304 Cin Encmetmine (Omective Tyre) Storage Capacity of a Reservoir Min. storage capacity of the reservoir = max. surplus + max. deficit =a + b demand curve | —~ supply tine §| HL 3 Cumulative 5 é Time ——> FIGURE 6.3 Types of Pipes Cast iron pipes. C.1. Pipes are resistant to con Steel pipes. They are affected by “pitting” because of highly acidic waters. They are coated with bitumen on exte for longevity They are quite common for rising mains. R.C.C. pipes. They are durable (life span cost. They are heavy and hence can be easily lai when it is empty) But they are brittle and heavy Asbestos cement pipes. They are light, surfaces and resist corrosion better They are brittle and easily punctured by Galvanised iron pipes. They are the m coating they last longer (= 40 years). Acidic waters may corrode the zine coal Plastic pipes. P.V.C. pipes are common} zoose neck etc. They are smooth and corrosion, Il. OBJECTIVE _}- Of the total content of water on globe ‘Scanned wih CamSeamnctWaren Surriy Encmernnc — 305 2 Water for domestic consumption should be (@) colourless, odourless and tasteless (0) hygienically safe > Apollutant is (a) any foreign element in excess concentration () an element causing change in quality (0) aharmful element (@ anadultrant, 4, For good taste a desirable temperature of water is (@) less than 11°C (©) 30°C ve (a) more bacteria (c) no bacteria § True colour of water is due to (a) suspended solids (¢) volatile solids 7. A source of colour in water is due to (a) silt (0 organic debris & Purest water may have (@) no colour (¢) dark blue colour & Highly coloured waters are (@) unaesthetic (o) require elaborate treatment 10. An industry that insists on colour free water is (a) fertilisers O (b) dairy (c) tannery D (a) steel. 2. (2) plain sedimenation (6) filtration 3 Permissible colour for drinking water is not (@) 5 units (®) colouring pigments in water (©) bacteria and algae in water A hot water or waste water sample may have Coloured waters may affect the following water treat D_(b) free from dissolved salts o O (Ad) attractive for looks. a o o o o (less than 20°C a O (d) room D (b) greater O @ less D(H) colloidal OD (@acidsin © (highly O @ rich ini oO }) o@ OB (50 units. 1D (b) iron and OD (A) corrosis ‘Scanned wih Cams306 Ci Ewcmernine (Onecrve Tver) 14 An equivalent of mg/lis (@) g/m OD (b) kg/m? o (T/MI © (@) ppm Qo \LABe Turbidity for domestic water is undesirable because it (a) is unaesthetic 1B (b) causes change of taste o (©) give apparent colour o (2) prevents light penetration and hence photosynthesis. o vel6. For a river in flash flood, turbidity is mainly due to (@) inorganic soil O (b) silica o (©) iron, manganese and zine © (A) organic wastes of plants and animals. \ 2% _Aurbidity depends on the presence of the (a) suspended solids o¢ ©) any material capable of preventing light (@) intensity of colouration. 18. Turbidity is mainly due to @) floating solids o (©) colloidal solids o 19. Turbidity is the ability of water to (2) scatter light o¢ (©) retain colloidal solids in suspension d) detain dissolved solids. 320. Turbidity is measured by the 2) concentration of suspended solids collected (b) concentration of colloidal and suspended (c) intensity of light scattered when light is (d) difference in suspended solid concentration 21. Turbidity of a water sample depends on (2) concentration and density of suspended and. (b) concentration of suspended, colloidal and ) concentration of organic and inorganic matter (4) concentration, size, shape and refractive in The standard unit of turbidity is produced a) 1 mg of silicon dioxide is dissolved in 1 1 mg of platinum is dissolved in 1 litre: 1 mg of sodium chloride dissolved in 1 4) 1 mg of cobalt