Overview of Global Water Challenges and Solutions - ACS Publications

Chapter 1

Overview of Global Water Challenges and Solutions Downloaded by 61.183.219.2 on December 28, 2015 | http://pubs.acs.org Publication Date (Web): December 3, 2015 | doi: 10.1021/bk-2015-1206.ch001

Satinder (Sut) Ahuja* Ahuja Consulting, 1061 Rutledge Court, Calabash, North Carolina 28467 *E-mail: [email protected].

Even though Earth is a water planet, we have a very limited quantity of fresh water available to us. Increasing human population, lifestyle and activities not only place high demand on the amount of usable water, but also diminish the quality of water. This chapter discusses water availability, quality, remediation, and sustainability. It also provides a broad overview of global water challenges and solutions. The solutions may be applicable in both developing and developed countries.

Introduction Water is the most crucial material for human survival, after air. Without water, life would not be possible. To detect potential life on other planets, our space program is constantly looking for water on various planets. Here on Earth, we need to know how much water is available to us and how much of it is polluted. We need to monitor pollutants vigorously, both at point and nonpoint sources, and purify water for drinking. Water reclamation (the act or process of recovering) is an absolute necessity because we have polluted our surface water, and even groundwater in some cases, to a point that water needs to be purified for drinking (see Chapter 1 in reference 1). The limited water availability issues discussed in this chapter also dictate the need for water reclamation. Most important, we have to use water judiciously and reclaim contaminated water. We need to find ways to make water more sustainable, i.e., water sustainability is an absolute necessity (1–7). The word sustainability is made up of two words—sustain (to provide what is needed for something or someone to exist) and ability (the power or skill to do something). To achieve sustainability, we © 2015 American Chemical Society In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

must ensure that we meet our needs and avoid compromising the ability of future generations to meet their needs (8). We have to address scientific, technical, economic, and social issues (4) to attain this objective. Globally, we face many water challenges in terms of availability, quality, and sustainability. This book provides information on various global water challenges and solutions.

Downloaded by 61.183.219.2 on December 28, 2015 | http://pubs.acs.org Publication Date (Web): December 3, 2015 | doi: 10.1021/bk-2015-1206.ch001

Global Water Resources and Use Patterns The data on water consumption in the world are available from the United Nations (UN/UNESCO). Worldwide water consumption is estimated to be around 914,546 billion liters/year. Agriculture accounts for 70% of all water consumption, industrial usage accounts for 20%, and domestic usage is 10%. In highly industrialized countries, however, manufacturing consumes more than half of the available water. In Belgium, for example, industries use up to 80% of the available water. Here is some important information about the availability and quality of our worldwide water supplies: • • • • •

Freshwater comprises only 3% of the total water available to us. However, only 0.06% is easily available. More than 80 countries in the world have water shortages. According to the UN, 2.7 billion people will face a water shortage by 2025. Almost 1.2 billion people drink unclean water today. Five million to ten million people around the world are killed by waterrelated disease yearly, mostly children.

Over the last 50 years, freshwater withdrawals have tripled. The demand for freshwater is increasing by 64 billion cubic meters per year (1 cubic meter = 1,000 liters) because of the following reasons: • • • •

The world’s population is growing by roughly 80 million each year. Changes in lifestyles and eating habits in recent years require more water consumption per capita. Water demand is rapidly increasing because of accelerated energy demand. The manufacture of energy from alternate sources such as biofuels has a major impact on water demand because 1,000 to 4,000 liters of water are needed to produce just one liter of biofuel.

Nearly 85% of the world population live in the dry part of our planet. This problem is further compounded because almost 2.5 billion people do not have access to adequate sanitation, and poor sanitation affects water quality. As a result, nearly 80% of diseases in developing countries are associated with water. Global population growth projections to around 3 billion people over the next 40 years, along with changing diets, will cause an increase in food demand 2 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


by over 70% by 2050. It is estimated that water consumption will increase by about 19% by 2050. And that number will be even greater if there is no technological progress or policy intervention. One of the greatest pressures on freshwater resources is the impact of water usage for irrigation and food production. As mentioned before, agriculture accounts for approximately 70% of global freshwater withdrawals (up to 90% in some fast-growing economies). Water availability is predicted to decrease in many regions, and future global agricultural needs are growing. Water is obviously not confined to political borders. Nearly 46% of the globe’s (terrestrial) surface is covered by trans-boundary river basins. An estimated 148 states have international basins within their territory, and 21 countries lie entirely within them. There are 276 across-border river basins in the world (64 transboundary river basins in Africa, 60 in Asia, 68 in Europe, 46 in North America, and 38 in South America). Of the 276 trans-boundary river basins, 185 are shared by two countries. And 256 out of 276 are shared by 2, 3, or 4 countries (92.7%), and 20 of 276 are shared by 5 or more countries. Interestingly, 18 nations share the Danube River basin. Nearly all Arab countries suffer from water scarcity. An estimated 66% of the Arab region’s available surface freshwater originates outside the region. About 66% of the African land mass is arid or semiarid, and more than 300 million of the 800 million people in sub-Saharan Africa live in water-scarce environments; i.e., they have fewer than 1,000 m3 per capita (9). The process by which land turns desert-like is not restricted to African countries, where the Sahara is stealthily growing southward by about 48 square kilometers a year. The major causes of desertification are climate change and poor soil conservation, which degrade the soil. The overuse of chemical fertilizers, failure to rotate crops, and irresponsible irrigation all rob the earth of its nutrients, and there is swift depletion of plant life and loss of topsoil. According to China’s State Forestry Administration, more than 27% of the country has undergone desertification. Inner Mongolia, in northern China, has experienced one of the worst cases. Desertification has hit 18 provinces and impacts more than 400 million people. The root causes are climate change and poor soil conservation, seriously degrading the soil. The overuse of chemical fertilizers, failure to rotate crops, and irresponsible irrigation rob the soil of its nutrients. Eventually, the land gives way to sand. While China loses arable land, the government is reclaiming land. About 20 years ago, the government began planting millions of trees, constructing terraces and small-scale dams. It also has banned grazing from some areas. Loess plateau, in central and northern China, for instance, covers more than 620,000 square kilometers and is highly prone to erosion because of silt. It is believed that many centuries ago the plateau was fertile and easy to farm, but deforestation and overgrazing turned it into a desert. It is one of the most severely eroded lands in China. A large part of the loess plateau has been reclaimed. According to Professor Charles Jia, University of Toronto, Canada, the other big problem is that China simply doesn’t have enough water. Large-scale industrialization has overwhelmed scarce supplies, and drinking water has become the biggest casualty. China has about 7% of the world’s freshwater but sustains more than 20% of the 3 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


