131. The length of rectangular sedimentation tank should not be more than_______________?
A. B
B. 2B
C. 4B
D. 8B
✅ The correct answer is option C.
Environmental Engineering MCQs
132. In water treatment, rapid gravity filters are adopted to remove_______________?
A. dissolved organic substances
B. dissolved solids and dissolved gases
C. floating solids and dissolved inorganic solids
D. bacteria and colloidal solids
✅ The correct answer is option D.
133. The percentage of filtered water, which is used for backwashing in rapid sand filters, is about______________?
A. 0.2 to 0.4
B. 0.4 to 1.0
C. 2 to 4
D. 5 to 7
✅ The correct answer is option C.
134. Chlorine demand of water is equal to________________?
A. applied chlorine
B. residual chlorine
C. sum of applied and residual chlorine
D. difference of applied and residual chlorine
✅ The correct answer is option D.
135. The hydraulic mean depth (HMD. for an egg-shaped sewer flowing two-third full is_______________?
A. equal to HMD when flowing full
B. less than HMD when flowing full
C. greater than HMD when flowing full
D. none of the above
✅ The correct answer is option C.
136. If the time of concentration is 9 minutes, then the intensity of rainfall according to British Ministry of Health formula will be__________________?
A. 4 mm/hr
B. lOmm/hr
C. 20 mm/hr
D. 40 mm/hr
✅ The correct answer is option D.
137. The layout of distribution system in which water flows towards the outer periphery is_________________?
A. ring system
B. dead end system
C. radial system
D. grid iron system
✅ The correct answer is option C.
138. Sewerage system is designed for_______________?
A. maximum flow only
B. minimum flow only
C. average flow only
D. maximum and minimum flow
✅ The correct answer is option D.