being dissolved in 1 litre of of turbidity are me ow potassium chloroplatinate units ow ‘Scanned wih CamSeamnctWaren Surrix Encmernne — 307 » Turbidity is undesirable because it («) renders waters unpalatable o (p) affects photosynthesis of aquatic life 9 (0) causes milky white colouration to water o (@) causes red and brown stains o [28 Turbidity can be removed by (a) coagulation and filtration (6) aeration and sedimentation So (©) activated carbon adsorption O (@ disinfection. So 26. Due to highly turbid waters efficiency of the following operation gets affected ~~ (a) sedimentation © (6) sedimentation aided by o (©) filtration O (@) disinfection. _ , Tastes along with odours are produced in natural waters (@) organic matter D. (b) inorganic (co) total dissolved solids O (@) alkaline If 20 ml of an odourous water sample is needed 180 produce 200 ml of odour free mixture, then the threshold (@) 10 Oo He (1 0 @09. . Water for domestic use should have (a) sweet smell O (b) faint smell (©) inoffensive smell O(a) no smell. Conductivity represents the concentration of the follow (2) total solids D (8) dissolved solix (c) volatile solids 0 (d) fixed solids. Conductivity directly depends on (2) total solids 1D (6) total dissolved (¢) ionised dissolved solids O (@) volatile or; Conductivity reflects ‘organic solid concentration DB. (b) inorganic (c) total dissolved solids 4) compounds which readily dissociate in solution. Conductivity is standardised at (a) 20° (o) 15°C 34. Suspended solids are less in ground water because O (b) they are fil O 375°C O (a) 25°C, (a) they are absorbed by the soil ) they are set floating on water DU) they readily “Seamed wih cans308 38 a. 4 43. 45. DL mm oymm fe oe” terme to 12 Civn Encintenme (Onjecrive Tyre) jolm te 10 yas wey oer The usual size of suspended solids is (@) > 100 xm 0 (b) <1 mmand > 1m oO (©) <1 um and > 10° um Dd) > Lumand < 100 um. o Suspended solids are undersirable in domestic waters because they (a) induce taste 1 (b) cause disease o (©) produce obnoxious odour O(a) are unaesthetic o Non-filterable residue of a water sample represent (@) floating solids 1D _(b) suspended solids QO (©) colloidal solids OD (id) dissolved solids. o Volatile solids represent (2) total dissolved solids (TDS) O (b) suspended and colloidal solids oO (©) organic dissolved solids 1 (@ inorganic dissolved solids. Oo A water sample is termed turbid when it fails to transmit light through it a (0) is rich in suspended solids ©) is rich in both suspended and colloidal (@) is rich in total solids. The content of total solids in drinking a) 50 mg/l (c) 500 mg/1 If a sample is heated to 600°C, the fr (a) fixed solids (c) total dissolved solids pH of water sample containing 0.1008 g @. o 4 o pH of a water sample is 7. pH of another mixture is (a) 750 (0) 7.26 Higher pH for water is undesirable becat a) it corrodes zinc, copper and lead pipes b) it induces sour taste ) it renders chlorination less effective 4) it promotes growth of iron and sulphur A desirable pH value for domestic 5109 ‘Scanned wih CamSeamnctAlkalinity in natural waters is due to {@) salts of weak bases strong acids (b) drainages from abandoned mines 5 {¢) industrial wastes from rayon mills and stee! mills 3 (@) photosynthesis of algae in water. . gg, The two alkalinities which do not co-exist are “* (@) carbonate and bicarbonate ©. (b) bicarbonate and hydroxide o (o) hydroxide and carbonate DB @any two. B gs Caustic alkalinity is because of (@) Caustic soda D (b) Hydroxides o {c) Carbonates © (a) Bicarbonates. o 48. 1f20 ml of 0.02 H,SO, is needed to produce methyl orange end poit sample, then total alkalinity of the water sample ic pT ately (@) 0.1 mg/l O () 10mg/i o (0) 100 mg/1 O (d) 400 mg/l. 50. 