineration andor other renewable resources with desalination for environmental protection as well as energy efficiency is worthy of investigation Engineering education is ideal for this facilitation By educating future engineers with this important environmental topic class discussions will provide the initiative for creating projects outside the classroom with industrial collaboration for alternative solutions of this increasingly problematic global condition

Proceedings of the 2005 American Society for Engineering Education Annual Conference amp Exposition Copyright copy 2005 American Society for Engineering Education

Introduction Water is essential to all life The very biochemistry that sustains life requires the input of it and many areas of the earth suffer from deficiency of this resource The oceans account for approximately 974 of the worlds water Another 2 is locked up in ice caps and glaciers Subtracting saline ground water and inland saline seas from the remainder less than 05 of the Earths water is directly suitable for human consumption agricultural or industrial uses 1 The earth is a closed biosphere and all the water that we have is all that we are going to get Overuse pollution and geologic scarcity are the major contributors to the need for it In the United States Ron Linsky of the National Water Research Institute in California realizes this and is quoted as saying ldquoThe country needs to improve the reliability of its supply and suggests that water could be on the commodities market in the next century We may ultimately face rationing or importingrdquo 2 This is the feeling in the western United States and many areas of the world such as those in developing countries or those located in arid regions which have a much more urgent need of usable water Areas located in close proximity to large bodies of salt or brackish water have had to resort to desalination of this seemingly unusable water The process of desalination contains many sub-methods of attaining potable water These sub-methods vary widely in their technologies with many cases being site-specific in application Even though desalination is used extensively it is more expensive than conventional methods of distributing potable or industrially usable water In comparison to the costs of most water sources developed and treated in industrialized countries by more conventional means desalinated water may be from 2 to 50 times more expensive 3 This illustrates an all too real fact that if finite supplies continue to dwindle due to a variety of reasons water will become very expensive and will have an economic and environmental influence on a global scale Insight and research into incorporations of new energy efficient technologies is worthy of investigation This water resource problem will approach epidemic proportions if it is not addressed in a timely manner Water resource education needs to be started immediately in all regions of the world This is not a field specific area for many areas of academia need informing A multidisciplinary approach should be taken involving the disciplines of engineering chemistry biology environmental science economics and many many others At Middle Tennessee State University a Pollution Control Technology class is offered to introduce important new technologies such as desalination Its importance makes it a popular topic now to be incorporated into future semestersrsquo discussion and projects for extracurricular application toward world-wide alternative solutions By teaching the problems and offering ideas for improvement to impressionable minds there will be continual hope for future generations Overview of desalination methods Several variations exist in desalination practices These can be broken up into two categories The first is phase change processes which include multiple stage flash vapor compression solar and multiple-effect distillation The second being non-phase change processes include reverse osmosis and electro dialysis


bull Multiple stage flash desalination utilizes heat transfer and evaporation for separation

purposes Each stage has a seawater condenser a brine flash chamber a demister distillate collecting and a transfer system The process begins in the stage where brine feed water enters the first stage in the system The heat supplied by the stage causes initial condensation of feed water to a collection apparatus This salt water is then transferred into a succession of stages where this continues After passing through the nth

stage the feed water reaches the brine heater where it is heated by steam Entering through the bottom it then flows back through the series of stages of lower ambient pressure where it violently flashes into vapor to be collected with the aid of demisters When the process completes its cycle the distillate is collected and distributed to users The worldrsquos distillation capacity is dominated by MSF plants which continue to be widely used as part of dual-purpose systems using waste steam as the primary source of energy 3

bull Multiple effect desalination is a process that begins in the first effect by spraying the feed

water to be treated over steam-heated exchanger material Distillate vapour is collected and flows through the second effect while brackish waste is also pumped to the second effect to flow over the exiting distillate and create additional vapour for the next effect of succeeding lower pressure in the continuing process This is carried out without the additional input of heat because of the pressure drop in succeeding stages Most horizontal tube MED plants operate at low first-effect temperatures (60-65degC) to limit scale formation The performance ratio of MED can be raised considerably by means of thermal or mechanical vapour recompression (TVC or MVC) Vapour formed in the lowest temperature effect is recompressed and introduced to the first effect MVC plants have the lowest energy consumption of any distillation process 3

bull Vapour compression desalination also utilizes the principal of reducing the boiling point

by reducing the pressure Vapour heat energy is gained by means of the thermodynamics of vapour compression This process is unique to other evaporative processes because no outside heat input is needed only mechanical energy is required

