Environmental (141-160)

Updated: Apr 26, 2020

141. For normal sludge, the value of sludge index for Indian conditions is 150 to 350

142. When there is no recirculation of sewage, then recirculation factor is 1


143. For the same solid content, if the quantity of sludge with moisture content of 98% is X, then the quantity of sludge with moisture content of 96% will be X/2


144. A pipe which is installed in the house drainage to preserve the water seal of traps is called antisiphonage pipe

145. In the two-pipe system of house plumbing, the pipes required are one soil pipe, one waste pipe and two vent pipes

146. The pipe which is used to carry the discharge from sanitary fittings like bath

rooms, kitchens etc. is called waste pipe

147. The gas from sludge digestion tank is mainly composed of methane

148. Most of the bacteria in sewage are saprophytic

149. The process of lagooning is primarily a means of disposing of sludge

150. The biochemical treatment of sewage effluents is essentially a process of oxidation

151. To divert excessive flow from combined sewers, the most commonly used weir is a leaping weir

152. Chlorine is used in the treatment of sewage to help grease separation

153.In the design of grit chambers the maximum velocity of flow is 30

cm per second

154

Acidity-Carbon dioxide Alum-Flocculation Cyclone-Particulate matter Skimming tank-Oils and greases

155.If the diameter of the main pipe is taken less than economic diameter then

1. head loss will be high

2. cost of pipe will be less

156.Incrustation of the tubewell pipes may result in reduced discharge from tubewell


157. The maximum velocity occurs in an egg shaped sewer when the ratio of depth of flow to vertical diameter is 0.81


158. Shrouding is provided in slotted pipe tubewell

159. If in a test conducted for determining relative stability, the period of incubation at 20°C is t days, the relative stability in % is given by 100[1 -(0.794)]

160. Ozone layer in the upper atmosphere is getting destroyed owing to its reaction with chlorofluorocarbons

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