Environmental Engg. Questions PDF

ENVIRONMENAL ENGG. 105 From the surface of reservoir, evaporation may be minimised by sprinkling (a) Spirit (b) Hydrochloric acid (c) Cetyl alcohol (d) Methane (e) None of these. 106 To pump water from a water reservoir 3 m deep and maximum water leve...

ENVIRONMENAL ENGG. 105 From the surface of reservoir, evaporation may be minimised by sprinkling (a) Spirit (b) Hydrochloric acid (c) Cetyl alcohol (d) Methane (e) None of these. 106 To pump water from a water reservoir 3 m deep and maximum water level at 135 m, a pump is installed to lift water up to R.L. 175 m at a constant rate of 36, 00, 000 litres per hour. If the length of the pipe is 1506 m and f = 0.01, ignoring other minor losses and assuming the economical diameter from Lea's formula D = 1.2 𝑸, the water horse power of the pump is (a) 400 (b) 450 (c) 500 (d) 580 (e) 600 107 For least effect on the water table, the tube wells must be dug one in every (a) 0.5 sq km (b) 0.75 sq km (c) 1.0 sq km (d) 1.25 sq km (e) 1.5 sq km. 108 According to Godrich the ratio of peak demand rate to mean demand is Max. daily demand (a) =180% Average daily demand Max. weekly demand (b) =148% Average weekly demand Max. monthly demand (c) =128% Average monthly demand Max. half yearly demand (d) =107% Averagehalf yearlydemand (e) All the above. 109 In rapid sand filters the ratio of length and diameter of the lateral, should not be greater than (a) 10 (b) 15 (c) 20 (d) 25 110 If average volume of sediment deposits is one-tenth million cubic metres per year in a reservoir of total capacity 10 million cubic metres, the dead storage will be filled up, in (a) 10 years (b) 15 years (c) 20 years (d) 25 years (e) 50 years. 111 Water losses in water supply, is assumed as (a) 5% (b) 7.5% (c) 10% (d) 22.5% (e) 15%. 112 Before constructing a dam, the factor to be considered for controlling sedimentation, is (a) selection of dam site (b) construction of check dams (c) providing vegetation screens (d) providing under-sluices in the dam (e) All the above. 113 If the specific capacity of a well is 0.3183 x 10-3 per sec, the discharge from a well of 4 m diameter under a depression head of 4 m, is (a) 8 litres/sec (b) 10 litres/sec (c) 12 litres/sec (d) 14 litres/sec (e) 16 litres/sec. 114 For a city developed haphazardly, the layout of distribution pipes preferred to, is (a) ring system (b) radial system (c) grid iron system (d) dead end system. 115 Consider the following statements: In water supply distribution network, 1. the grid-iron system requires more length of pipe lines and larger number of cut-off valves. 2. the design of the grid-iron system is difficult but economical. 3. employing a grid-iron system, the dead ends are completely eliminated. 4. employing a grid-iron system permits more water to be diverted towards the affected point from various directions. Which of the statements given above are correct? (a) 1, 2 and 4 (b) 1, 3 and 4 (c) 2, 3 and 4 (d) 1, 2 and 3 116 Match List-I (Equation/Method) with List-II (Application) and select the correct answer using the codes given below the lists: List-l List-II A. Manning's Equation 1. Frictional head loss estimation in pipe flow B. Darcy -Weisbach Equation 2. Sanitary sewer design C. Hardy Cross Method 3. Storm sewer design D. Rational Method 4. Water distribution system design Codes: A B C D (a) 2 1 4 3 (b) 1 4 1 3 (c) 2 1 3 4 (d) 1 4 2 3 117 In a pipe network of municipal water supply, a parallel pipe is sometime installed over a portion of the pipe mainly for (a) reducing water hammer pressure (b) decreasing the pumping power need (c) increasing the head available at the node (d) increasing the discharge 118 Consider the following statements in respect of cast iron pipes employed for water supply: 1. Easy to make joints 2. Strong and durable 3. Corrosion resistant 4. Long life Which of the above statements are correct? (a) 1, 2 and 3 only (b) 1, 3 and 4 only (c) 2, 3 and 4 only (d) 1, 2, 3 and 4 119 Consider the following statements regarding valves in a pipe line: 1. In long pipe lines, air will accumulate in the low point of the line and will interfere with the flow. 2. Pressure relief valves are used in pipe lines where pressure may increase beyond the maximum permissible pressure. 