bull Electrodialysis is a process that utilizes electro chemistry to separate dissolved solids

from water Feed water is pumped in and desalinated by means of filtration and electrostatic potential difference between electrodes The positive electrode attracts the anions while the negative electrode attracts the cations of the dissolved salts Electrodialysis systems consist of ldquostacksrdquo which contain partitions of membranes between electrodes to separate dilute and concentrated solutions Though more complex than reverse osmosis only standard lower pressure pumps is required and the associated piping and valves need not be stainless steel Stacks can be disassembled hand-cleaned and reassembled which though time and labour intensive may be preferred to purchasing new units as often required in reverse osmosis Reversal also almost eliminates the need for chemicals Also when comparing electrodialysis to reverse osmosis the Central Salt and marine Chemicals Research Institute of India has found that electrodialysis has the edge over RO being the lowest energy-consuming technique for waters of salinity between 1500 and 4000 ppm 3


bull Reverse osmosis desalination uses a semi-permeable membrane to filter out dissolved

solids from pure water Before water enters the membranes it is usually pretreated and extensively dosed to minimize the amount of problem causing materials When the water is sufficiently treated it flows to the high-pressure pump which supplies water to the membranes for filtration Flow rate can be affected by the pressure applied to the feed side of the membrane by high-pressure pumps as well as increased temperatures While this increased flow increases output careful monitoring of the expensive membranes show that extreme applications of these conditions compacts membranes and decreases efficiency As with other desalination processes production time is to be monitored as to ensure proper maintenance is conducted A major influence on reverse osmosis water production is the cost of the membranes and optimum conditions should be utilized to maximize operating life

bull Solar desalination is probably the least used method of desalination Three methods of

utilizing the suns rays include humidification distillation and photovoltaic 3 Solar humidification is the oldest method used dating back to ancient civilizations It imitates the natural hydrologic cycle by using the suns energy to vaporize pure water from a shallow body to be condensed on a cooler and collected for consumption The distillation application is not widely used It utilizes the sun to heat the feed water to be used in the high temperature end of a standard thermal desalination process 3 Photovoltaic applications convert the sunsrsquo energy into electrical energy for smaller scale standard desalination processes This photovoltaic use is quite convenient in remote areas of application

Causes for desalination practices Generally speaking water urgency may arise in several ways but can be summarized in three sources overuse neglect or lack of sufficient resource development and management These are the three summary methods to be discussed in this paper Where pollution is concerned desalination may prove less practical than remediation in certain geologic provinces but the idea presented entails the possible use of desalination if wide scale pollution were to emerge The principal of desalination could be used to separate potable water from pollutants The need for water would still be the same whether it is a result from any of the three sources We as humans are very good at neglecting our biosphere by means of poor environmental practices Every year pollutants contaminate millions of gallons of surface and ground water These can come from a variety of sources including industry small and large agriculture and the common resident Incidences of water pollution are all too common and many times have devastating consequences In Dickson County Tennessee USA a recent occurrence involved ground water pollution involving trichloroethylene (TCE) a common industrial solvent This suspected carcinogen and mutagen was found in elevated levels in several wells near the county landfill A local manufacturing plant was linked by manifesto to the chemical pollutant and is currently being sued by several residents because it additionally disposed of TCE on four private sites in close proximity to the landfill Ray and Cathy Flake is one couple involved in the litigation and say that after saving for 15 years and liquidating many of their assets to buy their


4

expand its water lines to 100 homes This is a similar vehicle to desalination in that it served as a remedy to potable water deficiency but what would be the remedy if the municipal supply were contaminated

