Description : During sewage treatment, effluent from which one of the following treatment units has minimum wt/vol amount of suspended solids? (a) Detritus channel (b) Primary sedimentation tank (c) Secondary sedimentation tank (d) Activated sludge process aeration tank
Last Answer : (d) Activated sludge process aeration tank
Description : Imhoff cone is used to determine A. Settleable solids B. Suspended solids C. Dissolved solids D. None of these
Last Answer : ANS: A
Description : Primary treatment of sewage consists of removal of A. Large suspended organic solids B. Oil and grease C. Sand and girt D. Floating materials
Description : Pick up the incorrect statement from the following: A. Septic tanks are horizontal continuous flow type of sedimentation tanks B. Septic tanks are generally provided a detention period of 12 to 36 hours C ... covered and high vent shafts are provided for the escape of foul gases D. None of these
Last Answer : ANS: D
Description : For the open drain (N = 0.025) shown in the below figure, the discharge is A. 26.88 cumecs B. 27.88 cumecs C. 28.88 cumecs D. 29.88 cumecs
Last Answer : ANS: C
Description : The domestic sewage in large cities (a) has a high BOD as it contains both aerobic and anaerobic bacteria (b) is processed by aerobic and then anaerobic bacteria in the secondary treatment in ... sewage contains adequate oxygen (d) has very high amount of suspended solids and dissolved salts.
Last Answer : (b) is processed by aerobic and then anaerobic bacteria in the secondary treatment in Sewage Treatment Plants (STPs)
Description : The sewage discharge in a detritus tank of a treatment plant is 576 litres/sec with flow velocity of 0.2 m/sec. If the ratio of width to depth is 2, the depth is A. 100 cm B. 110 cm C. 120 cm D. 150 cm
Description : Chlorination of water is done for the removal of A. Bacterias B. Suspended solids C. Sediments D. Hardness
Description : Lagoons used for purification of polluted water (A) Are large shallow artificial lakes also known as clarification lakes, maturation ponds or oxidation ponds (B) Use micro-organisms/bacteria in presence of dissolved oxygen (C) Gives an ... 1 mg/litre and BOD = 3.8 mg/litre (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
Description : Assertion A.: A free board of 0.3 m is provided above the top sewage line in septic tanks. Reason (R): It helps to accommodate the scum in the septic tank. A. Both A and R is true and R is the correct ... is not a correct explanation of A C. A is true but R is false D. A is false but R is true
Description : Which one of the following statements regarding septic tanks is wrong? A. A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided B. The outlet invert level is kept ... . The minimum width of septic level is 90 cm D. The depth of tank is kept equal to its width
Description : If the peak discharge of a storm water drain (S.W. Drain) is expected to exceed 150 cumecs, the free board to be provided, is A. 100 cm B. 90 cm C. 80 cm D. 50 cm
Description : The sewage treatment in septic tanks is due to A. Anaerobic decomposition B. Aerobic decomposition C. Parasitic decomposition D. None of these
Description : The ratio of design discharge to the surface area of a sedimentation tank is called A. Surface loading B. Overflow rate C. Overflow velocity D. All of these
Description : In a sedimentation tank (length L, width B, depth D) the settling velocity of a particle for a discharge Q, is A. Q/(B × D) B. Q/(L × D) C. Q/L D. Q/(B × L)
Description : The discharge per unit plan area of a sedimentation tank, is generally called A. Over flow rate B. Surface loading C. Over flow velocity D. All the above
Description : The function of skimming tank in sewage treatment is to remove – (1) oil and fatty substances (2) suspended solids (3) gritty substances (4) inorganic substances
Last Answer : (1) oil and fatty substances Explanation: Oil and grease traps are small size skimming basins provided to remove oil and grease and other small floating materials such as fats, vegetable debris, ... content of wastewater rise to the surface of wastewater and remains on top of liquid until removed.
Description : The function of sedimentation tank in sewage treatment is to: (1) Disinfect the sewage (2) Remove water content (3) Aerate the sewage (4) Remove suspended solids
Last Answer : (4) Remove suspended solids Explanation: The function of sedimentation tank in the sewage treatment is to remove suspended solids.
