day 4 recycle grey water
TRANSCRIPT
Day 4
Props: perforated pipe and ceramic pot
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Sand
Soil
Large stone
Gravel
PebblesCoconut shavingBroken Bricks
Or rice husk...
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 processAbstraction
Storage
Sedimentation
Aeration
Roughing filtration
Coagulation with settlement
To make white water this is the 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
Roughing Filters
Infiltration rate
SandClay
Clay isImpermeable
Sand is Permeable
(Rate which water will filter into soil)
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 water
Soil Type Infiltration Rate (l/m2/day) Infiltration Rate (l/m2/day)
Clean Water Dirty Water
Sand 2000 50
Clay 100 Not suitable
Clay isImpermeable
Sand is Permeable
Extras
• For storage of non-chlorinated water for filter rinsing and use in bio carbon tank.
• Special iron fillings to filter our arsenic
Roughing filters
• For pre-treatment removal of iron, parasites, colour, cysts,manganese, arsenic, 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 filter
• Vertical roughing 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) Barrel
Can 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 ofa) Rectangle and b) Circle?
Method 1
• Area of cross section is LxB.
• What if it is a square?
Length
BreadthHeight
• 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