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  • Building ServicesTopic: Water Treatment PresentationCreated By: Padraig McMahonStudent ID: 0236381Water TreatmentMr McMahon

    Mr. McMahonWater Treatment

    Hydrological CycleWater Conists in three formsSolid, Liquid, and vapourCirculates through the biosphereStep 1 (Evapouration)Water Leaves the earths surface and enters the atmosphereBy evaporation.(Transpiration of plants)Step 2 (Condensation)Vapour forms clouds. As the air pressure & temp change, the vapour condenses depositing moisture.

    Mr. McMahonWater Treatment

    Hydrological Cycle

    Mr. McMahonWater Treatment

    Hydrological CycleStep 3 (Precpipatation) Rainfall occurs when the droplets formed in condensation are large enoughDew Point The temp at which air cannot hold all the moisture in it and dew begins to formStep 4 (Infiltration)Rainwater Flows through rivers/ streams back to seaSoaks into soil (groundwater) and eventually runs back to ocean

    Mr. McMahonWater Treatment

    Hydrological Cycle

    Mr. McMahonWater Treatment

    Hydrological CycleProcess Provides Water that is constantly cycled & RecycledCleaned and repurified Maintains good stream quality

    Mr. McMahonWater Treatment

    Pure WaterSolids In WaterGreat ConcernProvides adsorption sites for biological and chemical agentsSolids Consists ofInorganic, organic or immisible liquids like oils,grease,etc..Inorganic particles could be clay,silt,soil,etc..Organic particles could be plant fibers, bacteria, etc..

    Mr. McMahonWater Treatment

    TurbidityThe passage of light through water, high turbidity can result from,Very small particulate Colloidal material e.g rocks, silt, etc..

    Pure WaterColour Pure Water has no colour, Foreign substances like Vegetation, minerals, wastes can often tint water. Waters colour can affectMarketabilitySafety issuesLaunderingFood ProcessingPapermaking, etc..

    Mr. McMahonWater Treatment

    TemperatureTemp of the water within the treatment plant can affect the strength at which the chemicals work at.Pure WaterDrinking StandardsAll these qualities are needed to create safe drinkable water.Regulations are needed and here is one chart of regulations from America

    Mr. McMahonWater Treatment

    Surface Water Sources may include Rivers, streamsLakesImpoundments (man made dam)SpringsRain catchmentsTundra ponds- or peat bogs

    4,250 billion gallons of water per day falls on US mainland 66% returns to the atmosphere by evaporation.

    Mr. McMahonWater Treatment

    Surface WaterSurface Water Advantages: Easy to locate Not tainted with minerals (leached out during contact with earths surfSurface Water DisadvantagesHuman interference (can affect run off rate as well)Easily contaminated with micro organisms

    Mr. McMahonWater Treatment

    Groundwater Water that has fallen below the earths crust and not evaporated is known as ground water. It travels through the earths crust reaches aquifers and passes on to what is known as a water tableAquifers are simply dissolved rocks that allow water to pass through them deep underground.

    Mr. McMahonWater Treatment

    GroundwaterAdvantages The water is not as easily contaminated. (Natural filtering process)Quality and quantity remains constant throughout the yearLess affected by short-term droughts Disadvantages Higher operational costs, (Groundwater has to be pumped)If contaminated very hard to disinfectDue to long contact with earth, minerals are present,Which leads to hardness in operational materials, e.g. pipes.

    Mr. McMahonWater Treatment

    Water Treatment ProcessSteps that water either Ground or Surfacewater passes through in order to be correctly treated

    Mr. McMahonWater Treatment

    Water IntakeWater has to be taken from source to treatment Facility

    Water QualityBest at surfaceVarious Entry pointsTop Ports are only opened

    AdvantagesOption of ports in seasonal changeControl of quantity, quality of water

    Mr. McMahonWater Treatment

    Water IntakeThere are various method of water intake, submerged ports, shoreline structures, etc..

