Freshwater pollution examples. Pollution of water, an important component of all life on Earth, is a global problem.

Humanity uses mainly fresh water for its needs. Their volume is slightly more than 2% of the hydrosphere, and distribution water resources By to the globe extremely uneven. Europe and Asia, where 70% of the world's population lives, contain only 39% of river waters. The total consumption of river waters is increasing from year to year in all regions of the world. It is known, for example, that since the beginning of this century, consumption fresh water increased by 6 times, and in the next few decades will increase by at least another 1.5 times.
The lack of water is aggravated by the deterioration of its quality. Water used in industry, agriculture and everyday life returns to water bodies in the form of poorly treated or completely untreated wastewater.
Thus, pollution of the hydrosphere occurs primarily as a result of the discharge of industrial, agricultural and domestic wastewater into rivers, lakes and seas. According to scientists' calculations, at the end of the twentieth century, 25 thousand cubic km may be required to dilute this wastewater. fresh water, or almost all actually available resources of such flow! It is not difficult to guess that it is precisely this, and not the growth of direct water intake, that is responsible for the main reason worsening fresh water problems.
Currently, many rivers are heavily polluted - the Rhine, Danube, Seine, Ohio, Volga, Dnieper, Dniester, etc. Pollution of the world's oceans is growing. Moreover, not only wastewater pollution plays a significant role here, but also the release of large quantities of petroleum products into the waters of the seas and oceans. In general, the most polluted inland seas are the Mediterranean, Northern, Baltic, Inland Japan, Java, as well as the Biscay, Persian and Mexican Gulfs.
In addition, humans transform the waters of the hydrosphere through the construction of hydraulic structures, in particular reservoirs. Large reservoirs and canals have a serious negative impact on the environment: they change the groundwater regime in the coastal strip, affect soils and plant communities, and, after all, their water areas occupy large areas of fertile land.
The most important anthropogenic processes of water pollution are runoff from industrial-urbanized and agricultural areas, precipitation of products of anthropogenic activity. This process pollutes not only surface waters (drainless reservoirs and inland seas, watercourses), but also the underground hydrosphere (artesian basins, hydrogeological massifs), and the World Ocean (especially water areas and shelves). On continents, the greatest impact is on the upper aquifers (ground and pressure), which are used for domestic and drinking water supply.
Accidents of oil tankers and oil pipelines can be a significant factor in the sharp deterioration of the environmental situation on sea coasts and water areas, in inland water systems. There is a tendency for these accidents to increase in last decade.
The range of substances that pollute water is very wide, and the forms of their occurrence are varied. The main pollutants associated with natural and anthropogenic processes of pollution of the aquatic environment are largely similar. The difference is that as a result of anthropogenic activities, significant quantities of such extremely hazardous substances, like pesticides, artificial radionuclides. In addition, many pathogenic and disease-causing viruses, fungi, and bacteria are of artificial origin.
In agricultural areas with high agricultural load, a noticeable increase in phosphorus compounds in surface waters was detected. There has also been an increase in persistent pesticides in surface and groundwater.

Introduction

1. The essence of the clean water problem

1.1 Declining freshwater supplies

1.2 Water pollution from domestic, agricultural and industrial wastewater

1.3 Thermal water pollution

1.4 Oil pollution of the oceans

1.5 Other water pollution

2. Possible solutions

2.1 Water purification

2.2 Water reuse

2.3 Desalination of salt waters

Conclusion

List of sources used

Application

INTRODUCTION

One could perhaps say that

a person's purpose

is to

destroy your family

first making a globe

unsuitable for habitation.

J.-B. Lamarck

Once upon a time, people were content with the water they found in rivers, lakes, streams and wells. But with the development of industry and population growth, it became necessary to manage the water supply much more carefully in order to avoid harm to human health and damage environment.

A previously inexhaustible resource - fresh, clean water - is becoming exhaustible. Today, water suitable for drinking, industrial production and irrigation is in short supply in many areas of the world. Already, 20 thousand people die annually due to dioxin pollution of water bodies in Russia.

The topic I have chosen is currently more relevant than ever, because if not us, then our children will definitely feel the full impact of anthropogenic environmental pollution. However, if you recognize the problem in time and follow the ways to solve it, then an environmental disaster can be avoided.

The purpose of this work is to get acquainted with the problem of clean water as a global environmental problem. Significant attention will be paid to the causes, environmental consequences and possible ways to solve this problem.

1. The essence of the clean water problem

Among the chemical compounds that a person encounters in his daily life, water is perhaps the most familiar and at the same time the strangest. Its amazing properties have always attracted the attention of scientists, and in last years In addition, they became a reason for various pseudo-scientific speculations. Water is not a passive solvent, as is commonly believed, it is an active actor in molecular biology; When it freezes, it expands rather than shrinks in volume like most liquids, reaching its greatest density at 4°C. So far, none of the theorists working on general theory liquids, is no closer to describing its strange properties.

Weak hydrogen bonds deserve special mention, thanks to which water molecules form quite complex structures for a short time. An article by Lars Pettersson and his colleagues from Stockholm University, published in 2004 in the journal Science, caused a lot of noise. In particular, it was stated that each water molecule is connected by hydrogen bonds to exactly two others. Because of this, chains and rings appear, with a length of the order of hundreds of molecules. It is along this path that researchers hope to find a rational explanation for the strangeness of water.

