Water pollution is a problem of great importance. The presence of H2O is one of the main prerequisites for the existence of life on Earth. It is an important part of all ecospheres. World's supplies are about 1386 million cubic kilometers which are unevenly partitioned onto the separate continents.
They include liquid (fresh and salt), solid (fresh) in the form of ice, and gas in the form of steam. The global ocean takes up about 97,5%. The fresh aqua, which has a salinity of up to 1%, is 2,5% of the world's supplies.
About 70% of it is located in the ice sheets and the polar zones of the mountain glaciers. In the upper part of the lithosphere, there are significant supplies of it. Around 1/10 of them are easily accessible and in many countries they provide the supplies and irrigation for the inhabited places.
People need a fairly small amount of drinking water, but still it is vital to their existence. Around the world about 70% of the used one is utilized in agriculture. About 25% of the total usage in the world goes to the industry. Apart from everyday life, health care, agriculture, and industry, it is also used for other purposes, for example as solvent, cooler, for cleaning and laundry, as an element in the production of chemicals, drinks and food.
It is a habitat of many different plants and animals which are needed to feed the population. The natural pools combined with the building of floating canals make an important means of transportation to inaccessible areas. The power of it is used for the production of electricity in hydroelectrical power plants. It moves from seas and oceans to the atmosphere, then to land and back to the oceans by changing one state with another – liquid, gas, and solid. The processes that make this happen create the movement on the planet. This movement is constant and is done in cycles, which is why it is called a water cycle. This cycle provides balance on the planet, i.e. the amount that goes out of the ocean and then goes back in it.
The shortage of fresh water is constantly growing. The reasons for this are the following:
- The population is growing and so is the development of fields that require a lot of it;
- Loss because of the decreasing amount in rivers;
- Sources with industrial, domestic, and other waste.
This leads to the following socio-economic and ecological consequences:
- People’s life and health are put at risk;
- The speed of economic development of different areas and countries is limited;
- The condition of the separate ecosystems is worsened.
There are two ways of using resources:
- usage – associated with keeping the amount the same (hydro genetics, transport, fishing industry, health care, tourism);
- consumption – associated with the usage of large amounts of it for industrial and domestic needs. It is single (full), consistent, and cyclical.
Water pollution of the sources
It refers to the decrease of their biological functions and their ecological significance, which is due to the toxic substances that are poured into them. The polluters are classified into three main categories:
- The chemical pollutants are the most common ones. It is the most resistant compared to others and is spread to the largest distances. It is subdivided into organic, inorganic, toxic, and non-toxic.
- The organic is associated with the insertion of organic substances. They arrive from domestic, agricultural, and industrial pollution. Then, the organic substances are decomposed by microorganisms and during this process the oxygen that has been dissolved is used up.
- Oil and petroleum products. All components of petroleum are toxic to the marine organisms. The oil contamination changes the ratio between species and reduces their variety.
- Other organic substances are faeces, waste from the leather, paper, dairy, cellulose industries, and others.
The inorganic one is associated with the entering of mineral substances, chemical compounds, and toxic waste. The biggest inorganic polluters are factories that produce metal, build machines, mine ores and coals; the factories that produce acids, building materials, and mineral fertilizers; logging companies, transport, etc.
Physical is associated with the presence of the radioactive waste, heat, and others. The presence of radionuclides is the most dangerous even in very small amounts. They cause radioactive contamination.
The radioactive waste is thrown out by nuclear power plants, hospitals, factories working with radioactive materials, the armed forces, and so on. Heat as a polluter heats up the industrial ones which later become waste. This is the so-called thermal оне. The other way it happens is by the contact between tham. It can also have natural origins /heat waves/ and unnatural origins /from the industry when electricity is produced – hydroelectric power plants/.
Biological is associated with the appearance of pathogenic bacteria, viruses, a few types of fungus, parasitic worms, and other. The microorganisms and viruses that spread diseases can be found in the badly purified or non-purified of the population and the animal farms. When they enter the drinking water, the pathogenic microbes and viruses cause different epidemics. They are distributed on large areas by the fresh and communal domestic ones. For the biological decomposition of the organic substances to take place, the ration between the biological necessity of oxygen and the chemical necessity of oxygen should equal or be above 50%.
