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SOLID WASTE
Some terms we need to know
REFUSE:Solid or semisolid waste matter produced in the normal course of
human activities. Generated from street sweepings, markets, stable
litter, industrial refuse, commercial refuse, etc.
RUBBISH:Solid wastes originating in houses, commercial establishments,
industries, excluding garbage and ash.
GARBAGE:Animal & vegetable wastes resulting from the handling, storage,
sale, preparation, cooking and serving of food.
ASH:Residue from burning of wood, coal, charcoal and other combustible
materials used for cooking and heating purposes in houses, industries
etc.
• Street refuse
• Market refuse
• Stable litter
• Industrial refuse
• Domestic refuse
Sources of solid wastes
In most of the countries the per
capita daily solid waste produced is
between 0.25 to 2.5 Kg
• Galvanized steel dust bin with cover (for households) – 0.05 to 0.1 cubic feet per capita per day.
– A bin with capacity of 1.5 cubic feet for a family of 5 members if collection is done every 3 days.
• Public bins.
Storage of solid wastes
• House-to-house collection
• Mechanical transport
• Dustless refuse collector
Collection of solid wastes
Methods of solid waste disposal
INSANITARY METHODS
1. Hog feeding
2. Dumping
SANITARY METHODS
1. Sanitary landfill/ Controlled tipping
2. Composting
3. Incineration
4. Manure pits
5. Burial
6. Biogas plant
SANITARY METHODS
Methods of solid waste disposal
INSANITARY METHODS
Dumping
– Refuse dumped in low lying areas
– Bacterial action over time, decreases volume of refuse which is gradually converted into humus
– Disadvantages
• Smell
• Unsightly appearance
• Free access to flies, rodents, hogs, dogs etc.
• Dispersal by wind
• Pollution of surface and ground water
Dumping
1. Sanitary landfill / Controlled tipping
–Laying of dry and condensed refuse in a trench or other prepared area with intervening earth coverings.
–Anaerobic digestion of the refuse takes place. The process takes 4-6 months to complete.
SANITARY METHODS
2-3
mete
r
4-12 meter
• Trench method
– Level ground
– Trenches 4-12 m wide, 2-3 m deep
– Refuse is compacted and then covered with excavated earth
• Ramp method
– Sloping terrain
• Area method
– Land depressions, disused quarries, pits
– May need soil from outside sources to cover the compacted refuse
2. Composting–Method of combined disposal of refuse and nightsoil or sludge.–Organic matter breaks down under bacterial action, producing “compost” –used as manure.
SANITARY METHODS
BANGALORE METHOD
MECHANICAL
COMPOSTING
VERMI-COMPOSTIN
G
Three methods of composting
Bangalore method
Anaerobic composting; also called “Hot fermentation process”IISc, Bangalore – Indian Council of Agriculture Research
800 metre
90
cm
4.5 – 10 m
A Trench excavated for
composting
Anaerobic
decomposition
4-6 monthsHumus
NIGHTSOIL
15
cm
5
cm
15
cm
5
cm
25
cm
REFUS
E
REFUS
E
NIGHTSOIL
REFUS
E
Earth
NIGHTSOIL
Mechanical composting
Refus
ePulverizing
equipmentPulverized refuse +
Sewage/Sludge/NightsoilIncubation
(Temperature, pH, Aeration, Moisture controlled)
Complete
composting
Screening
4-6 weeks
Vermicomposting
A method of garbage disposal
Garbage Earthworms
2-3 months
Compost
3. Incineration–Suitable for areas where land is not available for sanitary landfill–Example: Hospitals–Disadvantages:
•Expensive•No useful by-product•Air pollution
SANITARY METHODS
4. Manure pits–Used in rural households–Covered with earth after each days dumping–Two pits–Within 5-6 months decomposed refuse which is used as fertilizer
SANITARY METHODS
5. Burial–Suitable for small settlements/camps–Decomposed matter may be ready for use as manure within 4-6 months
SANITARY METHODS
1.5 m
2 m
20-30
cm
40 cm1 m
200 persons
1 week
6. Biogas plant• Biogas is produced by the
anaerobic breakdown of solid waste /excreta.
