Environmental problems of natural and waste waters articles. Global environmental problems

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, thousands of chemicals enter water sources, 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 and ponds.

Solid waste.

If there is a large number of suspended solids, they make it opaque to sunlight and thereby interfere with the process of photosynthesis in water basins. 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.

In industrial and agricultural Wastewater ah, which enter water sources, have a high content of nitrates and phosphates. This leads to an 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 BOD of such water increases. The release of biological wastes, such as wood pulp or untreated sewage water, into water also increases the BOD. 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.

The most famous case of 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 has been suggested that high levels of nitrates in water can lead to stomach cancer and cause increased child mortality.

Microbiological contamination of water.

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 a report on pollution of the Mediterranean Sea published in 1983 by the Conservation Program environment UN, 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. An estimated 85% of waste from 120 coastal towns is dumped into the Mediterranean Sea, where holidaymakers and locals swim and fish. Between Barcelona and Genoa every mile coastline accounts for approximately 200 tons of waste discharged per year.

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.

Other forms of water pollution

These include radioactive and thermal pollution. The main source of radioactive pollution of the sea is low-level waste removed from nuclear power plants. One of the most important problems arising from this contamination is that marine organisms such as algae accumulate, or concentrate, radioactive isotopes.

Thermal water pollution is caused by thermal or nuclear power plants. Thermal pollution is introduced into surrounding water bodies by waste cooling water. As a result, an increase in water temperature in these reservoirs leads to an acceleration of some biochemical processes in them, as well as a decrease in the oxygen content dissolved in the water. This causes rapid and often very significant changes in the biological environment in the vicinity of power plants. The finely balanced reproduction cycles of various organisms are disrupted. In conditions of thermal pollution, as a rule, there is a strong growth of algae, but the extinction of other organisms living in the water.

Durakhanova Suna Jalalovna

The objectives of our mini-research are:

Analysis of the state of water bodies in the vicinity of our village;

Identification of the causes of irrational water use;

Possible ways correct the situation.

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WORLD WATER DAY

RESEARCH

WASTEWATER POLLUTION:

WAYS TO SOLUTION THE PROBLEM

Completed by: Suna Dzhalalovna Durakhanova,

student 9 a class of Mikrakh secondary school

Dokuzparinsky district RD

Head: Radzhabov Ruslan Radzhabovich,

Biology teacher at Mikrakh Secondary School

year 2012

BRIEF SUMMARY

It is useless to talk about the value and importance of water for all life on Earth, everyone knows this. But, even understanding the importance of the role of water in life, people still continue to harshly exploit water bodies, irreversibly changing their natural regime with discharges and waste. In addition, water also serves as a habitat for many living creatures. Water is of great importance in industrial and agricultural production. It is well known that it is necessary for the everyday needs of humans, all plants and animals. Population growth, intensification Agriculture, a significant expansion of the area of ​​irrigated land, improvement of cultural and living conditions and a number of other factors are increasingly complicating the problems of water use. The demand for water is enormous and increasing every year. Most of the water, after being used for domestic needs, is returned to rivers in the form of wastewater.

GOALS

The goals of our mini-research are:

1. analysis of the state of water bodies in the vicinity of our village;
2. identifying the causes of irrational water use;
3. possible ways to improve the situation.

1. INCREASING THE RATE OF WATER CONSUMPTION

According to our estimates, approximately 70% of all water consumption is used in agriculture. A significant amount of water is spent on the household needs of the population. Most of the water, after being used for domestic needs, is returned to rivers in the form of wastewater.

Fresh water shortage is already becoming a global problem. But in mountainous and foothill areas, which includes our region, this problem is imperceptible. Firstly, because our nature is quite generous with springs, streams, small rivers and other sources of fresh water. Secondly, their reserves do not dry out, since they are fed by precipitation, which falls in abundance here, and also by glaciers in summer. But to have it does not mean that we should treat this priceless gift of nature recklessly and uneconomically.

