Primary Treatment

Q. What is sludge?

Q. _____ is a network of pipes that carry sewage from the households and industries to the wastewater treatment plant.

1. Sludge
2. Sewerage
3. Sewage
4. Sewers

Q. The water obtained after primary treatment of wastewater is called ____.

1. sewage
2. clarified water
3. sludge
4. purified water

Q.

Given below is a jumbled sequence of the processes involved in a wastewater treatment plant.

Arrange them in their correct sequence.

1. Sludge is scraped out and the skimmer removes the floating grease.
2. Water is made to settle in a large tank with a slope in the middle.
3. Large objects like plastic bags are removed by passing wastewater through bar screens.
4. Sand, grit, and pebbles are made to settle by decreasing the speed of incoming wastewater.
5. Wastewater enters a grit and sand removal tank.

Q. Sludge formation is a part of _________ process in the wastewater treatment plant.

1. primary treatment
2. secondary treatment
3. aeration
4. screening

Q.

Define the term sludge. Name two chemicals that are used to disinfect water? [2 MARKS]

Q. Activated sludge is obtained by passing air through the sludge obtained from primary treatment.

1. False
2. True

Q. A scraper removes floatable solids.

1. True
2. False

Q. Why is wastewater treatment plant important?[5marks]

Q.

Activated sludge is obtained after aeration, settling and filtration using sand beds. Choose the options that are true regarding activated sludge.

1. Activated sludge is dried and burnt as it is toxic.

2. Activated sludge is dried and used as manure.

3. Activated sludge is mostly made of settled bacteria and microbes.

4. Activated sludge is buried in deep pits to avoid contamination.

Q. Given below is a jumbled sequence of the processes involved in a wastewater treatment plant. Select the correct option that gives the correct sequence of the processes.

(A) Sludge is scraped out and skimmer removes floating grease.
(B) Water is made to settle in a large tank that is sloped in the middle.
(C) Large objects like plastic bags are removed by passing wastewater through bar screens.
(D) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater.
(E) Wastewater enters a grit and sand removal tank.

1. A → D → C → E → B
2. A → B → C → D → E
3. C → E → D → B → A
4. C → D → E → B → A

Q. What is the function of a skimmer in a wastewater treatment plant?

1. It helps in removing large objects.
2. It helps in removing floatable solids.
3. It helps in decomposing organic matter.
4. It helps in decomposing solids.

Q.

Question 20

Given below is a jumbled sequence of the processes involved in a wastewater treatment plant. Arrange them in their correct sequence.
(a) Sludge is scraped out and skimmer removes floating grease.
(b) Water is made to settle in a large tank with a slope in the middle.
(c) Large objects like plastic bags are removed by passing wastewater through bar screens.
(d) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater.
(e) Wastewater enters a grit and sand removal tank.

Q.

Is the water that we get for cooking and washing purposes fit for drinking? if not , how should we treat it?

Q.

Question 8.

1. Chlorination makes water fit for human consumption. How?

2. Name two chemicals used to disinfect water?

Q. Water is treated before it is supplied to our homes.

1. \N
2. \N

Q. Given below is a jumbled sequence of the processes involved in a wastewater treatment plant. Select the correct option that gives the correct sequence of the processes.

(A) Sludge is scraped out and skimmer removes floating grease.
(B) Water is made to settle in a large tank that is sloped in the middle.
(C) Large objects like plastic bags are removed by passing wastewater through bar screens.
(D) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater.
(E) Wastewater enters a grit and sand removal tank.

1. A → B → C → D → E
2. C → D → E → B → A
3. C → E → D → B → A
4. A → D → C → E → B

Q. Jose works in a water treatment plant. On testing a sample of water to be supplied for drinking, he found that it is not germ-free. What should he do?

1. Carry out filtration
2. Perform sedimentation
3. Release it to water distribution system
4. Pass chlorine through it

Q.

Wastewater needs to be treated in many stages because it contains many different types of impurities. Say true or false.

1. True

2. False

Q. Jose works in a water treatment plant. On testing a sample of water to be supplied for drinking, he found that it is not germ-free. What should he do?

1. Release it to water distribution system
2. Pass chlorine through it
3. Carry out filtration
4. Perform sedimentation

Q. In a wastewater treatment plant, which of the following contaminants can be removed using a bar screen?

1. Oil and grease
2. Grit and pebbles
3. Cans and rags
4. Bacteria and faeces