population (by comparison, the Great Lakes contain 21% of the world’s freshwater supply). The other big problem is that China simply doesn’t have enough water. Large-scale industrialization has overwhelmed scarce supplies, and drinking water has become the biggest casualty. Advanced countries like the US are not immune to water shortages. A severe drought in California is now approaching four years. It has depleted snow packs, rivers, and lakes; and groundwater use has soared to make up the shortfall. The Sierra Nevada snowpack, which Californians rely on heavily during the dry summer months for their water needs, continued to disappoint in the winter of 2014—15. A recent manual survey by the Department of Water Resources (DWR) at the Phillips snow course in the mountains 90 miles east of Sacramento found 0.9 inches of water content in the snow, just 5% of the March 3 (2015) historical average for that site. Recent electronic readings by the DWR indicate the water content of the northern Sierra snowpack is 4.4 inches, 16% of the average for the date. The central and southern Sierra readings were 5.5 inches (20% of average) and 5 inches (22%), respectively. A recent report from Stanford University asserts that nearly 60% of the state’s water needs are now met by groundwater, up from 40% in years when there are normal amounts of rainfall and snowfall. Relying on groundwater to make up for the shrinking surface water supplies comes at a rising price, and this hidden water found in California’s Central Valley aquifers is the focus of what amounts to a new gold rush. Well-drillers are working overtime, and farmers and homeowners short of water now must wait in line more than a year for their new wells. In most years, aquifers recharge as rainfall and stream flow seep into unpaved ground. But during droughts the water table—the depth at which water is found below the surface—drops as water is pumped from the ground faster than it can recharge. Central Valley wells that till now struck water at 500 feet must now be drilled down 1,000 feet or more, at a cost of more than $300,000 for a single well. And as aquifers are depleted, the land begins to shrink. Groundwater comes from aquifers—spongelike gravel- and sand-filled underground reservoirs—and we see this water only when it flows from springs and wells. In the United States, we rely on this hidden and shrinking water supply to meet our needs; and as droughts shrink surface water in lakes, rivers, and reservoirs, we rely even more on groundwater from aquifers. Some shallow aquifers recharge from surface water, but deeper aquifers contain ancient water locked in the earth by changes in geology thousands of years ago. These aquifers typically cannot recharge, and once this "fossil" water is gone, it is gone forever—potentially changing how and where we can live and grow food, among other effects (10). California has pushed harder than any other state to adapt to a changing climate, but scientists warn that improving its management of precious groundwater supplies will shape whether it can continue to supply more than half of the nation’s fruits and vegetables on an imminent hotter planet. As a drilling frenzy unfolds across the Central Valley, California’s agricultural heartland, the consequences of the overuse of groundwater are becoming very clear. In some places, water tables have dropped 50 feet or more in just a few years. With less underground water to buoy it, the land surface is sinking as much as a foot a year in spots, causing roads to buckle and bridges to crack. Shallow wells have run dry, depriving some poor communities of water. Some of the underground 4 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


water-storing formations so critical to California’s future—typically, saturated layers of sand or clay—are being permanently damaged by the excess pumping, and will never again store as much water as farmers are withdrawing. In normal times, agriculture consumes roughly 80% of the surface water available for human use in California, and experts say the state’s water crisis will not be solved without major involvement with farmers. California’s greatest resource in dry times is not its surface reservoirs, but its groundwater. Scientists say it is obvious that drought has made apparent the need for better controls. While courts have taken charge in a few areas and imposed pumping limits, groundwater in most of the state has been a resource anyone could grab. The land devoted to almond orchards in California has doubled in 20 years, to 860,000 acres. The industry has been working hard to improve its efficiency, but growing a single almond can still require as much as a gallon of California’s precious water. The expansion of almond, walnut, and other water-guzzling trees and vine crops has come under sharp criticism from some urban Californians. The groves make agriculture less flexible because the land cannot be idled in a drought without killing the trees. Putting strict limits in place is expected to take years. The new law, which took effect January 1, 2015, does not call for reaching sustainability until the 2040s. Worldwide Water Quality Developing and developed countries have different, yet similar, problems with water quality. These water quality issues in China and the US are discussed in some detail below, as they represent a fast developing country and a very developed country.

Developing Countries People need to be prudent when they drink water in Africa, Asia, and Latin America. The rivers in these areas are frequently considered the most polluted in the world. They have 3 times as many bacteria from human waste as the global average, and 20 times more lead than rivers in developed countries. In 2004, water from half of the tested sections of China’s seven major rivers was found to be undrinkable because of pollution. The Yangtze, China’s longest river, is “cancerous” with pollution. The pollution from untreated agricultural and industrial waste could turn the Yangtze into a “dead river” within a short time. This would make it impossible to sustain marine life or provide drinking water to the booming cities along its banks. Almost half of China’s water sources are polluted. Wells and aquifers are contaminated with fertilizers and pesticide residues and heavy metals such as arsenic and manganese from mining, the petrochemical industry, and domestic and industrial waste. More than three-fourths (76.8%) of 800 wells monitored in nine provinces and autonomous regions and municipalities, including Beijing, Shanghai and Guangzhou, failed to meet standards for groundwater in a 2011 national evaluation (11). 5 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


China, like many other countries, has failed to keep up with demand for clean water (12, 13). It is well known that decades of reckless pollution had spawned a string of “cancer villages.” These are communities near chemical, pharmaceutical, or power plants with unusually high death rates. Environmentalists, NGOs, and academics long argued that contaminated water that villagers rely on for drinking, cooking and washing, was the prime suspect. Nearly 450 cancer villages were identified in the late 1990s. The belated recognition appeared in a recent environment government ministry’s five-year plan for tackling pollution. The document said: “In recent years, toxic and hazardous chemical pollution has caused many environmental disasters, cutting off drinking water supplies, and even leading to severe health and social problems such as cancer villages.” China is the world’s largest grain producer. It has also become the world’s largest producer and consumer of fertilizers and pesticides. Its fields are a bigger source of water contamination than factory effluents, the Chinese government said in its first pollution census in 2010. More than half of China’s water pollution comes from fertilizers, pesticides, and livestock waste that are carried into lakes, rivers, wetlands, coastal waters, and underground aquifers by rainfall and snowmelt. Pig and poultry farms are also major polluters of water.