Previously for the whole family out of several people, only a few jugs of water were enough for the whole day. They knew how to value water, as well as the labor of the women who brought it. Now the situation has changed. In recent years, every household in the village has been provided with tap water. Baths and swimming pools were built, with vehicles, and car washes were built in the yard. The diameter increases every year water pipes, but the culture of water consumption is decreasing. By the way, having provided themselves with water taps, not many thought about where this water would then flow. As a result, already unsightly roads and streets turn into an extreme skating rink in winter, and full of puddles and mud in summer. In our region, the areas covered by moisture-loving crops (primarily cabbage) are constantly increasing. This leads to a significant increase in water consumption. Therefore, with the beginning of the irrigation season, uncontrollable flows of irrigation water will literally pour in the direction of agricultural land through several channels. When water is withdrawn from the upper reaches of the Chakhichay River, it is lost on thousands of hectares of farmland. As a result, the number of landslides and potentially dangerous areas within the village has increased.

The drama of the situation also lies in the fact that no one is doing anything to solve this problem. For district and local administrations, the absence of complaints from the population and the provision of citizens with drinking and irrigation water, on the contrary, is a source of pride rather than a problem.

2. POSSIBLE CONSEQUENCES

With an increase in the area of ​​irrigated land, the volume of drainage (waste) water increases. They are formed as a result of periodic watering, when there is excess water flow. Large volumes of drainage water are discharged into the Chakhichay and Samur rivers. Another problem is soil leaching (salinization). In these cases, the mineralization of river waters increases. It should be borne in mind that with drainage waters that flow into rivers, nutrients, pesticides and other chemical compounds that have a harmful effect on natural waters are carried away. Many of the impurities in water are natural and get there through rain or groundwater. Some of the pollutants associated with human activities follow the same path. Smoke, ash and industrial gases settle to the ground along with rain; chemical compounds and sewage added to the soil with fertilizers enter rivers with groundwater.

In places where there are large concentrations of people and animals, natural clean water is usually not enough, especially if it is used to collect sewage and transport it away from populated areas. If not much sewage enters the soil, soil organisms process it, reusing nutrients, and clean water seeps into neighboring watercourses. But if sewage gets directly into the water, it rots, and oxygen is consumed to oxidize it. A so-called biochemical demand for oxygen is created. The higher this need, the less oxygen remains in the water for living microorganisms, especially fish and algae. Sometimes, due to lack of oxygen, all living things die. The water becomes biologically dead - only anaerobic bacteria remain in it; they thrive without oxygen and during their life processes they emit hydrogen sulfide - a poisonous gas with a specific odor rotten eggs. The already lifeless water acquires a putrid odor and becomes completely unsuitable for humans and animals. This can also happen when there is an excess of substances such as nitrates and phosphates in the water; they enter water from agricultural fertilizers in fields or from wastewater contaminated with detergents. These nutrients stimulate the growth of algae, which begin to consume a lot of oxygen, and when it becomes insufficient, they die. Organic waste and nutrients become an obstacle to the normal development of freshwater ecological systems. But in recent years ecological systems Huge amounts of completely alien substances have fallen, from which they know no protection. Pesticides used in agriculture, metals and chemicals from industrial wastewater have managed to enter the aquatic food chain, which can have unpredictable consequences. Species at the beginning of the food chain can accumulate these substances in dangerous concentrations and become even more vulnerable to other harmful effects.

3.WAYS TO SOLUTION THE PROBLEM

Polluted water can be purified. The water cycle, this long path of its movement, consists of several stages: evaporation, cloud formation, rainfall, runoff into streams and rivers, and evaporation again. Throughout its entire path, water itself is capable of purifying itself from contaminants that enter it - products of decay. organic matter, dissolved gases and minerals, suspended solids. But polluted basins (rivers, lakes, etc.) take much longer to recover. In its endless circulation, water either captures and transports many dissolved or suspended substances, or is cleared of them. Industrial emissions not only clog, but also poison wastewater. And expensive devices for purifying such waters are not yet available.

To purify drainage water, it is necessary to organize its demineralization with simultaneous purification from harmful impurities.

When developing irrigation, it is necessary to base it on water-saving irrigation technology, which will contribute to a sharp increase in the efficiency of this type of reclamation. But until now, the efficiency of the irrigation network remains low, water losses amount to approximately 30% of the total volume of its intake.