But for the inhabitants of our planet, this is not what is primarily interesting about water: without clean drinking water, they will all simply die out, and its availability becomes more and more problematic over the years. According to the World Health Organization (WHO), currently 1.2 billion people do not have enough water, and millions of people die every year from diseases caused by substances dissolved in water. In January 2008, at the UN World Economic Forum (World Economic Forum Annual Meeting 2008), held in Switzerland, it was stated that by 2025, the population of more than half of the world's countries will lack clean water, and by 2050 - 75%.

The problem of clean water is looming from all sides: for example, scientists suggest that in the next 30 years the melting of glaciers (one of the main reserves of fresh water on Earth) will lead to strong jumps in the level of many large rivers, such as the Brahmaputra, Ganges, Yellow River, which will put One and a half billion people in Southeast Asia are at risk of drinking water shortages. At the same time, the flow of water, for example, from the Yellow River is already so great that it periodically does not reach the sea.

1.1 Declining freshwater reserveswater

Fresh water resources exist thanks to the eternal water cycle. As a result of evaporation, a gigantic volume of water is formed, reaching 525 thousand km3 per year. 86% of this amount comes from the salty waters of the World Ocean and inland seas - the Caspian, Aral, etc.; the rest evaporates on land, half due to transpiration of moisture by plants. Every year, a layer of water approximately 1250 mm thick evaporates. Some of it falls again with precipitation into the ocean, and some is carried by winds to land and here feeds rivers and lakes, glaciers and The groundwater. A natural distiller is powered by the energy of the Sun and takes approximately 20% of this energy.

Only 2% of the hydrosphere is fresh water, but it is constantly renewed. The rate of renewal determines the resources available to humanity. Most of the fresh water (85%) is concentrated in the ice of the polar zones and glaciers. The rate of water exchange here is less than in the ocean and amounts to 8000 years. Surface waters on land renew themselves approximately 500 times faster than in the ocean. River waters are renewed even faster, in about 10-12 days. Fresh waters from rivers are of greatest practical importance to humanity.

Rivers have always been a source of fresh water. But in modern era they began to transport waste. Waste in the catchment area flows along river beds into the seas and oceans. Most of the used river water is returned to rivers and reservoirs in the form of wastewater. Until now, the growth of wastewater treatment plants has lagged behind the growth of water consumption. And at first glance, this is the root of evil. In reality, everything is much more serious. Even with the most advanced purification, including biological, all dissolved inorganic substances and up to 10% of organic pollutants remain in treated wastewater. Such water can again become suitable for consumption only after repeated dilution with pure natural water. And here the ratio of the absolute amount of wastewater, even purified, and the water flow of rivers is important for people.

The global water balance showed that 2,200 km of water per year is spent on all types of water use. Effluent dilution consumes almost 20% of the world's freshwater resources. Calculations for 2000, assuming that water consumption standards will decrease and treatment will cover all wastewater, showed that 30-35 thousand km3 of fresh water will still be required annually to dilute wastewater. This means that the world's total river flow resources will be close to exhaustion, and in many areas of the world they are already exhausted. After all, 1 km3 of treated wastewater “spoils” 10 km3 of river water, and untreated waste water spoils 3-5 times more. The amount of fresh water does not decrease, but its quality drops sharply and it becomes unsuitable for consumption.

Humanity will have to change its water use strategy. Necessity forces us to isolate the anthropogenic water cycle from the natural one. In practice, this means a transition to a closed water supply, to low-water or low-waste, and then to “dry” or non-waste technology, accompanied by a sharp reduction in the volume of water consumption and treated wastewater.

Fresh water reserves are potentially large. However, in any area of ​​the world they can be depleted due to unsustainable water use or pollution. The number of such places is growing, covering entire geographic areas. Water needs are unmet for 20% of the world's urban and 75% of the rural population. The volume of water consumed depends on the region and standard of living and ranges from 3 to 700 liters per day per person.

Industrial water consumption also depends on economic development of this area. For example, in Canada, industry consumes 84% ​​of all water withdrawals, and in India - 1%. The most water-intensive industries are steel, chemicals, petrochemicals, pulp and paper and food processing. They consume almost 70% of all water spent in industry (see appendix). On average, industry uses approximately 20% of all water consumed worldwide. The main consumer of fresh water is agriculture: 70-80% of all fresh water is used for its needs. Irrigated agriculture occupies only 15-17% of agricultural land, but produces half of all production. Almost 70% of the world's cotton crops depend on irrigation.

The total flow of rivers in the CIS (USSR) per year is 4,720 km. But water resources are distributed extremely unevenly. In the most populated regions, where up to 80% of industrial production resides and 90% of land suitable for agriculture is located, the share of water resources is only 20%. Many areas of the country are insufficiently supplied with water. These are the south and southeast of the European part of the CIS, the Caspian lowland, the south of Western Siberia and Kazakhstan, and some other areas Central Asia, south of Transbaikalia, Central Yakutia. The northern regions of the CIS, the Baltic states, and the mountainous regions of the Caucasus, Central Asia, Sayan Mountains and the Far East are most supplied with water.

River flows vary depending on climate fluctuations. Human intervention in natural processes has already affected river flow. In agriculture, most of the water is not returned to rivers, but is spent on evaporation and the formation of plant mass, since during photosynthesis hydrogen from water molecules is converted into organic compounds. To regulate river flow, which is not uniform throughout the year, 1,500 reservoirs were built (they regulate up to 9% of the total flow). On the flow of rivers of the Far East, Siberia and the North of the European part of the country economic activity So far it has had almost no effect on humans. However, in the most populated areas it decreased by 8%, and in rivers such as Terek, Don, Dniester and Ural by 11-20%. Water flow in the Volga, Syr Darya and Amu Darya has noticeably decreased. As a result, the water inflow to the Sea of ​​Azov decreased by 23%, and to the Aral Sea by 33%. The level of the Aral Sea dropped by 12.5 m.

