In the primary treatment of sewage, floating debris is removed by _I and the grit is removed by _II_.

I - sedimentation, II - sequential filtration

No worries! We‘ve got your back. Try BYJU‘S free classes today!

I - sequential filtration, II - sedimentation

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

I - sedimentation, II - aerobic digestion

No worries! We‘ve got your back. Try BYJU‘S free classes today!

I - sequential filtration, II - aerobic digestion

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is B I - sequential filtration, II - sedimentation
The large quantities of waste water that is generated every day in cities and towns is known as sewage. It contains human excreta, large amounts of organic matter (food waste) and pathogenic microbes.

It is treated in sewage treatment plants (STPs) before it is discharged into natural water bodies to reduce pollution.

The first stage of sewage treatment is called primary treatment. It involves the physical removal of particles from the sewage through filtration and sedimentation.

Filtration: The floating debris is removed by sequential filtration during which sewage is passed through more than one filter of varying pore sizes in series.

Sedimentation: The filtrate obtained from sequential filtration is allowed to stand undisturbed for a certain time. The heavier particles such as soil and small pebbles (grit) settle down under the effect of gravity and form the sediment which is referred to as primary sludge. The supernatant formed is called the effluent and undergoes further biological treatment/secondary treatment.

The enzymatic digestion of the effluent by heterotrophic aerobic microbes such as bacteria and fungi takes place during the secondary/ biological treatment.

Suggest Corrections

Similar questions

Q. Read the following statements & about waste water treatment how many of them are correct

(i) In Primary treatment First, floating debris of waste is removed by sequence filters
(ii) The Soil and small pebbles are removed by sedimentation in settling tanks
(iii)The sediment is called primary sludge and supernatant is effluent.
(iv) The Sludge is taken for Secondary treatment.
(v) Lower the B.O.D., higher Is water pollution.
(vi)When DDT enters the food chain then they reach water and are easily degradable.
(vii)Discharge of sewage water into river water will decrease its B.O.D.
(viii) Chlorine is added to disinfect drinking water

Q. Study the following statements and select the incorrect ones.

(i) Physical removal of large and small particles through filtration and sedimentation is called primary sewage treatment.
(ii) Secondary sewage treatment is mainly a mechanical process.
(iii) Activated sludge sediment in a sewage treatment plant is a rich source of aerobic bacteria.
(iv) Biogas, commonly called as gobar gas, is pure methane.

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. Which of the following could be a substance found in waste water that floats on the top and is removed in the Primary Treatment of water?

Q. The process of removing oil and grease from sewage in a wastewater treatment plant is known as ___.

Join BYJU'S Learning Program

Explore more

Sewage Treatment

Standard VII Biology

Join BYJU'S Learning Program

In the primary treatment of sewage, floating debris is removed by ___I__ and the grit is removed by ___II___.

In the primary treatment of sewage, floating debris is removed by _I and the grit is removed by _II_.