Question

The amount of oxygen utilized by the microorganisms present in water to break down the organic matter is called (a) DO (b) BOD (c) COD (d) TLV

Short answer

The correct answer is (b) BOD.

Step-by-step solution

Understand the Terms

Identify what each term represents:(a) DO - Dissolved Oxygen: The amount of oxygen dissolved in water.(b) BOD - Biochemical Oxygen Demand: The amount of oxygen required by microorganisms to break down organic matter.(c) COD - Chemical Oxygen Demand: The amount of oxygen required to chemically oxidize organic and inorganic matter in water.(d) TLV - Threshold Limit Values: Guidelines for exposure limits to chemical substances.

Relate Terms to the Given Description

The description specifies the amount of oxygen utilized by microorganisms to degrade organic matter in water. This matches the term 'Biochemical Oxygen Demand' (BOD).

Verify the Answer

Confirm that BOD is the correct answer by cross-checking with the definitions. It accurately defines the oxygen consumed by microorganisms for breaking down organic matter.

Key concepts

Dissolved Oxygen

Dissolved Oxygen (DO) is the amount of oxygen present in water. It is crucial for the survival of aquatic life. Fish and other organisms require oxygen for respiration, just like humans do. The amount of DO in a body of water can be affected by temperature, salinity, and the presence of organic matter.

High levels of organic matter increase the activity of microorganisms, which consume more oxygen, reducing DO levels. This is why monitoring DO is essential to gauge the health and quality of water bodies.

• DO is measured in milligrams per liter (mg/L).
• Cold water can hold more oxygen than warm water.
• DO levels below 5 mg/L can stress aquatic life, and levels below 2 mg/L can be lethal.

Proper management of DO levels can help maintain a balanced ecosystem in water bodies.

Chemical Oxygen Demand

Chemical Oxygen Demand (COD) measures the amount of oxygen required to chemically oxidize both organic and inorganic matter in water. Unlike Biochemical Oxygen Demand (BOD), which only considers organic matter degraded by microorganisms, COD includes all chemically oxidizable substances.

COD testing involves using strong oxidizing agents to break down compounds in the water sample, measuring oxygen consumption. This measure helps to understand the potential impact of effluent discharges on receiving water bodies.

• COD is expressed in mg/L like DO and BOD.
• Higher COD levels indicate more pollution.
• It is a quicker test compared to BOD.

Effective water treatment processes aim to lower COD levels before wastewater is released into the environment.

Threshold Limit Values

Threshold Limit Values (TLVs) refer to guidelines that specify exposure limits to chemical substances and physical agents. These values are established by expert organizations such as the American Conference of Governmental Industrial Hygienists (ACGIH). TLVs are used to predict safe exposure levels for workers, helping to prevent adverse health effects.

TLVs can be presented in different forms, such as Time-Weighted Average (TWA), Short-Term Exposure Limit (STEL), and Ceiling Limit (C).

• TWA: Average exposure over a standard 8-hour workday.
• STEL: Maximum concentration allowed for a short period (15 minutes).
• C: Concentration that should never be exceeded.

Adhering to TLVs helps protect workforce health and safety by offering clear guidelines for workplace environments.