5

Disposal of solid waste is an ever-present dilemma that needs to be dealt with There are currently 53 operating landfills in Wyoming USA Groundwater pollution has so far been detected at 19 of these facilities This startling statistic aroused the attention of the Wyoming Department Environmental Quality (WDEQ) landfill operators managers consultants and many in the regulated community Notably none of the landfills with groundwater pollution were constructed with engineered containment systems (liners) 6 These environmental impacts are only one cause of water shortage Another is overuse of water resources Extreme ground water usage or ldquominingrdquo can have devastating effects Labeled as a lack of sufficient resource development and management it can yield land subsidence This is an initially unnoticed slow phenomenon that results in elevation drop of the land due to compaction of water-depleted geologic materials The eastern plain in north Chinas Hebei Province has a long record of groundwater over-exploitation Now it finds itself home to the worlds largest acreage of subsidence Geological experts estimate that the water table has dropped 40 to 60 meters in the eastern plane resulting in elevation drops ranging from 200 mm to over 2 meters and encompasses 43915 square km 7 This problem of land subsidence is not site specific in that worldwide documentation is noted The Mojave Desert in California USA has documented elevation changes by global positioning system (GPS) indicating that about 600 millimeters (2 feet) [plus or minus 1500 millimeters (5 feet)] of subsidence occurred at certain test sites in the desert 8 Also just east in Houston Texas USA ground water overuse has caused subsidence as well 9 When occurring in heavily developed areas financial implications can be devastating Structural damage to buildings roadways and utilities would entail astronomical costs of repair and re-design Overuse of water resources is easier to accomplish in some areas of the world than others Arid regions tend to have the most urgent need for humanly usable water because of geologic and climatic factors Morocco has a problem of uneven precipitation distribution While some northern regions get up to 2000 mm of rainfall a year some southern regions do not get more than 40 mm a year being fifty times less 10 As a country initiatives have to be taken to supplement the southern regions with needed water Dams have been built to aid in this but without additional water sources the water deficit will keep growing even if more dams are built in the future since they alone will not mobilize more water per capita Indeed the volume of water that can be mobilized per capita under normal climatic conditions has in recent years already reached its maximum 10 In 1975 Morocco instituted its first desalination plant to manage its water shortage problem and currently has eight in operation 10 Just to the north in Israel water poses a serious problem Israels water policy takes into consideration the need to share limited existing water resources with its neighbors Currently it is supplying water to the Jordanians and the Palestinians Unfortunately since the 1960s their fresh water has been exploited to its utmost The regions water supply depends on fluctuations in


rainfall which is in short supply The countries in the region also suffer from lack of storage capacity to regulate the water supply and to bridge over drought and dry cycles 11 Barriers associated with desalination

It is a fact of humanity that there is no man made operation that is completely without flaw The art of desalination is no exception There are many barriers and challenges associated with this practice in a scope of great variety

Whether it is sea or brackish water total dissolved solid counts are high with influent to plants being around 35000 ppm and mainly consisting of inorganic salts Seawater is a solution of salts of nearly constant composition dissolved in variable amounts of water There are gt70 elements dissolved in seawater but only 6 make up gt99 of all the dissolved salts all occur as ions - electrically charged atoms or groups of atoms

Chloride (Cl) 5504 wt Sodium (Na) 3061 wt

Sulphate (SO4) 768 wt Magnesium (Mg) 369 wt

Calcium (Ca) 116 wt Potassium (K) 110 wt

Source 12

Oceanographers use salinity -- the amount (in grams) of total dissolved salts present in 1 kilogram of water -- to express the salt content of seawater Normal seawater has a salinity of 35 gramskilogram (or liter) of water -- also expressed as 35 Seawater from Wormly in southern England is used as the international standard for seawater composition

As well as major elements there are many trace elements in seawater - eg manganese (Mn) lead (Pb) gold (Au) iron (Fe) and iodine (I) Most occur in parts per million (ppm) or parts per billion (ppb) concentrations They are important to some biochemical reactions both from positive and negative (toxicity) viewpoints 12

Apart from toxicity these dissolved salts can have negative aspects pertaining to desalination plants in the form of salt scale formation within equipment Many of the dissolved minerals will contribute to scale formation but one worthy of mention is gypsum (CaSO4) which begins to leave solution when water approaches about 95 degrees C (203 degrees F) This material forms a hard scale that coats any tubes or containers present The scale creates thermal and mechanical problems and once formed is difficult to remove One way to avoid the formation of this scale is to keep the temperature and boiling point of the water below that of a 95 degrees C temperature 13 Unfortunately heat intensive desalination methods are not the only processes to suffer from scale formation for processes that utilize membranes are subject to invasion as well

Even though these simple salts can cause complex expensive problems influent inorganic salts arenrsquot the only culprits in water chemistry for desalination The effluent can have very high TDS concentrations which are denser than normal seawater making them able to sink to the bottom Those solids can be toxic to marine organisms In the 1990rsquos Florida USA had a problem with major ion toxicity killing small shrimp Major ion toxicity pertains to unnatural concentrations of salts in the effluent water This phenomenon was caused by failure in the Environmental


