Effects of water pollution - class-VIII
Description: effects of water pollution | |
Number of Questions: 88 | |
Created by: Shaka Gupte | |
Tags: biology natural resources and agriculture not for breathing not for drinking environmental issues human influences on the environment |
BOD is ___________ in polluted water and ________in potable water.
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more, less
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less, more
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less in both
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medium in both
BOD of wastewater is amount of
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total organic matter
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biodegradable organic matter
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oxygen evolution
-
oxygen consumption
biological oxygen demand is the amount of Oxygen required by aerobic micro-organisms for the breakdown of organic matter present in waste water or polluted water.
Measurement of the rate of oxygen consumption in unit volume of water over a period of time is done to find out
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Biogas generation
-
Biological oxygen demand
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Biosynthetic pathways
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Fermentation
Decomposition of organic matter by microbes requires oxygen. Degree of impurity of water due to organic matter is measured in terms of 'Biological Oxygen Demand (BOD)'. BOD is the oxygen in milligrams required for 5 days in 1 litre of water at 20 degree centigrades for the microorganisms to metabolise organic wastes.
Biological Oxygen Demand (BOD) is a measure of
-
Industrial wastes poured into water bodies.
-
Extent to which water is polluted with organic compounds.
-
Amount of carbon monoxide inseparably combined with haemoglobin.
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Amount of oxygen needed by green plants during night.
Decomposition of organic matter by microbes requires oxygen. Degree of impurity of water due to organic matter is measured in terms of Biochemical oxygen demand or (BOD). BOD is the oxygen required by microorganisms to completely metabolise organic wastes present in water.
Huge quantity of sewage is dumped in a river. The BOD will.
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Increase
-
Decrease
-
Slightly decrease
-
Remain unchanged
A huge quantity of sewage increases Organic matter in the river water.
Biochemical oxygen demand measures
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Industrial pollution
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Air pollution
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Dissolved oxygen required for decomposers
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Pollution capacity of effluents
Multiple Choice Questions
Biochemical oxygen demand may not be good index for water bodies receiving effluents from.
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Sugar industry
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Domestic sewage
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Dairy industry
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Petroleum industry
Biochemical Oxygen Demand or BOD is the amount of dissolved oxygen in a water body, required by microorganisms for the aerobic breakdown of organic matter in the water. Petroleum waste consists of inorganic constituents that also may cut off the oxygen supply into the water body thus BOD may not be a good index for water receiving effluents containing it.
If a water body have high amount of DDT it's 'Biochemical Oxygen Demand' (B.O.D.) will
-
Decrease
-
Not affected
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Increase
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First decrease than increase
Biological Oxygen Demand (BOD) is one of the most common measures of pollutant organic material in water. BOD indicates the amount of putrescible organic matter present in water. Therefore, a low BOD is an indicator of good quality water, while a high BOD indicates polluted water. When BOD levels are high, dissolved oxygen (DO) levels decrease because the oxygen that is available in the water is being consumed by the bacteria. Since less dissolved oxygen is available in the water, fish and other aquatic organisms may not survive.
The enhanced growth of water hyacinth in lakes can be due to
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Disposal of solid wastes in water bodies
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Availability of more nutrients to the flora of a water ecosystem
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Discharge of sewage into water bodies
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All of the above
Water hyacinth (Eichhornia crassipes) also known as Bengal terror is waterweed often blamed for choking water bodies and creating problems for aquatic plants and animal due to less availability of oxygen. It mainly grows where organic nutrient is present in large amount. Level of the nutrient increase due to use of pesticide, weedicides, of discharge of sewage into the water bodies.
BOD of lake becomes high by :-
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Vehicles
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Wind mill
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Smoke and ammonia
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Detergents
Primary treatment reduces BOD, ranges from;
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30-60%
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0-70%
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30-35%
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20-80%
Composition of sewage water depends on its
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Nutrient
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Sources
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Water content
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Sunlight
How much BOD reduces in preliminary treatment?
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15 to 30%
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17 to 60%
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19 to 80%
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10 to 90%
If the river water is polluted with domestic sewage and garbage, it leads to the depletion of
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CO$ _2$
-
CO
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O$ _2$
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All of the above
A lake rich in domestic sewage and garbage nutrients will leads to eutrophication. Eutrophication is when the environment becomes enriched with nutrients. This can be a problem in aquatic habitats such as lakes as it can cause algal blooms and other aquatic plants. Following this, overcrowding occurs and plants compete for sunlight, space and oxygen. It deoxygenate the water enough to kill the fish and other animals. Thus, the correct answer is option C.
If BOD of river is high, it means that the river
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Is not polluted
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Is very polluted
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Does not have green plants
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Get least amount of light
Biochemical oxygen demand is a measure of how much dissolved oxygen is being consumed as microbes break down organic matter. A high demand, therefore, can indicate that levels of dissolved oxygen are falling, with potentially dangerous implications for the river's biodiversity. High biochemical oxygen demand can be caused by: high levels of organic pollution, caused usually by poorly treated waste water; high nitrate levels, which trigger high plant growth. Both result in higher amounts of organic matter in the river. When this matter decays, the microbiological activity uses up the oxygen.
