Environmental Engineering (Part-3) (General Engineering) (SSC JE)

The prescribed permissible noise level for various types of area–

Global warming means the rise in the average temperature of the near surface air and oceans since the mid-twentieth century and its projected continuation.
• Average temperature of the earth surface increases at the rate of 0.5ºC per year in global warming.

Biochemical cycle–The cyclic exchange of nutrient material between the living organisms and their non-living environment is called as biochemical cycle.

Biological cycle–The chain of transforming biological events one after another reaching at the end of cycle the initial condition as the life cycle of living organism.

Iron and manganese have no adverse effect on width. The generally acceptable limits for iron and manganese are 0.3 mg/l and 0.05 mg/l, respectively and that may cause colour problem in water.

Aeration– Aeration brings water and air in close contact in order to remove dissolved gases (such as carbon dioxide) and oxidizes dissolved metals such as iron, hydrogen sulfide and volatile, organic chemicals (VOCs). Aeration is often the first major process at the treatment plant.

Why we use Aeration –
• Oxidation of organic matter
• To increase dissolved oxygen content
• To reduce the concentration of taste and odour causing substances, such as hydrogen sulfide and various organic compounds, by volatilization/ stripping or oxidation
• To oxidize iron and manganese, rendering them insoluble
• Flocculation of colloids in sewage influent
• To remove those compounds that may in some way interfere with or add to the cost of subsequent water treatment.

Effects of nitrogen dioxide–
• Long-term exposure to high levels of nitrogen dioxide can cause chronic lung disease (acute bronchitis)

• High levels of nitrogen dioxide are also harmful to vegetation-decreasing growth or reducing crop yields.

Psychological effect of noise pollution–
• Insomnia as a result of lack of undisturbed and refreshing steep.
• Emotional disturbance
• Mental illness or reduction in mental capability.
• Depression and fatigue.
• Aggressiveness in behavior.
• Decrease in working efficiency, etc.
• Decrease in heart output and pain in heart is not a psychological effect, it is a physical effect of noise pollution.

Ill effect of depletion of the ozone layer–
• Skin diseases like cancer, sunburn
• Damage to the immune system
• Eyes ailment such as cataract
• Quick ageing in living organisms etc.

Acid rain–When sulphur dioxide and nitrogen di-oxide get mixed with the moisture present in the atmosphere produces sulphuric and nitric acid and precipitated.

The loudness of sound/noise is measured in bel(B) or decibel (dB).
• Hertz – Frequency
• Richter – Earthquake intensity (Magnitude)
• Tesla – Magnetic flux density