Water pollution.Water pollution - adverse changes in physical, chemical and

bacteriological water caused by the introduction of an excess of radioactive, organic and inorganic substances

(solid, liquid, gas), and finally heat which limits or prevents the use of water for drinking and farming purposes.

Water pollution causes :

The composition of polluted water.

• Water pollution is mainly caused by chemical substances, bacteria and other micro-organisms present in natural waters in increased amounts. Chemical substances, organic or inorganic (mineral) are in the form of solutions, dispersions and suspensions. The chemical composition of pollutants is formed by natural factors - disintegration of substances that can be found in soil and rocks, or development and dieback of aquatic organisms, and anthropogenic factors for example.

• The most common anthropogenic pollution of surface water includes pesticides, surfactants, petroleum hydrocarbons, phenols, chlorinated biphenyls and heavy metals: lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd), mercury (Hg) and zinc (Zn), and heated water (thermal pollution) that are particularly dangerous for surface water with little flow or stagnant water. Most of anthropogenic pollution is toxic to aquatic organisms. Pollutants persistent in the aquatic environment and difficult to wear by chemical and biochemical processes are called refractive substances.

• Most of the pollution gets into water with sewage. Other sources of water pollution are land and water transportation, the use of pesticides and fertilizers, and municipal and industrial waste. Water becomes contaminated as a result of eutrophication. The water cycle has been disturbed by man - deforestation, monoculture farming, inappropriate and excessive farming, urbanization.

Division of pollutants:• by origin:• natural - are those that come from the

pollutants contained in the surface waters and groundwater - eg. salinity, iron compounds;

• Artificial - also known as anthropogenic pollutants, they are related to human activity - sewage, runoff from agricultural lands, and municipal solid waste. Artificial pollutants can also be divided into a biological (bacteria, viruses, fungi, algae) and chemical (oil, gasoline, grease, oil, fertilizers, pesticides, acids, bases).

• by hazard they bear:• directly harmful - phenols (gasworks, coke),

hydrocyanic acid (gasworks), sulfuric acid and sulfates, acid rain (factory fertilizers, pulp mills, factories, artificial fibers),

• indirectly harmful - those which reduce the amount of oxygen in the water below the level necessary to sustain the life of aquatic organisms.

• According to the pollutants lastingness:

• degradable - pollutants that contain potentially toxic organic substances and can be dissolved by bacteria into simple inorganic compounds (domestic sewage)

• non degradable - contain substances that do not undergo any greater chemical changes and are not attacked by microorganisms (salts of heavy metals)

• lasting- contain substances that are degradable to the minimal extent and remain unchanged in the environment for a long period of time(pesticides, phenols, petroleum distillates)

• by source:• point sources - wastewater

mainly from industrial and urban areas discharged in an organized manner by sewage systems,

• pollution of surface or areas - rain pollution flushed from urbanized areas that do not have sewer systems, and agricultural or forest areas,

• pollutants from linear or zone sources - pollutants produced by the means of transport which are flushed from the roads or peat bogs, or from the oil and gas pipelines, sewers.

Assessment of the degree of pollution. • The degree of waters pollution is determined

with so-called gauges of pollution which shows the amount of the substance in milligrams per 1 cubic dm of water. A concentration of dissolved oxygen which can reach the maximum level of 8,9 mg/dm is one of the most important indicators of surface water pollution - lower level of the oxygen concentration proves that water is polluted with organic compounds that are biodegradable; the decrease in the oxygen level below 4 ³ mg/dm causes many aquatic organisms die. The other indicators of natural water pollution is a biochemical oxygen demand which is a measure of the biochemical biodegradation of the organic compounds; a chemical demand of the oxygen - the measure of the content of all organic compounds; a presence of a mineral and organic suspensions as well as inorganic and organic compounds of nitrogen and phosphorus.

Depending on the composition of aquatic organisms, there are several water quality categories:

• pure, • polluted • Class II - water for fish except salmonids,

breeding livestock, facilities used for recreation and water sports;

• Class III - the water used to irrigate farmland, horticulture and crops in greenhouses, supply of industrial plants with the exception of those that require water of drinking water quality.

• Evaluation of the quality of lakes in Poland in 2002:

• 5.8% - Class I • 39.2% - Class II • 40.8% - Class III • 14.2% - water does not meet standards, • The European Union aims to protect domestic

surface, coastal and groundwater water flow. The EU member states were required to prevent the deterioration of the water and the renewal of all surface water resources.

Wastewater Treatment • Wastewater treatment - removing

pollutants contained in wastewater in order to minimize detrimental impact on groundwater or soil.

• To refine the wastewater the physical processes are used - straining, sedimentation, flotation and filtration - those processes are used to remove solid impurities from the wastewater;

• Biological processes - resulting from the activities of living micro-organisms, including bacteria and algae and plants - are used to remove colloidal and dissolved organic and inorganic pollutants from the wastewater, and to process the sludge in the way it can be used again.

• Chemical processes - are used to purify industrial wastewater, as well as to remove biogenic compounds from municipal wastewater.

• The equipment and facilities for the wastewater treatment is called wastewater treatment plant. Particular water purification processes are conducted in allocated devices on bigger wastewater treatment plants where central plumbing is in use. The methods of purifying water that enable the simultaneous processing of the sewage in a simple unit are recommended at local wastewater treatment plants due to the fact that it significantly lowers the costs. Those units are:

• mud drums - processes of sedimentation and flotation take place here, causing the release of particulate pollutants from wastewater and processes of anaerobic decomposition of sewage sludge,

• filters - mainly the processes of filtration and absorption take place here, but also the aerobic biological decomposition of pollutants from retained wastewater,

• chambers - with extended aeration of activated sediment or biological resources where intensive biological aerobic processes occur with intensive participation of microorganisms processes of pollutant decomposition in wastewater, and aerobic sludge stabilization,

• Biological ponds and natural sewage treatment plants - a kind of "ecological reactor" where processes used in artificial sewage treatment plants occur, and also the processes characteristic for the natural environment with a vast share of vegetation (photosynthesis, photo-oxidation, uptake of pollutants by plants and others)

• In small sewage treatment plants can also be used cultures of microorganisms in the form of so-called. activated sludge or mixed with wastewater as a bacterial membrane, seeded on the surface of the biological bed.

• The most common unit for wastewater treatment in the local systems are septic tanks called rotting pits. The volume of such septic tank must be adapted to the features of wastewater and sludge treatment which should be periodically removed together with a scum.

• Due to the nature and quantity of treated wastewater the sewage treatment plants are distinguished in following groups - municipal, group, neighbourhood, domestic and industrial sewage treatment plants.

• The degree of purification of industrial and municipal waste in 2003:

• 2 km ³ of wastewater were treated per 2.2 km ³ / year of wastewater requiring treatment including:

• 0.6 km ³ / year - wastewater treated with the use of physical processes

• 0.2 km ³ / year - wastewater treated with the use of chemical processes

• 0.6 km ³ / year - wastewater treated with the use of biological processes

• 0.6 km ³ / year - treatment of wastewater with increased nutrient removal.

Thank you for watching our presentationGROUP 2

Wiktoria Waniak- PolandPatrycja Orman – Poland

Zuzanna Pruchniak -PolandGloria Fernández Barbusano - Spain

Alba García Gómez - SpainEduardo González Anelo - Spain

Abraham González Guisado - SpainJanet González Rodríguez - SpainAdriana Mañero Santana - Spain

Pascal - Germany