(anw=v) (Chopiew WATER TREATMENT AND ANALYSIS | (Theory Hrs. 12, To [INTRODUCTION Toei and alo the wast abundant fal cher etances. plays an import pain 2 wie a8 erences |Water present on earth passes through a remarkable ce of changes. Thus f tes pena TE cana ceain mater and fr a mineral water, wer water and finaly comes 20210 25 ‘he common impurities present inthe natural water may be dassfied a follows (2) ‘suspended impurities, 2) Dissolved ties, (3) Colloidal impurities, (4) Biological impurities. impurit 1. suspended impurities pe ater may contain suspended impurtis such as clay, mud, gn, industria wast, pended in water. They produce turbidity, colour and odour and may cause Seas, ‘organic matter etc. These remain 2. Dissolved impurities: There may be two types of dissolved impurities viz (a) Gases, () Mineral sls: 2 vrton dovde oxides of nitrogen hydrogen sulphide, sulphur diode ates, bicarbonates, sulphates and chlorides of ent in water itis known 2s (a) Gases : The gases present in air suchas ox7980, are soluble in natural water {b) Mineral salts: The commonly observed salts in nat ‘calcium, magnesium, sodium and potassium. When s hard water, Such a water cannot be used for washing clothes 2 3. Colloidal impurities + + Colloidal particles of clay, Such impurities neither settle down on stan leis about 10+ crn to 10-7 em. ‘main source tural water are carbon ats of calcium and magnesium are prest din boilers. Aine mc, decayed leaves organic mater (insects and fang may Be Present 9 water ding nor can these be removed by filtration. + size of colloidal partil ‘These are the charged particles. These become the ‘of epidemic when associated with bacteria, ‘ete are considered as pathogenic. the efficiency of heat transfer equipment. ich might restrict its usefulness. 4. Biological impurities + Slime growth such as algae, «+ Such impurities may be present in natural wat + Biological growth can also contribute to corresio «© Such water is dangerous for human consumprion = ‘micro-organism te. bacteria, fungi ter and it may affect wn and cause odours of water whi nd health ae thet ie wells produce lather (foa) readily with soap wie duce lather with soap only with difficulty. develops curd (a wiite scum) i termed 25 ops lather readily is known as Soft water: rater from some sources li a HARDNESS @y + This a common observation that w from other sources ike rivers springs oreven certain wel Pr ‘good lathe with soap solution readily but + Water which does not produce roduce curd with soap solution but deve hard water, Water which does not Pr (4a)=a (e6,1E, 19) Game of are ont PT hea — 1,0 + COz—¥ HsCs HyC03 + CaCO, —> CAIHCOs2 (souble 1) cnn ute er tre acer nd hor eau and magnestum and there SS 2 Sable terides and sulphates of alum ang ates, hi ins bicarbonates, Gi not produce good lather with roa, water. ’ 1! Thus, water flowing over rocks and siface yer nee Ts te inthe asalved state. Such pater town i ard ee ution. ur salt) sso oeanntr mature of acum sts of ay ais ke teat cel 26 plc a Soap (sodium sl) Shy menses insoluble calcium | nwater and forms lather due to which it has pone" ‘+ When soap is added to hard water containing calcium a salts (ie. C27" 2 ‘and magnesium salts are obtained by double decorpost “2Ciy Hyg COONA + CaCl > —Ca(Cy7 Has COOIp + 2NACI {Seluble socium sterate: i. soap Grsoluble cai stearate) 2CyyHygCOONa + Ca(HCO,)y > CalCsy Has COOH * 2NAHCOs (Unsolube cau steorate) Ma{Cir Hys COO} ++ NB:SO soluble magnesium stearate) ie vai id ie. white scum. Until all the calcium or magnesium ions a sted in hard water. magnesium 2,7 HysCOONa + MgSO4 -» “+ This insoluble calcium or magnesium stearate is known 25) are remeved in tis way, soap wil ot be avaiable fr cleaning purposes, Thus, much soap is Wo Moreover clothing washed wit sop in tard water gets angy appearance due to the adherend sticky scum inthe fabric. Detergents are better cleansing agents than soap as fhey are not effected by hard water. 4.4.2 Types of Hardness | + | Types of fo yd | ” Temporary Permanent | or carbonate |) | orron-carbonate hardness i hardness, \ 4+ There are two types of hardness such as | 1. Temporary or carbonate hardness. 2. Permanent ereenorte ares 1. Teniporary or Carbonate hardness: «This defined as the hardness due to bicarbonates of calcium and magnesium. + Temporary hardness is mostly removed by mere baling ff water, where bicarbonates are decomposed producing Freolble vabonates catton doxde ecapés as itis nat solpile at higher temperature xy CAIHCOs), > CaCO, 4 CO,T + HO ) (Soluble) Gnsoubh Mg(HCO;), > MigCO, J+ CO) T + HO Goble) dnsolube) \(EE,1E,'S) a3 pa seatment and Analy, nalysts || pel || permanent or Non-casbonate hardness de [ERENT ate te tesco ose wrt T emg hs peat testo he 1 reuse ci entra vt rt or ots ing te | 7 MISSIN e camera tease ste ae ftaning methods dung whied | «Thesoftening methods used on fe | : tening methods used on lege sale in industries ar me-soda, zeolite or permut and ion-exchange | 4.4.3 Difference Between Temporary and Permanent Hardness of Water Sis ihnracen Havas i eee ae eis type of hardnes is due to sokble bcarbonates of |2. kis due to souble clodde and sph ‘aium and magnesium. and megnesium. Tn is due to carbonates, hence Known as carbonate [2_ It's due to other sas hence Known hardness. hardness. . 3TH ope of rec removed by simple process | 3 This type of harness cannat be moved PY simple ye Peiing, The name temporary iceate the | techniques. Henee the tem. permanent 'e used to property which isnot dificult to be changed. describe these characteristics \ TZ Methods used to remove temporary hardness (ike boing | 4. Methods us \ ble in and salts of alum | soap ble ‘as non-carbonate fd to remove permanent hardness (permut \ Clark's) cannot be used to remove permanent hardness. fon exchange) also remove temporary hardness frorn | water. \ 4A.4 Measurement of Degree of Hardness “me The total hardness of water i estimated by trating & measured volume of water, ether with a standard £03P \ solution or by EDTA (ethylene diamine tetra acetic ci) solution. “The extent of hardness is measured in terms of concentration of fons conioutng hardness. fuse CaCO, has molecular weight 100 and tt is usually expressed in terms of equivalent amount of CaCOs bec ‘equivalent weight 50 which are convenient for precise caleon Hardness of wate is expressed in ppm (pats pe milion or maitre) Hardness of water can be determined by two methods. "e be bY 1. Soap solution method : «Total hardness of water can be alcoholic soap solution. ion of stable lather which persists fortwo minutes i the ‘end point of titration, srdnese causing ions 2s their respective stearates > (Calscooyce 4 +2NeCl Calcium stearate —s (CxHxCOOLMg 4 + 2NaCl ‘Magnesium stearate with soap is called soft water wheres: led hard water) terrined by tvating 2 fed volume of water srnpe (200 rH) agains standard + Format In the beginning, sodium soap will precipitate all () 2GHssCOONA + CAC Soap solation i) 2GxH4yCOONa + MgSOs +s water which forms scum or precipitate and (Thus water which readily lathers does not form lather immediately is ca 2, EDTA method: «The hardness of water can be estimated or determined by EDTA method. 