• Biogas (Methane, CO2, Hydrogen) can be used as a fuel for any heating purpose, such as cooking.
SANITARY METHODS
EXCRETA
Spread of disease from excreta
Sanitation barrier
Methods of excreta disposal
INSANITARY METHODS
1. Bucket type
2. Conservancy system/Cartage
SANITARY METHODS
WATER CARRIAGE SYSTEM
1. Bore hole latrine
SANITARY METHODS
Methods of excreta disposal
2.Dug well/pit latrine
3. Water seal type
of latrinea) P.R.A.I
b) R.C.A
c) Sulabh
sauchalya
4. Septic tank
5. Aqua privy
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3.latrine suitable for
camps
i. Shallow trench
latrines
ii. Deep trench latrine
iii.Pit latrine
iv.Bore hole latrine
Water carriage system and sewage treatment
A) PRIMARY TREATMENT
• screening
• Removal of grit
• Plain sedimentation
B ) SECONDARY TREATMENT
• Trickling filters
• Activated sludge process
c) OTHER METHODS
a) Sea outfall b) river outfall
c) Sewage farming d) oxidation ponds 33
INSANITARY METHODS OF EXCRETA DISPOSAL
1. Open defecation
2. Cartage (Conservancy
system)•Example: Bucket latrine
•Disadvantages:
Smell
Flies
Health risk to people handling
the excreta
Health risk from food crops
fertilized with raw excretaBucket
latrine
SANITARY METHODS OF EXCRETA DISPOSAL
9b. Bore Hole Latrine
• Introduced in India by Rockefeller Foundation in
1930’s as a component of hookworm control
programme.
• Consists of a circular hole dug by an equipment
called “auger”.
20 f
eet
16 feet
1a. Simple pit latrine
Lo
ca
tio
n o
f a
pit
la
trin
e
Ad
va
nta
ge
s &
D
isa
dva
nta
ge
s• Advantages:
– Easy and cheap to construct
– Slab and shelter can be reused
– Excreta are isolated
• Disadvantages:
– Unpleasant odors
– Flies
• A circular pit about 75cm in diameter and 3-3.5m deep is dug into ground for reception of nightsoil.
• The pit lined with pottery rings to prevent of soil reenter.
• Concrete squatting plate is placed on top.
• Merits: 1. easy to construct
• 2. longer life
1b. Dug well latrine
0.5 m
Semi
dark
Shelter
Water Seal Latrine:• Hand flushed water seal latrine.
• Water seal
• Types of water seal:
44
Wa
ter
se
al
latr
ine
The Water Seal
2a. Direct & Indirect WS Latrine
Direct Indirect
2c. PRAI & RCA Latrine
• PRAI Latrine was developed by the Planning, Research & Action Institute, Lucknow
• RCA latrine was developed by the Research Cum Action project of the Ministry of Health
The RCA Latrine
1. Location
2. Squatting plate
3. Pan
4. Trap
5. Connecting pipe
6. The pit
7. Superstructure
8. Maintenance
9. Modifications
Location
•Depends on porosity of soil and ground water level
•Usually, at least 15 m away from water source
Squatting plate
•Made of impervious material (cement concrete)
•3’x3’x2”
•Raised footsteps
Pan
•Receives nightsoil, urine and water
Trap
•A bent pipe connected to the pan
•Holds water and serves as a water seal (2 cm depth)
Connecting pipe
•Needed when pit is sited away from squatting plate
•Not needed in Direct type RCA Latrine
•3.5” diameter with a bend at the end
The pit
•Covered, rectangular/circular
•75 cm diameter, 3-3.5 m deep
• Underneath squatting plate(Direct) or offset (Indirect)
Superstructure
Maintenance
•Regular cleaning of the squatting plate
•Flushing with 1-2 lts of water after every use
Modifications
•Using prefabricated squatting plate/pan made of china
clay
•Using a septic tank instead of the pit
Squatting plate13-03-2015 Free template from
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Pan and connecting pipe
54
• The aquaprivy is a water tight tank filled with water into which excreta fall via a drop pipe, connected to a seepage pit (soakaway) to dispose of sullage and effluent.