A significant reserve for the normal use of moisture is the correct

selection and rational use of various methods of irrigation of agricultural land. To save water, developed countries use sprinkling irrigation, which provides almost 50% water savings.

In order for natural systems to recover, it is necessary first of all to stop the further flow of waste into rivers. To protect water from pollution, it is necessary to know the nature and intensity of the possible harmful effects of pollution at certain concentrations, and especially the limit of permissible concentrations (MAC) of water pollution. The latter should not be exceeded so as not to disrupt the normal conditions for cultural and domestic water use and not to cause damage to the health of the population located downstream from the wastewater discharge site.

Treatment plants are different types depending on the main method of waste disposal. With the mechanical method, insoluble impurities are removed from wastewater through a system of settling tanks and various kinds traps. In the past, this method was widely used for the treatment of industrial wastewater. The essence of the chemical method is that reagents are introduced into wastewater at wastewater treatment plants. They react with dissolved and undissolved pollutants and contribute to their precipitation in settling tanks, from where they are removed mechanically. But this method is unsuitable for treating wastewater containing a large number of different pollutants.

When treating domestic wastewater, the best results are obtained by the biological method. In this case, aerobic biological processes carried out with the help of microorganisms are used to mineralize organic contaminants. The biological method can be used both in conditions close to natural and in special biorefinery facilities.

4. LIST OF REFERENCES USED

1.Avakyan A.B., Shirokov V.M. “Rational use of water resources.” Ekaterinburg: “Victor”, 1994.

2. Cherkinsky S.N. “Sanitary conditions for the discharge of wastewater into reservoirs.”

Moscow: Stroyizdat, 1977.

Pollution is the introduction of pollutants into the natural environment that cause adverse changes. Pollution can take the form of chemicals or energy such as noise, heat or light. Components of pollution can be either foreign substances/energy or natural pollutants.

Main types and causes of environmental pollution:

Air pollution

Coniferous forest after acid rain

Smoke from chimneys, factories, Vehicle or from burning wood and coal make the air toxic. The effects of air pollution are also clear. The release of sulfur dioxide and hazardous gases into the atmosphere causes global warming and acid rain, which in turn increases temperatures, causing excessive rainfall or droughts around the world, making life more difficult. We also breathe every contaminated particle in the air and as a result, the risk of asthma and lung cancer increases.

Water pollution

Caused the loss of many species of flora and fauna of the Earth. This happened due to the fact that industrial waste discharged into rivers and other water bodies causes an imbalance in aquatic environment, resulting in severe pollution and death of aquatic animals and plants.

In addition, spraying insecticides, pesticides (such as DDT) on plants, contaminates the groundwater system. Oil spills in the oceans have caused significant damage to water bodies.

Eutrophication in the Potomac River, USA

Eutrophication is another important cause of water pollution. Occurs due to untreated wastewater and the run-off of fertilizers from the soil into lakes, ponds or rivers, due to which chemicals penetrate into the water and prevent the penetration of sunlight, thereby reducing the amount of oxygen and making the water body uninhabitable.

Pollution of water resources harms not only individual aquatic organisms, but also the entire water supply, and seriously affects the people who depend on it. In some countries of the world, due to water pollution, outbreaks of cholera and diarrhea are observed.

Soil pollution

Soil erosion

This type of pollution occurs when harmful chemical elements enter the soil, usually caused by human activities. Insecticides and pesticides suck nitrogen compounds from the soil, making it unsuitable for plant growth. Industrial waste also has a negative impact on the soil. Since plants cannot grow as required, they are unable to hold the soil, resulting in erosion.

Noise pollution

This pollution occurs when unpleasant (loud) sounds from the environment affect a person's hearing organs and lead to psychological problems, including tension, high blood pressure, hearing loss, etc. It may be caused industrial equipment, airplanes, cars, etc.

Nuclear pollution

This is a very dangerous type of pollution, it occurs due to malfunctions of nuclear power plants, improper storage of nuclear waste, accidents, etc. Radioactive pollution can cause cancer, infertility, loss of vision, birth defects; it can make the soil infertile, and also negatively affects air and water.