Developed Countries Nearly 40% of the rivers in the US are too polluted for fishing, swimming, or aquatic life. The Mississippi River drains nearly 40% of the soil and water of continental United States, including its central farmlands, and it carries an estimated 1.5 million metric tons of nitrogen pollution into the Gulf of Mexico every year. Nearly 1.2 trillion gallons of untreated sewage, storm water, and industrial waste are discharged into US waters annually. Lakes are even worse—46% of them are extremely polluted. Two-thirds of US estuaries and bays are either moderately or severely degraded from eutrophication (nitrogen and phosphorus pollution). Even the most advanced country, like the US, is facing a water crisis. Most experts agree that the US water policy is in chaos. Decision making about allocation, repair, infrastructure, and pollution is spread across hundreds of federal, state, and local agencies. • • •

Over 700 different chemicals have been found in US drinking water as it comes out of the tap! The EPA classifies 129 of these different chemicals as being particularly dangerous. The EPA sets standards for approximately 90 contaminants in drinking water.

The quality of water in Europe’s rivers and lakes worsened between 2004 and 2005. Almost one-third of Ireland’s rivers are polluted with sewage or fertilizer. The Sarno River in Italy is the most polluted river in all of Europe, featuring a mix of sewage, untreated agricultural waste, industrial waste, and chemicals. The Rhine, which flows through many European countries, is regarded by many as the 6 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


dirtiest large river; almost one-fifth of all the chemical production in the world takes place along its banks. The King River is Australia’s most polluted river, suffering from a severe acidic condition related to mining operations. Canadian rivers are also polluted. The failure of safety measures relating to production, utilization, and disposal of a large number of inorganic/organic compounds from arsenic to zinc can cause contamination of our water supplies (7). The discussion below briefly covers various contamination problems with water. Arsenic contamination affects almost 200 million people worldwide, even in developed countries such as the US. The most polluted area in the world, Bangladesh, has arsenic-contaminated groundwater over 85% of its total land area. Naturally occurring arsenic contaminates millions of wells that were installed to eliminate microbial contamination. After years of drinking this water, residents face arsenicosis, which can lead to a slow and agonizing, painful disease, resulting in death. In searching for a possible solution, the author organized workshops in Bangladesh and India. Then several symposia were planned by him at the American Chemical Society, UNESCO, and International Union of Pure and Applied Chemistry meetings. Detailed discussion on how groundwater is contaminated with arsenic, desirable methods for monitoring arsenic contamination at ultratrace levels (below one part per million), and the best alternatives for reclamation are available in a text entitled Arsenic Contamination of Groundwater (2). Over 80% of used water worldwide is not collected or treated. The need for groundwater recharge may ultimately limit how much water farmers can have from surface irrigation systems, even in flush years—the same way that credit card limits determine how many fancy dinners one can eat. Yet in a state where irrigation rights have been zealously guarded for generations, such limitations may not go down easily. The treatment of wastewater requires significant amounts of energy, and demand for power to do so is expected to increase globally by 44% between 2006 and 2030 (14), especially in countries not covered by the Organization of Economic Cooperation and Development where wastewater currently receives little or no treatment. Pollution knows no borders either. Up to 90% of wastewater in developing countries flows untreated into rivers, lakes and highly productive coastal zones, threatening health, food security, and access to safe drinking water and bathing water. Sources of Contamination Drinking water comes mainly from the following sources: rivers, lakes, wells, and natural springs. These sources are exposed to a variety of conditions that can cause contamination of water. Some of the sources of contamination are listed alphabetically below. • • •

Combustion products of coal/oil (gasoline) Detergents Disinfectants 7 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


• • • • • • • •

Drugs (pharmaceuticals and illicit drugs) Fertilizers Gasoline and its additives Herbicides Insecticides Pesticides Phthalates Volatile and semi-volatile compounds

About 12,500 tons of antimicrobials and antibiotics are administered to healthy animals on US farms each year. A 2002 US Geological Survey found pharmaceuticals (hormones and other drugs) in 80% of the streams sampled in 30 states. These contaminants are suspected in the increase of fish cancer, deformities, and feminization of male fish. The world’s seas are inundated by a variety of water pollution problems. The Baltic Sea, Yellow Sea, Bohol Sea, Congo Basin and Victoria Lake are affected severely by eutophication. The primary problem with the Gulf of Mexico is microbiological contamination, and the Aral Sea contains a variety of pollutants. Solid waste and radionuclides are the primary pollutants around the Pacific Islands and the Benguela Current (West Coast of Africa). The Caribbean Sea has problems with suspended solids and spills. The extensive use of plastics and their careless disposal has led to pollution of various water bodies. Large parts of the Pacific Ocean are referred to as “plastic oceans,” where enormous gyres, about the size of Texas, are covered with plastic debris. The Pacific is the largest ocean realm on our planet, approximately the size of Africa—over 10 million square miles—and it is the home of two very large gyres. The Atlantic Ocean contains two more gyres, and other plastic oceans exist in other bodies of water. Volatile organic contaminants (VOCs) may enter directly into our water resources from various spills, by improper disposal, or from the atmosphere in the form of rain, hail, and snow. In general, VOCs have high vapor pressures, low-to-medium water solubilities, and low molecular weights. These properties allow them to move freely between water and air. Many volatile organic contaminants find their way to our drinking water (4).

Monitoring Water Contaminants Our civilization has managed to pollute our waters to the point where we must disinfect water for drinking. To assure water purity, we need to monitor contaminants from arsenic to zinc (7). In the 1978 Metrochem meeting, the author emphasized the need to analyze very low levels of various contaminants, in a paper entitled “In Search of Femtogram” (a femtogram is 10−15g, or one part per quadrillion), to fully understand their impact on animals. For example, dioxin (2,3,7,8-tetrachloro-dibenzodioxin) can cause abortions in monkeys at the 200 parts-per-trillion (ppt) level (15). PCBs (polychloro biphenyls) at the 0.43 ppb 8 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


(parts-per-billion) level can weaken the backbones of trout (16). This suggests that ultratrace analysis is necessary to monitor materials like PCBs and dioxin (17–19). We have known for some time now that water that we call potable may actually contain many trace and ultratrace contaminants, as exemplified by an analysis of Ottawa drinking water (20). It contained insecticides like α-BHC (an isomer of lindane), lindane, and aldrin, at ppt levels. In addition, it contained phthalates at significantly higher concentrations. In 2010, a UN resolution declared the human right to “safe and clean drinking water and sanitation.” A simple definition of potable water is “any water that is clean and safe to drink. National primary drinking water regulations control water quality in the US, in response to public concern about degraded water quality and the widespread view that pollution of our rivers and lakes was unacceptable. The Clean Water Act (CWA) became law in 1972. Control of point-source contamination, traced to specific “end of pipe” points of discharge or outfalls, such as factories and combined sewers, was the primary focus of the CWA. Other nations adopted similar measures and have seen improvement in point-source contamination as well. In the US, potable water must be cleaner than the maximum contaminant level mandated by local, state, and federal guidelines (USEPA national primary drinking water regulations). Water is a clear liquid, though a layperson might describe water’s color as white or blue. The fact is that many colors that have been ascribed to water relate to the materials that may be present in it (see below). For example, blue water generally refers to ocean water, which gets its color from the reflection of the color of the sky; and we have seas that are described by various other colors because of their appearance: Red Sea, Yellow Sea, Black Sea, and White Sea. Water generated from activities such as laundry, dishwashing, and bathing is called gray water, and water which has come into contact with fecal matter is called black water. Frequently, municipal water may have an odor at times, and that odor relates to the chlorination of water. A musty odor in drinking water may be the result of by-products of blue-green algae. The tests commonly carried out on drinking water are turbidity, total organic carbon, chlorite, chlorine dioxide, fluoride, sulfate, and orthophosphate (21). Some unregulated substances are also investigated. Surprisingly, testing of arsenic is not performed regularly. The impact on water quality of a variety of contaminants has been discussed earlier (22).

Water Reclamation Over 80% of the used water worldwide is not collected or treated. This situation has to change, as we don’t have an unlimited supply of safe water for our needs; and water reclamation is absolutely necessary (22). Some examples of wastewater reclamation are discussed below. According to a 2012 Ministry of Water Resources of the People’s Republic of China, China Water Resources Bulletin 2011 (China Water & Power Press, 2012), a closer look at how water is used reveals that this problem is tractable. Almost two-thirds of municipal water is used by industry, agriculture, and construction. 9 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Households consume the remaining one-third (365 million people used 15.3 billion tons of water in 2011). Of that, laundry, bathing, and dishwashing take up the most (together more than 80%). Cooking and drinking use just over 2% (1.1 billion tons). In other words, most household water does not need to be drinkable. Bringing a large developing country such as China up to the same standards as a developed country will require more intensive water treatment. This has environmental consequences. In Jiangsu province, for example, carbon dioxide emissions increased by 28% in 2012 when a type of water filtration called ozone–biological activated carbon treatment was extended to one-quarter of the provinces’ supply (5.3 million tons per day). China and other underdeveloped countries need cheap, energy-efficient methods of water purification that minimize chemical use. Water purification systems that improve drinking water at the point of use are a good fit in many areas. In Kenya, Bolivia, and Zambia, water purifiers have been shown to reduce diarrheal disease by 30–40%. Fewer than 5% of Chinese homes currently have these purifiers, despite a unit’s low cost of only around 1,500 to 2,000 renminbi. China’s water-purification industry is growing by about 40% a year—fewer people are buying water dispensers and barreled water. But water-purification devices are unregulated. Incomplete after-sales service leads to improper maintenance, and delays in changing filter cartridges can introduce microorganisms. Filters and units made from toxic materials such as nonfoodgrade plastic are ineffective. Treated gray water (wastewater from showers and baths) and black water (from toilets) are increasingly used in China for industrial and irrigation purposes, and for flushing toilets in new residences. But this type of recycling is impractical for most existing households because of the high cost and the disruption in the home while installing the necessary plumbing. It has been suggested that by using cheap, low-carbon water purifiers in all homes, China can avoid the technology “lock-in” that leads developed countries to waste potable water, and China can leapfrog to a sustainable supply system. In the long term, the improvement of water sources will ensure that most people have safe drinking water.

Producing Drinking Water from Rivers River water is frequently used for drinking, after purification. An example from India is provided here. Water for drinking is obtained from the Yamuna River before it is subjected to local contamination in Delhi. The recently constructed Sonia Vihar Water Treatment Plant helps meet the great demand of more water for the 15 million residents of Delhi. Various steps involved in the purification of water are shown in Figure 1. Water from the Ganges River can also be utilized with this same process.

10 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

Producing Drinking Water from the Ocean


It is necessary to desalinate ocean water before using it for drinking or cooking. Desalination removes some amount of salt and other minerals from salt water. The principal process uses membranes to desalinate water by reverse osmosis. This process uses semipermeable membranes and pressure to separate salts from water. This system uses less energy than does thermal distillation, leading to a reduction in overall desalination expenses over the past decade. Desalination continues to be energy-intensive, however, and future costs will continue to rely on the price of both energy and desalination technology.

Figure 1. Water purification process at the Sonia Vihar Plant. Various desalination methods are listed below: • • • •

Mechanical vapor compression Multi-effect distillation Multistage flash distillation Reverse osmosis

Reverse osmosis uses the least amount of energy, compared to the other methods shown above. Energy consumption of seawater desalination can be as low as 3 kWh/m3 including pre-filtering and ancillaries; this far exceeds 0.2 kWh/m3 or less required for freshwater supplies from local sources. All desalination processes generate large quantities of a concentrate that may have residues of pretreatment and cleaning chemicals, their reaction by-products, and heavy metals because of corrosion. Chemical pretreatment and cleaning are a necessity in the majority of desalination plants, typically including treatment against biofouling, scaling, foaming, and corrosion in thermal plants, and against biofouling, suspended solids, and scale deposits in membrane plants. Some methods of desalination, in combination with evaporation ponds, solar stills, and condensation traps, do not discharge brine. They don’t use chemicals in their processes, nor do they burn fossil fuels. Membranes or other critical parts, 11 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


such as components that include heavy metals, are not utilized; thus they do not cause toxic waste (or high maintenance). There is a new approach that works like a solar still, but is on the scale of industrial evaporation ponds. It is called “full desalination” because it converts the entire amount of saltwater intake into distilled water. One of the unique advantages of this type of solar-powered desalination is the feasibility of inland operation. Other advantages include no air pollution from desalination power plants and no temperature increase of endangered natural water bodies from power plant cooling-water discharge. Another important advantage is the production of sea salt for industrial and other uses.

Producing Drinking Water from Poisoned Wells Arsenic contamination of groundwater has been reported in a large number of countries in the world; Bangladesh and Bengal (India) suffer most. Almost one-hundred million people in Bangladesh are at risk, as they consume arseniccontaminated water at levels of 10 ppb or greater. Inorganic arsenic above the 10 ppb level can increase the risk of lung, skin, bladder, liver, kidney, and prostate cancers.

Sources of Arsenic Contamination Water contamination in Bangladesh and India has been attributed to the geology in parts of those countries. Microbially mediated reduction of assemblages comprising arsenic sorbed to ferric oxyhydroxides is gaining consensus as the chief mechanism for the mobilization of arsenic into groundwater. A recent microcosm-based study has provided the first direct evidence for the role of indigenous metal-reducing bacteria in the creation of toxic, mobile As(III) in sediments from the Ganges delta (2). Arsenic contamination from other sources is possible anyplace in the world because arsenic compounds are used commercially for the following applications: • • • • •

Pesticides: monosodium methyl arsonate, disodium methyl arsonate Insecticide: dimethylarsenic acid Aquatic weed control and sheep and cattle dip: sodium arsenite Defoliating cotton bolls: arsenic acid, arsenic pentoxide Some pharmaceuticals and decolorizing glass: arsenic trioxide

Large areas in the west, midwest, and northeast US have high arsenic concentrations. For example, in North Carolina, arsenic was found in 960 wells statewide in January 2000. According to the Wilmington Star News of August 18, 2003, half of the state’s population depends on groundwater. The state toxicologist, Ken Rudo said “for new wells, arsenic test is pretty much not done.”


Monitoring Arsenic at Ultratrace Levels


A number of methods can be used for analyzing arsenic in water at 10 ppb or an even lower level (2). The speciation of arsenic requires separations based on solvent extraction, chromatography, and selective hydride generation. Detection limits for arsenic down to 0.0006 µg/L can be obtained with inductively coupled plasma mass spectrometry (ICP-MS -I). HPLC CP-MS is currently the best technique available for determination of inorganic and organic species of arsenic. The main problem is the high cost. Using hydride generation (HG), arsenic can be determined by a relatively inexpensive atomic absorption spectrometer or atomic fluorescence spectrometer (AFS) at single-digit µg/L. For developing countries, there is a need for low-cost, reliable instrumentation and dependable field test kits.

Remediation The following methods can be used for remediation of arsenic contamination of water: • • • • • • • • • • • •

Coagulation with ferric chloride or alum Sorption on activated alumina Sorption on iron oxide–coated sand particles Granulated iron oxide particles Polymeric ligand exchange Nanomagnetite particles Hybrid cation exchange resins Hybrid anion exchange resins Polymeric anion exchange Reverse osmosis Nanomagnetite particles Sand with zero valent iron

Two filters that stand out in terms of their usefulness for serving a small family or a community are briefly described below.

Single Family Systems These systems are based on solid sorbents. Special emphasis has been placed on iron-based filters because they appear to be chemically most suitable for arsenic removal, they are easy to develop, and they are environmentally benign. Arsenic removal mechanisms for a SONO filter are based on surface complexation reactions, sorption dynamics, and kinetics (see details in Chapter 12 in reference (2)). This is one of the four filters approved by the Bangladesh government for public use. The manufacturer claims that the filtered water meets Bangladesh standards (50 ppb of arsenic vs 10 ppb standard in the US), has no 13 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


breakthrough, works without producing toxic wastes. These figures are based on EPA guidelines (3). The filter costs about $40, lasts for five years, and produces 20–30 L/hour for daily drinking and cooking needs of one or two families. A large number of these filters have been used all over Bangladesh and continue to provide more than a billion liters of safe drinking water. This innovation was recognized by the National Academy of Engineering Grainger Challenge Prize for Sustainability, with the highest award for its affordability, reliability, ease of maintenance, social acceptability, and environmental friendliness. It should be noted that the flow rate may decrease 20–30% per year if the groundwater has high iron levels (>5 mg/L), because of formation and deposition of natural HFO in sand layers. The sand layer (about one-inch thick) then has to be removed, washed and reused, or replaced with new sand. A protocol for elimination of pathogenic bacteria should be used once a week in areas where coliform counts are high. It should be noted that, as with all commercial filters, the consumer needs to be alert to manufacturing defects, and mishandling during transportation.

Community-Based Filters A community filter can serve about 200 households and requires no chemical addition, pH adjustment, or electricity (see Chapter 13 in reference (2)). A large number of these filters have been installed since 1997, and have the following characteristics: • •

Utilize activated alumina as an adsorbent media that can be regenerated Purify Influent arsenic solutions ranging from 100 μg/L to 500 μg/L, containing both As(III) and As(V) species

When the filter is exhausted, the media can be replaced and the spent media is then taken to a central regeneration facility for further reuse. An arsenic-laden spent regenerant form is converted to a small volume of sludge that can be contained in an aerated, coarse sand filter. The process is claimed to be environmentally sustainable because the treatment residues are not toxic under normal environmental conditions. It is also economically sustainable, as the villagers collectively maintain the units by paying a monthly water tariff of about $0.40.

Recycling Wastewater to Groundwater The Orange County Water District (OWCD) in California treats and injects 70 mM gallons/day into groundwater. It takes treated sewer water that would otherwise be discharged into the ocean, purifies it to near distilled quality and then recharges it into the groundwater basin. OCWD ensures the Orange County 14 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

groundwater basin is free of contamination and that usage is sustainable. It uses microfiltration, reverse osmosis, and ultraviolet (UV) to purify wastewater. Microfiltration removes bacteria and protozoa, and also particles and suspended solids. Reverse osmosis removes viruses, bacteria, and chemical contaminants such as dissolved salts, metals, organic compounds, including endocrine disruptors and other pharmaceuticals. UVlight inactivates microbes and prevents replication; UV with hydrogen peroxide is used to destroy small organics.


Recycling Wastewater to Surface Water A preliminary treatment process used by NEWater in Singapore removes debris and sandy materials from used water. The primary treatment process allows the solid pollutants in suspension (primary sludge) to settle to the bottom of the tanks and lighter materials like scum or greasy materials to float to the surface of the tank. The secondary treatment takes the upper layer of water and puts it into the aeration tank that is a bioreactor and final clarifier. The used water is mixed with a culture of microorganisms, known as activated sludge, in the aeration tank. The microorganisms absorb and break down the organic pollutants. The clear supernatant water at the top of the tank is collected and discharged from the tanks as the final effluent. The sludge is allowed to remain in the digesters for 20–30 days. Anaerobic digestion of the organic matter in sludge produces biogas, which contains 60—70% methane.

Reclaiming Wastewater for Drinking Singapore gets 30% of its water requirements via the purification process developed by NEWater. To produce drinking water, the following treatment steps are used in addition to those listed above: • • • •

Membrane filtration Reverse osmosis Elimination of bacterial impact Capture of nutrient value

The amount of testing done to reclaimed water should relate to how it is going to be recycled. For example, if it is recycled into a surface water supply, its quality after purification should match or exceed the requirements of the surface water to which it is being added. Similar rules may be followed for mixing with groundwater. Recycled wastewater for drinking must meet potable water requirements, with the added assurance by ultratrace analysis that no toxic contaminants are present (4). A variety of global challenges to water and solutions are covered below. 15 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Raising Awareness of Water Issues: The Education Connection, the Educational Potential The challenges posed by finite amounts of clean, potable water and a continuously growing human population are still not well understood by a significant portion of the population (Chapter 2). An increased awareness of water concerns, specifically of wastewater treatment technologies and sanitation practices, can be attained if these issues are addressed thoroughly and repeatedly in general chemistry classes at both high school and college levels, and in upper level undergraduate chemistry curriculum courses such as industrial chemistry and environmental chemistry. Engineering classes should include courses related to water problems. This chapter presents a detailed approach to raising the awareness of current water topics by repeated exposure in college chemistry classes in several different courses.

The Effects of Climate Change on Water Resources of Small Developing Countries – A Case Study of the Republic of Macedonia In the absence of high-resolution climate-change model predictions, employing empirical data collected over a long period may be the only viable option to predict the climate change impact on small and developing countries where the socioeconomic structure is strongly rooted in water- dependent sectors such as agriculture or energy production (Chapter 3). The overarching goal of this study is to demonstrate the suitability and significance of employing empirically obtained historical data in predicting the impact of future global climate change trends in a small country like the Republic of Macedonia. The climate change effects on the national surface water resources of Macedonia were assessed by examining temperature trends and other descriptors of global warming spanning over 50 years, by testing three data-driven hypotheses. The analysis extended over 50 years of historical records, and three data-driven hypotheses were tested. The records describe statistically significant trends: increase in national average temperatures, surface water resources depletion, and fluctuations in the magnitude of precipitation. These grim scenarios indicate substantial socioeconomic and environmental challenges for the Republic of Macedonia for fear that adequate mitigation measures are not implemented.

Drinking Water and Sanitation in Central America: Challenges, Perspectives, and Alternative Water Treatment Chapter 4 analyzes plausible alternatives for water treatment and wastewater sanitation aimed to improve the population’s health by assuring their access to safe drinking water in countries in Central America. Water treatment alternatives for the region are proposed as centralized and non-centralized systems. Challenges 16 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

and perspectives for the region are considered on the basis of intervention of low-cost water technologies, education about safety practices, and awareness for governments in implementing water management strategies.


Water Challenges and Solutions for Brazil and South America Freshwater is unevenly and temporally distributed across the planet or is located in places that are difficult to access. South America is relatively well-endowed with freshwater, although millions of people suffer from restrictions on potable water and proper sanitation systems, because of longer drought periods, as well as the lack of an adequate infrastructure and proper governance (Chapter 5). It is estimated that 60—80% of water is used in agricultural irrigation in developing countries in South America. As for energy, South America has one of the greenest energy mixes, when the large contribution of hydropower, wind power, and biofuels are taken into account. The water demand for power generation from different sources focuses our attention on water-energy nexus in South America.

Critical Water Issues in Africa Water scarcity, purity, and delivery have become major challenges of humanity, especially in Africa (Chapter 6). On that continent, 325 million people lack access to safe water. The majority of those who lack water live in rural areas. Africa is second to Australia in dryness, but it is home to 15% of the global human population and has only 9% of global renewable water resources. Most of Africa’s surface water has become polluted by human activities, and its wells are rapidly becoming dry. Impacts of climate change and climate variability are making water scarcity even more stressful. Technologies used for water harnessing are outmoded and inefficient. African countries need to modernize water purification technology; it is essential that these countries adopt new methods like roof, pavement, and urban water catchment to recharge its declining groundwater level. Provision of safe drinking water policy needs to change from piped water in every home to appropriate water-use technology in every home. Some potential new technologies still require further research. Chapter 6 highlights some recent developments of nanomaterials that give promise to future water purification trends. Similarly, small-scale water harnessing technologies are outlined for groundwater recharge and drinking water purification. The design of water education in African nations is reviewed, and specific steps for improvement are also given in this chapter.



Organochlorine Pesticide Contamination in the Kaveri (Cauvery) River, India: A Review on Distribution Profile, Status, and Trends Water sources such as rivers are often reported to contain various organochlorine pesticides (OCPs) because of their tremendous usage in agriculture and vector control activities (Chapter 7). Monitoring studies on rivers in India are limited, and the presently reviewed Kaveri River is one such river in southern India that has served as a lifeline (agriculture, drinking water, and industry) for centuries. The frequently reported OCPs in this river include hexachloro-cyclohexane (HCH), dichloro-diphenyl-trichloroethane (DDT), endosulfan, aldrin, dieldrin, and heptachlor epoxide. The concentrations of HCH, DDT, and endosulfan residues in Kaveri’s water were detected at levels up to 2300 ng/L, 3600 ng/L and 15400 ng/L, respectively. While in sediment, HCHs and DDTs were reported with maximum concentration of 158 ng/g dw and 9.15 ng/g dw, respectively. Even biota (fish, shrimp) samples collected in the river were found to contain significant levels of HCH (228 ng/g) and DDT (2805 ng/g) residues. The levels of some of the OCPs in the Kaveri River exceeded safety guideline values; therefore, these waters are considered a threat to the population because continuous exposure cannot be ruled out.

Ganges River Contamination: A Review Persistent organic pollutants (POPs), pesticides, organotin compounds, perfluorinated compounds, heavy metals, and other emerging contaminants like pharmaceuticals, personal care products, steroids, hormones, phthalates, plasticizers, etc., have been used in a wide range of agricultural, sanitation, and industrial commodities in the Ganges River basin, resulting in vigorous deterioration of the river (Chapter 8). India has recently prepared the National Implementation Plan (NIP) of the Stockholm Convention. The Ganges is believed to be highly polluted with POPs and other contaminants; however, no systematic study and analysis of POPs and other toxics have been conducted. This chapter aims to examine the present status, spatial and temporal distribution pattern of POPs and other chemicals in multi-compartment Ganges River surroundings. This review leads to the conclusion that the Ganges River is highly contaminated with DDT, HCHs, and heavy metals, etc. However, the scarcity of data on other POPs and emerging contaminants makes it challenging to assess their exposure in the entire length of the river. No evidence of a general decline in DDT and HCH residues in the river and its biota were found in this study.

Water Challenges in India and Their Technological Solutions Problems associated with water can be broadly grouped as (a) inadequate availability of water, (b) poor quality of water for its intended use, and (c) indiscriminate use of this valuable natural resource (Chapter 9). The technological approaches for solving the problems may therefore emanate from (a) recovering 18 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

water from sustainable resources, (b) augmentation of quality of water from available and accessible sources, and (c) renovation for recycling. Technology missions on reclamation, augmentation, and renovation for water was initiated in 2009 to address the water challenges following three-pronged technological approaches stated by the Union Ministry of Science and Technology. The mission shaped several research-led solutions through nationally coordinated approaches.


Water Resources, Water Scarcity Challenges, and Perspectives The continuously growing global water scarcity and the evidence for climatic changes require a refocus on reliable and sustainable water supplies, especially in arid and semiarid regions, as they are the most water-deprived regions in the world (Chapter 10). Population growth, urbanization, and increasing water demands intensify the pressure on many water resources, causing rapid depletion of supply and quality degradation to a degree that part of the resources may not be safe to use and can cause health and environmental risks. Such adverse development is strongly apparent in the Middle East and other places where global warming impacts are already apparent, leading to a situation in which available water resources are depleted, deteriorated, and unable to satisfy basic needs. To provide an integrated picture of water challenges and possible solutions at global and regional scales, a drivers-pressures-state-impacts-responses (DPSIR) framework is applied to give details regarding the water shortage issue and mitigation measures, with examples from the Middle East, California, India, and other regions facing these challenges. Reversing the trend of growing water shortages, while securing basic water needs for all, is a challenging and ambitious task, but an achievable one provided that comprehensive and consolidated water management strategies are implemented. A comprehensive and integrated water management policy combining advanced management and conservation as well as the harnessing of nonconventional water resources (water reuse and desalination), together with trans-boundary cooperation on shared water resources can provide a sound solution to the challenges posed by water scarcity are discussed in this chapter.

Contaminated Profiles of Perfluorinated Chemicals in the Inland and Coastal Waters of Japan Following the Use of Fire-Fighting Foams This chapter deals with the impact of two natural disasters (earthquake followed by tsunami) and consequent human activities on the quality of inland and coastal waters of Japan (Chapter 11). Two cases of accidental petrochemical fires in Japan that involved the use of aqueous film-forming foam (AFFF) have been investigated as potential sources of perfluoroalkly substances (PFASs) in inland and coastal waters of Japan. PFASs were identified and quantified in seawater, lake water, snow, runoff, and surface soil samples. Concentrations of individual PFASs were measured in water samples employing the use of high-performance liquid chromatography with electrospray tandem mass spectrometry. The 19 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


total concentrations of the sum of PFASs in seawater and lake water samples from Tomakomai ranged from 0.32 to 405 ng/L. The greatest concentration of perfluorooctane sulfonate (PFOS) was found at T19 (311 ng/L) of December 2003. Total fluorine (TF), inorganic fluorine (IF) and extractable organic fluorine (EOF) were also measured in the samples, using a newly developed method, namely combustion ion chromatography for fluorine (CIC-F). The results revealed that IF was the major contributor to TF in water samples. However, the major portion of organofluorine fraction still remains unknown, suggesting the occurrence of other unknown fluorinated organic compounds, in addition to known individual PFASs such as PFOS, PFOA, and perfluorononanoic acid. Additionally, composition and profiles of PFASs in two locations impacted by AFFF were different. This suggests different sources of organic fluorine released from AFFF. In Tomakomai, the release of AFFF is expected to be a major source of PFASs; while in Kashima, other sources such as the fluorochemical industry appears to contribute to a major source of contamination.

Overcoming the Water Treatment Challenges and Barriers in Small, Rural, And Impoverished Communities in Developing Countries Many developing countries face unique water treatment challenges and barriers because the communities do not have a well-established socioeconomic, educational, and technological infrastructure that is capable of supporting conventional water treatment solutions (Chapter 12). It is not uncommon for many proposed and implemented water treatment solutions to fail in developing countries, especially in small, needy, and rural communities. This chapter examines underlying factors that contribute to water treatment challenges and barriers in developing world communities and proposes a systems approach for developing a sustainable water treatment solution in these communities. Five different categories of challenges and barriers to water treatment solutions in developing countries are identified and examined: economics-driven factors; knowledge-based factors; sociocultural implications; adequacy of supporting infrastructure; and environmental specifics. A systems approach, which stems from the need to resolve these challenges, is elucidated in an attempt to minimize the failure rate of implementing inadequate water treatment solutions in little rustic deprived communities of the developing world.

Building a Sustainable Water Management System in the Republic of Serbia: Challenges and Issues The Republic of Serbia is an example of a developing country with a water management system that has not adequately transitioned to address the need of the new socioeconomic paradigm (Chapter 13). The goal of this study is to identify and evaluate the existing barriers that hinder the development and implementation of an integrated national water resources management system and find ways to mitigate the upcoming effects of climate change and successfully manage the 20 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

water resources for the next generations. To achieve this goal, the water resources management system in Serbia is examined through the prism of regulations, management, engineering, and education, which represent principal pillars of every national socioeconomic system. The key findings and the outcome of this study reveal that an in-depth analysis of the existing situation and identification of barriers represent the initial steps in the process of developing and implementing an integrated national water management system.


Sustainable Water Cleaning System for Point-of-Use Household Applications in Developing Countries to Remove Contaminants from Drinking Water A point-of-use (POU) water treatment system that is based on pyrolysis of banana peels (PBP) adsorption was evaluated with synthesized and real water samples (Chapter 14). PBP resulted in the formation of a large porous surface area adsorbent with strongly negative surface charges. Batch and continuous flow studies were conducted to determine the adsorption capacity and the rate of removal of pollutants.

Potential Uses of Immobilized Bacteria, Fungi, Algae and Their Aggregates for Treatment of Organic and Inorganic Pollutants in Wastewater Bioremediation of wastewater using microorganisms and their aggregates is recognized as an efficient green treatment (biological origin) with a relatively low cost compared to conventional physical and chemical treatment processes (Chapter 15). Heterotrophic microorganisms such as bacteria, fungi and often microalgae are used for removal of targeted pollutants from wastewater. Microorganism can be used in the following ways • •

Direct mixing of free microorganisms with waste water; there is no separation between microorganisms and treated water. Microorganisms immobilized in bedding materials or encapsulated within a matrix; there is a distinct separation between microorganisms and the treated water.

