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Topic: Water Treatment Presentation. Building Services. Created By: Padraig McMahon Student ID: 0236381. Water Treatment. Mr McMahon. Hydrological Cycle. Water Conists in three forms Solid, Liquid, and vapour Circulates through the biosphere. Step 1 (Evapouration)
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Topic: Water Treatment Presentation Building Services Created By: Padraig McMahon Student ID: 0236381 Water Treatment Mr McMahon
Hydrological Cycle • Water Conists in three forms • Solid, Liquid, and vapour • Circulates through the biosphere • Step 1 (Evapouration) Water Leaves the earths surface and enters the atmosphere By evaporation.(Transpiration of plants) • Step 2 (Condensation) Vapour forms clouds. As the air pressure & temp change, the vapour condenses depositing moisture.
Hydrological Cycle • Dew Point The temp at which air cannot hold all the moisture in it and dew begins to form • Step 3 (Precpipatation) Rainfall occurs when the droplets formed in condensation are large enough • Step 4 (Infiltration) Rainwater Flows through rivers/ streams back to sea Soaks into soil (groundwater) and eventually runs back to ocean
Hydrological Cycle • Process Provides • Water that is constantly cycled & Recycled • Cleaned and repurified • Maintains good stream quality
Pure Water • Solids In Water • Great Concern Provides adsorption sites for biological and chemical agents • Solids Consists of • Inorganic, organic or immisible liquids like oils,grease,etc.. • Inorganic particles could be clay,silt,soil,etc.. • Organic particles could be plant fibers, bacteria, etc..
Pure Water • Turbidity • The passage of light through water, high turbidity can result from, • Very small particulate Colloidal material e.g rocks, silt, etc.. • Colour • Pure Water has no colour, Foreign substances like Vegetation, minerals, wastes can often tint water. • Waters colour can affect • Marketability • Safety issues • Laundering • Food Processing • Papermaking, etc..
Pure Water • Temperature • Temp of the water within the treatment plant can affect the strength at which the chemicals work at. • Drinking Standards • All these qualities are needed to create safe drinkable water. • Regulations are needed and here is one chart of regulations from America
Surface Water • Sources may include • Rivers, streams • Lakes • Impoundments (man made dam) • Springs • Rain catchments • Tundra ponds- or peat bogs • 4,250 billion gallons of water per day falls on US mainland 66% returns to the atmosphere by evaporation.
Surface Water • Surface Water Advantages: • Easy to locate • Not tainted with minerals (leached out during contact with earths surf • Surface Water Disadvantages • Human interference (can affect run off rate as well) • Easily contaminated with micro organisms
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 table • Aquifers are simply dissolved rocks that allow water to pass through them deep underground.
Groundwater • Advantages • The water is not as easily contaminated. (Natural filtering process) • Quality and quantity remains constant throughout the year • Less affected by short-term droughts • Disadvantages • Higher operational costs, (Groundwater has to be pumped) • If contaminated very hard to disinfect • Due to long contact with earth, minerals are present, • Which leads to hardness in operational materials, e.g. pipes.
Water Treatment Process • Steps that water either Ground or Surfacewater passes through in order to be correctly treated
Water Intake • Water has to be taken from source to treatment Facility • Water Quality • Best at surface • Various Entry points • Top Ports are only opened • Advantages • Option of ports in seasonal change • Control of quantity, quality of water
Water Intake • There are various method of water intake, submerged ports, shoreline structures, etc..
Water Intake Ports Screening
Screening • The removal of debris (most important for surface water) • Various types • Trash screens or rakes • Travelling screens • Drum screens • Bar screens • Etc…
Screening • Step 1 Largest Debris is taken by trash screens or rakes they are made from steel High Density Polymers are becoming used more often • Spacings of 1.5inches to 4inches (37mm-100mm) • Mountained on a fixed structure
Screening • Traveling Water Screens • Series of wire mesh panels,Bolted to frames and attached to aligned roller chains • Placed in Channel of flowing Water • Removes floating debris • High Pressure sprays remove debris at top of screens
Screening • Very few moving parts • Simplicity of design & construction means low • Instillation Costs • Operational costs • Maintenance Costs • Drum Screens • Screen is mountained on a horizontal axis, it turns slowly picking up debris flowing through it
Screening • More Common at wastewater facilities • Handles large debris • Debris is removed by wiper mechanism • Bar Screens
Coagulation • Process Purpose Screened 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.. remains • Cogulation process provides help. • Rapidly mixing chemicals • Slowly stirring mixture • Finally sedimentaion removes the particles
Coagulation • Cogulation Rapidly mixes certain chemicals into the water to allow particles to clump togeather easlier • Types 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”!!
Flocculation • The clumping of particles as a result of cogulation, It is the most critical factor that affects particle removal. • Slow mixing process (designed to bring particles into contact) • Collide, stick, agglomerate (grow), & settles • Warnings • Too much mixing (breaks floc down into smaller units • Speed of mixing water (strictly controlled • Gentle agitation for about 30mins using redwood paddles is standard
Flocculation • Warnings • Too much mixing (breaks floc down into smaller units • Speed of mixing water (stricly controlled • Gentle agitaion for about 30mins using redwood paddles is standard Flocculation Tank Coagulation Tank Big Red-Wood Panels
Flocculation • 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 water
Sedimentation • Sedimentation (or Clarification) is a physical process that seperates solids from influent water by gravitional action • Process • Water flows horizontally through sedimentation basins. • Detention time 1-10hrs (typically) • Water rises floc settles, to bottom • Expelled mechanically by sludge removal machinery
Sedimentation • Floc Particals still remain, • Lighter Particles flow out • Sludge disposed of in lagoon. • Sedimentation balances time efficiency against removal rate efficiency • Physical laws of gravity are evident for the removal of particales too small for intial screening to halt
Filtration • Filtration is also a physical process. • Last physical step in process • Generally 5% of suspended impurities remain after sedimentation • Filtration is a polishing process, and it involves passing water through a porous granular material • Various Types • Rapid sand, slow sand, diatomaceous earth, package systems
Filtration • Slow Sand Filters • Bacteriological action • Sand develops a film of fine particales. • Gradual loss of flow • Fine pore spaces clog easily • Maual scraping of top 20mm’s of sand is required every fortnight
Filtration • Anthracite Coal Filters • Consists of coal and fine sand • Coal traps large floc • Fine sand traps smaller impurities • The 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 in slow sand filters
Chlorination • In USA the disinfectant choice has been chlorine • Effective, • Relatively inexpensive, • Meets Regulation Standards • In USA the disinfectant choice has been chlorine • Effective, • Relatively inexpensive, • Meets Regulation Standards
Chlorination • All Vacuum Chlorinator • Vacuum Formed by water flowing through ejector unit at high velocity • Chlorine is sucked out along with the water • “Venturi” Tightning of a tube to create higher pressure & velocity at the point e.g carburettor
Chlorination • Other Modern methods include: • Uv radiation • Ozonation • Electrodialsis • Reverse Osmosis • This ultraviolet (UV) radiation and oxidation technology uses UV radiation, ozone, and hydrogen peroxide to destroy toxic organic compounds