Effects of water pollution - class-VIII

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.

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.

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.

A huge quantity of sewage increases Organic matter in the river water.

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.

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.

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. 

Primary treatment in wastewater treatment typically reduces BOD by about 30-35% through physical processes like screening and sedimentation. This level of reduction is consistent with standard wastewater treatment engineering data. Higher reductions (like 30-60% or more) usually require secondary treatment with biological processes.

The composition of sewage water is highly variable and depends primarily on the sources of the waste, such as domestic, industrial, or commercial runoff.

Preliminary treatment, which includes screening and grit removal, is designed to remove large debris and heavy inorganic solids, typically reducing BOD by about 15 to 30 percent.

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.

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.

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. 

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. 

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 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. 

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.

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 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. 

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. 

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.

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 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.

Biochemical Oxygen Demand (BOD) measures the amount of oxygen required by aerobic microorganisms to decompose organic matter. High BOD indicates a high concentration of organic pollutants in the water.

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.

Chemical Oxygen Demand (COD) measures the total amount of oxygen required to chemically oxidize all organic matter, whereas BOD only measures biodegradable organic matter. Therefore, COD is almost always higher than BOD.

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.

Algal blooms lead to excessive organic matter. As this matter decomposes, aerobic bacteria consume dissolved oxygen, leading to a decrease in O2 levels and an increase in BOD, which harms aquatic life.

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. 

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 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.

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.

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.

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). 

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.

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.

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.

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.

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.

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. 

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.

BOD-Biological oxygen demand is the measure of organic matter in water

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.

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 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.

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.  

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.

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. 

(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.

 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'.

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.

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.

The disposal of sewage and industrial effluents directly into water bodies introduces pollutants that contaminate the water, rendering it unsafe for various uses.

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

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. 

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. 

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. 

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.

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. 

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.

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.

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. 

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. 

Dissolved oxygen (DO) refers to the amount of oxygen dissolved in the water. It depends on the following factors:

 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 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.

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.

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.

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.

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.

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.

• 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. 

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 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.

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.

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 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.