'Biological Oxygen Demand' (BOD) is a measure of
-
Industrial wastes poured into water bodies
-
Extent to which water is polluted with organic compounds
-
Amount of carbon monoxide inseparably combined with haemoglobin
-
Amount of oxygen needed by green plants during night
Biochemical oxygen demand is a measure of how much dissolved oxygen is being consumed as microbes break down organic matter. A high demand, therefore, can indicate that levels of dissolved oxygen are falling, with potentially dangerous implications for the river's biodiversity. High biochemical oxygen demand can be caused by high levels of organic pollution, caused usually by poorly treated wastewater; high nitrate levels, which trigger high plant growth.
Measuring 'Biochemical Oxygen Demand' (BOD) is a method used for
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Estimating the amount of organic matter in sewage water.
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Measuring the activity of Saccharomyces cervisae in producing curd on a commercial scale.
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Working out the efficiency of RBCs, about their capacity to carry oxygen.
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Working out the efficiency of oil driven automobile engines.
Biochemical oxygen demand (BOD) is the amount of oxygen, expressed in mg/L or parts per million (ppm), that bacteria take from water, when they oxidize organic matter.
BOD is
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The-amount of $O _2$ utilised by organisms in water
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The amount of $O _2 $ utilised by micro organisms for decomposition
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The total amount of $O _2 $ present in water
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All of the above
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period.
The major source of BOD in the river Ganga is
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Leaf litter
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Fishes
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Human waste
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Aquatic plants
The Ganges river basin is one of the most fertile and densely populated regions in the world that covers an area of 1,80,000 $km^2$. The river flows through 29 cities with population over 100,000; 23 cities with population between 50,000 and 100,000, and about 48 towns.
'Biological Oxygen Demand' (BOD) is a measure of
-
Industrial wastes poured into water bodies.
-
Extent to which water is polluted with organic compounds.
-
Amount of carbon monooxide inseparably combined with haemoglobin.
-
Amount of oxygen needed by green plants during night.
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The BOD measures the amount of oxygen consumed by biochemical oxidation of waste contaminants. The total amount of oxygen consumed when the biochemical reaction is allowed to proceed to completion is called as the ultimate BOD. The BOD is universally adopted as a measure of relative pollution effect.
BOD is related with
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Organic matter
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Microbes
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Both A and B
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None of the above
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period.
Increase in BOD of water reservoir is due to
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Algae
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Soil
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Moss
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Waste product
Biochemical oxygen demand is a measure of the quantity of oxygen used by microorganisms (e.g., aerobic bacteria) in the oxidation of organic matter. Natural sources of organic matter include plant decay and leaf fall. However, plant growth and decay may be unnaturally accelerated when nutrients and sunlight are overly abundant due to human influence. Urban runoff carries pet wastes from streets and sidewalks, nutrients from lawn fertilizers; leaves, grass clippings, and paper from residential areas, which increase oxygen demand. Oxygen consumed in the decomposition process reduces other aquatic organisms of the oxygen they need to live. If dissolved oxygen concentrations drop below 5 parts per million (ppm), fish will be unable to live for very long. This can occur in the form of organic pollution for sources such as domestic sewage, septic tank leakage, and fertilizer runoff, or could be in the form of inorganics from domestic or industrial sources.
What is B.O.D.?
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The amount of $O _2$ utilised by organisms in water.
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The amount of $O _2 $ utilized by microorganisms for decomposition.
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The total amount of $O _2$ present in water.
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All of the above.
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period.
A water body has high BOD, indicating that water is
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Being contaminated with sewage
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Being aerated
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Receiving minerals
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Atrophic
Biological oxygen demand (BOD) is one of the most common measures of pollutant organic material in water. BOD indicates the amount of putrescible organic matter present in water. Therefore, a low BOD is an indicator of good quality water, while a high BOD indicates polluted water. The BOD test serves an important function in stream pollution-control activities.
BOD of a pond is related to .......... in per unit volume of water.
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All the plants
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All the nektons
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All the microbes
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All the animals
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic microorganisms to break down organic material present in a given water sample at certain temperature over a specific period of time. Thus, the correct answer is option C.
BOD is related to
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Organic pollutants
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Detergents
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Putrescibility
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Inorganic pollutants
BOD is abbreviated form of biological oxygen demand. It is the amount of oxygen required by microbes to break down the organic matter present in a certain volume of a sample of water. The amount of BOD in the water is a measure of a number of organic pollutants in the water.