Limited and even scarce freshwater supplies in many countries are being significantly reduced due to pollution. Typically, pollutants are divided into several classes depending on their nature, chemical structure and origin.

1.2 Household water pollutionmarketing, agricultural andindustrial wastes.

Organic materials come from domestic, agricultural or industrial wastewater. Their decomposition occurs under the influence of microorganisms and is accompanied by the consumption of oxygen dissolved in water. If there is enough oxygen in the water and the amount of waste is small, then aerobic bacteria quickly transform them into relatively harmless residues. Otherwise, the activity of aerobic bacteria is suppressed, the oxygen content drops sharply, and decay processes develop. When the oxygen content in water is below 5 mg per liter, and in spawning areas - below 7 mg, many fish species die.

Pathogenic microorganisms and viruses are found in poorly treated or untreated sewage from residential areas and livestock farms. When pathogenic microbes and viruses get into drinking water, they cause various epidemics, such as outbreaks of salmonelliosis, gastroenteritis, hepatitis, etc. In developed countries, the spread of epidemics through public water supplies is rare. May be infected food products, for example, vegetables grown in fields that are fertilized with sludge from domestic wastewater treatment (from German Schlamme - literally mud). Aquatic invertebrates, such as oysters or other shellfish, from contaminated water bodies were often the cause of outbreaks of typhoid fever.

Nutrients, mainly nitrogen and phosphorus compounds, enter water bodies with domestic and agricultural wastewater. An increase in the content of nitrites and nitrates in surface and groundwater leads to contamination of drinking water and the development of certain diseases, and the growth of these substances in water bodies causes their increased eutrophication (an increase in the reserves of nutrients and organic substances, due to which plankton and algae rapidly develop, absorbing all the oxygen is in the water).

Inorganic and organic substances also include heavy metal compounds, petroleum products, pesticides (pesticides), synthetic detergents (detergents), and phenols. They enter water bodies with industrial waste, domestic and agricultural wastewater. Many of them either do not decompose at all in the aquatic environment, or decompose very slowly and are capable of accumulating in food chains.

An increase in bottom sediments is one of the hydrological consequences of urbanization. Their number in rivers and reservoirs is constantly increasing due to soil erosion as a result of improper farming, deforestation, and regulation of river flow. This phenomenon leads to a disruption of the ecological balance in aquatic systems and has a detrimental effect on bottom organisms.

1.3 Thermal water pollution

The source of thermal pollution is heated waste water from thermal power plants and industry. An increase in the temperature of natural waters changes the natural conditions for aquatic organisms, reduces the amount of dissolved oxygen, and changes the metabolic rate. Many inhabitants of rivers, lakes or reservoirs die, the development of others is suppressed.

Just a few decades ago, polluted waters were like islands in a relatively clean natural environment. Now the picture has changed, continuous areas of contaminated areas have formed.

1.4 Oil pollutionWorldocean

Oil pollution of the World Ocean is undoubtedly the most widespread phenomenon. From 2 to 4% of the water surface of the Pacific and Atlantic oceans is constantly covered with an oil film. Up to 6 million tons of petroleum hydrocarbons enter sea waters annually. Almost half of this amount is associated with transportation and offshore development. Continental oil pollution enters the ocean through river runoff.

The world's rivers annually carry more than 1.8 million tons of petroleum products into sea and ocean waters.

At sea, oil pollution takes various forms. It can cover the surface of the water in a thin film, and during spills the thickness of the oil coating can initially be several centimeters. Over time, an emulsion of oil in water or water in oil is formed. Later, lumps of the heavy fraction of oil, oil aggregates, appear that can float on the surface of the sea for a long time. Various small animals are attached to the floating lumps of fuel oil, which fish and baleen whales readily feed on. Together with them they swallow oil. Some fish die from this, others are completely saturated with oil and become unfit for consumption due to the unpleasant smell and taste. .

All components of oil are toxic to marine organisms. Oil affects the community structure of marine animals. Oil pollution changes the ratio of species and reduces their diversity. Thus, microorganisms that feed on petroleum hydrocarbons develop abundantly, and the biomass of these microorganisms is toxic to many marine inhabitants. It has been proven that long-term chronic exposure to even small concentrations of oil is very dangerous. At the same time, the primary biological productivity of the sea is gradually falling. Oil has another unpleasant side effect. Its hydrocarbons are capable of dissolving a number of other pollutants, such as pesticides and heavy metals, which, together with oil, are concentrated in the surface layer and further poison it. The aromatic fraction of oil contains substances of a mutagenic and carcinogenic nature, for example benzopyrene. There is now extensive evidence of the mutagenic effects of a polluted marine environment. Benzpyrene actively circulates through marine food chains and ends up in human food.

The largest quantities of oil are concentrated in a thin near-surface layer of sea water, which plays a particularly important role for various aspects of ocean life. Many organisms are concentrated in it; this layer plays the role of a “kindergarten” for many populations. Surface oil films disrupt gas exchange between the atmosphere and the ocean. The processes of dissolution and release of oxygen, carbon dioxide, heat exchange undergo changes, and the reflectivity (albedo) of sea water changes.