1f20ml of 0.02 H,SO, could produce phenolpthalein end point with a 100 ml water sample then its hydre (a0 OD (b) 100 () 200 mg/1 OD (@) 300 51, Phenolpthalein end point represents (@) bicarbonate alkalinity (b) full carbonate + half bicarbonate alkalinity (©) half bicarbonate + full hydroxide alkalinity (d) full hydroxide + half carbonate alkalinity. 32. 1f50 ml of a water sample titrated against 0.02 H,SO, point of 10 ml and methyl orange end point of 30 ml (a) 10 mg/l of hydroxide and 20 mg/1 of carbonate (b) 10 mg/1 of carbonate and 20 mg/l of bicarbonate (©) 10 mg/1 of bicarbonate and 20 mg/1 of carbonate (4) 10 mg/! of bicarbonate and 20 mg/! of hydroxide. \B Aminimum amount of ....... mg/l of alkalinity is (a) 10 OD (bh) 20 () 50 © (A) 100. 5 Excess alkalinity i irable in swimming pools (a) Nervous system is affected (6) Skin infections caused eye is altered ca (9 Lacrimal fluid around th (4) Swimmer’s itch is caused310 Cn Encnereame (Onsecrive Tree) X58. Excess alkalinity causes CHLOROSIS in plants which is the loss of green pigment ‘chlorophyy \ Pp oP! because of (@) precipitation of Iron as Iron hydroxide: Qo (b) leaf not getting nutrients o (©) photosynthesis is prevented o (a) chlorine bleaches all the colours a 56, Because of excess alkalinity @) corrosion is caused © (b) pitting and tuberculation is induced o (©) water is coloured (a) incrustations develop. 5 5% Due to the photosynthetic activity of algae pH of pools of water will not get changed 1 (b) increases during the day time o ©) increases during the night time (i) progressively increases with time. oO a.58. pH range of mineral acidity is 45 OD (b)>45but<83 a 7 O W@)>83. o $58. pH range of CO, acidity is 45 o 7 o 60. Excess acidity causes eye irritation of swimmers a chlorosis in plants a 61. Chloride that is insoluble in water is Sodium chloride a (c) Calcium chloride o 62. Salty taste is mainly due to a) NaCl o MgCl, o Laxative effect is because of caso, o MgC o A buffer is that hock absorber of pollutants maintains same temperature maintains same pH {) maintains same dissolved oxygen concent _§% A minimum amount of D.O. desirable in " oa Scanned wih CamSeamnctWaren Surry Enomernms = 317 “py ina D.O. test oxygen is replaced by equivalent in {a & (a) iodine O () sodium thiosulphate 8 _{c) manganous sulphate @) sulphuric acid & Sodium Azide is added to the D.O. test to neutralise the effect of (a) iodine D (sulphuric acid S {@ manganous sulphate OD @ nitrites. o Greater D.O. is undesirable in (@) boilers D () aerobic treatment Ss (c) natural water bodies OD (d) anaerobic treatement. 5 Supersaturation of any water with D.O. causes (@) Eutrophication (6) Gas bubble disease of fish a {o) Methamoglobinemia O @ Endemic Goitre. o BOD represents (@) pollutional strength of a waste (©) pollutional strength of an organic fraction of wastes (c) pollutional strength of inorganic fraction of wastes (2) pollutional strength of bio-degradable organic fraction of BOD equation is @y=L,0-10*) 0 ®x=L0- (0) Ky = Kyo (1.047)? GO @x=Ki-1 In the BOD equation K is called (2) oxygenation constant (b) deoxygenation constant (c) reaeration constant d) combined deoxygenation and reaeration constant. In the figure shown for BOD, AB represents 4) carbonaceous stage o ) Nitrogenous stage o (©) proteinous stage o { (¢) frst phase o For ordinary domestic sewage BOD reaction is 3 expected to get completed in about (at 20°C) (4) 5 days o (>) 10 days )20 days (4) 30 days, ooo ‘Scanned wih Cans312 Cyn Exoweermmee (Onecrve Ter) 2S Usual population equivalent of BOD is a) 10 g/capita/day © (b) 20g/capita/day oO (©) 50 g/eapita/day (a) 80 g/capita/day Qo 76. BOD test is standardised at (0) 10°C and 10 day © (b) 20°C