Protection Agency guidelines for toxicity of effluent The plant was allowed to continue production however on the basis that the phenomenon was discovered after the EPA guidelines were written 2 Thermal pollution and turbidity at discharge can also be problems Effluent waters can run about 10deg to 15deg F (ie 5deg to8deg C) above feed water temperatures may or may not be a potential concern depending on the organisms near the point of concentrate discharge 14 However temperature can be detrimental to sensitive organisms near the discharge point for the increased temperature of a liquid decreases the solubility of dissolved gases Oxygen which is vital to most marine life is not exempt from this chemical mechanism Other challenges involved are aqueous metal ions from plant structure contact and the sheer corrosiveness of saline water Effluent-dissolved metal ions can accumulate in sediment near discharge areas and be taken in by benthic organisms resulting in transfer to higher trophic levels within the vast food web of marine environments Corrosiveness which is the main source of these metal ions is a very costly and labor-intensive factor in the desalination process and could cause plant downtime if serious enough Proposals for alternative energy incorporations Whether they are membrane mechanical or distillation processes desalination practices require massive amounts of energy The power needed to produce 1000 gallons of desalinated water is 22kWh for RO 38 kWh for MVC 8 kWh for thermo compression and MED and 16 kWh for MSF 15 Most of the utilized energy currently comes from a vast array of conventional sources but there exists many alternatives worthy of investigation Innovations are currently being taken to optimize energy requirements for desalination practices One example is the coupling of desalination processes to electrical power generation plants in order to use waste steam as heat Similarly power generation plants are sometimes coupled with solid waste incineration processes in order to use the heat of combustion to create steam for driving the generation equipment With this mutual correlation between the mentioned processes it is permissible to investigate the positive aspects of incorporating waste incineration or other heat generating renewable resources with desalination processes for environmental and efficiency purposes Solid waste Solid waste is a virtually unavoidable problem in all societies The way in which this renewable resource is dealt is key to sustainable development Table-1 indicates that in the year 2001 the United States generated 2292 million tons of solid waste with 336 million tons being incinerated and 1276 million tons being sent to the landfill 16 This land-filled waste is kinetic energy that municipalities could squander away if itrsquos untapped The majority of landfills are located in rural areas with close proximity to urban areas These landfills are site-specific also for they must satisfy certain requirements such as soil and geologic specificity Trafficking of this solid form of potential energy creates excess traffic noise pollution air pollution and various other related environmental and economical costs In


addition to these aspects of land-filling waste there is the idea of the ldquonot in my back yardrdquo principal The vast majority of people strongly oppose waste disposal sites within reasonable distances of their homes

Source 16

Table-1 Municipal Solid Waste Management 1960 to 2001 (million tons)

Management

Method

1960 1970 1980 1990 1995 1999 2000 2001

Generation 881 1211 1516 2052 2137 2314 2320 2292

Recycling 56 80 145 290 462 508 512 514

Composting --- --- --- 42 96 147 165 166

Incineration 270 251 137 319 355 340 337 336

Landfilling 555 879 1234 1401 1224 1318 1306 1276

Having a higher population density the urban areas are responsible for a greater contribution to the amount of waste generated The urban incineration of solid waste may short cut some of these disturbances and keep most of the solid waste nearer to its point of origin Many concerns cloud the issue of solid waste incineration Emissions of particulate ash dioxins and furans are causes of apprehension to many citizens in proximity to incinerators The truth is that emissions from landfills are far worse and more significant to the environment and to mankind than are the emissions from modern incinerators (even prior to the CAAA of 1992) The emissions from the trucking required to get the solid waste to distant landfills are far worse than the emissions from modern incinerators One old truth about incinerators is that the trucks waiting to unload are putting out more and worse pollution than the incinerator does in burning the trash all day long 17 New technologies also exist to drastically limit incinerator emissions In an effort to meet US EPA maximum achievable control technology regulations a major chemical plant upgraded its incineration process with state-of-the-art technology that increased burning efficiency to 999 18 Incorporation and education of this clean incinerator technology could alleviate citizen concerns about local waste incinerators With the introduction of this efficient incineration method it seems only logical to utilize this renewable form of energy in the process of desalination This in fact has been theoretically modeled in a limited number of situations One example involves two separate resort hotels in Sharm El Sheikh Egypt that hypothetically used the incineration of their solid waste to desalinate water from the surrounding Red Sea In each case thermo vapor compression distillation was the technology of choice because of the advantage of direct thermal coupling with the waste thermal treatment unit 19 The conclusions drawn from the study suggest that more than enough fresh water could be supplied by means of using only their solid waste for input energy


