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

Ozone layer absorb (97 to 99)% of sun's medium frequency ultraviolet light which other wise result damage expose life near the surface.
• Ozone layer found in 2nd layer (stratosphere)
• UV rays can cause skin cancer to humans

Hydrophobia is a fear of water which is caused by dog bite (Rabies) and infection of rabies takes place.

Fluoride pollution mainly affects teeth. Fluoride is a mineral found in bones, teeth.
• It is important for the optimal formation of dental enamel and bone mineralization.
• It has negative effects on the joints bones and causes fluorosis in the teeth.

Industrial waste is the main factor of water pollution, because industrial waste are dumped into rivers without being treated.

The process of removal of harmful bacterias (pathogens) from drinking water is termed as disinfection. Generally chlorine is used for drinking water as a disinfectant.

Sullage– It is a term used to indicate the waste water from both rooms, kitchens, washing places and wash basins etc. It does not create load smell since organic matter in it is either absent or is of negligible amount.

Rubbish– Rubbish indicates sundry solid wastes from offices, residences and other buildings. It also includes waste building materials, broken furniture, paper, rags etc. Generally, rubbish is dry and is of combustible nature.

Organic matter can be decomposed by anaerobic decomposition.

• For anaerobic respiration NO⁻₃ , Saₗ², CO₂⁻ or fumarate can serve as terminal electron acceptors, depending on the bacterium studied. The end result of the respiratory process is the complete oxidation of the organic substrate molecule and the end products formed are primarily CO₂&H₂O.

Grit chamber also called or grit channels or grit basin are intended to remove the inorganic particles (specific gravity about 2.65) which is much greater than those of organic solid in the waste water.

Activated sludge process is a biological process involving aerobic bacteria + protozoa + algae.
• Activated sludge process is an aerobic suspended growth type biological process that uses the active micro-organism, kept in suspension in the reactor to decompose & stabilize the soluble and particulate organic matter present in waste water.

• Sludge digestion is stabilization of sludge means must be treated prier to its disposal.
• Digestion of organic sludge can be done either in presence of oxygen or in absence of oxygen.