4 EDTAIs an abbreviation of ethylene diamine tr9 acetic acd. HOOCH;C, 5 4, CH{COOH cry CH Coot 4OOCH,C’ iry (EE, 11S) Appl Selene: Che i i and st ised or expe Pose ops ‘+ EDTA dizzolves in water with great dificult, hen: eae ic soubiiy in water. cer | * eat carbons He“ cy,cOONe, \ i ° viaee 15 duet the for | ' zs £* and Ma" fone ‘observed on th «This compound forms a highly table complex confound (chelate cmeten with Ca ‘and Mag" ions prea, “evaporntes 2 |” water. Therefore, this methods called as complexe tration | eae fistciaomseenss eect! jee | «EDTA forms stable complexes with Ca"* and Mg" ois present in water ctheiwng,, | © ome ‘© Thus, in hard water sample, the total hardness can Ub determined by titrating noi ni ‘ hada sn @ by using | with standard solution of Na-EDTA jing buffer solftion (NHCENHLOH buffer of Pl a oa | Ganacthement ints . ee wt |+ Atl 10, €8T indicator forms wine red coloured unsfable complex with Ca""/MS"” ions it en i by adv [+ This wine ed solution then tated wih standard tion of NaEDTA il the coir changes 19 ANE naming an | 3h Catt lone (ail ee ea |e etue colour appears due to the férmation of stale complex of EDTA with Ca°"/Mg"* fons (Colouress) and + VINE A | releasing of E6T indicator (blu in colo. Ds harass Reaction | 7 ole ae Ea + Foaming cog") + EST oe pariau (rom nas wat . ees Soouross) Complex. ne red face an + Theres wa Na-EDTA ow + @ te [eor-c="mo'] \ we Stabe complex \\ «esi I ‘Cobutess) i re 4 Thus noting the colour change, endpoint can be dette and hardness of water can be called Pe (4:2) EFFECTS OF HARD WATER IN BOILERS AND PREVENTION = «By f “¢ The manufacturing industries need water for a great voety of purposes out of which steam generation is the most rey important one. i boi *| Water containing csoled sas of states, births, cries of cdi and magnesium, ron sats has an | * 1 x adverse effect on steam boilers. «| Hence, water for raising steam in boilers must be soft a must nat contin too much dissolved or suspended matte: $2 51a he vies of oreo 9 afr 6) nn and ering Sand Spe formation 1. Boiler Corrosion : + Se in bollers, is corosion. “Corrosion canbe defined as the |) dengan echnical ef nth er enone \ i} ‘© Water containing various types of impurities cause corrosipn of the inner surface of the boiler. Corrosion in boiler 's dus " tothe following reasons viz () Dissolved gases, i Diss salts nd (i Act or alka of wate \ | ter in boiler and it is generally observed | | 2. Caustic Embrittlement (or Caustic Corrosion) | This is a type of boiler corrosion, caused by tlc use boiler which operates under a high pressurei added. tn igh pressure boiler, ering water sottniog process » smal quantity of sodium cobONeS {asc oe re dacomposes to give sodum hydroxide ad carbon dIONOS Na,COs + H:0 + 2NaOH + COT alaline. A 98 cracks are 04 smb of inte any action. Here water «pur to the formation of oun hyronde (ast ode, water Becomes reson eu ete i ning of Boer This alaie water lows to Such TS cracks by cori | Shports and the lssobed cautic soda is fet hind The sreent rie fe soda gone 00 wereasng SOA Srapensie evaporation. The alkaline action of caustic ode tacks the fing aan of ace tere oa eo ne bole, Ti causes erbaterment of ole pars, pa 2 pressed pats He ves Ben Joris ee caving evan a fare ofthe bolt. samp] * steentettonat on be avoided Batol" bring scum tehae ‘pstead of sodium carbonate for softeing wate To eating tannin or grin af adaves to he bole ater nce these ek he arinute cracks thereby preventing infitration of caustic soda solution, a) by adjusting the alkainty of mater to optimum evel (OH =7 129) the boiler th the steam and pass fom |. Priming and Foaming : ce mived wit of improper 5) ang + When 2 bole is steaming rapidly. some paris of liquid water ong with the steam. This process is known as priming, icc vo dssoled solids, particularly the suspended sod or high St" velocities ‘The cause of priming is ve: which do not break easly. Foating ofcurieg — boiler design. «Foaming isthe production of persatent foam of bubbles in boll | pariculaty at the water surface i due to the present ff large quantity of dissolved matter In water, bby which the | Pinface tension of waters lowered, Tiss responsible forthe ‘phenomenon of foaming. |, there are some disadvantages of priming process | {The actual height of water in balers notjudged Sy {i To adjust the steam pressure in the bos, mors Net 8 required. Therefore, efficiency of the process is decreased inery which decreases the life ofthe machinery boilers, avoiding rapid changes in ved salts may enter the parts of machi led by using mechanical steam purifier, | «Ping ca be 08 Pain ao arg ur wt. Fong can Be éding castor oil or anti-foaming agents. 4, Scale and Sludge Formation | iy Water and disol ‘maigtaining low levels in Mes by blowdown operations to predatermines intervals, 1c, When their concentration Boller: alls of the 4 water in the boiler, conc solved salts increase entration of dis .e form of precipitates on the inner We + By continuous evaporation o nost a oreo ne saturation paint they ae tron ou of te YEE 1h boiler. van 1 Hthe precatate i loose and sim. f Known as sudge’ On the other hand, ifthe precpates Maer forms a hard verre coating on the inner wal of he bot MONT ‘seal’ . all sy EI Her: ge | | “inner red hot metal | Boiler water of boiler Seale {hard adherent | | Sludge coating) \ i (loose precipitates) (a) Scale and sludge in boilers {b) Boiler scale in a hot-water pipe | Fig. 4.1 ____— _—_———‘Applied Sclonce = Chemisty (EE, 16,5) Scale Formation in Boilers ‘The formation of sludge is ngt a major by brushing. Many times sludges are formed along Sometimes, excess of sludge formation disturbs the working of the boilet. ane nme suroce ofthe boiler which called ote Sludges ate poor conductors of heat, so they tend to waste 3 enact em ata apc ia) * aun Scales are 30 hard and adherent that it is cfc 6 aaenl SOUS ae ren vOBIIEME paphate9 One + mee “+ Scales are of following types :() Carbonates: (i) a vsepresentin he WO . devel cae 1 tye trims ocala depen yon hate oop se pcm ad onan 1 Themen rubles a formes cue ote prsans FUE ST cases overeating] inefens sales reorient and or ret ee a ‘off or washing out. ie . aces carbonate ome» non-adherent scl and canbe easly removed BY DOWiNG ff oF 9 5 Thelife of «+ Magnesium chocide, it present inthe scale will bring about corrosion of tubes and boiler plates. wo oe wee ‘Sludge Formation in Boilers eal they the boiter and do not stick up permanent, + When @ sf lose slimy deposts are formed ide ame sludges: ‘collect in areas ofthe produc + Studges are generally formed at comparatively cooler parts ofthe bolls, and te < ksi ee the flow rte fs slow or at bends nthe line. In such parts they bulld up 2 deposi wh a + Sudges oe formed by substances which have geste sluts in hot water than in cold Waler © MgSO, MgCO ete. portion of eat generated 4.2.2 Ren problem, becouse it canbe removed by frequent blow-down operation], sing oi With withthe scales then these two are mined and both get deposited {4 «i By mae x 5 usi josie “Sieg RE Form an adherent coating within the boiler which