If a single resort hotel is capable of producing enough solid waste to fuel a desalination process it can be assumed that large municipalities would be more than capable of meeting this requirement as well Four tonnes of municipal solid waste contains as much energy as one tonne of coal 20 This fact illustrates that municipal solid waste could alleviate emissions associated with fossil fuel burning Geothermal and natural heat transfer Geothermal energy can be described as heat energy taken directly from the natural earth This process of withdrawing natural heat from the earth is currently being used in many areas of the earth with applications ranging from heating residencies to producing electricity Several different temperature ranges are available in this earthen setting so only certain locations have the capability to expel enough heat to be used to produce electricity or be used for water separation The most promising areas for geothermaldesalination purposes are areas located at or near to subterranean plate boundaries Evidence of potential plate activity could be geysers hot springs or volcanoes in close range These geologic phenomena are indicators of the nearness of molten magma to the surface and thus mark an excellent source of heat energy to be used by either heat exchanger or direct flash into steam The one area of the earth with the highest density of seismic activity is the ring of fire that ridges the Pacific Ocean Southeast Asia western North America and Central and South America are all captured by this ring and thus have the potential for geothermal energy production Presently the main utilization of this process is by electricity production However future inquiry may prove to be environmentally and economically beneficial especially in the situation of binary cycle systems Binary cycle systems is a term used to loosely describe the process when water is not hot enough to flash into steam but is hot enough to heat a more volatile fluid into pressurized vapor This has been done naturally in the case of using the ocean naturersquos largest heat sink as a heat source The vastness of the ocean allows for extensive stratification and permits it to have a natural heat exchanger medium In the tropics the warm surface water around 80degF and cooler deeper ocean water is near 40degF This is an excellent set up for a natural heat exchanger One example which incorporates these principals utilizes a refrigerant called propylene This refrigerant boils at low temperatures (67 degrees F) under pressure of 150 psi 21 The warmer water is pumped near the volatile propylene which causes it to flash into high-pressure vapor where it is then used to drive turbines for electrical generation The cooler water is then used to condense the propylene back into liquid where the cycle begins once more An additional application of this process could be to use the mechanical energy to drive pumps in the desalination process or even use the generated electricity for the water plant An additional advantage to this process is that fresh water is produced as a by-product or if desirable the cycle can be designed to produce only fresh water 21 This could be in addition to the fresh water produced from desalination Solar applications Our nearest star and sustainer of most all biological life is the sun This is the sole supplier of energy to earth and it gives freely at no charge Many mechanisms exist to employ these


quantum packets of energy in work for humans and once the harnessing device is installed the energy source is free The field of active solar design has met many of the same hurdles as its predecessors in the area of emerging technology Investors and users alike do not want to be the first to try a new function of technology without proven numbers and results Fortunately there have been advancements in the field of active solar design incorporated into large-scale operations such as power generation and also over the past ten years decreases in capital cost have been 50 and further decrease is expected to reach 25 over the next ten years 22 Also according to an analysis of the World Bank generation costs compare favorably with those for a number of hydro power schemes in developing countries 22 This green power could propose a new vision in the field of desalination Solar energy is at optimum capability for harvest in the plusmn 40deg latitude areas Africa Australia China India the Mediterranean region the Middle East the southwestern United States and Central and South America 22 These areas of the earth also have a common thread in that they at one place or another utilize methods of desalination With new designs of instruments capable of harnessing massive amounts of solar energy such as those employed in solar electricity generation a possible connection of technology is feasible in the field of desalination

bull Parabolic trough collectors This design incorporates the principal of a reflective parabola that concentrates the sunrsquos rays onto a central receiver tube located in the focal line of the system heating the fluid flowing in the tube which is then transported through pipes to a steam turbine generator The troughs are normally designed to track the sun along one axis predominantly north-south This technology may be used to provide process heat or to drive chemical reactions but is currently best known for its applications in providing electrical power These parabolic troughs are assembled in collector fields and are currently responsible for all commercially produced solar thermal power with a total installed capacity of more than 350 MWe in California representing over 90 of the worlds installed solar capacity 23

bull Solar dishes A dish concentrates solar energy onto a receiver at its focal point The

receiver absorbs the energy and converts it into thermal energy This can be used directly as heat or can support chemical processes but its most common application is in power generation The thermal energy can either be transported to a central generator for conversion or it can be converted directly into electricity at a local generator coupled to the receiver Dishes track the sun on two axes and thus are the most efficient collector systems because they are always pointing at the sun Concentration ratios usually range from 600 to 2000 and they can achieve temperatures in excess of 1500degC 24