High BOD values for a river means that river water
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Have no microbes
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Have more bacteria
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Is highly polluted
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Is highly clean
C.O.D. stands for
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Chemical oxygen demand
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Control of diesel
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Csiumoxide deposition
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Cemistry of depositions
C.O.D. stands for chemical oxygen demand. It is the measurement of the pollution which is based on the chemical decomposition of organic and oxidation of the inorganic contaminants present in dissolved water. It is mainly used against waste water which is contaminated by domestic and industrial wastes.
In the polluted water, the values of
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C.O.D. slightly higher than B.O.D.
-
C.O.D. much higher than B.O.D.
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B.O.D. slightly higher than C.O.D.
-
B.O.D. much higher than C.O.D.
When huge amount of CO$ _2$ is dumped into a river, the BOD will
-
Increase
-
Slightly decrease
-
Remain unchanged
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Decrease
Biological Oxygen Demand is a measurement of the amount of dissolved oxygen that is used by aerobic microorganisms when decomposing organic matter in water. It is expressed in milligrams of oxygen consumed per liter of the sample during 5 days of incubation at 20°C and is used to determine the degree of organic pollution of water. Hence when a huge amount of carbon dioxide is added BOD will not be affected. Thus, the correct answer is option C.
A rapid growth of photosynthetic algae in water develops 'bloom'. How would it affect the environment of water?
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The environment becomes comfortable for all forms of life.
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O$ _2$ level is decreased or BOD becomes high.
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O$ _2$ level of water is increased.
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Fish production is increased.
For how long and at what temperature an experiment is run to determine the value of BOD of a water body?
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$10^oC$ for 10 days
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$20^oC$ for 5 days
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$20^oC$ for 2 days
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$5^oC$ for 20 days
BOD or biochemical oxygen demand is the amount of dissolved oxygen which is required by the aerobic organisms during the decomposition of organic matter. The BOD is measured at a specific temperature and specific period of time. BOD value is represented in the form of oxygen which is consumed per litre of the sample used for testing. The sample is tested before and after 5 days of incubation at 20 °C. The value describes the amount of organic material present in the contaminated or waste water.
Which of the following enhances B.O.D. of water ?
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Sugar mill effluents
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Algae
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Sand
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Moss
The measurement of rate of oxygen utilisation by a unit volume of water over a period of time is to measure.
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Biochemical oxygen demand
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Biosynthetic path
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Biogas generation
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Fermentation
BOD or Biochemical oxygen demand is the amount of dissolved oxygen which is required by the aerobic organisms during the decomposition of organic matter. The BOD is measured at a specific temperature and specific period of time. BOD value is represented in the form of oxygen which is consumed per litre of the sample used for testing. The sample is tested before and after 5 days of incubation at 20 °C. The value describes the amount of organic material present in the contaminated or waste water.
Water pollution can be identified by testing its
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PH level
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Biological Oxygen Demand (BOD)
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Both a and b
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None of these
Water pollution can be identified by testing its PH level and Biological Oxygen Demand (BOD) Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans, aquifers and groundwater). This form of environmental degradation occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds. Acid rains, dumping of chemicals into the water by individuals, industries, and communities.; steam from coal mine drainage etc affect the pH of the water in its reservoir. Thus by testing the pH of water, on the scale from 1 to 14, the pollution in water can be identified. Biochemical oxygen demand is a measure of the quantity of oxygen used by microorganisms (e.g., aerobic bacteria) in the oxidation of organic matter. This value varies with the amount of pollution in water hence pollution can be determined by BOD.
Biochemical Oxygen Demand (BOD) in a river water
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Remains unchanged when algal bloom occurs.
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Has no relationship with concentration of oxygen in the water.
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Gives a measure of salmonella in the water.
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Increases when sewage gets mixed with river water.
Sewage is waste water having food residue, animal and human excreta, detergent, discharges from industrial and commercial establishments. Degree of impurity of water due to organic matter is measured in terms of BOD or biochemical oxygen demand. BOD is the oxygen in milligrams required for 5 days in one litre of water at 20 degree centigrade for the micro organisms to metabolise organic wastes. If the water, is polluted with sewage and other organic wastes, the BOD will increase.
BOD stands for
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Biological organism death
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Biochemical organic matter decay
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Biotic oxidation demand
-
Biochemical oxygen demand
Biochemical Oxygen Demand (BOD) is the oxygen in milligrams required for 5 days in one litre of water at 20 degree centigrade for the micro organisms to metabolise organic wastes present in water.
Which of the following does not occur when the sewage is discharged into water?
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Increase in $O _2$
-
Cyanophycean blooms occur
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Depletion of $O _2$ layers
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Eutrophication
Decomposition of organic matter by microbes requires oxygen. Degree of impurity of water due to organic matter is measured in terms of Biochemical oxygen demand or (BOD).
A lake with an inflow of domestic sewage rich in organic waste may result in:
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Drying of the lake very soon due to algal bloom.
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An increased production of fish due to lot of nutrients.
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Death of fish due to lack of oxygen.
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Increased population of aquatic food web organisms.