cannot be removed even by mechanical means. Scales are harder and more permeable. Scales are bad conductors of heat. ‘These are formed throughout the metal surface in contact Form slimy or less adherent coating within the boil can be removed by mechanical means. ‘Sludges are soft and less permeable. Sludges are poor conductors of heat. These are formed at comparatively cooler portions boiler. (eg. in bends of lines). with water, 4 Disadvantages of Scale and Sludge Formation in Boilers Wastage of fuel: The scales are hard and bad conductors of heat. Hence it does not allow the transfer of heat from hot plates of 4.3. the water inside, Therefore in order to get e steady supply of steam more heat has to be applied. This results i] consumption of fuel. The wastage of fuel depends upon thickness of the scale 2. Lowering safety of boiler : ‘© Due to scale formation, overheating of boiler isto be done in order to maintain a constant supply of stear The overheating of the boiler tube makes the boiler material soft (due to damage of joints and rivets) and make the boiler unsot pressure boilers and weaker and this causes distortion of bl © pressure of the steam, especiallyena, nce: mi 516 zs rupted a led boy, 3. banger of explosion: \ ‘when thick scales crack due to uneve \ rs cau umn uns aed le main ewe nen oF chi . a fvesheated ion plates of boller. ‘his causes the formation of a large amount of steams evsloped, which may cause explosion ofthe belles seidenty inside the bolt, Hence, sudden high presse des. . 2 ag pecronse in efficiency: iii |. Seales may sometimes deposit in the valves and condens i a in decrease | sien. condenses of boiler ana eating them partly This reste e shortening the life of baller: Jout aoe thei ofabolleris shortened due othe following reasons: fy The star reacts wth re hot ron plats fe booming ne aT yon oxide and liberates the hydrogen g35 ne ree nares thinning ofthe bol pates with the continuovs reaction of star °Y are | are + AH, FeO, HT vtroresion of bes and bole ates ike 2 ca eae {ey Mageesium chloride, if present in the sae wil bring abo f the syste producing HCl again and again. MgCl + 2,0 > Mg(OH), b+ 2HCL 2m pipes. reg. Cag} Fe + 2HCI> Fech + HT Fel, + 2H,0 > Fe(OH + 2HC seeraton 4.2.2 Removal of Seales and Sludges re sen we sales ac shytges ae haf they shold Bereaved TOMAS te oie) a wnt lp of scraper kif, blade or 2 piece of wood PY Wie ‘prshing, if the scales are loosely adhering | Ga By giving thermal shocks (ie. heating the bolt vc then cooling sueny with ok wat, they are Di \ fponate scale can be removed BY \ adherent. Thus, calcium caf if they are hard and ethylene Oi be cissolved by adding EDTA jamming Tevra Aceti ac) Jome chemicals, (ip By dissolving them in 5 phate scale con using 5 - 15% HCl, calcium sul (i) By frequent blow-down operation H whe scales are loosely adhering the boils [g-3” WATER SOFTENING “The process of removing solubl oftening of hard water, the soluble water can be obtained. ‘om hard water is called softening the water ted into insoluble sats. . fe calcium and magnesium salts f “+ During the process of 5 salts are conver ‘+ These insoluble salts cat re used for softening of water fess, (b) Cold lime-soda process. be removed by fitration and 0 portions | «Following methods a iy (a) Lime - soda process (a) Hot lime-soda proc {@) Zeolite or permutit process (3) Ionexchange process. jates of 4,3,4 Lime-Soda Process results int © inthis process, ime Ca(OH)2 (calciu both temporary and ef tes and chiori sn hydroxide) and soda Na,CO (sod carbonate) are used to sften the water manent hardness of water can be removes sicarbonates and carbonates are des are removed by sod 1 +2H,0 + By this method, removed by lime while sulphat 1 CalHCO3)2 + COOH): > 2.CaCOs + CalOHihp + CaCOs + + MOE! Mg(HCO3}: MgCOs + Ca(OH), > aco) + M(H: + 21,0 special!40 a Applied Science : Chemistry (EE, E; 15) L n thon both soda and lime are required. *#ifwater contains sulphates and chlorides of magnesi wees + Filtered sot (MgSO, + Na:COs + Ca(OH}, -» Mg{OHY2 + CaCOs | + Ni + a aie MgCl, + Na,CO, * Ca’OH), ~» Mg(OH); + CACO, saa 7 * sis se ' rnd cloves of cakum are present then only soda-ash i require, + On the other hand the sulphates and chores CaSO4 + NajCOs -» CaCOs 1 + NaSOx ' a a ono If the process is carried out in * Lime soda process can be carried out elther in cold sare ee ee cola ied out in hot water then, itis process, called as cold-lime soda process. Hit is anid out 1. Cold-Lime Soda Process 1 at room temperature. 5) Bit nd oad qeany oe wend me a OES oo SN J + Te preciptate obtained i nly vided and to coagulate the precipitate, a small quantity of coagulant ug should be wsed, Removal of precipitate by filtration gives soft water. + The process can be cated out by two methods viz, batch process and continuous process (2) Batch Process: ge tank made up of stel plates. tis provi + A.aleuated quantity of ime and sodo-ssh is added to water in a large tank made up of steel plates. tis px "mechanical sive for siting or agitating the miature, (Refer Fig 4.2). [- Chemicals b. Hot-Lime Raw water—»i a and Sotened «= wor So a «Mechanical sire @ te as | Studge | ute a i) Th L Fig. 4.2 : Batch cold-time soda process i) Th * Alter thorough mining, mechanical siting i stopped anda small quantty of coagulant (alum) is added to coagd (Th precipitate of impurities ee AIYSOqs + BCALHCOD), > 2ANOH) | + 3C0S0, + 6CO, 7 ae * The precipitated impurities ie, sludge settle down atthe bottom ofthe tan. ‘+ The water is pumped out and allowed to obtained. * To complete the process, 2to 3 hours are required, After removal of sl The same procedure described above is repeated a: (b) Continuous Process : 13ges the tank is washed with water, gain to soften more quantity of hard water, This process is a continuous process and therefore, In this process, hard water and calculated quantity inner vertical circular chamber fitted with a vertical time is not wasted during the operations, . 2 vigorous siting and continuous mixing takes place, “The softened water as it comes into the outer coayal chamber, ies upwards. The hes Settles down in the outer chamber by the time t the softened water rushes up. “The softened water then passes through a filtering ‘medium (usually sludge), avy sludge (or precipitated made of wood fibres to ensure complete rem . (@) Batch pass through a fiter unit of sand and coal, After filtration the soft “+ + {b) Conpgp Setence: Chemie (EE, 118) Fitored soft water finaly flows out continuously the ‘The sludges atthe bottom are removed through si (ough the outlet neatly at the top. judge outlet occasionally. «This process provides water containing hardness of $0 to 60 pom. ae Feed init es} tet Sf hasan! Coagulant [=== ster Fitered softened “= ‘water outlet ant such, Sludge butt rovide, Fig. 4.3 : Conti ] 2. Hot-Lime Soda Process: “There are certain advantages of hot-lime soda 15 minutes. tation, {i The coagulant is not needed for preci J (ip The dissolved gases such as CO are removes (o) The wat (The process of fitration becomes much faster (ui) The softening capacity of this (a) Batch Process: Hard wa Calculated quantity of ime and soda is odd speed of the reaction can be increased. With By using 2 water removed from the tank. The tan} (b) Continuous Process : op ints | 4 The apparatus consists ofa tank | 6 The tower end of the inner chamber is funn ted" The outer chambers big mo This faites rise of water from the Bowton, from the third inlet, steam is allowed to «+ In this process, hard water is treated with lime-soda at a tem an elevated temperature, the speed of the reaction increases a {) The rate of precipitating reaction is faster at efevates ler obtained by this process is much softer as compare teris taken ina rectangular tank made up o pump the clear and soft water i pu is washed thoroughly with larger cross section at the top th: pass to in inuous cold-lime soda process feof 80 to 150°C. Since the process is cared out at perature minutes. 