Environmental Engineering (Part-2) (General Engineering) (SSC JE)

• Stratosphere ozone filters out harmful UVB radiation, CFC pollution damaged the ozone layer. The more the ozone depletion, the larger the increase in incoming UVB.

• Stratosphere ozone protects all life on the surface of the earth from the ready exposure to UVB.

• UVB radiation is high-energy light produced by the sum that damages DNA and can lead to mutations.

• Sulphur dioxide reacts with oxygen to form sulphur trioxide which combines with water to form H2SO4 which caused acid rain.

• Sulphur oxides caused damage to lungs, it mixes with smoke and fog to form smog which is very harmful.

• Sulphuric acid and nitric acid are responsible for lowering of rainwater pH resulting in the environmental concern known as acid rain.

Chlorine immediately reacts with ammonia present in water to form chloramines.
• Chloramines are combined form of chlorine and are less effective than freely available chlorine.

Forms in which chlorine is added are–
1. As free chlorine
2. Bleacing powder or hypochlorite (CaOCl₂)
3. Chloramines
4. Chlorine dioxide (ClO₂)

• Effective in disinfection–
ClO₂ > HoCl > Chloramines > OCl⁻

• Chlorofluoro carbons (CFCs) are green house gas compounds that contain only carbon, florine and chlorine : chlorofluorocarbons and related compounds including halogens.

• The chlorofluorocarbons and ozone layer is a good absorber of ultraviolet radiation.

• L₁₀ is the level exceeded for 10% of the time the sound or noise has a sound. Pressure level above L₁₀.
• L₅₀ is the level exceeded for 50% of the time. It is statistically the midpoint of the noise readings.
• For a varying sound L₁₀ is greater than L₅₀ which in turn is greater than L₅₀.

• Green house gas occur naturally and allow us to survive on earth by warming air near earth's surface.

• These greenhouse gases are produced both by natural processes and by human activities.

• The glasses of artificial green house are transparent to incoming solar radiation.

• The green house effect warming of the lower atmosphere and surface of a planet takes place by a complex process involving sunlight, gases and particle in the atmosphere.

Design period–According to IS 456-1978, The time period for which a structure or a structural element is required to perform without damage is known as design life.
Design period or life for various type structure is–
Components                Design period (years)
Dam/Storage reservoirs       30
Distribution system                30
Water treatment unit             15

Pathogen–Pathogen is an organisms that infecting or transmitting the disease to human being.
• Generally pathogen classified as bacteria, viruses, fungi, protests, parasite worms.
• Presence of Escherichia coli or coliform bacteria in water is indication of contamination.
• Process of killing pathogenic bacteria from water is called as disinfection.

Turbidimeter–It is based on the optical phenomenon that occur when incident light through water body is scattered by the existence of foreign particles which are suspended within.

• This review paper elaborates on the standards and factors that may influence the measurement of turbidity.

• Modern commercial turbidimeter which works on the principle of scattering of light at right angles to the incident light is called nephlometer.

Polycyclic aromatic hydrocarbons (PAHs) major source is ambient air, which include residential and commercial heating with wood, coal or other biomass.

• Carcinogenic hydrocarbon and benzo (α) pyrene is component of PAHs, it occurs largely in a result of anthropogenic emissions such as fossil fuel burning, motor vehicle etc.

• Its major source is road traffic.