bull Power tower systems In power tower systems heliostats reflect and concentrate sunlight

onto a central tower-mounted receiver where the energy is transferred to a heat transfer fluid This is then passed optionally to storage and finally to power-conversion systems which convert the thermal energy into electricity and supply it to the grid Power tower plants are defined by the options chosen for a heat transfer fluid the thermal storage medium and the power-conversion cycle The heat transfer fluid may be watersteam


molten nitrate salt liquid metals or air Thermal storage may be provided by phase- changing materials or ceramic bricks Steam-Rankine power conversion systems are used with the possible alternative of open-cycle Brayton power-conversion systems Power tower systems usually achieve concentration ratios of 300 to 1500 can operate at temperatures from 550degC up to 1500degC and are quite large - generally 10 MWe or more 25

bull Thermal hydraulic engines These thermal engines work on the principal of

thermodynamics Working fluid is heated with hot water (190degF) in the heat exchanger causing it to expand and push a piston out of a cylinder At the same time this piston is expanding a common rod is compressing hydraulic fluid in an adjacent piston and cylinder As it compresses the hydraulic fluid it passes through a hydraulic motor which in turn rotates a shaft that operates a pump electric generator or other device Cold water placed in the heat exchanger causes the working fluid to contract readying the piston for another stroke 26 This technology could prove useful in the fields of solar or geothermal energy because the process is not heat source specific and any form of heat is capable of heating the working fluid These systems are also capable of being retrofitted onto existing systems giving them an added advantage A schematic of the overall system is given below

Source 26

bull Rapid spray evaporation This category of technology is not an energy source for

desalination but it is equally important because it deals with the effluent water pollution problem In RSE contaminated water is ejected at high velocities through specialized injector-nozzles which creates water droplets The salt water changes from liquid to vapor within milliseconds of ejection As the solution evaporates the solids contained in the solution are flashed out or separated leaving pure water vapour that subsequently condenses and is collected without the solids previously dissolved and suspended in the solution The formerly-dissolved solids precipitate out as a dry product that can subsequently be mined for valuable minerals and chemicals or reused depending on the application 27 This method of desalination is very important in that it virtually eliminates


waste brine into usable salts for applications ranging from agriculture to industry if so chosen A five-million gpd facility generates 700 tons of salt which at US$ 44 per ton is worth US$ 30000 per day 27 If existing desalination processes were retrofitted with this process in the effluent side of operation great steps could be made in a more environmentally-friendly direction Economics is a driving force in industry investors and users alike want to see efficiency The possible recovery and recycling of a toxic waste product not only has environmentally-positive implications but also has financial gain

Engineering applications The skills taught throughout the field of engineering cover an expansive ground It is in this arena that new technologies like desalination can be adopted and applied toward solutions of environmental degradation The balance of dwindling water resources and our ever-growing population can be maintained through a collaboration of efforts exhibited by individuals of today and tomorrow Students of engineering can find prospects with this technology due to its multidisciplinary approach whereby interests in other subjects such as chemistry and geology can attain new measures of accomplishment Besides the classroom an understanding global community to share ideas on this increasingly problematic issue can solve more than if only discussed in one region For this reason among others the ASEE conference is extremely powerful as a tool for future development By being first introduced into the classroom through individual research and then by becoming part of recurring semestersrsquo topics desalination is just one example of many which will spur the progress of alternative solutions Projects outside of class pertaining to these will help engineering students become aware of growing problems Engineering and engineering technology fundamentals may become suited for constantly changing global conditions by focusing on the trends that may be noted more readily through this applied research Environmentally-friendly alternatives can then also be incorporated for industry use with the collaboration of industrial help for the tasks This is a beneficial situation for the industries as well to learn of ongoing research to improve their products so its international use can help solve a world-wide problem Students represent the bulk of progressive potential so it is up to the teachers and all those involved in the educational process to ensure that the very best opportunities are shown to them Conclusion With less than 05 of the earths water being directly suitable for human consumption agricultural or industrial uses 1 alternative methods of obtaining functional water have been sought using desalination Although this process of desalination is becoming increasingly efficient and is necessary in some parts of the globe there is still room for improvement The broad technology in the field of desalination results in site-specific procedures depending on a variety of factors Some areas may benefit more by using membrane processes while others may benefit better from evaporative methods Alternative methods of obtaining energy such as waste incineration or active solar design should be surveyed and will more than likely soon become necessary in our world of dwindling resources In addition to saving resources alternative energy will also reduce the emissions of pollutants An eclectic approach must be taken to resolve our