Birds suffer the most from oil, especially when coastal waters are polluted. Oil sticks the feathers together, it loses its heat-insulating properties, and, in addition, a bird stained with oil cannot swim. Birds freeze and drown. Even cleaning feathers with solvents cannot save all victims. The rest of the sea's inhabitants suffer less. Numerous studies have shown that oil that gets into the sea does not create any permanent or long-term danger to organisms living in water and does not accumulate in them, so its entry into humans through the food chain is excluded.

According to the latest data, significant harm to flora and fauna can only be caused in isolated cases. For example, petroleum products made from it - gasoline, diesel fuel, and so on - are much more dangerous than crude oil. High concentrations of oil in the littoral zone (tidal zone), especially on the sandy shore, are dangerous; in these cases, the concentration of oil remains high for a long time, and it causes a lot of harm. But fortunately such cases are rare.

Usually, during tanker accidents, oil quickly spreads through the water, becomes diluted, and its decomposition begins. It has been shown that oil hydrocarbons can pass through their digestive tract and even through tissues without harm to marine organisms: such experiments were carried out with crabs, bivalves, and various types of small fish, and no harmful effects were found for experimental animals.

1.5 Other water pollution

Chlorinated hydrocarbons, widely used as means of controlling agricultural and forestry pests and carriers of infectious diseases, have been entering the World Ocean along with river runoff and through the atmosphere for many decades. DDT and its derivatives, polychlorinated biphenyls and other persistent compounds of this class are now found throughout the world's oceans, including the Arctic and Antarctic. They are easily soluble in fats and therefore accumulate in the organs of fish, mammals, and seabirds. Being xenobiotics, i.e. substances of completely artificial origin, they do not have their “consumers” among microorganisms and therefore almost do not decompose under natural conditions, but only accumulate in the World Ocean. At the same time, they are acutely toxic, affect the hematopoietic system, suppress enzymatic activity, and greatly affect heredity.

Along with river runoff, heavy metals also enter the ocean, many of which have toxic properties. The total river flow is 46 thousand km of water per year. Together with it, up to 2 million tons of lead, up to 20 thousand tons of cadmium and up to 10 thousand tons of mercury enter the World Ocean. Most high levels coastal waters and inland seas are polluted. The atmosphere also plays a significant role in the pollution of the World Ocean. For example, up to 30% of all mercury and 50% of lead entering the ocean each year is transported through the atmosphere. Due to its toxic effects in the marine environment, mercury is particularly dangerous. Microbiological processes convert toxic inorganic mercury into much more toxic organic forms of mercury. Methylated mercury compounds accumulated due to bioaccumulation in fish or shellfish pose a direct threat to human life and health. Let us recall, for example, the notorious “minamato” disease, which received its name from the Gulf of Japan, where mercury poisoning of local residents manifested itself so dramatically. It claimed many lives and undermined the health of many people who ate seafood from this bay, at the bottom of which a lot of mercury accumulated from the waste of a nearby plant. Mercury, cadmium, lead, copper, zinc, chromium, arsenic and other heavy metals not only accumulate in marine organisms, thereby poisoning marine food, but also have a detrimental effect on sea inhabitants. The accumulation coefficients of toxic metals, i.e. their concentration per unit weight in marine organisms relative to seawater, vary widely - from hundreds to hundreds of thousands, depending on the nature of the metals and the types of organisms. These coefficients show how harmful substances accumulate in fish, shellfish, crustaceans, planktonic and other organisms. The scale of pollution of sea and ocean products is so great that many countries have established sanitary standards for the content of certain harmful substances in them. It is interesting to note that with mercury concentrations in water only 10 times higher than natural levels, oyster contamination already exceeds the limits set in some countries. This shows how close the limit of sea pollution is that cannot be crossed without harmful consequences for human life and health.

2. Possible solutions

In order to avoid a water crisis, new technologies are being developed for water purification and disinfection, desalination, as well as methods for its reuse. However, in addition to scientific research, effective methods for organizing control over the water resources of countries are needed: unfortunately, in most countries, several organizations are involved in the use and planning of water resources (for example, in the USA, more than twenty different federal agencies). This topic became the main topic for the issue dated March 19, 2007 scientific journal Nature. In particular, Mark Shannon and his colleagues from the University of Illinois at Urbana-Champaign (USA) reviewed new scientific developments and next-generation systems in the following areas: water disinfection and pathogen removal without the use of excessive amounts of chemical reagents and the formation of toxic by-products products; detection and removal of low concentration pollutants; reuse of water, as well as desalination of sea and inland water. Importantly, these technologies must be relatively inexpensive and suitable for use in developing countries.

2.1 Water purification

Disinfection is especially important in developing countries of Southeast Asia and Sub-Saharan Africa: it is there that pathogens living in water most often cause widespread illness. Along with pathogenic organisms such as helminths (worms), protozoa, fungi and bacteria, viruses and prions pose an increased danger. Free chlorine, the most common disinfectant in the world (as well as the cheapest and one of the most effective), works well against intestinal viruses, but is powerless against diarrhea-causing cryptosporidium C. parvum or mycobacteria. The situation is complicated by the fact that many pathogens live in thin biofilms on the walls of water pipes.

New effective disinfection methods must consist of several barriers: removal using physicochemical reactions (for example, coagulation, sedimentation or membrane filtration) and neutralization using ultraviolet light and chemical reagents. Relatively recently, visible spectrum light has again begun to be used for photochemical neutralization of pathogens, and in some cases, combining UV with chlorine or ozone is effective. True, this approach sometimes causes the appearance of harmful by-products: for example, the carcinogen bromate may appear from the action of ozone in water containing bromide ions.

In India, where the need for water disinfection is felt quite acutely, Javel water is used for these purposes.

