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Effective Solid Waste Disposal Methods for Health and Environment

Learn about solid waste disposal methods, health hazards, sources of refuse, storage, collection, and disposal techniques like dumping, landfill, incineration, composting. Understand the importance of proper waste management for public health and environmental sustainability.

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Effective Solid Waste Disposal Methods for Health and Environment

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  1. SOLID WASTE DISPOSAL Dr Navya N Assistant Professor Department of Community Medicine Yenepoya Medical College

  2. INTRODUCTION • Term “solid waste” includes- garbage (food wastes) -rubbish (paper, plastics, wood, metal, throw away containers, glass - demolition products( bricks, masonary, pipes) - sewage treatment residue (sludge and solids from the coarse screening of domestic sewage) - dead animals -manure - other discarded material

  3. HEALTH HAZARDS • Solid waste if allowed to accumulate , is a health hazard : • It decomposes and favours fly breeding • It attracts rodents and vermin • Pathogens in the solid waste may be conveyed back to man’s food through flies and dust. • There is a possibility of water and soil pollution • Heaps of refuse present an unsightly appearance and nuisance from bad odours

  4. SOURCES OF REFUSE • Refuse collected -street cleansing service or scavanging- street refuse • Refuse - collected from market – market refuse • Refuse collected from stable- stable litter • Industrial refuse- completely inert to highly toxic and explosive compounds • Domestic refuse- ash, rubbish, garbage.

  5. STORAGE AND COLLECTION • Galvanized steel dustbin with close fitting cover – suitable • Capacity – depends - no of users and frequency of collection • Recent innovation – western countries- paper sack • Public bins – large no of people • India – without cover • Kept-concrete platform – raised above ground level – prevent flood water • Municipalities – handled and emptied mechanically – lorries fitted with cranes • Method of collection – funds available • House to house collection – best method

  6. METHODS OF WASTE DISPOSAL • Principal methods of refuse disposal : • Dumping • Controlled tipping or sanitary landfill • Incineration • Composting • Manure pits • Burial

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  8. Dumping • Refuse - dumped in low lying areas • Bacterial action decreases the volume of refuse – converted gradually into humus • Kolkata disposes- refuse- dumping and reclaimed land is leased out for cultivation • Drawbacks: • Refuse is exposed to flies and rodents • Source of nuisance from smell and unsightly appearance • Loose refuse - dispersed by the action of the wind • Drainage from dumps - pollution- surface and ground water.

  9. Controlled Tipping / Sanitary Landfill • Most satisfactory method of refuse disposal. • The material is placed in a trench or other prepared area , adequately compacted and covered with earth at the end of the day. • Modified sanitary landfill- compaction & covering done once or twice a week • 3 methods are used : • The trench method • The ramp method • The area method

  10. Controlled Tipping / Sanitary Landfill The trench method : • When level ground available • A long trench is dug out- 2-3m (6-10ft) deep and 4-12m(12-36ft) wide • Refuse- compacted and covered with excavated earth The ramp method : • When terrain is sloping Area Method : • Filling land depressions , disused quarries, clay pits • Refuse – deposited, packed, consolidated- uniform layers – 6-8 ft deep • Disadvantage – supplemental earth

  11. Controlled Tipping / Sanitary Landfill • Chemical, bacteriological and physical changes- buried refuse • Temperature rises over – 60 degree celsius within 7 days • Kills all pathogens and hastens decomposition process • 2-3 weeks – cool down • 4-6 months – complete decomposition of organic matter- innocuous mass • Tipping of refuse in water should NOT be done

  12. Controlled Tipping / Sanitary Landfill

  13. Incineration • Burning • Method of choice- suitable land not available • Hospital waste – incineration • A preliminary separation of dust or ash is needed • All this involves – heavy outlay and expenditure • Disposal of refuse by burning - loss to the community in terms of manure • In India limited application.

  14. Composting • Combined disposal of refuse and nightsoil or sludge. • Process of nature – organic matter breaks down under bacterial action- formation of relatively stable humus- like material • Considerable manurial value for the soil • Principal by- products- carbon dioxide , water and heat • Heat produced – 60 deg C or higher , over a period of several days • Destroys eggs and larvae of flies, weed seeds and pathogenic agents. • End product compost- contains few or no disease producing organisms good soil builder containing small amounts of major plant nutrients such as nitrates and Phosphates

  15. Composting and Vermicomposting

  16. Methods of composting • Bangalore Method ( Anaerobic method) • Mechanical composting (Aerobic method) Bangalore Method ( Hot fermentation process) • Trenches are dug 90cm( 3ft) deep , 1.5- 2.5m (5-8ft) broad , 4.5-10m(15- 30 ft ) long • Depths greater than 90cm (3ft) not recommended- slow decomposition • Pits should be located not < 800m (1/2 mile) from city limits . Composting procedure is as follows : • A layer of refuse about 15cm (6in) thick- spread at the bottom of the trench • Over this nightsoil is added -to a thickness of 5cm (2in) • Alternate layers of refuse and nightsoil are added in the proportion of 15cm(6in) and 5cm(2in) tilll heap rises 30 cm ( 1 ft) above the ground level

  17. Bangalore Method ( Hot fermentation process) • The top layer should be of refuse – atleast 25cm(9in) thickness • Within 7 days due to bacterial action heat (over 60deg C) is generated • Intense heat persist over 2-3 weeks – decomposes refuse and nightsoil – destroys all the pathogenic and parasitic organisms. • At the end of 4-6 months – decomposition is complete • Resulting manure- well decomposed Odourless innocuous material of high manurial value

  18. Mechanical Composting • Compost manufactured in a large scale by: • Processing raw materials and turning out a finished product • The refuse is cleared of : rags, bones ,metals , glass- interfere with grinding operation • Pulverised in a pulverising equipment- reduce the particles to < 2inches • Pulverised refuse- mixed with sewage , sludge or nightsoil in a rotating machine and incubated • Carbon- nitrogen ratio, temp, moisture , Ph and aeration • Entire process complete in 4-6 weeks • This method used in – Holland, Germany, Switzerland , Israel

  19. MECHANICAL COMPOSTING

  20. Manure Pits • Rural areas • The garbage, cattle dung , straw and leaves- dumped into manure pits • Covered with earth after each day’s dumping • 2 such pits will be needed • 5-6 month’s time- refuse converted into manure – returned to fields

  21. Burial • Suitable for small camps • A trench 1.5m wide and 2 m deep is excavated • At the end of each day refuse is covered with 20-30cm of earth • When the level in the trench is 40cm from ground level – trench filled with earth and compacted • A new trench is dug out

  22. SUMMARY • Definition of solid waste • Health hazards of solid waste • Sources of solid waste • Methods of collection and Storage • Methods of waste disposal

  23. THANK YOU

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