Environmental Studies · Chemistry

Water and Wastewater Treatment

1,423 Questions

This topic deals with water purification, wastewater treatment methods, and industrial effluent management. It includes questions on filtration, disinfection, and water hardness removal. These concepts are tested in environmental science and engineering exams.

Water purificationWastewater treatmentBioremediation strategiesWater hardness removalIndustrial effluent management

Water and Wastewater Treatment Questions

Multiple choice biology wastewater story basics of water pollution sewage treatment wastewater treatment - need and methods personal and public cleanliness who will do this? water borne disease hygiene - a key to healthy life

During sewage treatment the microorganisms participate under which step?

  1. Primary

  2. Secondary

  3. Teritiary

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sewage treatment generally involves three stages, called primary, secondary and tertiary treatment. 

Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. 
Secondary treatment removes dissolved and suspended biological matter. Secondary treatment is typically performed by indigenous, water-borne micro-organisms in a managed habitat. Secondary treatment may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment. 
Tertiary treatment allows rejection into a highly sensitive or fragile ecosystem like estuaries, low-flow rivers, coral reefs etc. 

Multiple choice biology wastewater story basics of water pollution sewage treatment wastewater treatment - need and methods personal and public cleanliness who will do this? water borne disease hygiene - a key to healthy life

The process of mixing chlorine in the water to kill the germs is  called

  1. filtration

  2. chlorination

  3. purification

  4. distillation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Chlorination is the specific chemical process of adding chlorine to water to disinfect it and kill harmful germs. Filtration removes physical particles, whereas chlorination targets biological pathogens.

Multiple choice biology wastewater story personal and public cleanliness who will do this? basics of water pollution water borne disease hygiene - a key to healthy life

Aeration process change the odour of wastewater.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Aeration is mixing of oxygen into the water. It increases the microbial growth in the water. The microbial growth acts on the organic matter and creates flocs which settle. The degradation of organic matter leads to the change in the pH of the water and production of gases like hydrogen sulfide which creates an odour.

So, the correct answer is option B.

Multiple choice chemistry production of metals extraction of metal from concentrated ore basics of metallurgy extraction of metals from ore

Extraction of chlorine from brine is based on:

  1. reduction

  2. displacement

  3. oxidation

  4. evaporation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
In the extraction of chlorine by electrolysis of brine, oxidation of ${ Cl }^{ - }$ ion to chlorine gas occurs.
$2{ Cl }^{ - }+2{ H } _{ 2 }O\rightarrow 2{ OH }^{ - }+{ H } _{ 2 }+{ Cl } _{ 2 }$
Multiple choice chemistry adsorption and colloids adsorption theory of heterogeneous catalysis enzymes and catalysts catalysis

Removal of adsorbate from the surface of adsorbent is called _____.

  1. desorption

  2. absorbation

  3. adsorbation

  4. none
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Removal of adsorbate from the surface of adsorbent is called desorption.
It is the reverse of adsorption. 

For example, when hydrogen gas is adsorbed on the surface of Pt and the temperature is raised or pressure is lowered, some of the hydrogen gas escapes from the surface of Pt. This is known as desorption.

Multiple choice geography in the land of kerala introduction to metallurgy occurrence of metals study of kerala

The process(es) by which lighter earthy particles are freed from the heavier particles using water is/are:

  1. Gravity separation

  2. Levigation

  3. Hydraulic washing

  4. Leaching
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

During concentration of ores, lighter earthy particles are freed from the heavier particles using water. This is carried out by gravity separation or hydraulic washing or levigation.
During leaching, the soluble material is extracted from insoluble material by dissolving out in a suitable solvent.

Multiple choice biology for a pollution free nation water borne disease hygiene - a key to healthy life basics of water pollution

Natural water is generally impure and requires treatment process before it is made potable.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Potable water is generally impure and requires treatment before use. It is first purified using sedimentation process which is then followed by chemical coagulation and flocculation which allows grouping particles together into flocs of bigger size. 

Thus, the correct answer is option A. 

