This set of Environment Management MCQs focuses on “Effects and Control Measures of Marine Pollution”.
1. What is the first step in primary sewage treatment plants?
a) Fine screening
b) Course screening
c) Chlorination
d) Primary settling tank
View Answer
Explanation: Sewage treatment is one of the efficient ways to reduce the pollution load happening on marine waters. The primary treatment first undergoes for course screening which then proceeds to other steps like fine screening and all.
2. What is called for the removal of sand, gravel in the primary treatment of sewage treatment plant?
a) Course screening
b) Fine screening
c) Grit removal
d) Chlorination
View Answer
Explanation: The removal of sand and gravel from the sewage in the primary treatment of sewage plant is known as grit removal. This is the third step in primary treatment after course screening and fine screening.
3. What is called for the place where lighter, organic material settles in the primary treatment of sewage plant?
a) Primary settling tank
b) Secondary settling tank
c) Grit chamber
d) Coursing chamber
View Answer
Explanation: The place where lighter and organic material settles in the primary treatment of sewage plant is called as grit chamber. This chamber comes after the screening of influent by removing the pollutants.
4. Where can we find rotating arm sprays in sewage treatment?
a) Primary treatment
b) Secondary treatment of trickling filter
c) Secondary treatment of activated sludge process
d) Secondary process of oxidation pool
View Answer
Explanation: Rotating arm sprays water over rocks can be seen in secondary treatment of trickling filter. Rotating arm is followed by a circular bed of first size rocks and filter. That treated wastewater along with slim goes to secondary settling tank, which treats the water.
5. In which secondary treatment of sewage treatment sludge is broken down in an anaerobic digester?
a) Oxidation pool
b) Activated sludge process
c) Trickling filter
d) Bed filter
View Answer
Explanation: In sedimentation tank, during sludge treatment sludge is broken down in an anaerobic digester. The digester sludge is pumped onto sludge drying beds. The dried sludge is a good source of manure.
6. In sewage treatment of oxidation pond we can see the water up to 2 meters deep.
a) True
b) False
View Answer
Explanation: In oxidation pond of the secondary treatment of sewage treatment plants the influent is transferred into effluent. Partially treated sewage is directed to settle 2 meters deep in a vessel. This vessel settles the pollutants inside and floats the pollutant free water upwards.
7. In which of the following treatment of sewage plant we can find disinfection as a step?
a) Secondary process of oxidation pool
b) Secondary treatment of trickling filter
c) Primary treatment
d) Advanced sewage treatment
View Answer
Explanation: We can find disinfection as a step in advanced sewage treatment. Influent after primary and secondary treatment proceeds to chemical treatment and then to filtration and then to disinfection process after this effluent comes out.
8. How many percentage of BOD removes in primary treatment?
a) 15%
b) 25%
c) 35%
d) 45%
View Answer
Explanation: Primary treatment involves various processes like screening which is proceeding by sedimentation where pollutants are removed during sedimentation. Primary treatment normally removes about 35% of the BOD and 60% of the suspended particles.
9. What is the main objective of secondary treatment of sewage plants?
a) To remove the suspended particles
b) To remove the contaminants
c) To remove the BOD
d) To remove the organic material
View Answer
Explanation: The main objective of secondary treatment of sewage plants is to remove most of the BOD. BOD decided the contamination of water pollutants. Secondary treatment of sewage treatment can remove at least 85% of the BOD.
10. How many common approaches are used in secondary treatment?
a) One
b) Two
c) Three
d) Four
View Answer
Explanation: Three commonly used approaches are used in the secondary treatment of sewage plants. The three commonly used approaches are trickling filters where we can see rotating arm, activated sludge process where we can see aeration tank and the last one is oxidation pond.
11. What is the meaning of ‘Tainting’ related to marine pollution?
a) Unpleasant flavor of seafood
b) Unpleasant flavor of water
c) Unpleasant flavor of soil
d) Unpleasant flavor of air
View Answer
Explanation: Tainting imparts an unpleasant flavor to fish and seafood and is detectable even at extremely low levels of contamination. Thus, the economic loss from oil slicks on fish and shellfish happens.
12. When drill cutting dumped on the seabed which toxic is produced?
a) Toxic nitrites
b) Toxic fluorides
c) Toxic sulphides
d) Toxic hydrates
View Answer
Explanation: When drill cuttings dumped on the seabed and it creates anoxic conditions. These anoxic conditions result in the production of toxic sulphides in the bottom sediment, thus eliminating the benthic fauna.
13. What happens if liquid oil contaminates a bird’s plumage?
a) Birds bone become week
b) Birds lost its memory
c) Birds digestive system becomes weak
d) Birds lost its water-repellent properties
View Answer
Explanation: If liquid oil contaminates a bird’s plumage, its water-repellant properties are lost. Water then penetrates the plumage and displaces the air trapped between the feathers and skin. With this, the plumage becomes water-logged and the birds may sink and drown.
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