Domestic sewage leads to organic loading or occurrence of excess organic matter inside water. Its putrefaction decreases dissolved oxygen. Blue green algae present in the bloom also release toxins. Both toxicity and decreased oxygen level kill aquatic animals. Anaerobic putrefaction produces pollutants like methane, hydrogen sulphide, and ammonia. They kill the bloom forming plants as well. The water body comes to have foul smell, brown colouration, bad taste and oil.
Bio-indicators are used for
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Oxygen demand
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Air pollution
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Mineral present
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All of the above
Bioindicators are organisms, which have a special requirement for some specific mineral or abiotic factor or show some specific response to a particular abiotic factor. Thus, they are good indicators of environmental health. Oxygen demand, presence of minerals, occurrence of petroleum products, radioactive minerals and pollution etc. are some of the responses that can be detected using bioindicators. Lichens are very sensitive to air pollution specially due to sulphur oxides and do not grow in areas having high sulphur dioxide pollution. It is a very commonly used bio-indicator.
Increase of BOD in water leads to
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Increase in the dissolved O$ _{2}$ concentration.
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Decrease in the dissolved O$ _{2}$ concentration.
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Maintenance of dissolved O$ _{2}$ concentration at the same level.
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No effect on dissolved O$ _{2}$ concentration.
Organic loading is occurrence of excess organic matter inside water due to sewage disposal and eutrophication. This leads to an increase in biological oxygen demand (BOD) for putrefaction. Explosive multiplication of alga leads to algal bloom. These conditions result in decrease in dissolved oxygen in water. Both toxicity due to algal toxins and decreased levels of dissolved oxygen kill aquatic animals.
What will be the effect of addition of organic material on water?
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COD remain unaffected
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BOD remain unaffected
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Increases BOD
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Reduces BOD
Decomposition of organic matter by microbes requires oxygen. Degree of organic impurity of water is measured in terms of 'Biological Oxygen Demand' or BOD. BOD is the oxygen in milligrams required by microorganisms to metabolise organic wastes. When more organic matter are added to water, the BOD of the water will increase.
When domestic sewage mixes with river water
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Small animals like rats will die after drinking river water.
-
The increased microbial activity releases micro nutrients such as iron.
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The increased microbial activity uses up dissolved oxygen.
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The river water is still suitable for drinking as impurities are only about 0.1%.
Organic loading is occurrence of excess organic matter inside water due to sewage disposal and eutrophication. This leads to an increase in biological oxygen demand (BOD) for putrefaction by microorganisms. Also explosive multiplication of blue green alga leads to algal bloom. These conditions result in decrease in dissolved oxygen in water. Both toxicity due to algal toxins and decreased levels of dissolved oxygen kill aquatic animals.
Measuring 'Biochemical Oxygen Demand' is used for
-
Estimating the amount of organic matter in sewage water.
-
Working out the efficiency of oil driven automobile engines.
-
Measuring the activity of Saccharomyces cerevisiae in producing curd on a commercial scale.
-
Working out the efficiency of R.B.Cs. about their capacity to carry oxygen.
Degree of pollution or impurities in water due to organic matter is measured in terms of 'Biological Oxygen Demand' or BOD. Biological oxygen demand or BOD is the oxygen in milligrams required for five days in one litre of water at 20 degree centigrades for the microorganisms to metabolise organic waste.
Which of the option shows following examples in ascending order in terms of BOD?
(i) Distilled water (ii) Tap water(iii) Sewage wastes drained in river
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ii- i- iii
-
i- ii- iii
-
iii- i- ii
-
iii- ii- i
BOD is the oxygen required by microorganisms to metabolise organic wastes in the water. Biological treatment of wastewater will reduce the organic impurities or an organic load of polluted water, thus curtail the level of BOD. The greater the content of organic waste in the water greater will be the BOD. Organic waste will be maximum in the sewage waste. Hence it will have the highest BOD. Thus the correct answer is option B.
Study the lists and find the correct match.
I | II | ||
---|---|---|---|
(a) | BOD | (i) | Treatment of sewage |
(b) | KVIC | (ii) | Measure of organic matter in water |
(c) | LAB | (iii) | Biological methods for controlling plant diseases |
(d) | STPS | (iv) | Increases vitamin B$ _{12}$ |
(v) | Production of biogas |
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a-iv, b-iii, c-ii, d-v
-
a-v, b-ii, c-iii, d-i
-
a-ii, b-i, c-iv, d-v
-
a-ii, b-v, c-iv, d-i
BOD-Biological oxygen demand is the measure of organic matter in water
Limit of BOD prescribed by Central Pollution Control Board for the discharge of industrial and municipal waste waters into natural surface waters, is -
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< 3.0 ppm
-
<10 ppm
-
< 100 ppm
-
< 30 ppm
BOD is Biological oxygen demand. It is the total amount of oxygen required by the microorganisms present in a water body to break down the organic matter. If BOD is more, it means that there is abundance of microorganisms in that water body and hence it is polluted with organic matter.