Part of it in nature manage to clean them. Self-cleaning is an aggregation of all natural processes, which aim to restore their original consistency and features. It depends on factors such as solar radiation, the activity of microorganisms and plants.
However, self-cleaning is not sufficient to deal with the anthropogenic factors. The contamination of ecosystems itself poses a threat to all organisms and human beings. Their stability is weakened by the activity of the polluters in the ecosystems because of breaches in the food pyramid and broken biogenetic connections, microbiological, eutrophication, and other unfavourable processes.
A source of thermal pollution are the heated industrial waste and those of hydroelectric power plants. When the temperature rises, changes in the gas and chemical composition take place. This leads to increased reproduction of anaerobic bacteria and to emitting toxic gases.
In direct contact of humans with bacterial infections or when there are different types of parasites, it can penetrate the skin and cause serious illnesses. This is typical for tropical and subtropical areas.
There are three main ways for rational use:
- Improvement of manufacturing technologies and methods of consumption through technologies, replacement of cooling with air cooling, applying systems for constant usage, lowering usage in manufacturing by employing scientific norms;
- Improvement of systems;
- Using methods of the economical and administrative mechanisms: optimal prices and limits; financial stimulation and sanctions for domestic and industrial use.
When choosing a system and a scheme for sluicing out from industrial companies, the following factors should be considered:
- Requirements to the qualities in the different technological processes;
- Amount, content and features of different productions, industrial units, and factories;
- A possibility of rationalization of the technological production;
- A possibility to reuse waste;
- Expedient extraction and usage of substances;
- A possibility and expediency for cooperative sluicing of several factories and their common cleaning;
- A possibility to use cleaned domestic wastewater in technological processes;
- Expedient local cleaning of separate units of a certain enterprise;
- A possibility to use cleaned domestic one in agriculture;
- Self-cleaning, the conditions of throwing away in it, and the degree of their cleaning;
- The correct choice of one method or another.
Various means for cleaning exist mechanical, physicochemical, biological and others. They are selected in accordance with the features and degree of harmfulness. Sometimes, a few cleaning methods have to be used at the same time.
During the mechanical cleaning from industrial waste through permeation, precipitation, and filtration of the admixture, up to 90% of the insoluble mechanical admixture is exuded, and up to 60% from domestic waste. For that to happen are used grids, different types of catchers, and filters. Neutralization and oxidation refer to the main chemical methods. Neutralization is used for the processing of industrial waste in many fields of industry that contain acids and foundation.
The following methods are used in the physicochemical cleaning:
Coagulation – coagulants are introduced (ammonium salt, copper, iron, etc.), flaky admixtures are formed which are easily exuded afterwards;
Some substances such as clay activated charcoal and others absorb the contamination. Through the sorption method, valuable soluble substances with following absorbency are extracted.
Flotation – air is omitted. Gas bubbles catch on their surface /active substances, petroleum, oil, and other polluters/ during their movement upwards, and form on their surface easy-to-catch foamy layer.
Biological cleaning (biochemical) is a widely used method for processing communal domestic water from the food, petroleum, paper, cellulose, and other industries. Biological oxidation is carried out by microorganisms that use organic and non-organic compounds for their development.
Apart from different bacteria, more complex organisms are used as well: algae, fungus, etc., which are all connected and united by complicated interrelations.
The main measures associated with the protection of underground pollution consist of prevention of the exhaustion of supplies and their protection against it. The battle against the exhaustion of underground that can be adjusted to the need for drinking water requires many different measures which include:
- Regulated collection;
- A more rational permutation of the collecting areas according to their acreage;
- Defining the value of the exploitation supplies as a limit to their usage.
In conclusion, we can say that water is a symbol of life. It is the part of the environment in which all biological reactions take place and without which life on Earth will be impossible. If mankind really wants to preserve the variety of living creatures on Earth and save the planet from disasters and catastrophes, it should put more effort in protecting and purging its resources.