Last Answer : Remove suspended solids
Description : The function of skimming tank in sewage treatment is to remove (1) oil and fatty substances (2) suspended solids (3) gritty substances (4) inorganic substances
Last Answer : oil and fatty substances
Description : Pick up the correct statement from the following: A. In treated sewage, 4 ppm of D.O. is essential B. Only very fresh sewage contains some dissolved oxygen C. The solubility of oxygen in sewage is 95% that is in distilled water D. All the above
Description : The function of skimming tank in sewage treatment is to remove __________ substances. (A) Dissolved solid (B) Suspended solid (C) Oil & fatty (D) Gritty & inorganic
Last Answer : (C) Oil & fatty
Description : Before discharging the foul sewage into rivers, it is generally treated by A. Screening B. Sedimentation C. Oxidation D. All the above
Description : Traps A. Are water seals which prevent the entry of foul gases B. Are used to trap the rats entering sewers C. Dissolve the foul gases D. Create symphonic action to increase the quick disposal of sewerage
Description : The sewer which collects the discharge from a collecting system and delivers it to a treatment plant, is known A. House sewer B. Lateral sewer C. Branch sewer D. Sewer outfall
Description : In domestic sewage, suspended solids, colloidal and dissolved materials constitute
Last Answer : In domestic sewage, suspended solids, colloidal and dissolved materials constitute A. 0.1 B. 0.056 C. 0.027 D. 0.001
Description : Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low (A) Hardness (B) Dissolved solids content (C) Suspended solids content (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Turbidity of water is an indication of the presence of (A) Suspended inorganic matter (B) Dissolved solids (C) Floating solids (D) Dissolved gases
Last Answer : (A) Suspended inorganic matter
Description : Removal of __________ is accomplished by aeration of water. (A) Dissolved gases (B) Suspended solids (C) Dissolved solids (D) None of these
Last Answer : (A) Dissolved gases
Description : For treating the sewage of a large city, you will recommend A. A sedimentation tank and an activated sludge treatment plant B. A plant consisting of Imhoff tanks with low rate trickling filters C. Sedimentation tanks with high rate trickling filters D. None of these
Description : How deep can a septic tank be. Is it ok to put gravel on top, or dirt Will it hurt the drain field?
Last Answer : Septic tanks may be installed at any depth in the soil. The main factors that determine the depth of the tank are sewer line depth, and the site conditions. It is ok to put gravel or dirt over ... you can grow grass as well.Putting gravel or dirt over the septic tank will not harm the drain field.
Description : How do I know when I need to drain my septic tank?
Last Answer : The best way to tell when your septic tank needs to be drained is when it overflows and leaks into the surrounding area. Once it overflows too much then the surrounding area will be leaking and overflow.
Description : In septic tanks, decomposition of organic bacteria, is done by A. Anaerobic bacteria B. Aerobic bacteria C. Both types of bacterias D. None of these
Description : Q No: 271 Pick up the correct statement from the following: A. Turbidity is more in strong sewage B. The black colour indicates septic sewage C. The sewage omits offensive odours after four hours D. All the above
Description : The digested sludge from septic tanks, is removed after a maximum period of A. 3 years B. 3.5 years C. 4 years D. 5 years
Description : The clarigesters are A. Circular septic tanks B. Rectangular septic tanks C. Circular Imhoff double tanks with bottom hoppers D. Circular Imhoff double storey tanks without bottom hoppers
Description : Antisyphonage pipe is fitted A. At the end of septic tanks B. On manholes C. With a W.C. trap D. At the beginning of sewer line
Description : The bottom of the sewage inlet chamber of septic tanks, is provided an outward slope A. 1 in 5 B. 1 in 10 C. 1 in 15 D. 1 in 20
Last Answer : ANS: B
Description : In septic tanks, A. Free board of 0.3 m may be provided B. The baffles or tees are extended up to top level of scum C. The clear space between the baffle top and covering slab is about 7.5 cm D. All the above
Description : The rate of accumulation of sludge in septic tanks is recommended as A. 30 litres/person/year B. 25 litres/person/year C. 30 litres/person/month D. 25 litres/person/month
Description : If the over land flow from the critical point to the drain is 8 km and the difference in level is 12.4 m, the inlet time is A. 2 hours B. 3 hours C. 4 hours D. 5 hours
Description : If the length of overland flow from the critical point to the mouth of drain is 13.58 km and difference in level between the critical point and drain mouth is 10 m, the inlet time is A. 2 hours B. 4 hours C. 6 hours D. 8 hours
Description : Which of the following is the most efficient for removal of very finely divided suspended solids and colloidal matter from the polluted waterstream? (A) Sedimentation tank (B) Circular clarifier (C) Mechanical flocculation (D) Chemical coagulation
Last Answer : (D) Chemical coagulation
Description : In 1000 kg of sewage, the total solids approximate A. 0.5 to 1.0 kg B. 1 kg to 2.0 kg C. 5 kg to 7.5 kg D. 7.5 kg to 10 kg
Description : In sewage, the solids in mg per litre is A. 100 to 500 B. 500 to 1000 C. 1000 to 1500 D. 1500 to 2000
Description : In primary sedimentation, the 0.2 mm inorganic solids get separated if specific gravity is A. 2.25 B. 2.50 C. 2.55 D. 2.65
Description : For evaporation and measurement of settable solids, the apparatus used, is A. A jar B. A breaker C. A test tube D. An Imhoff cone
Description : Imhoff cone is used to measure A. Total organic solids B. Total solids C. Total in organic solids D. Settleable solids
Description : Which of the following pumps in used to pump sewage solids with liquid sewage without clogging the pump is? A. Centrifugal pump B. Pneumatic ejector C. Reciprocating pump D. None of these
Description : For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed A. 3 ppm B. 4 ppm C. 5 ppm D. 10 ppm