Environmental Engineering (Part-4) (General Engineering) (SSC JE)

Hydrogen sulphide (H₂S) has rotten egg smell. It is highly inflammable and toxic in nature. It is heavier than air.

Leaching–The chemical process in which mining for extracting valuable mineral from ore takes place is called as leaching.

Drilling–The process of penetrating through the ground in order to extract something for analysis is termed as drilling.

Blasting–The process of reducing a solid body in order to change into fragments and pieces using an explosive, is termed as blasting.

Mineral resource estimation–It is used to estimate the ores present below the ground level.

Ozone hole causes–
1. Genetic mutations
2. Global warming
3. Skin cancer/Sun burns
4. Weak immune system.

Non-biodegradable–Those substances that can be decomposed by natural organism are known as non-biodegradable.

Example– Polythene bags, plastic bags, plastic straws etc.

When lime is added to water, its pH increases because of basic nature of lime. Higher pH represent the alkalinity of substance.
0 pH = highly acidic
14 pH = highly basic

Gobar gas is an anaerobic decomposition of organic wastes from plants animals etc. It is a mixture of methane (CH₄), carbon dioxide (CO₂) and hydrogen sulphate (H₂S). It is also known as biogas that is a source of energy.

Ammonium nitrate (NH₄NO₃)–A crystalline solid having a white or colourless. It is uded as explosive material having melting point of 169.6ºC.

Slow sand filter–
• Filtration rate = 100 l/m² /hr - 200 l/m² /hr
• Effective size = (0.2 – 0.4) mm
• Uniformity constant 'Cᵤ' = (1.8 – 3.0)
• Cleaning period = (1-3) month.
• Bacterial removal efficiency = 98–99%
• Maximum filter head = 65-85% of filter media (thickness)

Slow sand filter– The maximum filter head in slow sand filter is equal to 65%-85% of filter media thickness.
• Bacterial removal efficiency of SSF = 98–99%.

Five-day BOD is considered as standard BOD that is 65% of ultimate BOD.
• Five day BOD is carried out at 20ºC temperature.