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