and 5 day Qo (©) 87°C and 3 day © (a) 50°C and 2 day. 0 s7% Light is excluded in BOD incubator to (o) encourage anaerobic conditions © (0) prevent growth of algae o control aerobes 1D (@) encourage growth of fungi o 78 A waste water sample of 2 ml is made upto 300 ml in a BOD bottle with distilled water * initial D.O. of the sample is 8.0 and after 5 days it is 2.0. Its BOD is (a) 6 mg/l D(H) 894 mg/l Qo 200 mg/l OD (d) 2400 mg/L 0 29 A waste water sample of 5 ml is made upto 300 m1 with distilled water. The sample had an initial D.O. of 8.0 mg/l and after 5 days the D.O. is O. BOD of the sample Smg/l O (b) 472mg/l a ) 480 mg/1 O (a) test 80. In a BOD test, three samples gave the followi Initial D.O. If the dilution ratio is 50, then the exact BOD (a) 50 mg/t o 60 90 mg, 5 @) 8}. The effluent of a biological treatment unit she g/l D 30 a wo s not well suited to industrial wastes. slow process ow the waste lacks in nutrients 0 @o 83. Second Phase BOD is exerted because of the 0) Carbonaceous matter into CO, and H,O pids into CO, and H,O - ‘Scanned wih CamScamnctw 92. Waren Surry Enomeenne 313 For any waste (#) COD may be less than BOD (0) BOD and COD are equal (©) COD is always greater than BOD. depending upon the percentage of biodegradable matter, it may be either way, Result of COD is generally higher than that of BOD because the strong oxidising conditions in the test (©) complete oxidation of organic and inorganic compounds (0) oxidation of gases like ammonia («) the stablest compounds are being oxidized, ina COD test the most common interference is caused by the ions of (a) chlorides oooo oooo 1D (b) ferrous iron (©) sulphates Od nitrites. 9 Time taken for COD test is about (a) 3 hrs. O (b) ahr. (0) 3 days. O (d) 30 days. An advantage of COD test over BOD test is (a) oxidized all matter including toxins o (b) it cannot oxidize benzene, pyridine ete (0) it is relatively a quick process («) biodegradable matter cannot be distinguished from the rest. Presence of the following indicates recent pollution (@) ammonical nitrogen © (b) albuminoidal (©) nitrites OW nitrates Presence of nitrogen in a waste water sample is due to the (a) carbohydrates G (b) proteins (©) fats © @) vitamins. Eutrophication of a lake is («) organic pollution (0) inorganic pollution (0) enrichment of water quality with nutrients, (4) deterioration of water bodies with biological growths, One of the important elements responsible for eutrop! (@) nitrates (0) phosphates (©) sulphates DW) chlorides, Combined available chlorine means (@) HCl + HOCI O (b) HOCL (©) NH,Cl + NHC1, DW NHCl+ ‘Scanned wih CamScamnctoy. 9 102. 303. ‘Cron Encnveenina (Onyecrive Tyre) Methemoglobinemia (Blue baby syndrome) is due to {@) Oxidation of haemoglobin a (©) Nitrates replacing oxygen in haemoglobin Qo (©) Nitrites replacing oxygen in haemoglobin o (@ Carbon monoxide replacing oxygen in haemoglobin. Q » Gastro intestinal irritation is produced because of excess of the following in water (@) chlorides © (b) sulphates Qo (©) nitrates © (a) phosphates. o Dental Caries” will be absent where the following is present (@) mottled enamel of teeth DO (i) itai-itai o (©) methamoglobinemia OD @ cancer. Concentration of fluorides desirable in water is (@) #1 mg/l D @)1to2 (©) 10 to 20 mg/l D (@not More than 1 mg/I of fluorides (@) cause dental caries O Wea (©) cause skeletal fluorosis (a) prevent dental cavities and tooth decay in children. Fluoridation is done to (a) protect children’s teeth (®) protect from dental fluorosis ©) protect from both dental and skeletal fluorosis (2) add taste to water. Sudden increase in chloride concentration in water (a) sewage contamination ) ground water mixed with surface water ) fresh water being mixed with sea water (d) increase in hardness of water. Kidney damage may be caused due to the excess (a) fluorides O (b) nitrates (c) chlorides O (a) nitrit Absolutely soft waters are required for (a) drinking, Oo (ib) (c) prevention of corrosion in pipes (dy Besides Ca and Mg, the other metallic ions (a) Na and K o (c) Cland SO, a ‘Scanned wih CamSeamnct05. 