Waste disposal and management

solid waste disposal and management

1. WASTE DISPOSAL AND MANAGEMENT - Neeraja A

2. SOLID WASTES Solid wastes are the wastes arising from human and animal activities, that are normally solid and that are discarded as useless or unwanted materials

3. STATUS, NATURE AND COMPOSITION Solid wasted include crockery, bottles, plastics, and other wastes thrown out as garbage. Old Automobile spares, machines, etc,. Building material wastes, settled solid components of sewage, dead animals, chemicals, paints from industries and crop residue from agriculture, pathogenic materials from hospitals, etc,.

4. Amount of soliD waste in india SOURCES QUANTITY [Mt/annum] Municipal wastes 25-39 Agricultural residues 350 Cattle manure 210 Poultry manure 3.3 Out of 30 Mt/annum of municipal wastes, 8.5 Mt/annum comes out from nine metropolitan cities only. About 60-80% of these wastes are collectes on daily basis and rest is left to deacy .

5. Management and disposal of solid wastes

6. Methods of solid waste disposal SOLID WATES SANITARY LANDFILL INCINERATION COMPOSTING RECYCLING

7. SANITARY LANDFILL A sanitary landfill is designed to reduce the amount of waste that leaks out in the environment. The landfill is lined with clay to prevent leaching, methane produced by rotting of garbage in the dump may need to be vented to prevent possible fire or explosion. The methane thus collected is used for electricity production. The water leaching must be treated before reaching ground water.

8. SANITARY LANDFILL

9. composting Composting is a common practice of solid waste disposal in rural areas for the production of manure and biogas. Composting is a process biological degradation or breakdown of organic matter under aerobic conditions. The organic compost resulting from this process makes a nutrient rich soil amendment that aids water retention, slow soil erosion and improves crop yeilds .

10. composting

11. Incineration The most quick & convenient method. It reduces the amount of wastes that goes to the landfill, They can also generate electricity from the heat generated by burning the garbage. They are designed to burn thousands of tonnes of wastes per day. However, it causes pollution adding fly ash, particulates and gases. Wastes do not completely burn even at high temp (1,300°C). The residues are taken to landfill or sea to dispose.

12. incineration

13. recycling Recycling of wastes helps in reducing pollution. The materials that can be recycled collecte from the wastes are paper, cloth, metals, glass, rubber & plastics. Other recyclable materials are cars, electronic goods such as computers, etc.

14. Hazardous wastes

15. Any discarded material containing substances known to be toxic, carcinogenic, mutagenic or teratogenic to humans or other life forms; ignitable, explosive, or highly reactive is called hazardous wastes. The wastes containing certain chemicals, metals and pathogenic organismsare also hazardous in nature. These can damage the environment as well as endanger life at low cocentrations .

16. Management of hazardous wastes

17. Waste reduction (minimization) Hazardous waste management costs heavily therefore waste reduction should be incorported . Toxic substances should be replaced by non-toxic substances. Transferring the waste to some other industry where they can be utilized in some other ways. Substituting the raw materials. Recycling and reprocessing.

18. Treatment of hazardous wastes 1) Thermal treatment 2) Chemical treatment 3) Physical treatment 4) Biological treatment

19. Thermal treatment Wastes must be heated to about 1200ºC for a sufficient period to complete destruction. The ash resulting is reduced in volume upto 90% and the rest is stored in a landfill. Plenty of oxygen is added for quick and complete burn. Gaseous hydrocarbons are not consumed in the incinerator. Scrubbers and precipitators remove minerals, particulate and other pollutants from the stack.

20. Chemical treatment Chemical treatment can transform toxic substances to non-toxic substances. Neutralization, removal of metals/halogens & oxidation are few chemical processes. Neutralization is followed in treating acidic or alkaline wastes. Acidic wastes is neutralized by slaked lime Ca(OH)2, caustic soda ( NaOH ) or soda ash (Na2CO3). