Environmental Engineering (Part-5) (General Engineering) (SSC JE)

• Biochemical oxygen demand (BOD) is the amount of oxygen taken up by microorganism that decompose organic waste matter in water.

• It is therefore used as a measure of the amount of certain types of organic pollutant in water.

• If the water is more polluted, more will be the BOD because more will be the organic matter present in it and hence, more oxygen will be required to decomposed it.

• Hence, BOD is a river water will increase it sewage gets mixed up with the river water because more organic matter will be added in the river.

Eutrophication is the phenomenon of nutrient enrichment (nitrogen, phosphorous) of water body that initially supports a dense growth of plants and animals life, the extensive increase of algae growth in water bodies is called water bloom (algal bloom).

• Due to death of these algae, their organic matter get decomposed, due to which oxygen gets depleted and the aquatic animals die. Hence, eutrophication results in the reduction of dissolved oxygen.

Pyrolysis– • Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures in the absence of oxygen.

• In involves the simultaneous changes of chemical composition and physical phase, and id irreversible.

• Pyrolysis is a type of thermolysis and is most commonly observed in organic materials exposed to high temperature.

Acid rain results when gaseous emission of sulphur dioxide and nitrogen oxides (NOₓ) interact with vapour & sunlight and are chemical converted to strong acidic compound (H₂SO₄ and HNO₃)

Biochemical oxygen demand or biological oxygen demand (BOD) is the amount of dissolved oxygen used by microorganism to break down organic matter in water.
• A low BOD is an indicator of good quality water, while a high BOD indicates polluted water.

Biodegradable pollutants which can be broken down into simpler, harmless, substances in nature is due course off time (by action of micro-organism like certain bacteria) are called biodegradable pollutants. It means biodegradable pollutants are quickly degraded by natural means.
Ex– Domestic waste, urine, faucal matter, sewage.. etc.

Water pollution is the contamination of water bodies, usually as a result of human activities, water bodies includes for example lakes, rivers, ocean… etc. • Cause of water pollution.
(i) bacteria,
(ii) In organic chemicals,
(iii) Oil spills from industries
(iv) Leaking sewage
(v) vehicle emission.

The major contributors to the greenhouse gases are factories, automobiles, deforestation etc.

KMnO₄ is a very strong oxidizing agent and hence O₃ cannot oxidise it. More ever, Mn in KMnO₄ exists as Mn⁷⁺ and hence oxidation is not possible further.