109. 10, 1B. » pty Ecineenine Hardness is desirable for fe moncleting O (boiler feed water (o) wash water of sinks and porcelain tubs. O(a) cardiovascular diseases A desirable feature of hardness is (a) more soap consumed (0) skin roughened (o) vegetables toughened (@) scales formed inside pipes protect them from corrosion. 315 oa oooo If the total alkalinity of a water sample is 100 mg/I and its total hardness is 300 mg/I, then its carbonate and non-carbonate hardness are respectively (a) 100 mg/l and 200 mg/1 (c) 200 mg/l and 100 mg/1 O (&) 300 mg/land zero OD (@) 100 mg/l and zero. o o If the total alkalinity of a water sample is 300 mg/I and total hardness is 100 mg/l, then the carbonate and non-carbonate hardnesses are respectively (@) 100 mg/1 and 200 mg/1 (©) 200 mg/1 and 100 mg/1 D (300 mg/l and 0 D (@ 100 mg/l and 0. Excess concentration of sodium salts in water causes (@) hardness O (b) bitter taste (c) alkalinity O (@) laxative effect. Excess concentration of magnesium salts in water causes (a) hardness O (0) bitter taste (6) alkalinity 1 (a) laxative effect. Iron in water causes (2) stains on clothes O (b) eutrophication (© must D (a corrosion. Lead in water causes (a) plumbo solvency © (b) stains on clothes and paper (©) damages nervous system O(a) permanent bluish skin. A communicable disease is (@) cancer OD (6) fluorosis (c) tuberculosis O @) goitre. A water borne disease is (@) malaria D (6) cancer (c) dysentery O(a) encephalitis. Due to improper storing of water the following disease spreads (a) tuberculosis O (0) filaria (0) methamoglobinemia O (a) fluorosis. ‘Scanned with Camscannct o one. use 123. pew Exomrenne (Onjecrive Tyre) For health, presence of traces of the following elements is a must in drinking water (@) fluorides and iodine 1 (by chlorides and nitrates o (©) phosphates and carbonates © (a) chlorides and sulphates QO A water borne virus infection is (2) cholera D (6) swimmer’s itch a (©) jaundice O (@ cancer. o An indicator organism is (a) pathogenic bacteria 1 (b) non-pathogenic bacteria o (©) facultative bacteria 9 (@) non-pathogenic bacteria of the same family of pathogens. An indicator organism (2) should be a pathogen (6) és of human origin but not found in water (©) harmless bacterium found in some types of waters (d) should produce more gas when incubated. Bacteria utilise (a) liquid food O (6) soluble (c) solid food O (@) inorganic Autotrophic bacteria derive energy from (a) inorganic compounds OD ( organic (c) ultraviolet rays of the sun. O (@ both Oily odour and taste producing substances are prodi (a) bacteria D (6) protozoa (©) algae O @) rotifers. An indicator organism for bacteriological quality of (a) salmonella typhi © (t) escherchia (c) mycobacterium tuberculosis O (@) shigelta In drinking water number of coliform bacteria shoul (a) 0/100 ml O (1/100 mt ) 10/100 ml OD (d) 100/100 The average domestic demand for an Indian city is (a) 135 Iped ) 500 Iped Kuichling’s formula for fire demand is Q = i P (a) 3182 JP Qo wo 1136[ ) 4640 JP (1-0.01 VP) 3 (a) 5660 ¥P Scanned with CanSeamnctWaren Surrey Encivernina = 317 A factor affecting domestic demand is J ) dead end system or recticul: lation system of network of pipes (0) timing of water supply (o water supplied is soft or hard {@) climatic conditions. gqaoa yr. Foran old city with constraints for growth the best method of forecasting future population is (@) arithmetical increase method & ©) geometrical increase method (©) graphical method O (a) incremental increase method. Bf lithe present population of a city is ‘a’, rate of increase per decade ish’, incremental increase per decade is ‘c’, percentage growth per decade is o o ‘r, then population after ‘n’ decades by incremental increase method is (a+nb D Wa+nb+o o atnds ed, a ah ey, o Z 100. 