Light pollution

Light pollution on planet Earth

Occurs due to noticeable excess illumination of an area. It is common, as a rule, in large cities, especially from billboards, gyms or entertainment venues at night. In residential areas, light pollution greatly affects people's lives. It also interferes with astronomical observations, making the stars almost invisible.

Thermal/heat pollution

Thermal pollution is the deterioration of water quality by any process that changes the temperature of the surrounding water. The main cause of thermal pollution is the use of water as a refrigerant by power plants and industries. When water used as a refrigerant is returned to the natural environment at more high temperature, temperature changes reduce the oxygen supply and affect the composition. Fish and other organisms adapted to a particular temperature range can be killed by a sudden change in water temperature (or a rapid increase or decrease).

Thermal pollution is caused by excess heat in the environment creating undesirable changes over long periods of time. This is due to the huge number of industries, deforestation and air pollution. Thermal pollution increases the Earth's temperature, causing dramatic climate change and the loss of wildlife species.

Visual pollution

Visual pollution, Philippines

Visual pollution is an aesthetic problem and refers to the effects of pollution that impair the ability to enjoy the natural world. It includes: billboards, open garbage storage, antennas, electrical wires, buildings, cars, etc.

Overcrowding of the territory with a large number of objects causes visual pollution. Such pollution contributes to absent-mindedness, eye fatigue, loss of identity, etc.

Plastic pollution

Plastic pollution, India

Involves the accumulation of plastic products in the environment that have an adverse effect on wildlife, animal habitats or people. Plastic products are inexpensive and durable, which has made them very popular among people. However, this material decomposes very slowly. Plastic pollution can adversely affect soil, lakes, rivers, seas and oceans. Living organisms, especially marine animals, become entangled in plastic waste or suffer from chemicals in plastic that cause disruptions in biological functions. People are also affected by plastic pollution by causing hormonal imbalance.

Objects of pollution

The main objects of environmental pollution are air (atmosphere), water resources (streams, rivers, lakes, seas, oceans), soil, etc.

Pollutants (sources or subjects of pollution) of the environment

Pollutants are chemical, biological, physical or mechanical elements (or processes) that harm the environment.

They can cause harm in both the short and long term. Pollutants come from natural resources or are produced by humans.

Many pollutants have toxic effects on living organisms. Carbon monoxide ( carbon monoxide) is an example of a substance that causes harm to humans. This compound is absorbed by the body instead of oxygen, causing shortness of breath, headache, dizziness, rapid heartbeat, and in severe cases can lead to serious poisoning, and even death.

Some pollutants become dangerous when they react with other naturally occurring compounds. Oxides of nitrogen and sulfur are released from impurities in fossil fuels during combustion. They react with water vapor in the atmosphere, turning into acid rain. Acid rain negatively affects aquatic ecosystems and leads to the death of aquatic animals, plants, and other living organisms. Terrestrial ecosystems are also affected by acid rain.

Classification of pollution sources

According to the type of occurrence, environmental pollution is divided into:

Anthropogenic (artificial) pollution

Deforestation

Anthropogenic pollution is the impact on the environment caused by human activities. The main sources of artificial pollution are:

• industrialization;
• invention of automobiles;
• global population growth;
• deforestation: destruction of natural habitats;
• nuclear explosions;
• overexploitation of natural resources;
• construction of buildings, roads, dams;
• creation of explosive substances that are used during military operations;
• use of fertilizers and pesticides;
• mining.

Natural (natural) pollution

Eruption

Natural pollution is caused and occurs naturally, without human intervention. It can affect the environment for a certain period of time, but is capable of regeneration. To sources natural pollution relate:

• volcanic eruptions, releasing gases, ash and magma;
• forest fires emit smoke and gaseous impurities;
• sandstorms raise dust and sand;
• decomposition of organic matter, during which gases are released.

Consequences of pollution:

Environmental degradation

Photo on the left: Beijing after the rain. Photo on the right: smog in Beijing

The environment is the first victim of air pollution. An increase in the amount of CO2 in the atmosphere leads to smog, which can prevent sunlight from reaching the earth's surface. In this regard, it becomes much more difficult. Gases such as sulfur dioxide and nitrogen oxide can cause acid rain. Water pollution in terms of oil spills can lead to the death of several species of wild animals and plants.

