Given below are two statements:
Statement I: In India, under the Ganga Action Plan and Yamuna Action Plan, it is proposed to build a large number of sewage treatment plants so that the sewage discharged into these rivers is treated sewage.
Statement II: In a sewage treatment plant, the effluent from the primary settling tank is generally released into natural water bodies like rivers and streams.
In the light of the above statements, choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Only Statement I is correct.
Sewage is treated in two stages. Primary treatment removes floating debris, grit and settled solids by physical means. The effluent left after this still has a lot of organic matter, so it goes for secondary (biological) treatment before it can be let out.
Statement I: In India, under the Ganga Action Plan and Yamuna Action Plan, it is proposed to build a large number of sewage treatment plants so that the sewage discharged into these rivers is treated sewage. — True. The Ministry of Environment and Forests started these two plans to save the rivers from pollution. The aim is that only treated sewage reaches the rivers.
Statement II: In a sewage treatment plant, the effluent from the primary settling tank is generally released into natural water bodies like rivers and streams. — False. The effluent from the primary settling tank is taken for secondary treatment. It is the effluent from the secondary treatment plant, with its BOD reduced, that is released into rivers and streams.
NCERT Extract:
Microbes in Sewage Treatment – “… All solids that settle form the primary sludge, and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment.”
Microbes in Sewage Treatment – “… The effluent from the secondary treatment plant is generally released into natural water bodies like rivers and streams.”
Microbes in Sewage Treatment – “… The Ministry of Environment and Forests has initiated Ganga Action Plan and Yamuna Action Plan to save these major rivers of our country from pollution. Under these plans, it is proposed to build a large number of sewage treatment plants so that only treated sewage may be discharged in the rivers.”