In developing countries, technology is used to disinfect water in polyethylene terephthalate (PET) bottles using firstly sunlight and secondly sodium hypochloride (this method is used mainly in rural areas). Thanks to chlorine, it was possible to reduce the incidence of gastrointestinal diseases, but in areas where the water contains ammonia and organic nitrogen, the method does not work: chlorine forms compounds with these substances and becomes inactive.

It is expected that in the future, disinfection methods will include the action of ultraviolet radiation and nanostructures. Ultraviolet radiation is effective in combating bacteria living in water and protozoan cysts, but has no effect on viruses. However, ultraviolet light can activate photocatalytic compounds, such as titanium (TiO2), which in turn can kill viruses. In addition, new compounds, such as TiO2 with nitrogen (TiON) or with nitrogen and some metals (palladium), can be activated by radiation in the visible part of the spectrum, which requires less energy than irradiation with ultraviolet light, or even just sunlight. True, such disinfection installations have extremely low productivity.

Another important task in water purification is the removal of harmful substances from it. There are a huge number of toxic substances and compounds (such as arsenic, heavy metals, halogenated aromatic compounds, nitrosamines, nitrates, phosphates and many others). The list of substances suspected of being harmful to health is constantly growing, and many of them are toxic even in minute quantities. Detecting these substances in water and then removing them in the presence of other, non-toxic impurities, the content of which can be an order of magnitude higher, is difficult and expensive. And among other things, this search for one toxin may interfere with the discovery of another, more dangerous one. Methods for monitoring pollutants inevitably involve the use of sophisticated laboratory equipment and the use of qualified personnel, so it is very important to find inexpensive and relatively simple ways identification of contamination.

A kind of “specialization” is also important here: for example, arsenic trioxide (As-III) is 50 times more toxic than pentoxide (As-V), and therefore it is necessary to measure their content both together and separately for subsequent neutralization or removal. Existing measurement methods either have a low accuracy limit or require qualified specialists.

Scientists believe that a promising direction in the development of methods for detecting harmful substances is the method of molecular recognition motif, based on the use of sensor reagents (like litmus paper familiar from school), together with micro/nanofluidic manipulation and telemetry. Similar biosensor methods can be applied to pathogenic microorganisms living in water. However, in this case, it is necessary to monitor the presence of anions in the water: their presence can neutralize methods that are quite effective - under other conditions. Thus, when treating water with ozone, bacteria die, but if there are Br- ions in the water, oxidation to BrO3- occurs, that is, one type of pollution changes to another.

water from the opposite side. In accordance with the laws of hydrostatics, water seeps through the membrane, purifying itself onto the road. In general, there are two ways to combat harmful substances - influencing the micropollutant using chemical or biochemical reagents until it turns into a non-hazardous form, or removing it from the water. This issue is resolved depending on the location. Thus, Sono filtration technology is used in wells in Bangladesh, and reverse osmosis is used in factories in the USA to solve the same problem - removing arsenic from water.

Reverse osmosis system used in the USA: the water pressure on the side of the synthetic membrane where the pollutants are located exceeds the pressure of clean water on the opposite side. In accordance with the laws of hydrostatics, water seeps through the membrane, purifying itself onto the road.

Currently, they are trying to convert organic harmful substances in water through reactions into harmless nitrogen, carbon dioxide and water. Serious anionic contaminants such as nitrates and perchlorates are removed using ion exchange resins and reverse osmosis, and toxic brines are disposed of in storage. In the future, bimetallic catalysts may be used to mineralize these brines, as well as active nanocatalysts in membranes to transform anions.

2.2 Water reuse

Nowadays, environmentalists are passionately dreaming of reusing industrial and municipal wastewater, previously treated to drinking water quality. But in this case, you have to deal with a huge number of all kinds of pollutants and pathogens, as well as organic substances that must be removed or transformed into harmless compounds. Consequently, all operations become more expensive and more complicated.

Municipal wastewater is typically treated in treatment plants, where microbes are suspended to remove organic matter and food residues, and then in settling tanks, where solids and liquids are separated. Water after such purification can be discharged into surface water bodies, and can also be used for limited irrigation and for some factory needs. Currently, one of the actively implemented technologies is membrane bioreactors. This technology combines the use of biomass suspended in water (as in conventional wastewater treatment plants) and aqueous micro- and ultra-thin membranes instead of settling tanks. Water from MBR can be freely used for irrigation and industrial needs.

MBRs can also be of great benefit in developing countries with poor sanitation, especially in fast-growing megacities: they can directly treat wastewater, separating useful substances from it, clean water, nitrogen and phosphorus. MBRs are also used as water pre-treatment for reverse osmosis; if you then treat it with UV (or photocatalytic substances that react to visible light), then it will be suitable for drinking. In the future, it is possible that "water reuse" systems will consist of only two stages: an MBR with a nanofiltration membrane (eliminating the need for a reverse osmosis step) and a photocatalytic reactor, which will serve as a barrier to pathogens and destroy organic pollutants with little molecular weight. True, one of the serious obstacles is the rapid clogging of the membrane, and the success of the development of this direction of water purification largely depends on new modifications and properties of membranes.

Environmental laws also pose a significant barrier: in many countries, the reuse of water for municipal purposes is strictly prohibited. However, due to the lack of water resources, this is also changing: for example, in the United States, water reuse is increasing by 15% annually.