1d the process is completed in 25 process over coldslime soda process short time of 1d temperature, hence, the reaction is completed in 2 because the precipitate settles rapidly at higher temperature, 1d with cold lime soda process. and easier, process is much higher than the cold-lime soda process stat plates, whicis provided by heating cols to the tank. By increasing the temperature of water to about 150°C, the § minutes the process i completed cout and allowed to pass through a fiter unit. Sudges are Jed in 1 smped and the same procedure is repeated again. with two concentric evindrical chambers el-shaped and consists of three inlets. ‘an at the bottom. se hard water and chemicals are added through the left side inlets and ‘crease the temperature of the water.430 Applied Selence : Chemistry (EE, IE, 15) and soft d settles atthe Bottom selonen this method, 4 ie reduced to 25 ppm from b fer pas nie = lg tonsa | eneraton + When t | 10% | more | | Studgo outer _____fig. 4.4: Continuous hot-lime soda pr a 4.3.2 Zeolite or Permutit Process () If hard ness of water. ions * This is the process used for removing both temporary and permanent hardness of wat ions fc * Permutit or zeolites are complex silicates of several metalic and non-metallic oxides. They have on oppraia (iy. har formuta (Na,AlsSizOy 6H,0), These silicates hold sodivm ions loosely, hence these are called as Sodium, Mo" _©F Sodium zeolite (NazZ) where permutit and zeolite stand for Al,SizOg - 620. releas a) War ae 10% brine 7 | wor {ati ston rontages | : @ They fy The | scot @ wator wis | | crzecte 7 (oy) The Gravel ke | 3.3 Ic | | .oti | wa “ce l _ Permutit’s process of softening of hard water Joy Principle: +t © Sedtam permatit(NaiP) wien comes in contact with hard water, it exchanges its Na ions with Cat* and @ form insoluble calcium permutit (CaP) and magnesium pert (4g) _ Procedure: {fol pratt is placed ina suite container and hard waters allowed to pass tough k Refer ig, ‘The caclum and magnesiom sats react witht forming insoluble calcium and magnesium permatte (oA fetaine in the fier bed and water ater reaction is therefore, fee from calcum and magnesium sete h sodium salts are left in the water. The following reactions take place in the process For temporary hardness CAtHCOs) + NayP > CaP 1 + 2NaHCO, oF Ma(HCOs), + NaP + MgPL + 2NaHCO, ‘, nemlstry (EE, EIS) _ “one For permanent hardiness CaCl, + NayP -> CaP L + 2NaCl MgCl; + NajP > MgP 4+ 2NaCl CaSO + NazP -» CaP 4 + NeyS0y \ (MgSO, + NagP > MgP 4 + Na;SOq \ nen the process fs continued for sbout 12 hours, al! the Nat ions fom the perma are replaced cat* and Mo** \ iit is found that the permutit stops working and water is no more softened: Fons an regeneration reaction > ‘When the permutit is exhausted (Le. itis completely converted into Cat 30 % brine (NaCI) solution for a few minutes, sodium permutit (Naz?) 1 ‘more hard water. The reactions in regeneration can be shown as follows CaP + 2NaCl + Na,P + CaCh, 1p and Mg?) it is regenerated by treating with Horned and can again be used for softening of | MgP + 2NaCl -» Na? + MgCl, pions of Permit or Zeolite Process: yay 9°) (9 tf hard water contains large quantities ofcloured tons tke manganese ions ions form manganese or iron permutit, Such permutit cannot be regenerated eas in zeolite process only cations like Cat *s be used in boilers a5 CO2's (Mnt*) of ferrous ions (Fe**) then these Proxim, ¢)Ithard water contains mineral cis then itmay destroy permutts, Moreove u eee Im pen Ma¥* are replaced but anions ite CO; HCO et. ems in water, Such water cannot released from it and is extremely corrosive to boiler materia urbidity may log (or block the pores of permutitand it restricts the flow of water. iy if hard water is turbid, then t ‘Advantages of Permutit or Zeolite Process: 0) 0057 {The water having zero hardness can be obtained ie. itremoves the hordness completely. {The equipment used is compact, thus occupying 2 smal space recipitated and hence, there is no sludge formation. {iy this. a dean process 35 no impuriis ae (a) The procets automaticaly aust itself diferent hardness of incoming wae (0) teeequires less time |4.3.3 lon-Exchange ( 4 Thisis the modern devel | «Certain organic compounds possess @ property ii + synthetic compounds are known as resins. or Deionisation or Demineralisation) Process lopment in water softening method. e zeolite ie, they are capable of exchanging fons. Such orgaric change resins, (2) Anion exchange resins. | There are two types of resins : (1) Cation ex able of exchanging rapidly cation by H* fons. Cation exchange resins can nd oe (@) Cation exchange resins : These resins 21¢ <2 sion with cations (eg. Ca**) 8 be represented as RH, so their exchange reac Ry + Gott > RC + DHT 5.5) | a (8) Anion exchange resins: These resins ae capable of exchanging apicly anions by CH ions. Anion exchange resing an on be epresented as R(OH), 50 their exchange reaction ‘with anions (¢.9..S04_ 15 ROH; + $0, -? R'S0.+ 20H + From the above tis clear that, if hard waters passed fist through cation exchanger and then though anion the fesulting water wil be free from both cations and anions and water is sad to be ‘deionised or emineralse gh anion exchanger4.4.2 Coagulation at ‘As per other concept : 4.4.3 Filtra’ Two types of filters are commonly used in domestic water treatment ant Applied Science : Chemistry (EE, 1,8) 4.4.1 Sedimentation ies by otowing spend ips BY i cles in a setting cee tow ype tanks in whic Wate Hg, continu tational force, the Stspendeg en ‘+ “Sedimentation isthe process of removing large tanks when most of the susrended par from the tank with the help of pumps. The is fed out in“ entation is generally carried 0 ‘a slow and uniform ‘where they C2F The process of sedi iva horizontal, or vertical direction at settled down at the bottom of the tank, from continuously, 1m water by the adcltion of hare along with sedimentation. loidal (or fire sized) This process usually ther do nots + “Coagulation isthe process of removing coll known as coagulants before sedimentation.” atte down at all or take 0 ey + Actually the colloidal (or fine sized) pats presentin water el alan or used. Teco 3s known as 603 + moxserto hve a ust of hse ae, ctin EMIS A 0 feo uphatt F260y coagulants ar iron and aluminium e: agulants are the salts of ron and aluminium way genous rect alld and form in wate and 1m water and forming + These coagulants react with bicarbonates presenti eae : suspended fine particles fro flocks descend through water, they absorb or catch which settle down quicly «+The adalition of coagulants to water also removes colour, odour and improves its taste [AL{SOq)) + 3CO(HCOs}p > 2AV|OHY 1 + 362504 + 6CO2T (Coagelant) Calum {ouity gelatinous flaca bicarbonate FeS04 + — Mg(HCOsl > Fe(OH}S + MCOs + HO + CO2T (Coagulant) Magnesium (Ferrous hydroxide) bicarbonate AFe(OH): + 2Hj0+0, 5 4Fe(OH)s + (issoWved Feric hydroxide ovyger) (Heavy flock) «Colloidal particles are very small sized (10+ to 10-7 cm) particles possessing either positive or negative cha similar charge, they repel. one another and do not come together. Therefore, they do not settle sedimentation. + Colloidal particles of clay possess negative charge. When alum (coagulant) is added to water, it provides| ‘aluminium ions Al?