However, immobilized or encapsulated cells are considered more efficient than free cells as they have better metabolic activity, less vulnerability to toxic substances, and greater plasmid stability. Lignocellulosic biomasses, ceramics, polymers from both natural and synthetic origin are commonly used as bedding materials or for entrapment of microorganisms within it. These immobilized cells show immense potential to clean up a wide range of pollutants including phenolic compounds, hydrocarbons, propionitrile, organic and inorganic dyes, N,N-dimethylformamide, pyridine, benzene, toluene, xylene, heavy metals, and unwanted amount of nutrients such as nitrogen and phosphorus from 21 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

the wastewater streams. Integrated process of assimilation, adsorption and biodegradation is the sole responsible mechanism behind wastewater remediation by immobilized microorganisms.


Improving the Water Holding Capacity of Soils of Northeast Brazil by Biochar Augmentation The northeast area of Brazil, a semiarid region, frequently experiences severe drought (Chapter 16). Despite rainfall during two or three months of the year, the presence of soils with low water retention capacity, together with intense insulation, results in infiltration of water to deeper soil layers, rapid evaporation, and deficiency of water during the remainder of the year. In this work, the authors propose that the use of soil conditioners derived from agricultural and industrial wastes improves soil water supply. Five biochars, prepared by slow pyrolysis, were produced from green coconut shells, orange peels, palm oil bunch (PO), sugarcane bagasse (SB), and water hyacinth (WH) plants. Charcoal fines obtained from the metallurgy industry were also used. The soils investigated were two quartzarenic neosols denoted QN1 and QN2. After mixing with 5% (m/m) of biochar, both soils showed an increased water-retention capacity, compared to the original samples. The biochars that provided the best water retention were PO and SB (absolute increases of 5.5% and 6.5%, respectively) for soil QN1, SB, and WH (absolute increases of 7% and 8%, respectively) for soil QN2. These results could be explained by the polarity of the biochars, as shown by their hydrophilicity, measured by 13C NMR spectroscopy, as well as by the increased presence of micropores that could physically retain water (revealed by scanning electron microscopic analyses).

Reclaimed Water Systems: Biodiversity Friend or Foe Surface-flow type constructed wetlands are commonly prescribed by local authorities for stormwater and wastewater treatment in many parts of Australia and elsewhere (Chapter 17). Despite the fact that little is known about the biodiversity in constructed wetlands up to now, artificial wetlands can potentially develop and become complex ecosystems with a variety of fauna and flora, including macroinvertebrate communities. Such communities could play an important role in the ecological functioning of healthy aquatic ecosystems because they process detritus and algae and also provide food to other aquatic animals. In the meantime, nuisance macro-invertebrate species including chironomid midges and mosquitoes associated with man-made systems could raise significant health concerns as disease vectors. Water quality conditions such as dissolved oxygen, temperature, nutrients, pH, heavy metal, and organic contaminants are the key determinants of macroinvertebrate populations in man-made reclaimed water systems. Therefore, the potential impact of different reclaimed water quality parameters on aquatic macroinvertebrate assemblage has been reviewed systematically. This chapter underscores the importance of promoting biodiversity 22 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

through the maintenance of healthy wetlands, i.e., water-quality monitoring and control aspects, and beneficial and sustainable ecosystem services that have consequences for human health, i.e., disease vector regulations.


Nanotechnology Solutions for Global Water Challenges The rapid and continued growth in the area of nanomaterial-based devices offers significant promise for addressing future water quality challenges (Chapter 18). Meager availability of clean and safe drinking water is responsible for more deaths than war, terrorism, and weapons of mass destruction combined. This suggests that contaminated water poses a significant threat to human health and welfare. Additionally, standard water disinfection approaches such as sedimentation, filtration, and chemical or biological degradation are not fully capable of destroying emerging contaminants (e.g., pesticides and pharmaceutical waste products) or certain types of bacteria (e.g., Cryptosporidium parvum). Nanomaterials and nanotechnology-based devices can potentially be employed to solve the challenges posed by various contaminants and microorganisms. Nanomaterials of different shapes, namely nanoparticles, nanotubes, nanowires and fibers, have the ability to function as adsorbents and catalysts. They have an expansive array of physicochemical characteristics, making them highly attractive for the production of reactive media for water membrane filtration, a vital step in the production of potable water. As a result of their exceptional adsorptive capacity for water contaminants, grapheme-based nanomaterials have emerged as a subject of significant importance in the area of membrane filtration and water treatment. Also, advanced oxidation processes, with or without sources of light irradiation or ultrasound, have been found to be a promising option for water treatment at near ambient temperatures and pressures. Furthermore, the uses of visible light-active titanium dioxide photocatalysts and photo-Fenton processes have shown a significant potential for water purification. A wide variety of nanomaterial- based sensors for monitoring water quality are also reviewed in detail.

Sustaining Water Resources: A Global Imperative Global freshwater is finite, and its supply is severely strained by competing forces of an expanding world population on the one hand and alterations in the water cycle as a result of climate change on the other (Chapter 19). A range of regional concerns regarding freshwater use have been identified and must be addressed in order to maintain the sustainability of this precious resource. Rigorous conservation methods constitute an essential approach, whether this involves farm use, electric power generation, all related emerging energy technologies, or domestic use. Innovative technologies such as water reuse, desalination, and additional water storage infrastructure to replenish groundwater supplies are effective in providing restorative measures to augment world water 23 In Water Challenges and Solutions on a Global Scale; Ahuja, Satinder, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

supplies. But water is unevenly distributed globally, resulting in water-deprived regions with no available safe water. As demand for water intensifies, regional integration will provide benefits of enhanced security of supply, improved public health, more reliable food supply, and better economic efficiency.


Conclusions A variety of water challenges are faced by various countries globally. Some of the challenges and solutions have been highlighted here. It is important to remember that water pollution in our modern society is inevitable. We need to improve monitoring of point and nonpoint source pollution. Furthermore, it is important to use effective safety measures that can prevent further pollution. Rain and snow are nature’s way of recycling water; however, rain and snow are now usually contaminated with various pollutants that we have added to the atmosphere. It is still desirable to collect rainwater and use it for a variety of purposes. To achieve water sustainability, water must be used judiciously, and production of wastewater should be minimized. Some water reclamation methods are covered here. Diverse solutions are essential for different countries; recognition of various solutions that have been found can help both developing and developed countries.

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