Human health

Lung cancer

Decreased air quality leads to several respiratory problems, including asthma or lung cancer. Chest pain, sore throat, cardiovascular diseases, and respiratory diseases can be caused by air pollution. Water pollution can cause skin problems, including irritation and rashes. Similarly, noise pollution leads to hearing loss, stress and sleep disturbance.

Global warming

Male, the capital of the Maldives, is one of the cities facing the prospect of being flooded by the ocean in the 21st century

The release of greenhouse gases, especially CO2, leads to global warming. Every day new industries are created, new cars appear on the roads, and trees are cut down to make way for new homes. All these factors, directly or indirectly, lead to an increase in CO2 in the atmosphere. Rising CO2 is causing the polar ice caps to melt, raising sea levels and creating dangers for people living near coastal areas.

Ozone depletion

The ozone layer is a thin shield high in the sky that blocks ultraviolet rays from reaching the ground. Human activities release chemicals such as chlorofluorocarbons into the atmosphere, which contributes to the depletion of the ozone layer.

Badlands

Due to the constant use of insecticides and pesticides, the soil can become infertile. Various types of chemicals generated from industrial waste end up in water, which also affects soil quality.

Protection (protection) of the environment from pollution:

International protection

Many are particularly vulnerable because they are exposed to human influence in many countries. As a result, some states are banding together and developing agreements aimed at preventing damage or managing human impacts on natural resources. These include agreements that affect the protection of the climate, oceans, rivers and air from pollution. These international environmental treaties are sometimes binding instruments that have legal consequences in the event of non-compliance, and in other situations they are used as codes of conduct. The most famous include:

• The United Nations Environment Program (UNEP), approved in June 1972, provides for the protection of nature for the present generation of people and their descendants.
• The United Nations Framework Convention on Climate Change (UNFCCC) was signed in May 1992. The main goal This agreement is to "stabilize the concentration of greenhouse gases in the atmosphere at a level that will prevent dangerous anthropogenic interference with the climate system"
• The Kyoto Protocol provides for the reduction or stabilization of the amount of greenhouse gases emitted into the atmosphere. It was signed in Japan at the end of 1997.

State protection

Discussions of environmental issues often focus on the government, legislative and law enforcement levels. However, in the broadest sense, environmental protection can be seen as the responsibility of the entire people, not just the government. Decisions that impact the environment will ideally involve a wide range of stakeholders, including industry, indigenous groups, environmental groups and communities. Environmental decision-making processes are constantly evolving and becoming more active in different countries.

Many constitutions recognize the fundamental right to protect the environment. In addition, in various countries there are organizations and institutions dealing with environmental issues.

Although protecting the environment is not just a responsibility government agencies, most people consider these organizations to be paramount in creating and maintaining basic standards that protect the environment and the people who interact with it.

How to protect the environment yourself?

Population and technological advances based on fossil fuels have severely impacted our natural environment. Therefore, we now need to do our part to eliminate the consequences of degradation so that humanity continues to live in an environmentally friendly environment.

There are 3 main principles that are still relevant and more important than ever:

• use less;
• reuse;
• convert.

• Create compost heap in your garden. This helps to dispose of food waste and other biodegradable materials.
• When shopping, use your eco-bags and try to avoid plastic bags as much as possible.
• Plant as many trees as you can.
• Think about ways to reduce the number of trips you make using your car.
• Reduce vehicle emissions by walking or cycling. It is not simple great alternatives driving, but also health benefits.
• Use public transportation whenever you can for daily transportation.
• Bottles, paper, used oil, old batteries and used tires must be disposed of properly; all this causes serious pollution.
• Do not pour chemicals and waste oil onto the ground or into drains leading to waterways.
• If possible, recycle selected biodegradable waste, and work to reduce the amount of non-recyclable waste used.
• Reduce the amount of meat you consume or consider a vegetarian diet.

