Solid waste and Solid waste disposal Terms related

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Solid waste and Solid waste disposal

Solid waste and Solid waste disposal

Terms related to Waste • Refuse: Solid or semisolid waste matter produced during daily

Terms related to Waste • Refuse: Solid or semisolid waste matter produced during daily human activities (market/street sweeps/commercial or industrial refuse) • Rubbish: Solid waste from houses/commercial establishments/industries. Excludes garbage and ash

 • Garbage: animal and vegetable waste from food preparation, cooking and consumption •

• Garbage: animal and vegetable waste from food preparation, cooking and consumption • Daily per capita waste production is 0. 25 – 2. 5 kg • Depends on dietary habits, life style, SES, urbanization

Health hazard due to solid waste • • • It decomposes and favors fly

Health hazard due to solid waste • • • It decomposes and favors fly breeding Attracts rodents and vermin May enter food chain Water and soil pollution Bad odors and nuisance Improper solid waste disposal and incidence of vector borne diseases correlate well

Sources of refuse • • • Street refuse Market refuse Stable refuse Industrial refuse

Sources of refuse • • • Street refuse Market refuse Stable refuse Industrial refuse Domestic refuse Garbage: waste arising from food preparation, cooking and consumption

Storage of solid waste • • • Storage while awaiting collection Should be covered

Storage of solid waste • • • Storage while awaiting collection Should be covered Household collection and storage Community bins: covered and uncovered Mechanized bin handling is ideal

Solid waste collection • House-to-house collection • Dispose in nearest public bin • Indiscriminate

Solid waste collection • House-to-house collection • Dispose in nearest public bin • Indiscriminate disposal: swept for collection by manual workers

Methods of disposal • • • Dumping Controlled tipping/sanitary land fill Incineration Composting Manure

Methods of disposal • • • Dumping Controlled tipping/sanitary land fill Incineration Composting Manure pits Burial

Dumping • • • Most insanitary method of disposal Refuse dumped in low lying

Dumping • • • Most insanitary method of disposal Refuse dumped in low lying areas Method of land reclamation Bacterial action reduces the volume Attracts flies and rodents

Controlled tipping TRENCH METHOD • Requires suitable land • Prior preparation of trenches •

Controlled tipping TRENCH METHOD • Requires suitable land • Prior preparation of trenches • 6 -10 feet deep and 12 -36 ft wide • Covered by earth after tipping and compacting

Controlled tipping RAMP METHOD Where the terrain is moderately sloping Some excavation for covering

Controlled tipping RAMP METHOD Where the terrain is moderately sloping Some excavation for covering material

Controlled tipping AREA METHOD • filling land depression, disused quarries and pits • Layers

Controlled tipping AREA METHOD • filling land depression, disused quarries and pits • Layers of refuse • 30 cm of soil cover each layer • Requires supplemental earth from outside sources

 • Physical, chemical and bacteriological changes occur in buried refuse • Temperature increases

• Physical, chemical and bacteriological changes occur in buried refuse • Temperature increases to 60 deg C in 7 days • Kills pathogens and hastens decomposition • Cools down in 2 -3 weeks • 4 -6 months for complete decomposition into innocuous matter

Incineration • Method of choice when land unavailable • Most commonly used for hospital

Incineration • Method of choice when land unavailable • Most commonly used for hospital waste in developing countries • In developed countries in large cities • Requires preliminary separation of dust or ash • Involves expenditure and systems in place • Also causes loss of manure

Incineration • Example: Hospitals waste • Disadvantages 1) Expensive 2) No useful by-product 3)

Incineration • Example: Hospitals waste • Disadvantages 1) Expensive 2) No useful by-product 3) Air pollution

Composting • Organic matter breaks down under bacterial action and results in formation of

Composting • Organic matter breaks down under bacterial action and results in formation of humus • Humus is stable and has manurial value • Water, carbon dioxide and heat are by products • Heats up to temp of 60’C for several days • All eggs and larvae are destroyed • Rich in phosphates and nitrates

Methods of composting • Bangalore method (anaerobic method) • Mechanical composting (aerobic method)

Methods of composting • Bangalore method (anaerobic method) • Mechanical composting (aerobic method)

Bangalore Method • • • Also called the hot fermentation method Developed at Indian

Bangalore Method • • • Also called the hot fermentation method Developed at Indian Institute of Science Anaerobic composting Satisfactory for town waste and nightsoil Can be done by towns with population less than one lakh

Bangalore Method • Trenches 3 feet deep, 5 -8 feet broad and 1530 feet

Bangalore Method • Trenches 3 feet deep, 5 -8 feet broad and 1530 feet long • Too much depth not recommended because of slow decomposition • Should be located at least 800 mts from town limits

Procedure in Bangalore method • First layer: 15 cm layer of thick refuse at

Procedure in Bangalore method • First layer: 15 cm layer of thick refuse at the bottom • Second layer: 5 cm thick layer of night soil • Alternate layers in this proportion are added till the heap is 1 feet above the ground level • Top layer is a refuse layer of 25 cm • Lastly it is covered by earth

 • Within 7 days bacterial action and rise in temperature to 600 C

• Within 7 days bacterial action and rise in temperature to 600 C • This heat persists for 2 -3 weeks • Decomposes and destroys pathogenic and parasitic organisms • After 4 -6 months: manure which is odorless, innocuous and rich

Mechanical composting • Compost manufactured on a large scale • Refuse cleared of rags,

Mechanical composting • Compost manufactured on a large scale • Refuse cleared of rags, bones, metal, glass, etc • Pulverized to reduce the size to less than 2 inches • This is mixed with sewage/sludge/nightsoil in a rotating machine

 • Incubated with controlled factors: Ø temperature Ø carbon-nitrogen ratio Ø p. H

• Incubated with controlled factors: Ø temperature Ø carbon-nitrogen ratio Ø p. H Ø Moisture Ø Aeration • Total time taken for the process: 4 -6 weeks

Vermicomposting

Vermicomposting

Manure pits Mainly used in rural areas Individual manure pits dug for refuse disposal

Manure pits Mainly used in rural areas Individual manure pits dug for refuse disposal Garbage, cattle dung, straw, leaves are dumped Twin pits: one is used while the other is full and closed • Refuse converts to manure in 5 -6 months • •

Burial • Suitable for small camps • Trench 1. 5 meters wide and 2

Burial • Suitable for small camps • Trench 1. 5 meters wide and 2 meters deep is excavated • At the end of each day, the refuse is covered with 20 -30 cm of earth • When the level is 40 cm from ground level: cover wit earth and compacted • A trench 1 meter long: It will last for 1 week for 200 persons

Biogas Plant • Biogas is produced by the anaerobic breakdown of solid waste and

Biogas Plant • Biogas is produced by the anaerobic breakdown of solid waste and excreta • Biogas: Methane, Carbon dioxide and Hydrogen • Used for fuel at household level