Microbes in Sewage Treatment Questions in English

(C) $B.O.D.$ stands for Biochemical Oxygen Demand.
It is defined as the amount of dissolved oxygen that would be consumed if all the organic matter in one litre of water were oxidized by bacteria.
Therefore,in the $B.O.D.$ test,oxygen is used by microorganisms to decompose and destroy waste organic matter present in the water sample.
Thus,the correct option is $(c)$.

(A) Micro-organisms,specifically aerobic bacteria,are used in the process of sewage treatment and water purification.
In the presence of oxygen,these micro-organisms oxidize complex organic pollutants present in the water into simpler inorganic forms,thereby reducing the biological oxygen demand $(BOD)$ and purifying the water.

(C) Sewage water contains a high amount of organic matter.
Micro-organisms,such as bacteria and fungi,play a crucial role in the treatment of sewage.
These organisms decompose complex organic compounds present in the sewage into simpler substances through biological processes,thereby purifying the water for recycling.

(B) Biological Oxygen Demand $(BOD)$ refers to the amount of dissolved oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria. The measurement of the rate of $O_2$ consumption in a unit volume of water over a specific period of time is the standard method used to determine the $BOD$ of a water sample. This value serves as an indicator of the level of organic pollution in the water.

(C) $E. coli$ (Escherichia coli) is a bacterium commonly found in the lower intestine of warm-blooded organisms.
Its presence in water bodies is a standard indicator of fecal contamination.
Since fecal matter is a major component of sewage,a high count of $E. coli$ in water serves as a direct indicator of sewage pollution.

(B) During waste water treatment:
$1$. Primary treatment involves the physical process of removing suspended particles through filtration and sedimentation.
$2$. Secondary treatment is a biological process that utilizes aerobic and anaerobic microorganisms to decompose organic matter present in the sewage.
$3$. Tertiary treatment involves the chemical removal of specific nutrients like phosphates,nitrates,and sulphates from the water.
Therefore,the correct stage involving biological treatment is secondary treatment.

(B) $Pseudomonas$ species are well-known for their metabolic versatility. They possess the ability to degrade a wide range of complex organic compounds,including hydrocarbons,pesticides,and other environmental pollutants. This property makes them highly useful in bioremediation,where they are employed to clean up oil spills and toxic waste sites.

(A) $1$. In a sewage treatment plant,the sediment of the settling tank is called activated sludge,which serves as an inoculum for the aeration tank and is a rich source of aerobic bacteria. Thus,option $A$ is correct.
$2$. Biogas is produced by the action of anaerobic bacteria (not aerobic) on cellulosic material present in animal waste (dung). Thus,option $B$ is incorrect.
$3$. $Methanobacterium$ is an anaerobic bacterium,not an aerobic one. It is found in the rumen of cattle. Thus,option $C$ is incorrect.
$4$. Biogas is a mixture of gases (primarily methane,$CO_2$,and $H_2S$),not pure methane. Thus,option $D$ is incorrect.

(D) Secondary sewage treatment,also known as biological treatment,involves the use of aerobic and anaerobic microorganisms to decompose organic matter present in the sewage.
Primary treatment is a physical process involving filtration and sedimentation.
Secondary treatment relies on the metabolic activity of microbes (bacteria and fungi) to reduce the Biological Oxygen Demand $(BOD)$ of the effluent.
Therefore,it is essentially a biological process.

(A) Sewage treatment is primarily a biological process that relies on the activity of microorganisms.
In the secondary treatment phase,also known as biological treatment,aerobic and anaerobic microbes are used to decompose the organic matter present in the sewage.
These microbes consume the organic waste,thereby reducing the Biological Oxygen Demand $(BOD)$ of the effluent before it is released into water bodies.

(B) Sewage treatment plants $(STPs)$ primarily rely on heterotrophic microorganisms naturally present in the sewage to purify the water. During the secondary treatment (biological treatment),these microbes consume the organic matter present in the sewage,thereby reducing the Biological Oxygen Demand $(BOD)$ of the effluent.

(B) The $BOD$ (Biochemical Oxygen Demand) refers to the amount of oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria.
During the secondary treatment of sewage,aerobic microbes consume the organic matter present in the effluent.
As these microorganisms break down and consume the organic pollutants,the amount of organic matter in the water decreases.
Consequently,the $BOD$ level of the effluent decreases,indicating that the water has become less polluted.

(C) In sewage treatment,the primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh-like structures). Once the $BOD$ of sewage is reduced significantly,the effluent is then passed into a settling tank where the bacterial flocs are allowed to sediment. This sediment is called activated sludge.

