Water Treatment and Air Pollution

Water Treatment Methods

Physical Filtration

Desbastement: Pass water through filters and/or grids of different porosity to remove large particles.

Activated Carbon Filter: Pass water through activated carbon, which has small pores, to remove salts, odors, and strange tastes through electroaffinity.

Decanting/Sedimentation: Let water sit in large containers so suspended solids settle to the bottom. Collect the surface water free of solids. Sometimes used after flocculation.

Ultraviolet Radiation: Use UV light to eliminate microorganisms.

Reverse Osmosis: Subject water to high pressure to force it through membranes, removing dissolved salts.

Chemical Treatment

Coagulation-Flocculation: Add a substance to the water to chemically bind finely divided, suspended particles together, forming larger flakes that sediment.

Chlorination: Add chlorine compounds to prevent microorganism contamination.

Ozonation: Add ozone to oxidize and eliminate microorganisms.

Water Quality and Contamination

In stagnant pond water, sedimentation of suspended solids occurs at the bottom. BOD (Biological Oxygen Demand) helps determine the amount of biodegradable organic matter in water. It refers to the oxygen microorganisms need to break down organic matter. BOD and O₂ have an inverse relationship. Contaminated surface waters are not saturated with O₂. Discharges of organic matter decrease oxygen concentration as it's used for decomposition, consequently increasing BOD. If BOD is less than dissolved oxygen, the system regenerates; otherwise, it degrades.

Sources of Anthropogenic Pollution

Occurs primarily in combustion processes: motor vehicles, thermal power plants.

Acid Rain

Nitrogen oxides react with atmospheric water in clouds to form nitric acid, resulting in acidic precipitation.

Ozone (O₃)

Forms in the troposphere when solar radiation interacts with nitrogen oxides at high temperatures.

Emission and Immission Values

Emission Levels: Concentrations of contaminants registered at a specific point, regardless of the source.

Emission Values: Quantity of a substance released from a specific point, like an industrial chimney.

• A-2: Anticyclonic thermal subsidence hinders air mass mixing.
• B-3: Strong winds and close isobars disperse smoke quickly.
• C-1: Low pressure increases vertical air movement, encouraging mixing.

Immission Value: Concentration of air pollutants.

Guide Value: Pollutant concentration with potential long-term health or ecosystem consequences.

Limit Value: Concentration not to be exceeded within a specific timeframe.

Smog

Smog (photochemical smog) occurs in cities with high sun exposure. It forms when hydrocarbons and nitrogen oxides react with oxygen under ultraviolet radiation. This creates oxidizing substances like ozone and PAN. Main air pollutants from automobiles include smog, hydrocarbons, carbon monoxide (CO), heavy metals (Pb, Fe, Ni, Cd...), nitrogen oxides (NOx), and sulfur dioxide (SO₂).