Drained sewage has B.O.D.
-
More than that of water
-
Less than that of water
-
Equal to that of water
-
None of the above
BOD refers to the biological oxygen demand by the microbes to decompose the organic matter present in the water body. The drained sewage is rich in organic waste that will be decomposed by the bacteria. So, the drained sewage will be deficient in oxygen than the normal water. The oxygen demanded by the microbes will be higher in sewage water.
BOD is
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Biological oxygen deficit
-
Biosphere oxygen demand
-
Biological oxygen demand
-
None of the above
BOD refers to the Biological Oxygen Demand. It refers to the amount of the oxygen required by the aerobic bacteria to decompose the organic compounds present in the water body. If the BOD of a water body is low, it is considered to be less polluted. The high BOD shows a large level of pollution because more organic pollutants are present now and the bacteria will need more oxygen to decompose them.
BOD (biological oxygen demand) is
-
Amount of oxygen consumed by microorganisms for decaying organic matter per unit volume of water
-
Amount of $CO _2$ consumed by microorganisms per unit of sewage water
-
Amount of oxygen required by aquatic plants for survival
-
None of the above
Biological oxygen demand refers to the amount of oxygen required for the complete decomposition of the organic mass present in the water body by the decomposing bacteria. More the amount of the organic mass, higher will be the BOD and more will be the level of pollution in the water body. As more and more oxygen will be consumed, the aquatic animals, especially fishes will die due to hypoxia. Their dead bodies will further enhance the organic mass.
Limit of BOD prescribed by Central Pollution Control Board for discharge of industrial and municipal waste waters into natural surface waters is
-
$< 3.0$ ppm
-
$< 10$ ppm
-
$< 30$ ppm
-
$< 100$ ppm
High BOD indicates
-
Highly polluted water
-
Less pollution in water
-
Less sewage
-
Less microorganisms
BOD or the Biological Oxygen Demand that is created when there is a large concentration of the organic matter in the water. To decompose this organic mass, the decomposing bacteria will be activated and there would be consumption of the dissolved oxygen in this process. So, more the organic matter, higher will be the BOD and as a result more will be the pollution in the water body. This causes severe decrease in the dissolved oxygen and kills the aquatic animals.
Biochemical oxygen demand in a river water
-
Remains unchanged when algal bloom occurs
-
Increases when sewage gets mixed up with river water
-
Has no relationship with concentration of oxygen in water
-
Gives a measure of Salmonella in water
BOD of eutrophied lake will be
-
Lower
-
Moderate
-
Higher
-
Same as any other lake
BOD level in fresh water should not exceed beyond
-
$5$ ppm
-
$10$ ppm
-
$25$ ppm
-
$50$ ppm
When domestic sewage mixes with river water, __________
-
Small animals like rats will die after drinking river water
-
The increased microbial activity released micronutrients such as iron
-
The increased microbial activity uses up dissolved oxygen
-
The river water is still suitable for drinking as impurities are only about $0.1\%$
Domestic sewage contains large amounts of organic matter. When domestic sewage mixes with river water, organic matter will content will increase in the river. This will lead to increase in BOD or Biochemical Oxygen Demand.
Match and find the correct option.
I | II | III | |||
---|---|---|---|---|---|
(a) | BOD | (i) | Supernatant as effluent | (p) | Useful aerobic microbes |
(b) | Flocs | (ii) | Measure of organic matter | (q) | All settled solids |
(c) | Primary sludge | (iii) | Masses of bacteria associated with fungi | (r) | Methane hydrogen sulphide carbon dioxide |
(d) | Biogas | (iv) | Anaerobic sludge digester | (s) | Polluting water has more BOD |
-
a-ii-s, b-iii-p, c-i-q, d-iv-r
-
a-ii-p, b-i-r, c-iv-q, d-iii-s
-
a-i-s, b-iii-q, c-iv-p, d-ii-r
-
a-iv-r, b-ii-s, c-iii-p, d-i-q
(a)BOD - (ii)Measure of organic matter-(s)Polluting water has more BOD-Biochemical Oxygen Demand is the amount of dissolved oxygen needed by aerobic microbes to break down organic material present in a given water sample at certain temperature over a specific time period. Polluting water has more organic matter thus required more oxygen for the breakdown. Hence polluting water has more BOD.
Water above the dissolved $O _2$ content may be considered uncontaminated.
-
$0.8$ mg/l
-
$0.008$ mg/l
-
$8.0$ mg/l
-
8 $\mu$g/l
Water pollination is best assessed by determining.
-
DO and BOD
-
BOD and turbidity
-
Do and acidity
-
BOD and alkalinity
D.O. is the dissolved gaseous form of oxygen that is essential for respiration of fish and other aquatic organisms. Wastewater from sewage treatment plants often contains organic materials that are decomposed by microorganisms. The amount of oxygen consumed by these organisms in breaking down the waste is known as the biochemical oxygen demand or BOD. BOD directly affects the amount of dissolved oxygen in rivers and streams. The greater the BOD, the more rapidly oxygen is depleted in the stream, thus reducing the oxygen available to higher forms of aquatic life. Pollution, therefore, increases the BOD of a water body. So, the water pollution status of a water body can be assessed by studying the dissolved oxygen (DO) and biological oxygen demand (BOD) of the water body. So, the correct option is 'DO and BOD'.
