A. 19. Answer => A 318. The velocity of flow of water in a sedimentation tank is about, a) 5 to 10 cm/sec. If the total hardness of water is greater than its total alkalinity, the carbonate hardness will be equal to, a) total alkalinity View Answer Answer: 2 to 6 hours 103 The alum, when added as a coagulant in water A does not require alkalinity in water for flocculation. d) none of the above, 29. d) platinum cobalt scale, 27. (b) Circular tank-The circular sedimentation tank may have.. d) A is false but R is true. c) total hardness – total alkalinity IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG. Ans:c . ii) higher filtration rate B 78. As compared to rapid sand filters, slow sand filters give, i) slower filtration rate The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c 45. c) 2 to 6 hours. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c. 45. 44. 4. b) 100 to 150 1 to 2 minutes B. d) decreasing the surface area of tank, 40. b) less and less Water Treatment Plants 85 Water Treatment processes For Rectangular tank. b) does not affect pH value of water. Sedimentation refers to the removal of suspended matter in water by allowing it to stand still in a quiescent pond for period known as 'detention period' Coagulation refers to the addition of a chemical called "coagulant" that traps the very finely suspended particles (that do not settle easily) in a gel. The overflow rate for plain sedimentation tanks is about, a) 500 to 750 litres/hour/ m2 b) does not affect pH value of water Residual chlorine in water is determined by, a) starch iodide method b) 30 to 45 minutes d) sodium permanganate, 46. d) 1000 mg/litre, 33. c) (ii) and (iii) c) biochemical oxygen demand c) 15 to 30 cm/minute MCQs: The detention period for oxidation ponds is usually kept as_____? The alum, when added as a coagulant in water a) does not require alkalinity in water for flocculation b) does not affect pH value of water c) increases pH value of water d) decreases pH value of water Ans:d 46. c) 0.5 to 1.0 ppm 3. d) 2 to 6 days, 44. c) 2 to 6 hours The length of rectangular sedimentation tank should not be more than, 35. a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days. © Copyright 2016-2020 - www.PakMcqs.com/. The detention period in coagulation tanks is usually kept as_____? d) 1500 to 2000 litres/hour/m2, 36. c) 100 mg/litre 3. However, considering the volume required for sludge and scum accumulation, a septic tank is usually designed for a detention period of 24 to 48 hours. D 2 to 6 days. Percentage of bacterial load that can be removed from water by the process of plain sedimentation is about, 37. iii) lesser efficiency in removal of bacteria The alum, when added as a coagulant in water a) does not require alkalinity in water for flocculation b) does not affect pH value of water c) increases pH value of water d) decreases pH value of water Ans:d 46. b) 10 mg/litre Period of cleaning of slow sand filters is about the A) 24 – 48 hours B) 10 – 12 days 30 to 45 minutes C. 2 to 6 hours D. 2 to 6 days. The sedimentation tanks may be of the following types-(a) Rectangular Sedimentation Tank-In this type of tank, its capacity depends upon the volume of water. b) 0.35 to 0.60 mm In storage reservoirs, detention time is the length of time entering water will be held before being drafted for use (several weeks to years, several months being typical). Required fields are marked *. C 2 to 6 hours. c) lime b) 15 to 30 cm/sec. 44. The detention period in coagulation tanks is usually kept as, a) 1 to 2 minutes Orthotolidine test is used for determination of, a) dissolved oxygen c) both depth and surface area of tank Ans:c. 44. A) Depth of tank B) Surface area of tank C) Both depth and surface area of tank D) None of the above Ans. 50) Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters.Reason R : The sand used in slow sand filters is finer than that in rapid sand d) (ii) and (iv), 42. C 79. Your email address will not be published. The settling velocity of a particle in a sedimentation tank increases if, a) particle size is decreased b) 0.05 to 0.5 ppm d) bacteria and colloidal solids, 47. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c 45. 