*. These positively charged aluminium ions neutralise negative charge of colloidal particle [As the charge is removed from the clay particles, they come nearer and combine to form particles, which settle the bottom of the container due to aravitational force. HP © Filtration is a process of removing insoluble colloidal and bacterial impurities by passing water through a bed sized material. * By filtration, suspended matter, insoluble colloidal matter, most of the bacterias, colours and odour of removed. ( Gravity sand filter, (i) Pressure filter.ence : Chemistry (EE, 16,18) 38 “Treatment and Analysis. aq. || @ Seavey send filter construction : + These filters are best suited for municipal water supply. It consists of a large shallow rectangular tank made of concrete (Refer Fig. 47). Ate ot te ik thefts rah wi ee goes out. Over this channel, a yer of coarse and fine gravel (about 30 em thik) and then a ayer of coarse sand (about 20cm thick) and rally yer of fine sand (about 50 cm thik are placed working = 4 Sedimented water enters the sand fier from the top. As the water pereclates though the sand bed, ne suspended panicles, most of the germs and bacerlas are retained by the top sand layer. Clean fered water is collected in the under drain channel, from where itis drawn out soem 200m . ‘adem Filtered water > DDD essen Under dra’ channels Fig. 4.7 : Gravity sand filter Cleaning: L the cate of fitration, after 24 hours of use becomes slow du to clogging of pores of the top sand layer by the 7 impurities retained in the pores. «therefore the portion ofthe top fine sand lye is scrapped aff and replaced by # new sand layer. The fiter is put to use again (ii) Pressure filter = Construction : «pressure ters are economical only for small sale use and not for water supplies such as municipal water Supply «consists ofa cylindrical vertical stct tank containing three layers of filtering media one above the other. # (a). Pebbles (L0 — 35 awn grain size) layer (0) Coarse sand! (5 - 7 mm grain size) layer, (c) Fine sand (1 ~ 2.mnra grain size) layAxptied Scion 1c0: Chemistry (EE, IE, tS) 418 Stor Treatment ang R ‘Detector pate oat ‘elorna a ere prt Woon water artical ATOM), Fine sand Coarse sand Pebbles Compressed arnt : Wash water inlet «= B+ Filtered waler outlet Fig. 4.8: Vertical pressure filter Impure sedimented water is mixed with a mall amount of alum solution. Itis then forced in under pressure freq of the tank (Refer Fig. 4.8), . Ade tm forms a aia smy yr onthe fier be and hs aps in emowl of clo a aca impurities. jp) The function of the deflector plate provided at the top isto distribute the simy layer uniformly over the top of bed, Filtered water as it comes out from the bottom of filter is under pressure and can thus be pumped directly. Cleaning : * Pressure filter gets clogged after its use for some time and its periodical cleaning is necessary. Ths is done washing, . The water under pressure is forced up from the tank which removes the matter has clogged the sand pores wash waters then allowed to go to drain * Now-a-days compressed airis used to agitate sand before back washing 4.4.4 Sterilization (Removal of Bacteria and Mi ro-organisms) + Water ater passing through sedimentation, coagulation an fitraton operations sil contain a small pre pathogenic (disease producing) bacteria Therefore. ts necesany to remove these bactera and mier- org water. * "The process of destroying these disease causing bacteria and micro-organisms et. from waters known as id or sterilization of water.” * The chemicals used for sterilization are known as ‘sterilizers’ The disinfection of water can be carrie! following methods Boiling i) Chlorinatio i) Ozonisation (iv) Aeration (Ultraviolet rays (vi) Removal of algae, (Boiling ; ‘+ Sterilization strictly speaking is the boiling of water b ore using for domestic purposes ® Boiling kills all the disease causing germs and eria during epidemics like cholera and ty * But this method is useful o» of water, ‘or household pur wecaus ery expensi 22: (2) BY using chlorine ga (©) By adding bleachin (0 By using clorain ) By using chlorine gas (2, CChlotine can be used reacts with water to Bp D However, excess of « mucous membrane, y adding bleaching pov Bleaching powders In practic, about 1 stand for several hou powder are powerful + The nascent oxygen + Only calculated qu smell to the water. isadvantages : + The use of bleach 1. Bleaching powder 2. Bleaching powder analysed for is ef 3. used inan exce Je). By using chloramine + Chlorine and am process is known + Chloramine is 2 considered as @oon ean canbe cari by he ooving mans + fe) By using cloine ges yy {e) By adding bleaching powder (oy using chloramine, op ay ea chlorine ga (2): pyri can be used dec 2 gu or ctlsn wate fer RELAY cf municipal water SUPP » rca wth water form hypocloou aci and recent oxen Hen powerful gemicies, Sg, (AP = Hone (eypotirous ci) —— Hod + HI + (asert one re from Germs + {0} + Germsare oxdsed «towever, ces of chlorine shoud be avoided because & NET, unplesant odour tase and tating ecko” on 0. -02 ppm at ree chlorine rove membrane The tested water should not contain more peace Jdding bleaching powder wy oy 1g powder (C20Cl) : leaching powders a good sterizar for small water wort was and the resulting ottion alowed © top ofth —* tn pracize, about 1 kg of Bleaching powder pe 1000 Te of water is mi 7 wor several hours. Hypoctlorous 2d (HOCH ane nasa ype (0) produce by he action of wate O° bleaching ponder are powerful germicies. , Caocl, + HO + CHOHR + Ch ve by ~ ch 4 HO > HO + HCl pores. 1H Hoc) = HCl +10) 5. Th (nascent onggen) ful bacteria sms and other harm e excess of it sent oxygen liberated, oxides Oe" il give a bad t The nasc owder should be used. «+ only calculated quantity of bleaching smell to the water pa ua genie e ‘The use of bleaching powder has the follov 1 introduces calcium in 3 continuous decompos sing disadvantages er thereby making it more hard sition during storast 1. Bleaching powde fe, Hence, before its Use, n as dish teaching powder deteriorates due 105 a erased forts ffecive coi content 4. sed nan excess amount imparts» PE taste and ésagreeabl sell t0 wate (© Byusing chloramine (CINH2) ¢ 6 Chlorine and arnmonia axe ified in the ratio 22 PY owume to produce 2 compound Known af chloramine, This | process is known a5 ‘ehloramination.” cp Ny 7 ONH2 + HCI (eroxaine) hence its ve compound and does not impart 27 isagreable smell and bad taste to wate micide than chlorine alone 4+ HO -» HOC + NH T HOC! + HCI + (0) (Nascent oxygen! « Chlorarine is 2 quite stabh considered as @ better ge" INHWater Treatment ‘Applied Selence : Chemisty (EE, IE, 15) 418 ‘Advantages of chloramination 1 ttremoves inating smell due to excess of chlorine 2. Teimparts good taste to water. 