Two bottles were half filled with water from Ganga ('P') and Kaveri ('Q') and kept under identical airtight conditions for 5 days. The oxygen was determined to be 2% in bottle ('P') and 10% in bottle ('Q'). What could because of this indifference?
-
Ganga is more polluted than Kaveri
-
Both the rivers are equally polluted
-
Kaveri is more polluted than Ganga
-
Kaveri has more minerals than Ganga
Consider the following statements regarding the ecosystem which helps in reducing the level of pollution in the atmosphere.
$1$. Ecosystems and ecological processes play an important role in maintenance of gaseous composition of the atmosphere, breakdown of wastes and removal of pollutants.
$2$. Some ecosystems, especially wetlands have the ability to breaking down and absorb pollutants.
$3$. Natural and artificial wetlands are being used to filter effluents to remove nutrients, heavy metals, suspended solids; reduce the BOD (Biological Oxygen Demand) and destroy harmful micro-organisms.
Which of the statements given is/are correct?
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$1$ only
-
$1$ and $2$
-
$2$ and $3$
-
All of the above
Multiple Choice Questions
BOD in river water
-
Remains unchanged when algal bloom occurs
-
Increases when sewage gets mixed up with river water
-
Has no relationship with concentration of oxygen in water
-
Give a measure for Salmonella in water.
Biochemical Oxygen Demand or BOD is the amount of dissolved oxygen needed by aerobic microbes to break down organic matter present in a particular water sample at a certain temperature over a specified period of time. Value of BOD increases, given that the organic matter content is high in the water sample. Sewage is rich in organic residues thus it increases BOD of river water upon mixing.
Multiple Choice Questions
BOD is a measure of
-
Industrial wastes passed into water bodies
-
amount of carbon monoxide combined with haemogloblin
-
extent of pollution with organic matter
-
amount of oxygen required by plants during night.
BOD or Biochemical Oxygen Demand measures the degree of impurity of a water body or sample due to organic matter. BOD is the amount of dissolved oxygen needed by aerobic microbes to breakdown the organic matter present in the water body.
Disposal of sewage and industrial effluents into water bodies, resulting in contamination of
-
Soil
-
Water
-
Air
-
Atmosphere
Limit of B.O.D. prescribed by Central Pollution Control Board for the discharge of industrial and municipal waste waters into natural surface waters, is
-
< 30 ppm
-
< 3.0 ppm
-
< 10 ppm
-
< 100 ppm
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. The central pollution control board prescribed the BOD limit for the discharge of industrial and municipal waste water as < 10ppm
-
The pollutants in the river has decreased due to efforts by Delhi government.
-
Despite efforts there are still dissolved minerals in the river.
-
Although efforts are being made, the pollution is still on an increase in Delhi.
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There is an algae in the river.
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. As the level of BOD increases, this shows that efforts are being made to clean Yamuna river but pollution is still on an increase in Delhi.
Increase of BOD in water leads to
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Increase in the dissolved oxygen concentration
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Decrease in the dissolved oxygen concentration
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Maintenance of dissolved oxygen concentration at the same level
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No effect on dissolved oxygen concentration
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. Domestic sewage primarily contains biodegradable organic matter, which readily decomposes by micro-organisms, which can multiply using these organic substances as substrates and hence utilise some of the components of sewage. It is possible to estimate the amount of biodegradable organic matter in sewage water by measuring biochemical oxygen demand (BOD). Micro-organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures.
Sewage drainage into water bodies is harmful for fishes because
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Excessive CO$ _2$ is added in water.
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It gives off a bad smell.
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It removes the competition with fishes to dissolved oxygen.
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It increase competition of fishes for dissolved oxygen.
Domestic sewage primarily contains biodegradable organic matter, which readily decomposes by bacteria and other micro-organisms, which can multiply using these organic substances as substrates and hence utilise some of the components of sewage. It is possible to estimate the amount of biodegradable organic matter in sewage water by measuring biochemical oxygen demand (BOD). Micro-organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures.
In a sewage plant, BOD is indicated as high. After sometime it shows a decrease then
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There is increase in bacterial growth but decrease in oxygen.
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There is decrease in bacterial growth but increase in oxygen.
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There is increase in bacterial growth but increase in oxygen.
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There is decrease in bacterial growth but decrease in oxygen.
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. BOD can be used as a gauge of the effectiveness of wastewater treatment plants. It is listed as a conventional pollutant in the U.S. Clean Water Act.
When domestic sewage mixes with river water
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Small animals like rats will die after drinking river water.
