Correct Answer - Option 4 : 1, 2 and 3
Concept:
BOD, COD, TOC and TOD all are associated with organic content of water. COD is related to both inorganic and organic content of water.
Chemical Oxygen Demand(COD)
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Biological oxygen Demand(BOD)
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Theoretical Oxygen Demand
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Total Organic carbon
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The amount of oxygen required by the bio degradable and non-bio-degradable organic matter present in waste water.
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The amount of oxygen required by the bio degradable organic matter present in waste water.
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Through chemical reaction equations, the exact amount of organic matter present represent Theoretical Oxygen Demand.
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It is a form of presentation of amount of organic matter in form of its carbon content.
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Other Important points:
COD is also known as Di-chromate demand.