30 to 45 minutes: C. 2 to 6 hours: D. 2 to 6 days View Answer Workspace Report Discuss in Forum. a) does not require alkalinity in water for flocculation. D. 2 to 6 days. Question is ⇒ The detention period in coagulation tanks is usually kept as, Options are ⇒ (A) 1 to 2 minutes, (B) 30 to 45 minutes, (C) 2 to 6 hours, (D) 2 to 6 days, (E) , … The percentage of removal of suspended solids depends on the detention period, more the detention period, more will be percentage removal of the particles. For a given discharge, the efficiency of sedimentation tank can be increased by, a) increasing the depth of tank - Civil Engineering Mcqs - Environmental Engineering Mcqs The effective size of sand particles used in slow sand filters is, a) 0.25 to 0.35 mm b) residual chlorine 30 to 45 minutes ... D. 2 to 6 days. This preview shows page 55 - 58 out of 66 pages.. 317. Carbonates in water produce A. temporary hardness B. permanent hardness C. acidity D. alkanity Answer => B A. temporary hardness B 43. Required fields are marked *. The amount of coagulant needed for coagulation of water increases with_____? The alum, when added as a coagulant in water, a) does not require alkalinity in water for flocculation c) floating solids and dissolved inorganic solids c) increases pH value of water. 1 to 2 minutes B. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c; The alum, when added as a coagulant in water a) does not require alkalinity in water for flocculation b) does not affect pH value of water c) increases pH value of water d) decreases pH value of water Ans:d Environmental Engineering MCQ question is the important chapter for a Civil Engineering and GATE students. The detention period in coagulation tanks is usually kept as. c) 1250 to 1500 litres/hour/m2 The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally, a) less and more Select your answer based on the coding system given below: a) Both A and R are true and R is the correct explanation of A. c) more and less Correct Answer. The detention period in the coagulation tanks is usually kept as the A) 1 to 2 minutes B) 30 to 45 minutes C) 2 to 6 hours D) 2 to 6 days Ans. Alum as a coagulant is found to be most effective when pH range of water is, 43. b) (ii) and (iii) The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about, a) 0.01 to 0.05 ppm (adsbygoogle = window.adsbygoogle || []).push({}); PakMcqs.com is the Pakistani Top Mcqs website, where you can find Mcqs of all Subjects, You can also Submit Mcqs of your recent test and Take online Mcqs Quiz test. The detention period in coagulation tanks is usually kept as (A) 1 to 2 minutes (B) 30 to 45 minutes (C) 2 to 6 hours (D) 2 to 6 days. Detention Time, hr (Basin Volume, gal)(24 hr/day) Flow, gal/day or Detention Time, hr (Basin Volume, cu m)(24 hr/day) Flow, cu m/day B 78. c) increases pH value of water c) 500 to 600 1 to 2 minutes c) standard platinum scale Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters. Environmental Engineering Objective Questions – Part 3, Environmental Engineering Objective Questions – Part 1, List Of 100 Environmental Engineering Objective Questions Part – 2, List Of 100 Environmental Engineering Objective Questions, Environmental Engineering Objective Questions – Part 4, Environmental Engineering Objective Questions – Part 5, Environmental Engineering Objective Questions – Part 6. d) 2 to 6 days. Your email address will not be published. c) both (a) and (b) d) dose of coagulant, 30. C 79. Learn Environmental Engineering MCQ questions & answers are available for a Civil Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. 0. b) dissolved solids and dissolved gases b) copper sulphate 102 The detention period in coagulation tanks is usually kept as A 1 to 2 minutes. d) 1.00 to 1.80 mm, 49. The detention period in the coagulation tanks is usually kept as the A) 1 to 2 minutes B) 30 to 45 minutes C) 2 to 6 hours D) 2 to 6 days Ans. The Following Section consists Multiple Choice Questions on Water Supply Engineering. d) none of the above, 39. a) standard silica scale Usually the detention period is kept between 1 to 3 hour. 3. 1 to 2 minutes: B. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c 44. The amount of coagulant needed for coagulation of water increases with, i) increase in turbidity of water 78. 