Multiple choice biology for a pollution free nation water borne disease hygiene - a key to healthy life basics of water pollution

The coliform count in drinking water is done

  1. To ascertain faecal contamination

  2. To assess hardness of water

  3. To determine the effect of chlorination

  4. To estimate the amount of suspended imputities
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Coliform bacteria are microorganisms that primarily found in the intestines of warm-blooded animals and thus, present in animal's faeces. By testing for coliforms, especially the Escherichia coli (E. coli), one can determine if the water has possibly been exposed to faecal contamination; that is, whether it has come in contact with human or animal faeces.

Therefore, the correct answer is option A.

Multiple choice botany bacteria bacteria - friend and foe useful and harmful bacteria bacteria; benefits and harmful effects

During sewage treatment, the microorganisms participate under which step?

  1. Primary

  2. Secondary

  3. Tertiary

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Sewage treatment is a process in which the pollutants are removed. The ultimate goal of sewage treatment is to produce an effluent that will not impact the environment. In the absence of sewage treatment, the results can be devastating as sewage can disrupt the environment.
The general processes of sewage treatment are primary, secondary and tertiary treatment. Primary treatment involves physical separation of sewage into solids and liquid by using a settling basin. The liquid sewage is then transferred to secondary treatment which focuses on removing the dissolved biological compound by the use of 'micro-organisms'. The micro-organisms usually use aerobic metabolism to degrade the biological matter in the liquid sludge. Then tertiary treatment is required to disinfect the sewage so that it can be released into the environment. The solid sewage separated from primary treatment is transferred to a tank for sludge digestion which involves anaerobic degradation using micro-organisms.
Therefore, the correct answer is option B.
Multiple choice chemistry chemistry in daily life antimicrobials and antifertility drugs therapeutic action of different classes of drugs drugs and their classification

Which one of the following is used as a disinfectant in water treatment?

  1. Alum

  2. Charcoal

  3. Kieselguhr

  4. Potassium permanganate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Water disinfection means removal, deactivation or killing of pathogenic microorganisms. Microorganisms are destroyed or deactivated resulting in termination of growth and reproduction.

Potassium permanganate is a weak disinfectant, hence, used in water. 

Multiple choice chemistry chemistry in daily life antimicrobials and antifertility drugs therapeutic action of different classes of drugs drugs and their classification

Which of the following solution is used as washing solution for eyes to free them from microorganisms?

  1. $1\%$ Phenol solution
  2. $2-3\%$ Iodine solution
  3. $0.2\%$ Phenol solution

  4. Dilute aqueous solution of Boric acid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Boric acid is the active ingredient contained in some brands of multipurpose contact lens cleaning solutions. Like hydrogen peroxide, boric acid is a disinfectant and anti-fungal agent used in contact lens solutions to prevent the growth of microorganisms on the eye. 

option D is correct

Multiple choice chemistry air and water pollution control environmental impact: global warming green house effect geobiochemical cycle

The important conclusions on the formation of trihalomethanes are which of the following?

  1. Chlorination of natural waters causes the formation of chloroform and other trihalomethanes because of the reaction of $OCl^-$ on DOC present in the water

  2. Use of both ammonia and chlorine in water treatment has reduced the level of the trihalomethanes due to the formation of the chloroamines, which react more slowly than free chlorine
  3. Finally, the concentration of the trihalomethanes above 100$\mu$ g/l are considered unsafe for drinking water

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chloroform, or trichloromethane, is an organic compound with formula $CH{ Cl } _{ 3 }$. It is a colorless, sweet-smelling, dense liquid.

Important conclusions on the formation of trihalomethanes are :

1. Chlorination of natural waters causes the formation of chloroform and other trihalomethanes because of the reaction of OCl−OCl− on DOC present in the water.

2.Use of both ammonia and chlorine in water treatment has reduced the level of the trihalomethanes due to the formation of the chloroamines, which react more slowly than free chlorine.

3.The concentration of the trihalomethanes above 100μμ g/l are considered unsafe for drinking water.