environmental problems and insight from many fields of academia is needed in order to have viable research and reasoning of problems associated with desalination Water is a precious resource that is in limited amount and we are to be good stewards of what we have been given Abuse and overpopulation can attribute to water problems having biotic and economic percussions that could limit the applications of sustainable development If future generations are to exist education of existing environmental problems needs to be addressed to impressionable minds as early as possible so that research and development from a professional standpoint can be continually encouraged By remaining on the cutting edge of technology curriculum taught to international engineering and engineering technology students will inspire new venues of progress while sharpening skills learned in the classroom Only when we realize a problem and act on it will there be solutions and education is key Future engineers and subsequently the world in which we live will benefit from educations greatly enriched by innovative applied research projects with alternative solutions such as desalination Bibliography (1) httpwwwncseonlineorgnlecrsreportswaterh2o34cfmampCFID=16807254ampCFTOKEN=93151298(2) Bates Lincoln ldquoWater issues prompt new look at desalinationrdquo The American City amp County Pittsfield Oct

1995 Vol 110(11) 32-41 (3) httpwwwcommonwealthknowledgenetDesalntnbinfdsalhtm(4)httpnlnewsbankcomnlsearchweArchivess_site=tennesseanampf_site=tennesseanampf_sitename=Nashville 20Tennesseanampp_theme=gannettampp_action=searchampp_field_base-0=ampp_text_base0=pollution20from 20landfillampSearch=Searchampp_perpage=10ampp_maxdocs=200ampp_queryname=700amps_search_type=keywordampp_product=NTNBampp_sort=_rank_3ADampp_field_date-0=YMD_dateampp_params_date0=date3AB2CEampp_text_ date-0=-(5) httpwwwnewschannel5comcontentnews5046aspq=waste+landfill+incineration(6) httpdeqstatewyusshwdN_SWGuidelines204asp(7) httpwwwchinadailycomcnendoc2004-0125content_300932htm(8) httppubserusgsgovpubswriwri034015(9) Meyer William B Corbley Kevin P ldquoHarris County Texas Combines Ground Survey with LiDAR to Create

New Flood Mapsrdquo Professional Surveyor Magazine July 2004 Vol 24(7) (10) httpwwwmedrcorgomwatermarkwatermark23Noheader_article1html(11) httpwwwjewishvirtuallibraryorgjsourceHistorydesalhtml(12) httpwwwusaskcageologyclassesgeol206geol206rr2html(13) httpwwwservecomdamienhomesolarwebdesalthermalhtml(14) httpwwwwwsprinceto`neducgi-binbyteservprl~otadisk219888842884207PDF (15) Parkinson Gerald with Crabb Charlene and Kamiya Takeshi Chemical Engineering New York March

1999 Vol 106(3) 32 (16) httpwastecisproductionsnetwebmoduleswebarticlesanmvieweraspa=459ampz=44 (17) httpwwwenvironmentalengineeringnetEnvFactsphp (18) Strzelecki Diane Pollution Engineering Troy May 2001 Vol 33 (4) 40-42 (19) M Abdel-Rahman A Connolly P Costen D Dajnak FC Lockwood ldquoApplication of the lsquowaste to waterrsquo

concept to Sharm El Sheikh through a CFD simulationrdquo 2002 Desalination 152 125-132 (20) D Dajnak FC Lockwood ldquoUse of thermal energy from waste for seawater desalinationrdquo Desalination 130

(2000)137-146 (21) httpwwwseasolarpowercomotechtml (22) httpwwwsolarpacesorgeconomicsoverviewhtml


(23) httpwwwsolarpacesorgtechnologytroughhtml (24) httpwwwsolarpacesorgtechnologydishhtml (25) httpwwwsolarpacesorgtechnologytowerhtml (26) httpwwwdelugeinccompage10html (27) httpwwwaquasonicscomtechhtml Biography DR SAEED FOROUDASTAN Saeed Foroudastan is a Professor in the Engineering Technology and Industrial Studies Department He received his BS in Civil Engineering (1980) his MS in Civil Engineering (1982) and his PhD in Mechanical Engineering (1987) from Tennessee Technological University Professor Foroudastans employment vitae includes Instructor of Mechanical Engineering for Tennessee Technological University Assistant Professor of Mechanical Engineering for Tennessee Technological University Senior Engineer Advanced Development Department Textron Aerostructures and Middle Tennessee State University Professor Foroudastan is involved with several professional organizations and honor societies and has many publications to his name He also holds US and European patents