    Mr. McMahonWater Treatment

    Water IntakeScreeningPorts

    Mr. McMahonWater Treatment

    ScreeningThe removal of debris (most important for surface water)

    Various types

    Trash screens or rakesTravelling screensDrum screensBar screensEtc

    Mr. McMahonWater Treatment

    ScreeningStep 1Largest Debris is taken by trash screens or rakes they are made from steel High Density Polymers are becoming used more oftenSpacings of 1.5inches to 4inches (37mm-100mm)Mountained on a fixed structure

    Mr. McMahonWater Treatment

    ScreeningTraveling Water ScreensSeries of wire mesh panels,Bolted to frames and attached to aligned roller chainsPlaced in Channel of flowing WaterRemoves floating debrisHigh Pressure sprays remove debris at top of screens

    Mr. McMahonWater Treatment

    Very few moving partsSimplicity of design & construction means lowInstillation CostsOperational costsMaintenance CostsScreeningDrum ScreensScreen is mountained on a horizontal axis, it turns slowly picking up debris flowing through it

    Mr. McMahonWater Treatment

    More Common at wastewater facilitiesHandles large debrisDebris is removed by wiper mechanismScreeningBar Screens

    Mr. McMahonWater Treatment

    CoagulationProcess PurposeScreened water is pumped into tanks and allowed settle.Gravity and sedimentation allows particles that are denser than water sink.

    Not all particles are removed, colloids, bacteria, turbidity, etc.. remainsCogulation process provides help.Rapidly mixing chemicalsSlowly stirring mixtureFinally sedimentaion removes the particles

    Mr. McMahonWater Treatment

    Cogulation Rapidly mixes certain chemicals into the water to allow particles to clump togeather easlier CoagulationTypes of chemicals mixed are dependent on individual plant or process schemes.The most common added is Aluminium Fact Colloidal particales must be coagulated to be removed!!

    Mr. McMahonWater Treatment

    The clumping of particles as a result of cogulation, It is the most critical factor that affects particle removal.FlocculationSlow mixing process (designed to bring particles into contact) Collide, stick, agglomerate (grow), & settlesWarningsToo much mixing (breaks floc down into smaller unitsSpeed of mixing water (strictly controlledGentle agitation for about 30mins using redwood paddles is standard

    Mr. McMahonWater Treatment

    WarningsToo much mixing (breaks floc down into smaller unitsSpeed of mixing water (stricly controlledGentle agitaion for about 30mins using redwood paddles is standardFlocculationBig Red-Wood PanelsCoagulation TankFlocculation Tank

    Mr. McMahonWater Treatment

    Summary

    Coagulation and Flocculation work together to remove much of the hidden debris within the water

    The smaller impurities that remain uses more complex processes to ratify the waterFlocculation

    Mr. McMahonWater Treatment

    SedimentationSedimentation (or Clarification) is a physical process that seperates solids from influent water by gravitional actionProcessWater flows horizontally through sedimentation basins.Detention time 1-10hrs (typically)Water rises floc settles, to bottomExpelled mechanically by sludge removal machinery

    Mr. McMahonWater Treatment

    Floc Particals still remain,Lighter Particles flow outSludge disposed of in lagoon.SedimentationSedimentation balances time efficiency against removal rate efficiencyPhysical laws of gravity are evident for the removal of particales too small for intial screening to halt

    Mr. McMahonWater Treatment

    Filtration is also a physical process.Last physical step in processFiltrationGenerally 5% of suspended impurities remain after sedimentation Filtration is a polishing process, and it involves passing water through a porous granular materialVarious TypesRapid sand, slow sand, diatomaceous earth, package systems

    Mr. McMahonWater Treatment

    Slow Sand FiltersBacteriological actionFiltrationSand develops a film of fine particales.Gradual loss of flow

    Fine pore spaces clog easilyMaual scraping of top 20mms of sand is required every fortnight

    Mr. McMahonWater Treatment

    Anthracite Coal FiltersConsists of coal and fine sandCoal traps large flocFine sand traps smaller impuritiesFiltrationThe Process is called in-depth filtration, as the impurities are not simply screened our or removed at the surface of the filter bed, as the case inslow sand filters

    Mr. McMahonWater Treatment

    In USA the disinfectant choice has been chlorineEffective,Relatively inexpensive,Meets Regulation StandardsChlorinationIn USA the disinfectant choice has been chlorineEffective,Relatively inexpensive,Meets Regulation Standards

    Mr. McMahonWater Treatment

    All Vacuum ChlorinatorChlorinationVacuum Formed by water flowing through ejector unit at high velocityChlorine is sucked out along with the waterVenturi Tightning of a tube to create higher pressure & velocity at the point e.g carburettor

    Mr. McMahonWater Treatment

    Other Modern methods include:Uv radiationOzonationElectrodialsisReverse OsmosisChlorinationThis ultraviolet (UV) radiation and oxidation technology uses UV radiation, ozone, and hydrogen peroxide to destroy toxic organic compounds