4. Tk checs the dssipation of chlorine (by stablizing chlorine) when wateris exposed to atmosphere especial «+The chtoramine tablets are used in the army for stabilizing the water. Water is collected in individual bot chloramine tablets are added followed by sodium thosulphate which removes excess of chlorine: (tii Ozonisation : «+ This is an effective method of sterilization of water. Ozone (03) is unstable and it decomposes into Moleg (2) and nascent oxygen (0). 0902101 ‘ascent onygen) i rms and bacteria +) Thenateant oxygen thus produce is very effective for ling athe awe + having perforated partition (Refer Fig «in exonisation, water i allowed to percolste though 3 tower having PRG CE eee allowed to enter from the bottom which ills the germs when they soni collected at the bottom of the tank, mi Impure water—»———— paiioem Gravel bed Cured partition Waste wat 7 having perforation s Sewag Ozone gos—+ = Constituer LD terized water Stesiized 7 2 tn 4.9: Ozone sterilizer he 2 This method is quite expensive and hence it is not employed for sterilization of municipal water supp in 4s ‘Advantages of ozonisati . wracter 1. Ozone acts not only as a sterilizing agent but also as a bleaching, decolourising and deodourising age ss 2, Itimproves the taste of water. : 3. Ineexcess itis not harmful, since itis unstable and decomposes into oxygen oa (iv) Aeration : ) Physi «© “The process of spraying water in the form of fine droplets into the atmosphere is known as ccration” a ; . ‘ This is the most modern method of purifying water for town supply. In this method, water ® a through a peroratd pipe Rte Fig, 10, As water sprays into at, it comes in inmate com™eM | a eee to the ultra-violet rays of the sun. This kills the bacteria and the oxygen onde in u fe water. It removes colour and odour also. The pure water is collected in a shallow tak Pa «It should be ni 7 = joted that as the exposure time is too short, the desirable effect may not be obt# ebWater Trestmentand Analysis | Puried water ig. 4.10 : Aeration Hi naa eration tater place in sreams and vers when the water fle slowly in ts bed or when fl fem 9 casi (9) vltra-vilet rays: ‘The invisible ultra-violet rays are very effective in ling al types of bacteria. Hamad Ac rte cin of swimming pool water, because it does not equi In this method, ultraviolet rays (from mercury lamps enclosed in a quartz glob However, this method is very costly and cannot be used for municipal supply water (GS: WASTE WATER TREATMENT t Toa Waste water or Sewage: sewage is defined asthe quid flowing ina ditch. But gee re any chemical to be 1) are simply focussed on flowing water rally, it means waste caried by water. Constituents of sewage: public and private 4 Domestic sewage : It indudes human excreta, discharged from Kichens, baths, lavatories ete. from buildings. 12. Industrial waste : It includes industial and trade wastes from manufacturing processes, such as tanneries, slaughter houses, laundiies, distilleries, textile mils, chemical plants et 3, Ground or sub-soil water: Ground water’ enters sewers through leaks. (Sewer Is an und removal for sewage) Jerground conduit used for the 4c Store water: hiss the an water rom houses oad grounds eS Characteristics of a sewage = ute liquid containing about 92.95% gall the time, Therefore its necessary 59% of impurities. The composition of f water and about 0.0% tment. to know the characteristics of sewage for its tres + Sewage is a very dil impurities is changing | the important characteristics of sewage ae 25 flows (@) Physical characteristics + tale’ (ie: not fresh) with all cxygen present in has gray colour. In 3-4 hours it Becomes ‘st 5 colour becomes dark. + Fresh sewage is odourless, it starts emitting offensive odour and its being practically used up. Hence it yecomes stronger. .9¢s on increasing as the sewage b ecause of heat added gut | «sewage is normally turbid and the turbicty 9 ure of sewage is higher than th nic The normal temperat at of the municipal water supply ute ow utilization of water.“Applied Selenea : Chemistry (EE, 1E, 1S) 420, Water Treatmen, (b) Chemical characteristics: «+ thindicaes the state of sewage decomposition its strength and the type of treatment needed, ‘alkaline and possesses good bacterial action Stale sewage being acidic difficult tobe tr dissolved, colloidal and seta + Fresh sewage is “+ The different chemical characteristics are total solids (such as suspended, such as H,S, NHy CHa, COs in addition to oxygen are present in sewage. (©) Biological characteristics : + These are due to presence of bacteria and other living micro-organisms much more active. (algae, fungi etc) in sewage ‘+ Bacterias are present in vast number (5-50 billion perlite) in sewage. + Most of these bacterias are harmless to man and these are largely engaged in converting com of sewage into simpler and stable organic compounds. This purifies the sewage. Some bacterias are harmful as they con produce diseases such as cholera, dysentry, typhoid etc pathogenic bacterias. ‘The harmless bacterias are of two types : (D ‘Aerobic bacteriat exist in the presence of light only. dissolved oxygen from sewage or free oxygen from ai. (i) ‘Anaerobic bacteria’ exist in dark and develop of free oxygen. They extract oxygen from the oxygen containing radicals of organic compounds and nitrites nitrates and sulphates. ‘© These bacterias ate of great importance in the process of decomposition of sewage. 4.5.1 Sewage Treatment ‘+ Itis the process of removing or changing the harmful compounds into harmless compounds so a to less offensive and dangerous. The main objects of sewage treatment are {) Torender sewage inoffensive so that it causes no odour or nuisance. (i). Toreduce or eliminate danger to the public health by possible contamination of water supplies (like rive (i) To prevent the destruction of fish and other aquatic life in river, canals etc. into which sewage disch made. ‘+ Sewage treatment generally includes physical, chemical and biological processes to remove these « produce environmentally safer teated waste water (or treated effluent) ‘¢ The basie purposes of these methods are (2) To reduce the solid contents of the sewage. (b) To remove all harmful organic matter. (0) To change the character of sewage, so that it can safely be discharged into the natural water sour applied on land, 4.5.2 BOD and COD of Sewage Water Biochemical Oxygen Demand (BOD) : plex orgeni @ CODIsth = nother y sewage. + Organic + organi + Therefor + The diss used up, + This der ssometin + Because centers i Membrane t = Vari pore + BOD of a