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From elementary school we are taught that man and nature are one, that one cannot be separated from the other. We learn about the development of our planet, the features of its structure and structure. These areas influence our well-being: the atmosphere, soil, water of the Earth are, perhaps, the most important components of a normal human life. But why then does environmental pollution go further and larger every year? Let's look at the main environmental issues.

Environmental pollution, which also refers to the natural environment and the biosphere, is an increased content of physical, chemical or biological reagents in it that are not typical for a given environment, brought in from the outside, the presence of which leads to negative consequences.

Scientists have been sounding the alarm about an imminent environmental disaster for several decades in a row. Research conducted in various areas leads to the conclusion that we are already facing global climate change and external environment under the influence of human activity. Pollution of the oceans due to leaks of oil and petroleum products, as well as garbage, has reached enormous proportions, which affects the decline in populations of many animal species and the ecosystem as a whole. The growing number of cars every year leads to large emissions into the atmosphere, which, in turn, leads to drying of the earth, heavy rainfall on the continents, and a decrease in the amount of oxygen in the air. Some countries are already forced to bring in water and even buy canned air because production has ruined the country's environment. Many people have already realized the danger and are very sensitive to negative changes in nature and major environmental problems, but we still perceive the possibility of a disaster as something unrealistic and distant. Is this really so or is the threat imminent and something needs to be done immediately - let's find out.

Types and main sources of environmental pollution

The main types of pollution are classified by the sources of environmental pollution themselves:

• biological;
• chemical
• physical;
• mechanical.

In the first case, environmental pollutants are the activities of living organisms or anthropogenic factors. In the second case, the natural chemical composition of the contaminated sphere is changed by adding other chemicals to it. In the third case, the physical characteristics of the environment change. These types of pollution include thermal, radiation, noise and other types of radiation. The latter type of pollution is also associated with human activity and waste emissions into the biosphere.

All types of pollution can be present either separately on their own, flow from one to another or exist together. Let's consider how they affect individual areas of the biosphere.

People who have traveled a long way in the desert will probably be able to name the price of every drop of water. Although most likely these drops will be priceless, because human life depends on them. In ordinary life, we, alas, do not attach such great importance to water, since we have a lot of it and it is available at any time. But in the long term this is not entirely true. In percentage terms, only 3% of the world's fresh water remains unpolluted. Understanding the importance of water for people does not prevent people from polluting an important source of life with oil and petroleum products, heavy metals, radioactive substances, inorganic pollution, sewage and synthetic fertilizers.

Contaminated water contains a large amount of xenobiotics - substances foreign to the human or animal body. If such water enters the food chain, it can cause serious food poisoning and even death for everyone in the chain. Of course, they are also contained in products of volcanic activity, which pollute water even without human help, but the activities of the metallurgical industry and chemical plants are of predominant importance.

With the advent of nuclear research, quite significant harm has been caused to nature in all areas, including water. Charged particles trapped in it cause great harm to living organisms and contribute to the development of cancer. Wastewater from factories, ships with nuclear reactors, and simply rain or snow in the nuclear testing area can lead to contamination of water with decomposition products.

Sewage, which carries a lot of garbage: detergents, food debris, small household waste and more, in turn contributes to the proliferation of other pathogenic organisms, which, when entering the human body, give rise to a number of diseases, such as typhoid fever, dysentery and others.

It probably doesn’t make sense to explain how soil is an important part of human life. Most of the food that humans eat comes from the soil: from cereals to rare types of fruits and vegetables. In order for this to continue, it is necessary to maintain the soil condition at the proper level for the normal water cycle. But anthropogenic pollution has already led to the fact that 27% of the planet's land is susceptible to erosion.

Soil pollution is the ingress of toxic chemicals and debris into it in high quantities, interfering with the normal circulation of soil systems. Main sources of soil pollution:

• residential buildings;
• industrial enterprises;
• transport;
• Agriculture;
• nuclear power.

In the first case, soil pollution occurs due to ordinary garbage that is thrown in the wrong places. But main reason it should be called landfills. Burned waste leads to contamination of large areas, and combustion products spoil the soil irrevocably, polluting the entire environment.

Industrial enterprises emit a lot of toxic substances, heavy metals and chemical compounds that affect not only the soil, but also the life of living organisms. It is this source of pollution that leads to technogenic soil pollution.

