WATER & ITS TREATMENT

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10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai1WATER & ITS TREATMENT10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai2ALTHOUGH WATER IS NATURE`S MOST WONDERFUL, ABUNDANT & USEFUL COMPOUND, YET IS ALSO THE MOST MISUSED ONE 10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai3Lesson Plan Various sources oI water Characteristics imparted by impurities in water Hardness oI water & various types oI hardness Disadvantages oI using hard water Boiler Ieed water & its problems (Scale, Sludge, Caustic Embrittlement, Boiler corrosion, Priming & Foaming) Internal treatment oI water (discussed as above) External treatment (soItening oI water) Lime soda method Zeolites method Ion exchange method10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai4Water Water occupies a unique position in industries. Probably its most important use as an engineering material is in the steam generation It is used as a coolant in power & chemical plants It is widely used in other Iields such as textiles, atomic energy, chemicals , ice , drinking bathing, sanitary, washing, irrigation etc10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai5Various Sources oI WaterSourcesSurface Water Under ground waterRain waterRiver waterLake waterSea waterSpring & Well water10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai6 Rain Water: Purest Iorm oI water. Since it is obtained as a result oI evaporation Irom surIace water. But during iourney downwards through the atmosphere, it dissolves a considerable amount oI industrial gases like CO2, SO2, NO2 etc & suspended particles. Lake water: has a more constant composition.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai7 River water: contains minerals oI soil such chlorides, sulphates, carbonates etc. It also contains organic & inorganic matter. Sea water: the most impure Iorm oI water. Underground water: in Iorm oI spring & well water. It is clearer in appearance due to the Iiltering action oI soil, but contains more oI dissolved salts.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai8Characteristics Imparted by Impurities in WaterCharacteristicsPhysical Chemical BiologicalColorTurbidityTasteOdourAcidityGasesMineral MattersMicro organismsWater bodies10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai9Physical Color :in water is due to dissolved substances & substances present as fine colloids. e.g.(i) metallic substances like salts oI Fe, Mn(ii) human materials, tannins(iii) Peat, algae, weeds, protozoa(iv) Industrial eIIluents (Irom paper & pulp, textile & tanneries etc) Color in water is not harmIul unless it is associated with toxic chemicals.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai10Turbidity It is an Optical propertv. It means water sample is scattering more light than transmitting in straight line. It is due to Colloidal &extremelv fine suspension .e.g. clay, silt, Iinely divided matter (organic & inorganic), micro-organisms, plankton etc. It is eliminated by sedimentation, coagulation & Iiltration.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai11Turbidity Measured by Jackson Turbitimeter. It is expressed in terms oI JTU (Jackson Turbidity Unit). Silica has been chosen as the arbitrary standard1JTU 1mg SiO2/litre Now a days suspension oI clay or standard suspension oI Formazin are used &it is expressed in Formazin Turbidity Unit FTU - JTU.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai12%,890 is usually interlinked with Odor. It is due to the presence oI dissolved minerals. Bitter: Fe, Al, Mn & sulphate salts, excess oI lime Soapy: Excess amount oI NaHCO3 Brackish: Unusual amount oI salts Palatable: Dissolved gases CO2 & nitrate minerals10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai13Odor It is most disagreeable & due toi. Presence oI living organismii. Decaying vegetation-algae, bacteria, Iungi, weedsiii. Sewage & industrial eIIluents The most common disagreeable odor in water bodies is due to presence oI small quantity oI Sulphides. 10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai14Chemical cids : released by DDT, high explosives, battery industries. It is caused by the presence oI CO2, mineral acids(H2SO4),weakly associated acids. Acidity is not a speciIic pollutant. It may be deIined as the power oI water to neutralize hydroxyl ions & is expressed in terms oI ppm (mg/L) of CaCO3 equivalent.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai15Gases Water contains dissolved gases eg.i. CO2: It is not assumed as an impurity, but water used in industries some times needed to get rid oI it. All natural water has it Irom atmosphere & biological oxidation oI organic matter.CH4 O2 CO2 H2Oii. O2: All natural water has dissolved oxygen. It is very imp Ior aquatic lives but it is a great nuisance in industrial purposes. 