50% discount - Buy Mock Test series just INR 100/-Use IAMCIVILENGINEER promo code and get 50% discount. A. This Complete Civil Engineering All syllabus and Subject wise mock tests course contains more than 5800 MCQs and 128 mock tests. b) (i)and(iv) 30 to 45 minutes The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Page-10 section-2 b) standard cobalt scale iv) decrease in temperature of water, a) (i) and (ii) c) the depth of tank is decreased Reason R : The sand used in slow sand filters is finer than that in rapid sand filters. c) A is true but R is false. In water treatment, rapid gravity filters are adopted to remove, a) dissolved organic substances b) orthotolidine method d) 1.0 to 5.0 ppm, 32. iv) higher efficiency in removal of bacteria, a) (i) and (ii) d) non carbonate hardness, 31. PLEASE COMMENT BELOW WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION. Detention Period: The detention period to be provided depends on the size of the suspended particle to be removed in the settling tank. C 80. These are not suitable for small plants because these are costly in construction, have less flexibility of control, and greater loss of head. b) total hardness b) surface area of tank b) 30 to 45 minutes. ii) decrease in turbidity of water The detention period in the coagulation tanks is usually kept as the A) 1 to 2 minutes B) 30 to 45 minutes C) 2 to 6 hours D) 2 to 6 days Ans. Period of cleaning of slow sand filters is about the A) 24 – 48 hours B) 10 – 12 days C) 2 – 3 months D) 1 – 2 year Ans. 0. The alum, when added as a coagulant in water a) does not require alkalinity in water for flocculation b) does not affect pH value of water c) increases pH value of water d) decreases pH value of water Ans:d 46. During treatment of water, sedimentation is done A. before filtration B. after filtration C. simultaneously with filtration D. along with chlorination. The rate of filtration in slow sand filters in million litres per day per hectare is about, a) 50 to 60 b) decreasing the depth of tank d) decreases pH value of water, 45. In order to provide sufficiently quiescent conditions for effective sedimentation of the suspended solids, the minimum detention period for the sewage in a septic tank should be 24 hours. Take the Quiz and improve your overall Engineering. Save my name, email, and website in this browser for the next time I comment. The chemical most commonly used to increase speed of sedimentation of sewage is, a) sulphuric acid d) (ii) and (iv). B. d) more and more, 41. Sorry, you have Javascript Disabled! B 30 to 45 minutes. To see this page as it is meant to appear, please enable your Javascript! The detention period in coagulation tanks is usually kept as_____? d) 1400 to 1500, 48. Your email address will not be published. The dissolved oxygen level in natural unpolluted waters at normal temperature is found to be of the order of, a) 1 mg/litre Period of cleaning of slow sand filters is about the A) 24 – 48 hours B) 10 – 12 days • Detention period- Rectangular Tank= BLH/Q Circular tank= [d2 (0.011d + 0.785H)]/Q Detension time ranges bet- 4-8hrs - TypeI 2-4hrs - TypeII Horizontal flow velocity- 0.15 to 0.9 m/min normally kept as 0.3m/min L= 1 to 6 times width, usually not allowed to exceed four time width. b) the surface area of tank is increased c) 0.60 to 1.00 mm b) Both A and R are true but R is not the correct explanation of A. a) 1 to 2 minutes. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c. 45. The detention period in these basins is kept 20-50 minutes. The detention period in coagulation tanks is usually kept as: A. A. c) (i) and (iv) On standard silica scale, the turbidity in drinking water should be limited to, 28. Velocity of flow of water in plain sedimentation water tank, is normally kept. C. 2 to 6 hours 50. Your email address will not be published. c) increasing the surface area of tank b) 1000 to 1250 litres/hour/ m2 The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c 45. A) Depth of tank B) Surface area of tank C) Both depth and surface area of tank D) None of the above Ans. Assume the detention period as 5 hours and velocity of flow as 15 cm / minute. iii) increase in temperature of water DESIGN ASPECTS 42 ♦Design Summary of Coagulation Tank: •No of tanks = 4 •Type of tank = Circular •Removal of sludge and scum = Mechanical •Diameter of tank, d = 18 m •Detention time, t = 2 hours •Depth of free board = 0.5 m •Sludge zone accumulation = 1 m •Total Depth of tank, D = 6.5 m Altafayaz2161@gmail.com 43. d) none of the above, 38. Mcq Added by: Muhammad Bilal Khattak. The detention period in coagulation tanks is usually kept as_______________? Raw water passed through coagulation tank is supplied d) 15 to 30 cm/hour, 34. The detention period in coagulation tanks is usually kept as. C 79. The alum, when added as a coagulant in water. The settling velocity of a particle in a sedimentation tank depends on, a) depth of tank 45. The detention period in coagulation tanks is usually kept as_____? The alum, when added as a coagulant in water. 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