Transport emissions of hydrocarbons, methane and lead, entering the soil, affect food chains - they enter the human body through food.
Excessive plowing of the land, pesticides, pesticides and fertilizers, which contain enough mercury and heavy metals, lead to significant soil erosion and desertification. Abundant irrigation also cannot be called a positive factor, since it leads to soil salinization.

Today, up to 98% of radioactive waste from nuclear power plants, mainly uranium fission products, is buried in the ground, which leads to degradation and depletion of land resources.

The atmosphere in the form of a gaseous shell of the Earth is of great value because it protects the planet from cosmic radiation, affects the relief, determines the Earth's climate and its thermal background. It cannot be said that the composition of the atmosphere was homogeneous and only began to change with the advent of man. But it was precisely after the start of active human activity that the heterogeneous composition was “enriched” with dangerous impurities.

The main pollutants in this case are chemical plants, the fuel and energy complex, agriculture and cars. They lead to the appearance of copper, mercury, and other metals in the air. Of course, air pollution is felt the most in industrial areas.

Thermal power plants bring light and heat to our homes, however, at the same time they emit huge amounts of carbon dioxide and soot into the atmosphere.
Acid rain is caused by waste released from chemical plants, such as sulfur oxide or nitrogen oxide. These oxides can react with other elements of the biosphere, which contributes to the emergence of more harmful compounds.

Modern cars are quite good in design and technical characteristics, but the problem with atmospheric emissions has not yet been solved. Ash and fuel processing products not only spoil the atmosphere of cities, but also settle on the soil and lead to its deterioration.

In many industrial and industrial areas, use has become an integral part of life precisely because of environmental pollution from factories and transport. Therefore, if you are concerned about the state of the air in your apartment, with the help of a breather you can create a healthy microclimate at home, which, unfortunately, does not eliminate the problems of environmental pollution, but at least allows you to protect yourself and your loved ones.

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, there is a need to manage water supplies much more carefully to avoid harm to human health and damage to the environment.

A previously inexhaustible resource - fresh, clean water - is becoming exhaustible. Today there is water suitable for drinking, industrial production and irrigation are 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 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 recent years they have also become a reason for various pseudo-scientific speculations. Water is not a passive solvent, as is commonly believed, but an active agent 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 it required quantity, 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 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 water land renews itself approximately 500 times faster than 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 the 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 returns 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 treatment, including biological treatment, all dissolved inorganic substances and up to 10% of organic pollutants remain in the 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 the economic development of the 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. This is the south and southeast of the European part of the CIS, the Caspian lowland, south Western Siberia and Kazakhstan, and some other regions of Central Asia, the 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 water does not return to the rivers, but is spent on evaporation and the formation of plant mass, since during photosynthesis hydrogen from water molecules passes 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 flow of water to Sea of ​​Azov- by 23%, to Aral - 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. Temperature increase natural waters cheats natural conditions for aquatic organisms, reduces the amount of dissolved oxygen, 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 permanently 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.

Every year the rivers of the world carry them into the sea and ocean waters more than 1.8 million tons of petroleum products.

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 thoroughly saturated with oil and become unsuitable for consumption due to unpleasant odor 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 amounts of oil are concentrated in a thin near-surface layer of sea water, which plays especially 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, different types small fish, and no harmful effects were observed in 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 into 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. Coastal waters and inland seas have the highest levels of pollution. 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 they accumulate harmful substances 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 water resources countries: 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 are involved in this). This topic became the main topic for the March 19, 2007 issue of the 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 chemicals and the formation of toxic by-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 South-East Asia and Sub-sugars: this is where pathogens living in water most often become the cause of mass diseases. 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 effective against bacteria living in water and protozoan cysts, but does not affect 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 visible light, which requires less energy than ultraviolet irradiation, 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 promising direction in the development of methods for detecting harmful substances is the 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 amount 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 low molecular weight organic pollutants. 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.

We can only hope that in the coming years science and technology will really make a big step forward - after all, even while 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 the purity of the natural environment. - M.: Nauka, 1986. - 206 s.

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

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

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