3. Non-return valves prevent water flowing back, i.e. in the opposite direction. Which of the above statements are correct? (a) 1 and 2 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3 120 The capacity of a service reservoir in a campus should cater to (a) Sum total of balancing storage, breakdown storage and fire reserve (b) Sum total of balancing storage and fire reserve (c) Sum total of breakdown storage and fire reserve (d) Balancing storage only 121 Which one of the following is NOT a factor affecting losses and wastes in water supply scheme? (a) Metering (b) Unauthorised connections (c) Water demand (d) Pressure in the distribution system 122 Which of the following pairs is not correctly matched? (a) BOD : Strength of sewage (b) Methane : Product of anaerobic decomposition (c) COD : Biodegradability of waste- water (d) Nitrate : Methemoglobinemia 123 The following data pertain to a sewage sample: Initial D.O. = 10 mg /l Final D.O. = 2 mg/l Dilution to 1% The BOD of the given sewage sample is (a) 8 mg/l (b) 10 mg/l (c) 100 mg/l (d) 800 mg/l 124 The following data pertain to a sewage sample: Initial D.O. = 10 mg /l Final D.O. = 2 mg/l Dilution to 1% The BOD of the given sewage sample is The second stage BOD as shown in the above figure is due to (a) Experimental error (b) Increased activity of bacteria (c) Nitrification demand (d) Interference by certain chemical reactions 125 Consider the following statements associated with water pollution parameters: 1. One of the primary indicators of the degree of water pollution is the concentration of organic matter. 2. Total organic carbon (TOC), chemical oxygen demand (COD) and biochemical oxygen demand (BOD) are important parameters of water pollution. 3. Generally TOC > COD > BOD Which of these statements are correct? (a) 1, 2 and 3 (b) 1 and 2 (c) 1 and 3 (d) 2 and 3 126 A 2% solution of a sewage sample is kept at an incubation temperature of 20°C. If initial DO (dissolved oxygen) and final DO values after 5 day's incubation period are 8.5 mg/1 and 5.5 mg/1 respectively, then the BOD will be (a) 50 mg/1 (b) 150 mg/1 (c) 250 mg/1 (d) 350 mg/1 127 For a waste, the 5-day BOD at 20° C is found to be 200 mg/l. For the same waste, 5-day BOD at 30°C will be (a) Less than 200 mg/l (b) More than 200 mg/l (c) 200 mg/l (d) Zero, as the bacteria cannot withstand such a high temperature. 128 The ultimate BOD value of a waste (a) Increases with temperature (b) Decreases with temperature (c) Remains the same at all temperatures (d) Doubles with every 10°C rise in temperature 129 In which one of the following tests is the organic matter in the waste water used as food by micro- organisms? (a) BOD (b) Most probable number (c) CODE. (d) Chlorine demand 130 A certain waste has a BOD of 162 mg/l and its flow is 1000 cubic metres per day. If the domestic sewage has a BOD of 80 gram per capita, then the population equivalent of the waste would be (a) 20.25 (b) 1296 (c) 2025 (d) 12960 131 Match List-I (Different forms of nitrogen in water) with List-II (Inferences) and select the correct answer: List-l List-II A. Nitrate nitrogen 1.Unsatisfactory microbial activity B. Total nitrogen 2.Satisfactory microbial activity C. Nitrite nitrogen 3.Eutrophication may result D. Ammonia nitrogen 4.Recent organic pollution Codes: A B C