• Drop pipe must reach below surface of the water.
• Night soil undergoes purification by anerobicdigestion
Vent open on top
Sludge removed at end.
4. Aqua privy
The AQUAPRIVY
Ad
va
nta
ge
s &
D
isa
dva
nta
ge
s• Advantages:
– Cannot be blocked with bulky anal cleaning material
– Nil problem with odor or flies
– Can be connected to a sewerage system at a later date
• Disadvantages:
– Expensive to build
– Need large volumes of water to work
– Water seal may be hard to maintain
– Tanks must be emptied about every 3 years
• Septic tanks are watertight chambers (single, double or multi chambered) which receive excreta and wastewater.
• They are connected to a soakaway which receives liquid overflowing from the tank.
5. Septic Tank
Wo
rkin
g o
f S
ep
tic T
an
k• Solids (“sludge”) settle down and are
purified by anaerobic digestion.
• The liquids (“effluent”) undergoes
aerobic oxidation in the upper layers of
the soil, outside the septic tank proper.
• The sludge is reduced in volume and a portion of solids is transferred to liquids and gases which rises to surface forming bubble.
• Liquid passes out called effluent which percolates into soil by open ended pipes laid in trenches.
• Aerobic bacteria attack organic matter and convert to end products .
•
• Complete purification of sewage.
62
Ad
va
nta
ge
s &
D
isa
dva
nta
ge
s• Advantages:
– Isolation and treatment of excreta
– No odor or fly problems
– May be connected to sewerage system at a later date
• Disadvantages:
– High cost of construction
– Need for periodic mechanical emptying
– Need for large volumes of flushing water
– Only suitable where flush toilets are used
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• A low cost, water seal type of latrine connected to a 3’x3’x3’ pit. It is a modified handflush latrine with a specially designed pan and trap – needs very little water for flushing.
• Sulabh International, an NGO, maintains SulabhCommunity Latrines – ‘pay-and-use system – in many parts of India.
6. Sulabh Shauchalaya
SHALLOW TRENCH LATRINE
• Simple trench dug with ordinary tools.
• Trench is 30cm wide 90-150cm deep.
• Separate for men and women
• Earth piled up a side and people instructed to cover up earth after each defecation.
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Shallow Trench latrine
Access
pathHandwashing
facilityDug soil (for back filling)
Trench depth
approx. 150
mm
Poles to attach
screeningSecurity screening
Superstructure
Plan View
1.5
m
5 m 4 m
Approx
.
300mm
DEEP TRENCH LATRINE:
• Used for camps in longer duration
• Trench is 1.8-2.5m
• 75-90cm wide
• Squatting plate is provided.
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De
ep
Tre
nch
la
trin
e
Superstructure
Modern sewage treatment.
• A) primary treatment
• B) secondary treatment
•
• PRIMARY TREATMENT
• 1.Screening
• 2. Grit Chamber
• 3. Primary Sedimentation.
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• Sewage made flow across tank , spends 6-8hrs in
tank
• Purification takes place mainly by sedimentation
• 50-70% settle down under influence of gravity.
Coli form organism formed called ‘sludge’
Biological action takes place were micro-organism
attack sewage
Sewage attack complex organic solids and break them 74
• Simpler soluble substance ammonia
• Contain grease and fat that come up called scum
• Then it is treated with lime ,aluminium sulpahte and ferrous sulphate.
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Secondary treatment:
• Types
76
ACTIVATED SLUDGE
PROCESS
Oxygen pond
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