2.3 Desalination of salt water

Increasing fresh water reserves by desalinating the waters of seas, oceans and saline inland waters is a very tempting goal, because these reserves make up 97.5% of all water on Earth. Desalination technologies have come a long way, especially over the past decade, but they still require a lot of energy and capital investment, which has held back their expansion. Most likely, the share of large water desalination plants using the traditional (thermal) method will decrease: they consume too much energy and suffer greatly from corrosion.

It is assumed that the future lies in small desalination systems designed for one or several families (this applies mainly to developing countries).

Modern desalination technologies use reverse osmosis membrane separation and temperature distillation. Limiting factors for the development of desalination are, as already mentioned, high energy consumption and operating costs, rapid fouling of plant membranes, as well as the problem of brine disposal and the presence of residual low molecular weight pollutants in water, such as boron.

The prospects for research in this direction are determined primarily by a reduction in specific energy costs, and here some progress is evident: if in the 1980s they averaged 10 kWh/m3, now they have decreased to 4 kWh/m3. But there are other important advances: the creation of new materials for membranes (for example, from carbon nanotubes), as well as the creation of new purification biotechnologies.

It remains to be hoped that in coming years science and technology will really make a big step forward - after all, even while still remaining almost invisible to many, the specter of a water crisis has long been wandering not only across Europe, but throughout the world.

CONCLUSION

The problem of ensuring adequate quantity and quality of water is one of the most important and has global significance.

Currently, humanity uses 3.8 thousand km3 of water annually, and consumption can be increased to a maximum of 12 thousand km3. At the current rate of growth in water consumption, this will be enough for the next 25-30 years. Pumping out groundwater leads to subsidence of soil and buildings (Mexico City, Bangkok) and a drop in groundwater levels by tens of meters (Manila).

Since the population on Earth is constantly increasing, the need for clean fresh water is also constantly increasing. Already at the present time, a lack of fresh water is experienced not only by territories that nature has deprived of water resources, but also by many regions that until recently were considered prosperous in this regard. Currently, the need for fresh water is not met for 20% of the urban and 75% of the rural population of the planet.

The limited supply of fresh water is further reduced due to pollution.

The main danger is wastewater (industrial, agricultural and domestic). The latter, getting into surface and underground water sources, pollute them with harmful toxic impurities that are dangerous to human health, as a result of which already limited fresh water reserves are reduced. Man needs clean, high-quality fresh water, and only he can preserve its reserves.

LISTUSEDSOURCES

1. Materials of the scientific journal Nature for 2007

2. Artamonov, V. I. Plants and purity natural environment. - M.: Nauka, 1986. - 206 s.

3. Nikoladze, G. I. Technology of natural water purification. - M.: Graduate School, 1987. - 132 p.

4. Podosenova, E. V. Technical means of environmental protection. - M., 1980. - 158 p.

5. Voronkov, N. A. Ecology. - M.: Agar, 2000. - 257 p.

How humans pollute the hydrosphere, you will learn from this article.

How does a person pollute water?

Hydrosphere is an aquatic environment that includes groundwater and surface water. Today, man's activities have led to massive water pollution.

Main types of pollution:

• Pollution from petroleum products and oil. Oil stains prevent entry sun rays into the water column, and slows down the process of photosynthesis.
• Wastewater pollution due to mineral and organic fertilizer soil and industrial production. Algae in water bodies begin to actively reproduce and lead to waterlogging and death of other ecosystems.
• Pollution with heavy metal ions.
• Acid rain.
• Radioactive contamination.
• Thermal pollution. Emissions from nuclear power plants and thermal power plants contribute to the development of blue-green algae and water blooms.
• Mechanical contamination.
• Biological and bacterial contamination promotes the development of pathogenic organisms and fungi.

How do people pollute the ocean and seas?

Every year more than 10 million tons of oil enter the Ocean. Today, about 20% of its area is covered with an oil film. The problem of pollution from industrial waste and household waste is especially acute. Often, marine inhabitants swallow plastic and bags and die either from suffocation or from the fact that this garbage gets stuck in the body. A serious environmental threat to the world's oceans and seas is the human burial of radioactive waste and the dumping of radioactive liquid waste.

How do people pollute rivers and lakes?

In the process of human industrial activity, the waters of lakes and rivers receive a large number of petroleum products, waste water, radioactive liquid substances. Pesticides are especially dangerous. Once in the water, they instantly dissipate and reach a maximum degree of concentration. Waste from nuclear fuel and weapons-grade plutonium destroys the fauna of these water bodies.

How do people pollute groundwater?

They suffer greatly from oil fields, filtration fields, the mining industry, slag dumps, chemical fertilizer and waste storage facilities, metallurgical plant dumps, and sewers. As a result, groundwater is polluted with phenols, copper, zinc, petroleum products, nickel, mercury, sulfates, and chlorides.

We hope that from this article you learned how people pollute water.

For a long time, the problem of water pollution was not acute for most countries. The available resources were sufficient to meet the needs of the local population. As industry grew and the amount of water used by humans increased, the situation changed dramatically. Now the issues of its purification and preservation of quality are dealt with at the international level.

Methods for determining the degree of contamination

Water pollution is usually understood as a change in its chemical or physical composition or biological characteristics. This determines restrictions on further use of the resource. Freshwater pollution deserves great attention, because its purity is inextricably linked to the quality of life and human health.

In order to determine the condition of water, a number of indicators are measured. Among them:

• color;
• degree of turbidity;
• smell;
• pH level;
• content of heavy metals, trace elements and organic substances;
• Escherichia coli titer;
• hydrobiological indicators;
• the amount of oxygen dissolved in water;
• oxidability;
• presence of pathogenic microflora;
• chemical oxygen consumption, etc.