Abstract

Introduction

Overview of desalination methods

Causes for desalination practices

Barriers associated with desalination

Proposals for alternative energy incorporations

Introduction Water is essential to all life The very biochemistry that sustains life requires the input of it and many areas of the earth suffer from deficiency of this resource The oceans account for approximately 974 of the worlds water Another 2 is locked up in ice caps and glaciers Subtracting saline ground water and inland saline seas from the remainder less than 05 of the Earths water is directly suitable for human consumption agricultural or industrial uses 1 The earth is a closed biosphere and all the water that we have is all that we are going to get Overuse pollution and geologic scarcity are the major contributors to the need for it In the United States Ron Linsky of the National Water Research Institute in California realizes this and is quoted as saying ldquoThe country needs to improve the reliability of its supply and suggests that water could be on the commodities market in the next century We may ultimately face rationing or importingrdquo 2 This is the feeling in the western United States and many areas of the world such as those in developing countries or those located in arid regions which have a much more urgent need of usable water Areas located in close proximity to large bodies of salt or brackish water have had to resort to desalination of this seemingly unusable water The process of desalination contains many sub-methods of attaining potable water These sub-methods vary widely in their technologies with many cases being site-specific in application Even though desalination is used extensively it is more expensive than conventional methods of distributing potable or industrially usable water In comparison to the costs of most water sources developed and treated in industrialized countries by more conventional means desalinated water may be from 2 to 50 times more expensive 3 This illustrates an all too real fact that if finite supplies continue to dwindle due to a variety of reasons water will become very expensive and will have an economic and environmental influence on a global scale Insight and research into incorporations of new energy efficient technologies is worthy of investigation This water resource problem will approach epidemic proportions if it is not addressed in a timely manner Water resource education needs to be started immediately in all regions of the world This is not a field specific area for many areas of academia need informing A multidisciplinary approach should be taken involving the disciplines of engineering chemistry biology environmental science economics and many many others At Middle Tennessee State University a Pollution Control Technology class is offered to introduce important new technologies such as desalination Its importance makes it a popular topic now to be incorporated into future semestersrsquo discussion and projects for extracurricular application toward world-wide alternative solutions By teaching the problems and offering ideas for improvement to impressionable minds there will be continual hope for future generations Overview of desalination methods Several variations exist in desalination practices These can be broken up into two categories The first is phase change processes which include multiple stage flash vapor compression solar and multiple-effect distillation The second being non-phase change processes include reverse osmosis and electro dialysis


















4


5









Source 12









Source 16


Management

Method

1960 1970 1980 1990 1995 1999 2000 2001

Generation 881 1211 1516 2052 2137 2314 2320 2292

Recycling 56 80 145 290 462 508 512 514

Composting --- --- --- 42 96 147 165 166

Incineration 270 251 137 319 355 340 337 336

Landfilling 555 879 1234 1401 1224 1318 1306 1276















Source 26
















Abstract

Introduction





















4


5









Source 12









Source 16


Management

Method

1960 1970 1980 1990 1995 1999 2000 2001

Generation 881 1211 1516 2052 2137 2314 2320 2292

Recycling 56 80 145 290 462 508 512 514

Composting --- --- --- 42 96 147 165 166

Incineration 270 251 137 319 355 340 337 336

Landfilling 555 879 1234 1401 1224 1318 1306 1276















Source 26
















Abstract

Introduction











Source 12









Source 16


Management

Method

1960 1970 1980 1990 1995 1999 2000 2001

Generation 881 1211 1516 2052 2137 2314 2320 2292

Recycling 56 80 145 290 462 508 512 514

Composting --- --- --- 42 96 147 165 166

Incineration 270 251 137 319 355 340 337 336

Landfilling 555 879 1234 1401 1224 1318 1306 1276















Source 26
















Abstract

Introduction








Source 16


Management

Method

1960 1970 1980 1990 1995 1999 2000 2001

Generation 881 1211 1516 2052 2137 2314 2320 2292

Recycling 56 80 145 290 462 508 512 514

Composting --- --- --- 42 96 147 165 166

Incineration 270 251 137 319 355 340 337 336

Landfilling 555 879 1234 1401 1224 1318 1306 1276















Source 26
















Abstract

Introduction

















Source 26
















Abstract

Introduction

















Abstract

Introduction





proposal for alternative energy applications in the field of desalination

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