Refer the given flowchart sewage treatment, accordingly mathc Column I with Column II and select the correct answer from the codes given below

Options

A. A-(vii), B-(vi), C-(v), D-(iv), E-(ii), F-(iii), G-(i)
B. A-(i), B-(iii), C-(v), D-(vii), E-(ii), F-(iv), G-(vi)
C. A-(i), B-(ii), C-(iii), D-(iv), E-(v), F-(vi), G-(vii)
D. A-(vii), B-(vi), C-(i), D-(ii), E-(iii), F-(iv), G-(v)

Answer

A

Explanation

Primary treatment involves physical removal of particles from the sewage by the process of sedimentation. All solids that settle form the primary sludge and supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment. The primary effluent is passed into large aeration tank where it is constantly agitated mechanically and the air is pumped into it. This allows vigorous growth of useful microbes into flocs that significantly reduce the biochemical oxygen demand.
Once the BOD of sewage or wastewater is reduced the effluent is then passed into a settling tank where the bacterial flocs are allowed to sediment. This sediment is called activated sludge. A part of activated sludge is used as inoculum in the aeration tank. The remaining is passed into a large tank called anaerobic sludge digester