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The increased microbial activity release micro nutrients, such as iron.
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The increased microbial activity uses up dissolved oxygen.
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The river water is still suitable for drinking as impurities are only about 0.1%.
Domestic sewage primarily contains biodegradable organic matter, which readily decomposes by bacteria and other microorganisms, which can multiply using these organic substances as substrates and hence, utilise some of the components of sewage. It is possible to estimate the amount of biodegradable organic matter in sewage water by measuring biochemical oxygen demand (BOD). Microorganisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures.
High BOD indicates
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Highly polluted $H _2O$
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Less pollution in $H _2O$
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Less sewage
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Less microorganism
Biological oxygen demand (BOD) is the rate at which microorganisms in water take up oxygen. A high BOD indicates two things - there is a high level of microorganisms in the water and there is a high content of organic material in the water that is broken down by the organisms. This is an indication of organic pollution.
BOD (biological oxygen demand) is
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Amount of oxygen consumed by microorganisms for decaying organic matter per unit volume of water
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Amount of CO consumed by microorganisms per unit of sewage water
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Amount of oxygen required by aquatic plants for survival
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None of the above
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. Biochemical oxygen demand is the amount of oxygen required for microbial metabolism of organic compounds in water.
Which one of the following statement is true?
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The greater the BOD of waste water, more is its polluting potential.
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The greater the BOD of waste water, less is its polluting potential.
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The lesser the BOD of waste water, more is its polluting potential.
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None of the above.
BOD(Biochemical Oxygen Demand) which is defined as amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. Therefore, the greater the BOD of waste water, more is its polluting potential.
Biological Oxygen Demand (BOD) is a measure of
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Industrial wastes poured into water bodies
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Extent to which water is polluted with organic compound
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Amount of carbon monoxide inseparably combined with haemoglobin
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Amount of oxygen needed by green plants during night
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. It is used as a measure of the degree of water pollution.
At DO below $4$ mg/$l$, water at normal temperature is considered as
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Heavily polluted
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Moderately polluted
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Little polluted
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Nearly pure
Dissolved oxygen (DO) refers to the amount of oxygen dissolved in the water. It depends on the following factors:
Fish die in water bodies polluted by sewage due to
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Pathogens
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Clogging of gills by silt
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Reduction in oxygen
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Foul smell
Oxygen enters the water through diffusion and water has the highest potential to hold oxygen. The high temperature, untreated sewage having biotoxins, hazardous waste can reduce the oxygen to an alarming level leading to the hypoxia in fishes, whereafter enduring at the maximum level they die resultantly. This occurs because the untreated sewage is rich in organic matter and microbes utilize the dissolved oxygen for the decomposition called biological oxygen demand (BOD). The more the value of BOD, the lesser will be the oxygen in the water.
Phosphate pollution is caused by _______.
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Weathering of phosphate rocks only
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Agriculture fertilizers
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Phosphate rocks and sewage
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Sewage and agricultural fertilizers
Phosphate pollution in the water is directly related to the release of the untreated sewage and agriculture fertilizers into the water body. This results in excessive algal bloom that forms a thick layer on the surface of the water and prevents the sunlight and oxygen from getting into the water. As a result, the underlying aquatic animals and plants suffocate and die. When this algal bloom dies, it further enhances the eutrophication process, greatly decreasing the dissolved oxygen in the water.
B.O.D. is connected with
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Organic matter
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Microbes
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Microbes and organic matter
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None of the above
BOD refers to the biological oxygen demand by the microbes to decompose the organic matter present in the water body. Oxygen enters the water through diffusion and water has the highest potential to hold oxygen. The high temperature, untreated sewage having biotoxins, hazardous waste can reduce the oxygen to an alarming level leading to the hypoxia in fishes, whereafter enduring at the maximum level they die resultantly. This occurs because the untreated sewage is rich in organic matter and microbes utilize the dissolved oxygen for the decomposition.
Measurement of rate of oxygen utilisation by a unit volume of water over a period of time is to measure
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Fermentation
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Biogas generation
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Biosynthetic pathway
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Biological oxygen demand
Biological Oxygen Demand (BOD) in simple terms is the amount of oxygen that would be used by the decomposing bacteria to decompose or break down the organic compounds in the water body. The increase in the BOD reflects that the concentration of the organic mass is tremendous and so a large amount of oxygen would be claimed by the bacteria. This results in the deficiency of the dissolved oxygen in the water and adversely affects the aquatic life due to hypoxia. So, the BOD can be defined as the measurement of the rate of oxygen utilization by a unit volume of water over a period of time.
Continuous sewage flow into a stream would lead to
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Eutrophication
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Algal bloom
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Depletion of oxygen
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Increase in temperature
Discharge of untreated sewage into streams which contains high quantity of nutrients induce the disproportionate growth of algae causing eutrophication which results into depletion of dissolved oxygen in the water. The continuous flow of sewage reduces the self-purification capacity of the water body. The condition of hypoxia arises due to depletion of oxygen. Increase in temperature favours the eutrophication and algal bloom is the cause of eutrophication. Depletion of oxygen is the adverse effect of the eutrophication.