In almost all countries there are supervisory authorities that must determine the quality of the contents at certain intervals, depending on the degree of importance of the pond, lake, river, etc. If deviations are detected, the reasons that could provoke water pollution are identified. Then measures are taken to eliminate them.

What causes resource pollution?

There are many reasons that can cause water pollution. This is not always associated with human or industrial activities. Natural disasters that occur periodically in different areas can also disrupt environmental conditions. The most common reasons are considered to be:

• Domestic and industrial wastewater. If they do not go through a synthetic purification system, chemical elements and organic substances, then, when they get into water bodies, they can provoke a water-ecological disaster.
• . This problem is not talked about so often as not to provoke social tension. But exhaust gases that enter the atmosphere after emissions from motor vehicles and industrial enterprises, along with rain, end up on the ground, polluting the environment.
• Solid waste that can not only change the state of the biological environment in a reservoir, but also the flow itself. This often leads to floods of rivers and lakes and obstructed flow.
• Organic pollution associated with human activity, natural decomposition of dead animals, plants, etc.
• Industrial accidents and man-made disasters.
• Floods.
• Thermal pollution associated with the production of electrical and other energy. In some cases, the water heats up to 7 degrees, which causes the death of microorganisms, plants and fish, which require a different temperature regime.
• Avalanches, mudflows, etc.

In some cases, nature itself is capable of purifying water resources over time. But the period of chemical reactions will be long. Most often, the death of reservoir inhabitants and the pollution of fresh water cannot be prevented without human intervention.

The process of moving pollutants in water

If we are not talking about solid waste, then in all other cases pollutants can exist:

• in a dissolved state;
• in suspension.

They may be droplets or fine particles. Biopollutants are observed in the form of living microorganisms or viruses.

If solid particles get into the water, they will not necessarily settle at the bottom. Depending on the current and storm phenomena, they are able to rise to the surface. An additional factor is the composition of the water. In the sea, it is almost impossible for such particles to sink to the bottom. As a result of the current, they easily move over long distances.

Experts point out that due to changes in current directions in coastal areas, the level of pollution is traditionally higher.

Regardless of the type of pollutant, it can enter the body of fish that live in a reservoir, or birds that look for food in the water. If this does not lead to the direct death of the creature, it can affect the further food chain. There is a high probability that this is how water pollution poisons people and worsens their health.

Main results of the impact of pollution on the environment

Regardless of whether the pollutant enters the body of a person, fish, or animal, a protective reaction is triggered. Some types of toxins can be neutralized by immune cells. In most cases, a living organism requires help in the form of treatment so that the processes do not become serious and lead to death.

Scientists determine the following indicators of poisoning, depending on the source of pollution and its influence:

• Genotoxicity. Heavy metals and other trace elements can damage and change the structure of DNA. As a result, serious problems are observed in the development of a living organism, the risk of diseases increases, etc.
• Carcinogenicity. Oncology problems are closely related to what kind of water people or animals consume. The danger lies in the fact that a cell, having turned into a cancerous one, can quickly degenerate the rest in the body.
• Neurotoxicity. Many metals and chemicals can affect nervous system. Everyone knows the phenomenon of whale strandings, which are provoked by such pollution. The behavior of sea and river inhabitants becomes inadequate. They are not only capable of killing themselves, but also begin to devour those who were previously uninteresting to them. When chemicals enter the human body with water or food from such fish and animals, they can cause a slowdown in brain reactions, destruction of nerve cells, etc.
• Violation of energy exchange. By affecting mitochondria in cells, pollutants can alter energy production processes. As a result, the body stops performing active actions. Lack of energy can cause death.
• Reproductive failure. If water pollution causes the death of living organisms not so often, then it can affect health in 100 percent of cases. Scientists are especially concerned that their ability to reproduce a new generation is being lost. Solving this genetic problem can be difficult. Artificial renewal of the aquatic environment is required.

How does water control and purification work?

Realizing that fresh water pollution threatens human existence, government agencies at the national and international levels create requirements for the activities of enterprises and the behavior of people. These frameworks are reflected in documents regulating water control procedures and the operation of treatment systems.

The following cleaning methods are distinguished:

• Mechanical or primary. Its task is to prevent large objects from entering water bodies. To do this, special gratings and filters are installed on the pipes through which the waste flows, trapping it. It is necessary to clean the pipes in a timely manner, otherwise the blockage may cause an accident.
• Specialized. Designed to capture pollutants of one type. For example, there are traps for grease, oil spills, and flocculent particles that are precipitated using coagulants.
• Chemical. Implies that wastewater will be reused in a closed cycle. Therefore, knowing their output composition, they select chemicals that can return the water to its original state. This is usually process water, not drinking water.
• Tertiary treatment. So that water can be used in everyday life, agriculture, Food Industry, its quality must be impeccable. To do this, it is treated with special compounds or powders that can retain heavy metals during multi-stage filtration, harmful microorganisms and other substances.

In everyday life, more and more people are trying to install powerful filters that eliminate pollution caused by old communications and pipes.

Diseases that can be caused by dirty water

Until it became clear that infectious agents and bacteria can enter the body with water, humanity was faced with. After all, epidemics that were observed periodically in one country or another claimed the lives of hundreds of thousands of people.

The most common diseases that can result from bad water include:

• cholera;
• enterovirus;
• giardiasis;
• schistosomiasis;
• amoebiasis;
• congenital deformities;
• mental abnormalities;
• intestinal disorders;
• gastritis;
• skin lesions;
• burns of mucous membranes;
• oncological diseases;
• decreased reproductive function;
• endocrine disorders.

