Domestic wastewater comes in large quantities from residential and public buildings, laundries, canteens, hospitals, etc. In wastewater of this type, various organic substances , as well as microorganisms, predominate , which can cause bacterial contamination.
A huge number of such hazardous contaminants, such as pesticides, ammonium and nitrate nitrogen, phosphorus, potassium, etc., is washed off from agricultural areas and enters water bodies without any purification, and therefore has a high concentration;
The gas-smoke compounds (aerosols, dust, etc.) that are deposited from the atmosphere on the surface of the catchment basins and directly on water surfaces are of considerable danger.
The scale of oil pollution of natural waters is enormous . Millions of tons of oil annually pollute marine and freshwater ecosystems in case of oil tanker ship accidents, oil fields in coastal zones, ballast water discharges from ships, etc.
In addition to surface water, underground water is constantly polluted, primarily in the areas of large industrial centers.
Infiltrating and seeping through the soil, water carries with it to the groundwater all soluble substances in it. The soil can not hold them back. Consequently, any chemical substance used, placed, spilled, spilled on the ground or caught in it, can contaminate groundwater .
Currently, the main sources of groundwater pollution are:
• improperly arranged landfills and other stores of poisonous substances from where they can infiltrate into groundwater;
• flowing underground reservoirs and pipelines. A particular problem is the leakage of gasoline from tanks at gasoline stations;
• Pesticides and fertilizers used in fields, lawns, in orchards;
• salt, which is sprinkled with roads in ice;
• Fuel oil, used on roads to bind dust;
• excess of wastewater used in the economy and sewage sludge;
• leakage during transport.