A water body has high BOD indicating that water is
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Being contaminated with sewage
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Being aerated
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Receiving minerals
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Atrophic
Biological Oxygen Demand indicates the increase in presence of organic matter in the water body. High BOD indicates the great amount of organic matter. The dissolved oxygen in water is consumed by bacteria to decompose the organic matter of sewage or other discharges thereby depleting the oxygen of the water body. The decrease in oxygen can kill the aquatic life in water body.
BOD is measure of.
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Industrial waste being poured in water body
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Extent of pollution with organic compounds
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CO combined with haemoglobin
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$O _2$ required by green plants during night
The microorganisms in polluted bodies use dissolved oxygen to metabolise organic matter in polluted waters. This is called biochemicalical oxygen demand. The more organic matter in sewage and polluted bodies, greater the BOD and hence less oxygen is left availble tor higher animals like fishes.
Which is the correct ascending arrangement of BOD of sewage(S) distillery effluent(DE), paper mill effluent(PE) and sugar mill effluent(SE)?
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SE$<$PE$<$S$<$DE
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PE$<$S$<$SE$<$DE
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S$<$DE$<$PE$<$SE
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SE$<$S<$PE$<$DE
- BOD is the Biological Oxygen Demand that is created when there is an excessive quantity of the organic matter in the water body and its decomposition is initiated by the decomposing bacteria. More the amount of organic waste, the higher will be the BOD and so more will be pollution in the water body.
- This causes an extreme reduction in the dissolved oxygen and suffocates the aquatic animals.
- Distillery effluent is rich in organic waste left from alcoholic fermentation and it has the highest BOD.
- Papermill effluent has the lowest concentration of the organic mass.
Arrange according to ascending order of BOD.
(a) Highly polluted pond water
(b) Unpolluted pond water
(c) Distilled water
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b-c-a
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c-b-a
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c-a-b
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a-c-b
The concentration of the organic waste and its subsequent decomposition determines the BOD of the water. If the organic concentration is high, there will be high BOD because more dissolved oxygen will be used to breakdown the organic mass by the bacteria. So, high BOD marks high pollution. Distilled water has no content of the organic substances as it has been treated and filtered. Unpolluted water pond will not have polluted source of organic mass but the existing organisms die and their dead bodies contribute to a little raised BOD. Highly polluted water will show a very high value of BOD as it will take a lot of dissolved oxygen to breakdown the organic mass in water body. So, distilled water is least polluted, followed by unpolluted pond water and then highly polluted pond water.
A large quantity of urban sewage is drained to a nearby river. Which among the given conditions would happen after mixing of sewage into the river?
(i) BOD of receiving water body increases.
(ii) DO of receiving water body decreases.
(iii) It will not cause mortality among fishes and other aquatic creatures.
(iv) It will lead to nutrient enrichment of receiving water body.
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i, ii and iii
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i, ii and iv
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ii and iii
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iii and iv
A large quantity of urban sewage will have a large amount of organic and inorganic material. Due to this, the decomposition of the organic mass will initiate the use of dissolved oxygen and so, the DO of receiving water body decreases. This will cause increase in the biological oxygen demand (BOD) by the decomposing bacteria. As the DO decreases, the aquatic animals will suffocate and die. Also, the inorganic nutrients, as well as the decomposed nutrients, will cause lush growth of algae, causing algal bloom over the surface of the water, which will further decrease the DO by not allowing the mixing of atmospheric oxygen.
Polluting strength of sewage is characterised by its
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BOD
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Ozone content
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Nitrogen content
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Eutrophication
The BOD test measures the amount of dissolved oxygen in the water that is used up due to the breakdown of organic pollutants, such as sewage, in a certain number of days. Raw sewage has a BOD of forty to 150 milligrams per litre, whereas drinking water has a BOD of less than 0.5 milligrams per litre. The BOD indicates the content of oxygen needed to decompose organic compounds in wastewater by bacteria.
Relation between DO and BOD is that they
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Are directly proportional
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Are inversely proportional
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Are not related
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Always remain equal to each other
Biological Oxygen Demand (BOD) is a measure of the oxygen used by microorganisms to decompose this waste. This results in a high BOD level. When BOD levels are high, dissolved oxygen levels decrease because the oxygen that is available in the water is being consumed by the bacteria.
A river/ lake with an inflow of domestic sewage rich in organic waste may result in
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Death of fish due to lack of oxygen
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Drying of the river/lake very soon due to algal bloom
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Increase population of aquatic food web organisms
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An increased production of fish due to biodegradable nutrients
A river with an inflow of domestic sewage rich in organic waste will reduce the dissolved oxygen (DO). The organic waste will increase biological oxygen demand of the river thus depleting the O2 content and may result in the death of fish due to lack of oxygen.