18. Design period mainly depends on (a) percentage interest at which the loan is taken o (0) capacity of the municipality to repay a (©) quality of fittings used o (q) rate of growth of population. Oo BL Ground water is (a) free from suspended solids but contain dissolved solids a (b) free from harmful bacteria but may contain harmless bacteria oO (6) free from floating impurities but may have suspended solids a (2) free from dissolved solids but may have colloidal solids o A shallow well is one tapping an aquifer (2) nearest to ground level o (b) below an impervious layer o (©) sandwiched in between two impervious layers o (@ runs through a number of strata. a Adeep well (2) easily gets dried up during summer a (+) may yield constant discharge a (9 is not deeper than a shallow well a (4) is formed by just tapping the nearest aquifer to the ground. o [A iver intake may be situated on (a) a straight reach (b) the convex side of a curved course: Oo (9 downstream side of outfall sewer O(a) proximity to industries, a ‘Scanned with Camscennct318 140. 141. 142. Comm Ewomuernnee (Onnerive Tree) River water may have (a) more suspended solids and less dissolved solids 8 (b) more dissolved solids and less suspended solids c (0) more dissolved solids and less floating solids c (@) more colloidal and dissolved solids. c A good source of water requiring practically the least treatment is (@) a perennial river 1D (b) an impounded reservoir t (©) a deep well 1 (d) anelevated lake. t Sedimentation may not be required for water from a (a) shallow well OD (b) deep well 1 (0) river © (@) canal t Waters from the following source is likely to be hard (a) river D (b) lake (0) deep well © (@ shallow well. Permissible velocity through coarse screens is (a) 1m/s o® (©) 0.3 m/s o A discrete particle is one (a) whose settling is unaffected by the neighl (6) whose settling influences neighbouring (©) for which hindered settling takes place (d) which settles as compressed settling. The main factor responsible for sediment (a) specific gravity of the particle (®) specific gravity of the medium (0) difference of sp. gr. of particle and medium (d) sum of sp. gr. of particle and medium. If Q = Quantity of water to be treated per detention period in hours is 24V o® oW@ Generally “flow through period” of a sedi (a) less than detention period (b) more than detention period ) exactly equal to the detention period (d) some time more and some time less. ‘Scanned wih CamScamnctwr & Ly 2 43. Optimum dose of coagulant means the least dose that produ Waren Surrey Encineeninc = 319 Over flow rate of a sedimentation tank is Oo Q Area of longitudinal section ef e Q aW@ Q aoe ( Cross-sectional area Plan area x Liquid depth ° ‘oagulant should be used for sedimentation when turbidity of raw water exceeds @ Plan area (a) 5 units O () 10 units a (©) 50 units 1D (@) 100 units. o Coagulation is affected because of higher concentration of (@) phosphates O @ nitrates a {(¢) bicarbonates © @ sulphates. a Coagulating power of a chemical increases with its (a) atomic weight O (6) molecular weight a (©) density D (@) valency. Colloidal particles are associated with (@) tyndal effect D (& discrete p: (©) Schmutzedecke OD (@ Brownian Lime is added to water or waste samples to (a) destabilise