10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai16GasesThe test Ior oxygen is carried out Ior determining Dissolved Oxygen |DO| oI polluted water & industrial eIIluents & constitutes a means oI controlling water pollution.iii. 3: it is acquired Irom decomposition (aerobic &anaerobic) oI Nitrogenous organic matter (in polluted & sewage water) and urea.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai17Mineral matter Origins Irom rocks & industrial eIIluents These includes Mineral, acids, Ca2, Mg2, Na, K, Fe2, CO32-etc. Industrially Hardness & alkalinity are important. 10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai18Biological Impurities There are some biological impurities which contaminate water, e.g. pathogenic bacteria, certain Iungi, viruses, parasitic worms etc. The imp source oI this contamination is Irom domestic & sewage waste, solid excreta Irom warm blooded animals including man, wild & domestic animals.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai19Biological ImpuritiesMicro-organism: Algae, Iungi,& bacteria Iorm 820& there by causing Iouling & corrosion. This slime clogs the spray nozzle & screens oI the circulating pipes oI AC & other industrial plants. In order to control these, chemical treatment like chlorination is done.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai20Water bodies Water bodies: includes (i) bacteria, organisms inhabitating the bottom sludge & (ii) organism & plankton developed at the water surIace. E.g. Ilat worms ,round worms, rotiIers etc. Usually most worms are parasitic in nature these are not only harmIul to Iishes but also to human health.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai21HARDNESS OF WATER Hardness oI water is that characteristic which prevents the lathering of soap. This is due to presence oI certain salts of , & other heavy metals dissolved in water. This water when treated with soap (Na or K salts oI higher Iatty acids like, oleic palmitic, or stearic) Iorms a white scum or ppt oI insoluble soaps oI Ca & Mg as Iollows-10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai22HARDNESS OF WATER2C17H35COONa CaCl2 (C17H35COO)2Ca | 2NaCl2C17H35COONa MgSO4 (C17H35COO)2Mg | Na2SO4 The hardness oI water is oI two types:10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai23TemporaryIt is due to the presence oI soluble salts oI bicarbonates oI Ca & Mg & other heavy metals & the carbonate oI iron. It can be easily removed by mere boiling oI water, when bicarbonates are decomposed , yielding insoluble carbonates or hydroxides- Ca(HCO3)2 CaCO3 H2O CO2 Mg(HCO3)2 Mg(OH)2 2CO210/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai24Permanent Non-carbonate hardness: is due to the presence oI Cl-SO42-oI Ca, Mg, Fe & other heavy metals. It can not be removed by boiling. |SoItening methods are used| The alkaline hardness is due to the presence oI bicarbonate & carbonate oI metals, while non-alkaline hardness is due to the presence oI Cl-, SO42-10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai25Disadvantages oI using hard waterDomestic use:i. Washing : no lather Iormation ,wastage oI soapii. Bathing: no lather Iormation. Also the resulting ppt stick on bodyiii. Cooking: due to dissolved salts boiling point oI water is elevated, causing unnecessarily wastage oI time & Iuel.iv: Drinking: bad eIIect on metabolic system. Calcium oxalate stones may develop in urinary tracts, iI used regularly. Also it causes deposition oI Ca in the bone ioints.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai26Industrial use:i: Textiles: loss oI soaps during washing oI yarn, & Iabrics. Ppt sticked on Iabric& when it is colored. Also Fe, Mn etc salts leave colored spots on Iabricsii. Sugar: crystallization oI sugar is aIIected.iii. Dyeing: react with costly dyes, ppt occurred. it may impure shades.iv: Paper: react with chemicals to provide smooth & glossy Iinishing to paper. Iron salts add unwarranted color in paper.v. Pharmaceuticals: undesirable products may be produced in medicines10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai27Problems oI Boiler Ieed water II the boiler Ieed water contain the excess oI impurities then it causes the Iollowing deIects:(a) Scale & sludge Iormation(b) Corrosion(c) Caustic Embrittlement (d) Priming & Ioaming 10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai28Sludge It is a soIt, loose & slimy ppt Collected in colder parts oI the boiler, where the Ilow oI water is slow & in area oI bends. Substances which have greater solubility in hot water than in cold water Iorm sludge e g MgCl2, MgSO4, MgCO3 &CaCl2.10/31/2011 Dr.Priy Brat Dwivedi,NMMS University, Mumbai29Sludge(a) Disadvantages:i: it is a bad conductor oI heat s