D (a) 3 2 1 4 (b) 1 4 3 2 (c) 3 4 1 2 (d) 1 2 3 4 132 The correct statement of comparison of ultimate BOD, COD, Theoretical oxygen demand (ThOD) and 5-day BOD (BOD5) is (a) BODu > CODE > THOD > BOD5 (b) COD > ThOD > BODu > BOD5 (c) ThOD > CODE > BODu > BOD5 (d) CODE > BODu > BOD5 > ThOd. 133 A waste water sample of 2 ml is made upto 300 ml in BOD bottle with distilled water. Initial DO of the sample is 8 mg/l and after 5 days it is 2 mg/l. What is its BOD? (a) 894 mg/l (b) 900 mg/l (c) 300 mg/l (d) 1200 mg/l 134 Presence of nitrogen in a waste sample is due to the decomposition of (a) Carbohydrates (b) Proteins (c) Fats (d) Vitamins 135 What is the theoretical oxygen demand of 300 mg/l glucose solution? (a) 300 mg/l (b) 320 mg/l (c) 350 mg/l (d) 400 mg/l 136 The below figure shows BOD curve when the experiment was conducted at 20° C. If the experiment is conducted at 30° C, then the portion AB of the curve (a) shifts to the left (b) shifts to the right (c) remains unchanged (d) shrinks 137 If the average sewage from a city is 95 × 106 l/day and the average 5-day BOD is 300 mg/l against a standard of 75 mg/day per capita at 20°C, then the population equivalent, of the city will be (a) 28,500 (b) 285 × 106 (c) 3,80,000 (d) 380 × 106 138 Consider the following statements regarding biochemical oxygen demand (BOD) of river water. 1. The BOD rate constant varies with river water temperature 2. The BOD rate constant does not depend on the BOD of the river water 3. The BOD rate constant is often different for different river waters 4. The BOD rate constant cannot be determined in a laboratory Which of the above statements are correct? (a) 1 and 4 (b) 1 and 3 (c) 2 and 3 (d) 2 and 4 139 Five-days BOD of a 10% diluted sample having Do = 6.7 mg/l, DS = 2 mg/l and consumption of oxygen in blank = 0.5 mg/l, will be (a) 22 mg/l (b) 42 mg/l (c) 62 mg/l (d) 82 mg/l 140 The waste water from a factory having a pH of 10, contains KOH only. For waste water discharge is 80m³/day. The total quantity of KOH per day will be nearly (a) 4.5 kg/day (b) 5.4 kg/day (c) 6.3 kg/day (d) 7.2 kg/day 141 Which one of the following is the process in which ammonia is oxidised to nitrites and then to nitrates by aerobic bacteria? (a) Nitrification (b) Denitrification (c) Adsorption (d) Regeneration 142 An industrial waste water enters a stream having a BOD concentration of 10 mg/L and a flow of 20 m³/s. If the flow of wastewater is 1.5 m³/s and its BOD concentration is 250 mg/L, then the BOD concentration in the stream at a point downstream of the point of confluence of wastewater with the stream will be (a) 2.67 mg/L (b) 12.09 mg/L c) 13.00 mg/L (d) 26.74 mg/L 143 A polluted stream undergoes self-purification in four distinct zones: 1. Zone of clear water 2. Zone of active decomposition 3. Zone of degradation 4. Zone of recovery The correct sequence of these zones is (a) 3, 4, 2, 1 (b) 2, 3, 4, 1 (c) 2, 4, 3, 1 (d) 3, 2, 4, 1 144 For fish habitat in a river, the minimum dissolved oxygen required is (a) 2 mg/l (b) 4 mg/l (c) 8 mg/l (d) 10 mg/l 145 Sewage sickness is a term used for (a) Persons who become sick after drinking polluted water (b) A treatment plant which does not function properly (c) A stream where the flora and fauna die due to sewage inflow (d) The condition of land where sewage is applied continuously for a long period 146 When a sewage is disposed in a river, the rate of depletion of dissolved oxygen of the river mainly depends on (a) Biochemical oxygen demand of the sewage (b) Chemical oxygen demand of the sewage (c) Total organic carbon present in the sewage (d) Dissolved oxygen present in the sewage 147 Match List-I (Standards of sewage effluents for the discharge in surface water sources) with List-II (Tolerance limits) and select the correct answer: List – l List – II A. BOD5, (mg/l) 1. 