(B) In $STPs$ (Sewage Treatment Plants),the primary and secondary treatment processes involve the breakdown of organic matter by microbes.
During the anaerobic sludge digestion process,methanogenic bacteria produce biogas (a mixture of gases like methane,hydrogen sulfide,and carbon dioxide).
Additionally,the remaining sludge after treatment is often used as manure (fertilizer) for agricultural purposes.
Therefore,both biogas and manure are obtained as byproducts of the sewage treatment process.

(B) In sewage treatment,the primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs. After this,the mixture is passed into a settling tank where the bacterial flocs are allowed to sediment. This sediment is called activated sludge. $A$ small part of this activated sludge is pumped back into the aeration tank to serve as the inoculum.

(C) $STPs$ stands for $Sewage$ $Treatment$ $Plants$. These are facilities where municipal wastewater (sewage) is treated to remove contaminants before it is released into the environment. This process involves physical,chemical,and biological methods to reduce the organic load and pathogens in the water.

(A) In sewage treatment,the initial step involves the physical removal of particles from the sewage through filtration and sedimentation.
$1$. First,floating debris is removed by sequential filtration.
$2$. Then,the grit (soil and small pebbles) is removed by sedimentation.
$3$. All solids that settle down during this sedimentation process form the primary sludge,while the supernatant forms the primary effluent.

(C) $BOD$ stands for Biochemical Oxygen Demand. It refers to the amount of dissolved oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria. Therefore,$BOD$ is a measure of the organic matter present in water,which is decomposed by aerobic microbes. Thus,it is related to both microbes (which perform the oxidation) and organic matter (which is being oxidized).

(C) The treatment of sewage is carried out in two main stages at sewage treatment plants (STPs):
$1$. Primary treatment: This involves physical removal of particles through filtration and sedimentation.
$2$. Secondary treatment (Biological treatment): This involves the use of aerobic and anaerobic microbes to digest the organic matter present in the primary effluent.

(C) In the process of sewage treatment,the effluent from the primary treatment is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh-like structures). Once the $BOD$ of sewage is reduced significantly,the effluent is then passed into a settling tank where the bacterial 'flocs' are allowed to sediment. This sediment is called activated sludge.

(A) In the process of sewage treatment,the primary treatment involves the physical removal of particles through filtration and sedimentation. During sedimentation,the solids that settle down at the bottom of the tank are known as primary sludge. Therefore,sludge is the mud-like sediment obtained after the sedimentation process.

(B) In sewage treatment,the primary treatment involves physical removal of particles through filtration and sedimentation. The sediment that settles down is called primary sludge,while the supernatant (the liquid portion remaining above the sediment) is called the primary effluent. This effluent is then taken for secondary treatment.

(A) The sewage treatment process involves three main stages:
$1$. Primary Treatment (Physical process): This involves physical removal of particles through filtration and sedimentation.
$2$. Secondary Treatment (Biological process): This involves the use of aerobic microbes to digest organic matter in the aeration tank.
$3$. Tertiary/Sludge Treatment (Anaerobic process): The sludge produced during secondary treatment is treated with anaerobic bacteria in anaerobic sludge digesters to produce biogas.

(B) In the process of sewage treatment,the primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of aerobic microbes into flocs. These microbes consume the major part of the organic matter in the effluent,which significantly reduces the $BOD$ (Biochemical Oxygen Demand). Once the $BOD$ of sewage or waste water is reduced significantly,the effluent is then passed into a settling tank where the bacterial 'flocs' are allowed to sediment. This sediment is called activated sludge.

(D) In Sewage Treatment Plants $(STPs)$,the term 'effluent' refers to the treated wastewater that is released into natural water bodies (like rivers or streams) after the completion of both primary and secondary treatment processes.
$1$. Primary treatment involves physical removal of particles through filtration and sedimentation,resulting in 'primary effluent'.
$2$. Secondary treatment (biological treatment) involves the growth of flocs (bacteria and fungal filaments).
$3$. After secondary treatment,the mixture is passed into a settling tank where the flocs are allowed to sediment. The sediment is called 'activated sludge',and the remaining clear water is the final effluent,which is safe to be released into water bodies.

(C) During the secondary treatment of sewage,the primary effluent is passed into large aeration tanks.
Here,it is constantly agitated mechanically and air is pumped into it.
This allows vigorous growth of useful aerobic microbes into flocs.
Flocs are masses of bacteria associated with fungal filaments to form mesh-like structures.
These microbes consume the major part of the organic matter in the effluent,significantly reducing the Biological Oxygen Demand $(BOD)$.