colloidal oil and organic emulsion suspensions (®) to assist precipitation of hydroxides of metals by lowering, (c) remove calcium hardness (@ convert calcium carbonate to calcium bicarbonate. (2) maximum amount of floc (b) floc whose density is very high (c) maximum amount of floc within the least time (@ readily settleable floc. ‘The jar test is to be carried out immediately after the col (@) concentration of dissolved gases as oxygen, nitrogen, carbon (6) sedimentation of Colloids do not take place before the test (c) quality of water may not get deteriorated (d) least amount of coagulant can be used. Methamoglobinemia is due to (@) Fluorides D1 (b) Chlorides (0) Nitrites O (d) Nitrates. When Alumina is used as a coagulant for neutral (2) AYOH), 1 (b) Al(OH); (0) Al(OH), + CaSO, 0 (@ Al(OH);+ ‘Scanned wih Cams320 183, 157, SS we. 160. 161 Civn Encoveenie (Onrenve Ter) A coagulant aid is one whieh ©. (t) stimulates floc formation (a) promotes coagulation 10a) narrows down the pH range (0) increases dosage of coagulant Copperas is © (b) ferric sulphate (a) ferric chloride 1D (i) ferrous sulphate (0) ferrous chloride Chlorinated copperas is chlorine and ferrous sulphate sIphate and ferric chloride. ow WW) ferric (a) chlorine and ashes of copper {© ferrous sulphate and ferrous chloride Detention time in a “floceulator” is (a) 10s to 208. © (b) 20 min to 30 min (0) Lhour to 8 hours 1D () Zhours to 3he Detention time in a Flash Mixer is. (a) 308 to. 608 8 (H) 20 min to 30 min, fo Uhto8h GO @2htodh. Schmutzedecke will be formed in (a) slow sand filters (©) pressure filters Back washing is highly effective in ¢ (2) slow sand filter (6) pressure filter Fine sand is used as media in case of (2) slow sand filter (c) pressure filter Effluent from this unit requires no o! (c) slow sand filter (©) pressure filter Coagulant may not be added for treat (a) slow sand filter (6) pressure filter Iso-electric point is the pH value at wl (a) the electrical charge of a colloid is zero. (b) the colloidal charge of a particle is (c) coagulation takes place quite ef (a) ideal concentration of Scanned wih CamSeamnctA 10 cm deep filters removes 90% susper PH ceeded, the depth of filter and filter perfo (a) 20 em and 0.909/em nded solids present in water. If prmance coefficient are © (b) Nemand 9/em (0) Mem and 0,909 /em D (a) 20cm and 9/em 466. Abighly flexible filter is (@) slow sand filter D (b) rapid sand filter Scere O (a) both rapid and stow sand filters. 1u7._ This is used to treat swimming pool water YY (@)stow sand filter (rapid sand fer (©) pressure filter O(a) both rapid and slow sand filters 149. Disinfection isthe process of (a) killing all the bacteria (0) killing only pathogenic bacteria {c) removal of causative organism for disease (@ complete destruction of life | 69. One of the physical agents responsible for disinfection is (a) ultra violet rays 1D ozone (6) heat D (lime. ‘A desirable property of a disinfectant is that it should (@) act instantaneously 1 (kill all the bacteria (6) not alter the quality of water 1D (@ be very cheap. 171. Efficiency of disinfection is @ No.of pathogens killed ___ 499 No. of micro-organisms present initially (6) —_No-of pathogens killed ___ 99 No. of pathogens present initially No. of micro-organisms killed @ x 100 No. of pathogens present initially (@ —_No.of micro-organisms killed __ 499, No. of micro-organisms present initially |. Mud balls are formed in a filter because of (a) raw water rolling over the filter surface (b) quick filtration of turbid water (¢) frequent back washing (4) bond developed between impurities and sand grains due to inetfic | | | I ‘Scanned with Cam came! nt back w 99% removal is Mmooo ao oa oo a oooa ashing. ——_—__t