250 B. COD, (mg/l) 2. 30 C. Oil and grease, (mg/l) 3. 20 D. Total suspended solids (mg/l) 4. 10 Codes: A B C D (a) 3 4 1 2 (b) 2 4 1 3 (c) 3 1 4 2 (d) 2 1 4 3 148 In dissolved oxygen sag curve, the sag results because (a) It is function of rate of addition of oxygen to the stream (b) it is a function of rate of addition of oxygen from the stream (c) it is a function of both addition and depletion of oxygen from the stream (d) the rate of addition of oxygen is linear, but the rate of depletion is non-linear 149 A municipal sewage has BOD5 of 200 mg/l. It is proposed to treat it and dispose off into a marine environment. For what minimum efficiency should the sewage treatment plant be designed? (a) 85% (b) 60% (c) 50% (d) 33.67% 150 A drain carrying 5m³/s of wastewater with its BOD of 100mg/l joins a stream carrying 50 m³/s flow with its BOD of 5mg/l. What will be the value of the BOD of the combined flow after complete mixing? (a) 3.6 mg/l (b) 13.6 mg/l (c) 33.6 mg/l (d) 53.6 mg/l 151 The maximum flow occurs in an egg shaped sewer when the ratio of depth of flow to vertical diameter is (a) 0.33 (b) 0.50 (c) 0.95 (d) 1.00 152 Consider the following statements: The basic difference between water pipes and sewer pipes is 1. in the material used for the pipes 2. in the pressure of the liquid flow 3. in the suspended solids they carry Which of the statements given above is/are correct? (a) 1 and 3 (b) 1 only (c) 2 and 3 (d) 1, 2 and 3 153 One sewer has a dia. of 300 mm and another one has a dia. of 600 mm. When both run half- full, what will be the ratio of velocities in the two pipes if the slope of both pipes is same? (a) 1 (b) 1/2 (c) (1/2)(2/3) (d) (1/2)(3/2) 154 If the slope of sewer A is 1/100 and that of sewer B is 1/400, the velocity of flow in the two sewers will have a ratio of (size of both the sewers being same) : (a) ½ (b) 1 (c) 22/3 (d) 2 155 At the same mean velocity of flow, the ratio of head loss per unit length for a sewer pipe running full to that for the same pipe flowing half-full is: (a) 2.0 (b) 1.67 (c) 1.0 (d) 0.67 156 A combined sewerage system is more appropriate for developed areas where (a) Rainfall occurs for a very few days in a year (b) Rainfall occurs almost uniformly throughout the year (c) Air temperatures are nearly uniform throughout the year (d) Air temperatures through the year include extremes during certain runs of days 157 Match List-I (Process) with List-II (Biological agent) and select the correct answer using the codes given below the lists: List-l List-II A. Oxidation ditch 1. Facultative bacteria B. Waste stabilization 2. Anaerobic bacteria pond C. Imhoff tank 3. Aerobic bacteria (suspended culture) D. Rotating Biological 4. Aerobic bacteria Contractor (RBC) (attached culture) Codes: A B C D (a) 4 1 2 3 (b) 3 1 2 4 (c) 1 2 3 4 (d) 3 4 1 2 158 One litre of sewage, when allowed to settle for 30 minutes gives a sludge volume of 27 cm³. If the dry weight of this sludge is 3.0 grams, then its sludge volume index will be (a) 9 (b) 24 (c) 30 (d) 81 159 The following are the sewage treatment processes: 1. Primary sedimentation 2. Screening 3. Grit removal 4. Secondary sedimentation When only preliminary treatment is to be given for sewage, select the required treatment processes including their correct sequence from the codes below: (a) 2, 3 (b) 2, 3, 1 (c) 1, 2, 3, 4 (d) 3, 1, 2, 4 160 Which of the following are claimed as advantageous in anaerobic sludge digestion as compared to aerobic digestion? 1. Lower BOD concentration in supernatant liquor. 2. Production of a sludge with excellent dewatering capacity. 3. Greater production of methane. 4. Lesser operating cost. 5. Lesser capital cost. (a) 1, 2 and 4 (b) 2, 3, 4 and 5 (c) 3, 4 and 5 (d) 1, 2 and 5