(C) In the secondary treatment of sewage,the primary effluent is passed into large aeration tanks.
Here,it is constantly agitated mechanically and air is pumped into it.
This allows for the vigorous growth of aerobic microbes into masses of bacteria associated with fungal filaments to form mesh-like structures called 'flocs'.
These flocs consume the major part of the organic matter in the effluent,significantly reducing the Biological Oxygen Demand $(BOD)$.

(C) The removal of physical particles from sewage is known as primary treatment.
Primary treatment involves two main steps:
$1$. Sequential filtration: This removes floating debris.
$2$. Sedimentation: This allows grit (soil and small pebbles) to settle down.
These steps are purely physical processes. Biological treatment is part of secondary treatment,and chlorination is a tertiary treatment process used for disinfection.

(B) During the secondary treatment of sewage,the primary effluent is passed into large aeration tanks.
In these tanks,the effluent is constantly agitated mechanically and air is pumped into it.
This allows for the vigorous growth of aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh-like structures).
These microbes are heterotrophic in nature,meaning they consume the organic matter present in the sewage,thereby significantly reducing the Biochemical Oxygen Demand $(BOD)$ of the effluent.

(B) In sewage treatment,the primary effluent is passed into large aeration tanks.
In these tanks,the effluent is constantly agitated mechanically and air is pumped into it.
This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh-like structures).
While growing,these microbes consume the major part of the organic matter in the effluent.
This significantly reduces the $BOD$ (Biochemical Oxygen Demand) of the effluent.
Once the $BOD$ of sewage or wastewater is reduced significantly,the effluent is then passed into a settling tank where the bacterial 'flocs' are allowed to sediment.
This sediment is called activated sludge.

(B) Assertion $(A)$ is true because the increasing human population generates a massive amount of sewage,which,if untreated,leads to water pollution and the spread of diseases. Therefore,more $STPs$ are required.
Reason $(R)$ is also true because,during the secondary treatment of sewage,anaerobic sludge digesters are used to digest the bacteria and fungi in the sludge,which produces gases like methane,hydrogen sulfide,and carbon dioxide,collectively known as biogas,which can be used as a source of energy.
However,the production of biogas is a beneficial byproduct of the treatment process,not the primary reason why we need more $STPs$ (the primary reason is pollution control). Thus,$R$ is not the correct explanation of $A$.

(D) In the process of sewage treatment,the primary sludge and the supernatant from the settling tanks are sent to large tanks called anaerobic sludge digesters.
In these tanks,other kinds of bacteria,which grow anaerobically,digest the organic matter present in the sludge.
During this digestion,bacteria produce a mixture of gases such as methane,hydrogen sulfide,and carbon dioxide,which form biogas.

(C) $1$. Methanogens are anaerobic bacteria,not aerobic,found in the rumen of cattle. Thus,option $A$ is incorrect.
$2$. Biogas is a mixture of gases (primarily methane,$CO_2$,and $H_2$),not pure methane. Thus,option $B$ is incorrect.
$3$. In sewage treatment,a large part of the sludge is pumped into tanks called anaerobic sludge digesters,where anaerobic bacteria digest the organic matter. This is a correct statement.
$4$. Biogas is produced by the activity of anaerobic bacteria,not aerobic bacteria,on organic waste. Thus,option $D$ is incorrect.

(B) In the process of sewage treatment,the primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh-like structures). When the sewage water is passed into a settling tank,the bacterial flocs are allowed to sediment. This sediment is called 'activated sludge'.

(C) In the process of sewage treatment,the primary treatment involves physical removal of particles through filtration and sedimentation.
$1$. The solids that settle down at the bottom of the primary settling tank are known as 'primary sludge'.
$2$. The supernatant liquid (the water that remains above the settled solids) is known as the 'effluent'.
$3$. This effluent is then taken for secondary treatment (biological treatment).
Therefore,the correct answer is 'effluent'.

(A) The process of sewage treatment in $STPs$ (Sewage Treatment Plants) occurs in the following sequence:
$1$. Primary treatment involves physical removal of particles through filtration and sedimentation,resulting in the formation of $Primary \ sludge$ and $Effluent$.
$2$. The $Effluent$ from primary settling tanks is taken for secondary treatment (biological treatment).
$3$. In the aeration tank,aerobic microbes grow to form $Flocs$ (masses of bacteria associated with fungal filaments).
$4$. These $Flocs$ consume the major part of organic matter,reducing the $BOD$ of the effluent.
$5$. The sediment formed after secondary treatment is called $Activated \ sludge$.
$6$. $A$ small part of this $Activated \ sludge$ is pumped back into the aeration tank,and the remaining major part is pumped into large tanks called $Anaerobic \ sludge \ digesters$,where anaerobic bacteria produce $Biogas$.
Therefore,the correct sequence is $Primary \ sludge \rightarrow Effluent \rightarrow Flocs \rightarrow Activated \ sludge \rightarrow Biogas$.

