Day 4Props: perforated pipe and ceramic pot This PowerPoint Presentation is developed and created by :
Sand Large stone Soil Gravel Or rice husk...Broken Bricks Coconut shaving Pebbles
Conclusions:• Did you record the experiment?• What were your conclusions about the various materials?
Layering• The different materials depends on the PURPOSE of the filter.• We are now going to look in detail at the filtration process.
Pre treatment/ Grey water process Abstraction Storage Sedimentation Aeration Roughing filtration Coagulation To make white water this is the with settlement pre treatment process
Abstraction• When finding water – try to remove level of suspended solids.• E.g. Take water to treat from A or B?
Storage and Sedimentation• Natural settlement of solids• Natural die off of pathogenic bacteria.• Maximise settlement time• Sunlight can reduce bacteria in open storage tanks. However in the presence of organic matter it can encourage growth of algae.
Aeration• Tastes and smells are commonly due to the presence of hydrogen sulphide in the groundwater or decaying organic and bacterial matter in surface water.• These tastes and smells can be reduced by aeration.• Maximise air/water contact area.• Discharge in a spray into tank.• If space let water fall down steps of perforated tiles or steps.
Coagulation• Some particles in water are quite small and do not settle to the bottom of the tank during sedimentation.• These particles must be encouraged to combine together to create heavier particles and then they can settle.• This process is called coagulation (and flocculation)• Chemicals: Most common coagulant is alum (aluminimum suphate)• Natural: Alum rock, crushed seedsof some plants but may provide organic matter for the growth of bacteria.• Stages: Rapid mixing and Flocculation
Infiltration rate (Rate which water will filter into soil)Clay Sand Clay is Sand is PermeableImpermeable
Infiltration time• Do you think rock has a longer or shorter infiltration rate?• Water will flow through rock quicker than both sand and clay.
Soil infiltration rate for white and dirty waterSoil Type Infiltration Rate (l/m2/day) Infiltration Rate (l/m2/day) Clean Water Dirty WaterSand 2000 50Clay 100 Not suitable Clay is Sand is Permeable Impermeable
Extras• For storage of non- • Special iron fillings to chlorinated water for filter filter our arsenic rinsing and use in bio carbon tank.
Roughing filters• For pre-treatment removal of iron, parasites, colour, cysts,manganese, arse nic, lead, mercury and turbidity.• Can be used as a pre treatment for a slow sand filration• Can be used for grey water treatment as long as not near a water source and is not going to be drunk directly.
Roughing filter: Layers• Horizontal roughing • Vertical roughing filter filter • In series or separate tanks
We used the Vertical roughing filter• But how well it filters the material also depends on the size of the filter.• Today we are going to look at volumes of materials we could use as filter. 1) Ceramic pot 2) BarrelCan you think of any other materials?
Calculating Volume• There are two methods to do this.• But first we need to agree on the Units to use. (e.g. Feet, inches, centimetre and meters)• We are going to use meters.• Therefore our final volume will be in m 3 3
Method 1• First: Calculations – Step 1: Measure the dimensions of the object. – Step 2: Work out the cross sectional area – Step 3: Times the cross sectional area by the height of the object. – How do you calculate the cross sectional area of a) Rectangle and b) Circle?
Method 1 • Area of cross section is LxB.Breadth Height • What if it is a square? Length
• Diameter is 2m, what is the area?• Height is 1m, what is the volume of this cylinder?
Method 2• Work out how many litres of water you can fit into the object.• 1Litre = 0.001 m 3
Question• Volume of – A) Ceramic pot – B) One barrel – C) Half a barrel