Purchasing bottled water and installing filters is a means of disease prevention. Some use silver objects, which also partially disinfect the water.

Water pollution can change the planet and make the quality of life completely different. That is why the issue of preserving reservoirs is constantly raised by environmental organizations and research centers. This allows you to attract the attention of enterprises, the public, and government agencies to existing problems and stimulate the beginning of active actions to prevent a disaster.

Water pollution is a decrease in its quality as a result of various physical, chemical or biological substances entering rivers, streams, lakes, seas and oceans. Water pollution has many causes.

Wastewater

Industrial wastewater containing inorganic and organic waste often discharges into rivers and seas. Every year in water sources thousands fall chemical substances, the effect of which on the environment is not known in advance. Hundreds of these substances are new compounds. Although industrial wastewater is often pre-treated, it still contains toxic substances that are difficult to detect.

Domestic wastewater containing, for example, synthetic detergents eventually ends up in rivers and seas. Fertilizers washed off the soil surface end up in drains leading to lakes and seas. All these reasons lead to severe water pollution, especially in closed lakes, bays and fjords.

Solid waste. If there is a large amount of suspended solids in the water, they make it opaque to sunlight and thereby interfere with the process of photosynthesis in water bodies. This in turn causes disturbances in the food chain in such pools. In addition, solid waste causes siltation in rivers and shipping channels, necessitating frequent dredging.

Eutrophication. Industrial and agricultural wastewater that enters water sources contains high levels of nitrates and phosphates. This leads to oversaturation of closed reservoirs with fertilizing substances and causes increased growth of protozoan algae microorganisms in them. Blue-green algae grows especially strongly. But, unfortunately, it is inedible for most fish species. The growth of algae causes more oxygen to be absorbed from the water than can be naturally produced in the water. As a result, the WIC of such water increases. The release of biological wastes, such as wood pulp or untreated sewage water, into water also increases the WPC. Other plants and living things cannot survive in such an environment. However, microorganisms that are capable of decomposing dead plant and animal tissues multiply rapidly in it. These microorganisms absorb even more oxygen and form even more nitrates and phosphates. Gradually, the number of plant and animal species in such a reservoir decreases significantly. The most important victims of the ongoing process are fish. Ultimately, the decrease in oxygen concentration due to the growth of algae and microorganisms that decompose dead tissue leads to the aging of lakes and their waterlogging. This process is called eutrophication.

A classic example of eutrophication is Lake Erie in the USA. Over 25 years, the nitrogen content in this lake has increased by 50%, and the phosphorus content by 500%. The cause was mainly the entry into the lake of household wastewater containing synthetic detergents. Synthetic detergents contain a lot of phosphates.

Wastewater treatment is ineffective because it removes only solids and only a small proportion of dissolved nutrients from the water.

Toxicity of inorganic waste. The discharge of industrial wastewater into rivers and seas leads to an increase in the concentration of toxic ions of heavy metals, such as cadmium, mercury and lead. A significant part of them is absorbed or adsorbed by certain substances, and this is sometimes called the self-purification process. However, in closed pools, heavy metals can reach dangerously high levels.

Most famous case this kind occurred in Minamata Bay in Japan. Industrial wastewater containing methyl mercury acetate was discharged into this bay. As a result, mercury began to enter the food chain. It was absorbed by algae, which were eaten by shellfish; Fish ate shellfish, and fish was eaten by the local population. The mercury content in fish turned out to be so high that it led to the appearance of children with congenital deformities and deaths. This disease is called Minamata disease.

Increased nitrate levels observed in drinking water are also of great concern. It is suggested that high content Nitrates in water can lead to stomach cancer and cause increased child mortality.

However, the problem of water pollution and unsanitary conditions is not limited to developing countries. A quarter of the entire Mediterranean coastline is considered dangerously polluted. According to the pollution report Mediterranean Sea, published in 1983 as part of the United Nations Environment Programme, eating shellfish and lobsters caught there is unsafe for health. Typhoid, paratyphoid, dysentery, polio, viral hepatitis and food poisoning are common in this region, and cholera outbreaks occur periodically. Most of these diseases are caused by the discharge of untreated sewage into the sea. It is estimated that 85% of waste from 120 coastal cities is dumped into the Mediterranean Sea, where holidaymakers and tourists swim and fish. local residents. Between Barcelona and Genoa every mile coastline accounts for approximately 200 tons of waste discharged per year.

Pesticides

The most toxic pesticides are halogenated hydrocarbons, such as DDT and polychlorinated biphenyls. Although DDT has already been banned for use in many countries, it is still used in others, and approximately 25% of the amount used reaches the sea. Unfortunately, these halogenated hydrocarbons are chemically stable and cannot be decomposed by microorganisms. Therefore, they accumulate in the food chain. DDT can destroy all life on the scale of entire river basins; it also prevents birds from breeding.

Oil leak

In the United States alone, approximately 13,000 oil spills occur annually. Up to 12 million tons of oil enter seawater annually. In the UK, over 1 million tons of used engine oil are poured down the drain every year.

Oil spilled into sea water has many adverse effects on sea life. First of all, birds die - they drown, overheat in the sun or are deprived of food. Oil blinds animals living in the water - seals and seals. It reduces the penetration of light into enclosed bodies of water and can increase water temperature. This is especially destructive for organisms that can exist only in a limited temperature range. Oil contains toxic components, such as aromatic hydrocarbons, that are harmful to some forms of aquatic life even in concentrations as low as a few parts per million.

O.V.Mosin