(C) Microorganisms,including bacteria,present in sewage treatment plants consume organic matter present in the water. During the secondary treatment (biological treatment),aerobic microbes consume the major part of the organic matter in the effluent. This significantly reduces the Biochemical Oxygen Demand $(BOD)$ of the sewage.

(D) In a sewage treatment plant,the primary effluent is passed into large aeration tanks.
In these tanks,the effluent is constantly agitated mechanically and air is pumped into it.
This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh-like structures).
These flocs consume the major part of the organic matter in the effluent,which significantly reduces the $BOD$ (Biochemical Oxygen Demand) of the effluent.
Therefore,the flocs are the active biological agents used in the aeration tank.

(B) The $BOD$ (Biochemical Oxygen Demand) refers to the amount of oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria.
Sewage water has a very high $BOD$ because it contains a large amount of organic matter.
During sewage treatment,the water is treated until the $BOD$ is significantly reduced.
The effluent water released from a sewage treatment plant into natural water bodies must have a low $BOD$ to prevent pollution.
In standard biological contexts,the $BOD$ of treated effluent water is typically considered to be less than $1$ $mg/L$ or very low compared to untreated sewage,though the specific value depends on the efficiency of the treatment process.

(A) Flocs are masses of bacteria associated with fungal filaments to form mesh-like structures.
These are formed during the secondary treatment of sewage,also known as biological treatment.
In the aeration tank,aerobic microbes grow rapidly into flocs,which consume the major part of the organic matter in the effluent,thereby reducing the $BOD$ (Biochemical Oxygen Demand) of the sewage.

(B) The process of treating wastewater by municipalities in cities is known as $Sewage$ $treatment$.
This process involves physical,chemical,and biological methods to remove contaminants from wastewater,primarily using microbes to break down organic matter in $Sewage$ $Treatment$ $Plants$ $(STPs)$.

(C) Sewage water is municipal wastewater that contains large amounts of organic matter and microbes.
Many of these microbes are pathogenic.
The organic matter consists of human excreta,food waste,and other biodegradable materials,which serve as a substrate for the growth of microorganisms.
Therefore,sewage water is primarily characterized by the presence of organic substances and a large population of microorganisms.

(B) During the secondary treatment of sewage,the primary effluent is passed into large aeration tanks.
In these tanks,the effluent is constantly agitated mechanically and air is pumped into it.
This allows for the vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh-like structures).
These microbes are primarily heterotrophic bacteria that consume the major part of the organic matter in the effluent,thereby significantly reducing the Biochemical Oxygen Demand $(BOD)$ of the sewage.

(D) Sewage treatment is primarily carried out in two main stages:
$1$. Primary treatment: This involves physical removal of particles through filtration and sedimentation.
$2$. Secondary (biological) treatment: This involves the use of aerobic and anaerobic microbes to decompose organic matter present in the effluent.
Therefore,the correct answer is $D$ (Two).

(C) The full form of $STPs$ is $Sewage$ $Treatment$ $Plants$. These are facilities designed to treat municipal wastewater,which contains large amounts of organic matter and microbes,before it is released into water bodies like rivers and streams.

(D) The first stage of sewage treatment is known as Primary Treatment.
This stage involves the physical removal of large and small particles from the sewage through two main processes:
$1$. Sequential filtration: This removes floating debris.
$2$. Sedimentation: This allows grit (soil and small pebbles) to settle down.
Therefore,both filtration and sedimentation are part of the primary treatment process.

(A) In the sewage treatment process,the initial stage is known as primary treatment. This involves physical removal of particles from the sewage through filtration and sedimentation. Sequential filtration is used to remove floating debris,while sedimentation is used to remove grit (soil and small pebbles). Therefore,floating debris is the primary material removed by sequential filtration.

(D) In the sewage treatment process,the primary treatment involves physical removal of particles through filtration and sedimentation.
$1$. Sequential filtration removes floating debris.
$2$. Sedimentation allows grit (soil and small pebbles) to settle down.
Therefore,both soil and grit are removed during the sedimentation process.

(D) In the process of sewage treatment,the primary treatment involves physical removal of particles through filtration and sedimentation.
$1$. Floating debris is removed by sequential filtration.
$2$. Grit (soil and small pebbles) is removed by sedimentation.
$3$. All these solids that settle down during primary treatment are collectively called primary sludge.

(B) In the process of sewage treatment,the primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh-like structures). Once the $BOD$ of sewage is reduced significantly,the effluent is then passed into a settling tank. In the settling tank,the bacterial flocs are allowed to sediment. This sediment is called activated sludge.