sewage is defined as “the amount of fee oxygen required in water by aerobic bacterias to sem ‘matter (ie. in the biochemical oxidation of organic matter) under aerobic conditions at 20°C and for a dl higt + The unit of BOD is mg/litre or ppm. At 20°C, a BOD has an average sewage of 50 maflitre. Iho : con BOD test is most important in sewage treatment ast indicates the amount of decomposable organi pre Larger the concentration of decomposable matter, greater is the BOD and consequently, more the ‘ sin potential. pre‘water Treatment and Analysis science : Chemistry (EE, IE, 18) 421 toyxgen Demand (COD) : : a1 athe messeet fa ‘of amount of exygen required forthe chemical oxidation of organi mater swage. tn other way, it an Important water reage. water quality parameter which measures the armaunt of oxisable impues present in ‘organic compounds suc Te pounds such as hydrocarbons get oxidised to CO, and 0 inthe presence of 99/98 sical oxidation forms NO SOx 0nd with COs and HiO+ camry ut oxidation. {form along with effluent water 15 tforsanic matter contain rtogen, sulphur also then che reo the presence of organic mater, omgen's rue (demanded 10 “me dissolved oxygen (D0) present in the sewage when organic mater isn Nauk mee conic mate is in ‘his depleted DO can lexd to anaerobic conditions a omatimes impossible. ecause of depleted DO, we find the sh dead and feating sd hence survival of bio-organism in such water f ificult and the sutace in ers and wells f contamina water id | enters in tei boa. s+ Higher €OD level means a greater amount of oxo . alae ovuiznbleexgoie matter in the sample senage, wie aNeS dissoved ne 4,5:3 Recycling of Waste Water asta water into woter tat can be reused for other PUPOSSS This recycling of water is the process of converting ws 1s water reclamation. process is also known 2s «+ pause may include iigation of agricultural fields, for recharge of ground water, in residences for gardering and toilet flushing and in industries. ch drinking water standards | | the waste water could even be treated to rea | pecaming for reuse applications insteas of using fresh vst applies can be awater-saving measure ag * The water recycling process utilizes very basic physical iological and chemical principles to remove contaminants FO" water Use of mechanical or physical systems to teak WAH mater is generally fered to 2s primary eaten tis referred to as a secondary treatment, ASSNON2 purificatios ay) ea biological processes to provide further treatment i is called tertiary or advanced treatment 4.6 DE-SALINATION PROCESS BY REVERSE osmosis | Membrane technique (Revers | | 6 various membrane technia \ e osmosis) + the solutes or contaminents on the Basis of ole, which selectively separate ues are av pore size. «The types of membr cis, hyperitration, ultrafiltration ete, Sut reverse osmosis is com" ane separation technologies include Teerse cosmo: monly used: tration solution through @ to lower conc: her than the osmotic pressure of Principle of reverse 0570: ‘olvent flow, from hight brane (SPM), by applying af lution is known as reverse O: shown in Fig. 4.11, where the solvent smipermeable membrane, until iff ‘The difference in levels represents the solution slightly higher ‘er concentration solution n external pressure slightly h © The reversal of 5 a semipermeable mem higher concentration 30! ysmosis. tion solution to highe a sufficient flows from low concent rence in water levels creates sis osmotic pressure of the solution ‘through the se" jnal flow. + Nommal osmosis proces concentration solution eract the orig pressure to count fe apply external than its osmotic fessure on higher concentration + Inreverse osmosis: pressure.422. lence chemistry (EE, 16 15) A i‘ ‘osmosis, + The to ot te serpereable membrane. Thus in Fever we separa solution, throus water. ‘contaminants rather than ‘centaminants from sccm ‘Semipermeable membrane (G, cone. > G, conc. | (@) Osmosis (b) Reverse osmosis cell Fig. 4.11 + Sea water i filed in reverse osmosis cell A pressure of 200-200 pst is applied on it to force the through SPM. (SPM has such porosity that it allows only HO molecules to pass through ang ions/molecules are prohibited from passing). «The membrane consists of very thin films of cellulose acetate, affixed to either side of 2 perforated more recently superior membranes made of polymethacrylate and polyamide polymers have come ea ree 1, What is soft water ? What is hard water ? * <2. Whatiis hardness of water ? 3. Which principle is applied to remove hardness of water? 4. Why hard waters unfit to use in boilers ? 5, Define : boiler corrosion, caustic embrittlement, priming and foaming, scale and sludge 6. Define temporary hard water and permanent hard water. 7. List any two limitations of permutit or zeolite process. 8. What is lime soda process ? Name the chemicals used 9, List two advantages of hot lime soda over cold lime soda 10. What is permutit or zeolite ? 11. Write principle of ion-exchange process. 12, Which water is called demineralized water ? 13, What is demineralization ? 14, Define BOD and COD. 15. Define sedimentation, coagulation, filtration and sterilization. 16. Name the filters used for filtration on large scale, 17, Name the methods of sterilization. 18, Write principle of chlorination. 19, What are the characteristics of potable water ? 20. Define sewage su. Whats waste wate 7p. canvwaste water 7. Define reverse os 24. A sample of perm 2s, Fiow cation excha (@ magnesium, (@ iron, tin and ‘One of the meth (a) magnesium (b) chloride an (0) calcium io (¢) calcium i which of the f (a) It lathers (a) Iris nots At a water | treatment is (a) coaguld (One of the small parti (a) fitrati Which twe (a) Cale (@ Mag Zeolite s (a) onl (©) bot The che (a) an (b) an (@ af @ 10. Hard (a) | | 1. Zeol re (a) ©F science : Chemistry (EE, 16,18) as ‘water Treatment and Analysis sp. Whats waste water? 5p. Gan waste water be recycled? How ? sp, Define reverse osmosis proces. A sample of other 2 permanent hard water contains microorganisms. Name one method 9 frnove microorganisms. 35. How cation exchange resins can be regenerated ? ee calcium and magnesium from hard water is known o§ (®) flocculation ‘The metallic constituents of hard water are (© sedan (a) magnesium, tin and iron . (@) cotcium, magnesium and iron (0. iron tin and caleium sea en gintntnnartmimeeana . as in water are replaced by calcium ions from the zeolite fe and magnesiun ions in woter are replced by coum ions from the seoite (@_caleium ions from wotr are replaced by sodium ons fom the 30e (@) coum ions in water ore replace by chloride ios fom the ein Which of the following is NOT a, property of hard water ? {o) Ittatherseosily with soap solution (9. tisnot good for steam generation. plant, one of the stages involves pos (a) water softening (b) Ithos nice taste uses scale formation in Ketles (a) tea snd and gravel Ths stage of sat 0 woter trea 5 reotment sing woter through a bed of 5 treatment i clled 05 {o) cooguiatign 6 One of the treatment of small particles to settle on (o) fitration 7. Which two of the following met {o) Calcium ond magnesium (a) sterilization (@) sedimentation floceulent (ike alu) heles () fitration nto large tanks where © woter for domestic use is t0 allow the bottom This method is known os @) sterilization sedimentation (a) coogulation to cause hardness in water? als, when in compound form © lnely (a. Magnesium ond potassiu” Zeolite softening process remove: porary hardness of water (b) only permanent hardness of w ss of woter 1) dssotved gases in permanent hard water (@) only tem anent hordes fo) both temporary and perm a. Thechemical oxygen demand (COP) measu ired for growth of f microorge {a amount of oxygen 1204 {0) amount of oxygen thot would PE pomowed from oe water order t0 OSS OF matter fo. amount of oxyge” requived to oxidize te ccm Preset in woste (a) none of these 10 Hardness of water does °2* {ay hhave any bad effect in our ) make cooking of foods eficut fo moke it unfit for drinking 1 couse dfclty a wasting of cates we soaps art water gets exhausted afer cera {ime Of usage but can 6 ment of hi 11 zeolte used in softening proces I regenerated by fusing with ium chioride solution b) 10% tion (a) 10% sodium chiorde solution magnesium sulphate solution (a) 10% calc (10% magnesium chlorde soluApplied Science : Chomistry (EE, 16,5) 426 12. Temporary hardness af water is caused byte resencE Fs aphatesof calcium ond rein oak ean (2) chlorides of calcium and magnesiv™ Ube oem Od ty | Rvs (9. bicarbonates of calcium and magnesium (@ semipermeable 13, Secondary treatment uses fee (@ filtration (©) mone in ion-exchange pro (0) microorganisms ‘ dilute ocd c0 of : _ | @ 14 Femara erate bene HEMET gy yrs ef stm ond eosin | non xs @ Hibs dat BI sem (9. of 04m ard Pte |e) tal © chlorides and sulphat ion ? When soap is adde . ‘coagulation 15. nicer ftoving cena oded ne roe (9 calcium chloride (© ronecfy (0) studge V7, 18. Permanent hardness of water may be removed by the 0 19. 20. 21, 22 23, 24. 25. 26. 27, 2. (2) aluminium sulphate (2) luminium oxide (0) chlorination (9 UV radiation Sedimentation is a physical process used to remove (0) colteidel particles (©) suspended particles () time (0) potassium permanganate The purest form of naturaly occurring woter is... () rain woter (0) river woter BOD stands fOr (2) biochemical oxygen demand (0) biological oxygen depletion . Zeolite softening process removes both temporary and permanent hardness of water. In this process, cali present in water are precipitated as .. (a) insoluble carbonates _(b) insoluble zeolites Woter which does not produce lather with soap is (a) mineral water () hard woter Permanent hardness is the hardness that cannot be removed BY .... (0) boiling () adding lime The liquid wastes from kitchens, bathrooms and wash basins are not called ...... (@) liquid wastes () sullage The amount of oxygen consumed by aerobic bacterias which cause aerobic biological decomposition of (a) Bio-chemical Oxygen Demand (8.0.0) (0) Chemical Oxygen Demand (C0.D.) The standard 8.0.0. of water is taken for ..... (0) 1day () 2days Pick up the correct statement from the following ..... (@) the black colour indicates stale sewage (@)_ the sewage omits offensive odours after four hours Fresh sewage may became stale in ..... (@) one hour (0) two to three hours — ies for the treatment of 16. Which ofthe following physical method is used as sterilization i" modern times fo Potable iddition of Permanent hordne (a) carbonate ha (0) both (a) and Boilers do not fc (2) treating with potassium permanganay, (@) treating with bleaching powder (microorganisms (A) lloftied (@) seale and stu (Q lubrication (b) soda ash Highly alkaline (d) sodium bicarbonate (a) corrosion (co) priming an (0) pond or lake water () wells When soft, loos (o) resins (0) british oxygen demand sass is not the n (@ Abrasion (@) british oxygen depletion (9 Danger o For domestic. (9) insoluble chlorides (A) insolutie) (0) sparkling Screening is (0) soft water (@ distitea] —(@ sealean Coagulation (© coagulation @ allof are (0) hardne © sewage (@ none off coagulant (@) biolog Sterilizatio (®) Dissolved Oxygen (0.0) (a) chi (@) none of these inch (a) chlor (@ Sdays (@) 10days hs. The prine (a) form (0) the fresh sewage is practically odourle (© form (@) all of these 46. In ozoni (a) oxy (¢)_ three to four hours (d) six‘ iy pee tee ee 42s Water Treatment nd Analysis fever 04m water purification echgue tat wes {@) coogulont {6} semipermeatie membrane eae Inion-exchonge process 1 so ms AY: eiceocie 8 of water softening, exhousted cation exchanger resin is regenerated by Using _ ease ©) alkol (@ coal (a) sand P aa 5 of water softening, exhausted anion exchanger resin is regenerated by Using = a (0) dilute acid (9 sond (d) zeolite 2 " a elt to hard water, a white precipitate of ......is formed. (a) sludge on wn = scale 5 permanent hardness i also known as aioe 7 “ (@) carbonate hardness (0) non-carbonate hardness (@ both (a) and (b) none oft 14. Ballers do not face the trouble of .... while using hard water to generate steam. —G@ scale and sludge formation ia ors (@ lubrication (d) priming and foaming 39, 4 a 44 45, ighty olkatine woter in boiler causes . {(b) scale and sludge formation (a) caustic embrittlement (@) corrosion (© priming and foaming when oft, loose slimy deposits are formed inside the Boiler and do not stick up permanenty then th () resins () zeolites (a scales (a) sludges is not the consequence of scale and sludge formation inthe boiler. (&) Wostage of fuel ley are known OS «+ (@) Abrasion (Danger of explosion (d) Decrease in efficiency i For domestic use, water must be (0) sparkling (b) free from salts (@ hygenically pure (@) free from chlorine from water. Sereening is the process of removing (@) scale and sludge (b) floating materials Coagulation process removes «~~~ (0) floating materials (@) suspended particles (0) colloidal particles (a) microorganisms Colloidal particles are responsible for (0) hardness of water (6) turbidity of water (0) odour of water (@) all of these Coagulant like alum is added to water to femove (0) biological impurities (b) floating materials Sterilization of water can be dane By «~~ (b) a0ration (@) suspended particles (@)_hardness (0. colloidal impurities (0) all ofthese (@) using UV rays (a) allof these (0) chlorination In chlorination process, germs are killed bY ~--- (@) bleaching powder (d) all of these (a) chlorine gos (0) chloramin The principle of chlorination is « {) formation of nascent oxygen (0) formation of oxygen molecules (@ formation of hydrochloric acid (9 formation of chlorine 905 In ozonisation ...- i used to sterilize water (a) oxygen gas (b) ozone gas (solid ozone (d) chlorine gas(o) allowing water to flow in citer a epee 5 tion ‘ (© cera @ Wag @ deotourtiogcoe — cay | ELE osmosis method ELECTRI for water treatment Electrochemist electrical energ The electroche (The study 6d) | 7) | 8&0 | 906) 18.(b) | 19.(a) | 20.(a) | 22. (b) 30.(a) | 31.(a) | 32.(c) | 33.(b) 42.(. | 43.(d) | 44.(@) | 45. (a) (i) The gener Acallis a dev electrical ener A cell consists The cells are. (9 Electroch Gi) Electroly In electroche electricity eg In electrolyt electrorefini These chemi The electric current is m (One amper A substanc graphite, fy Conductor: With inc eg. all m