engineering recuitment UKPSC AE Civil 2021 Mock Test (Re-Exam) Environmental Engineering Disposing of Sewage Effluents
The following zones are formed in a polluted river under the self – purification process
1) zone of clear water
(2) zone of active decomposition
(3) zone of recovery
(4) zone of pollution
The correct sequence in which these zones occur progressively downstream in a polluted river is:
1
4, 2, 1, 3
2
4, 2, 3, 1
3
2, 4, 3, 1
4
2, 4, 1, 3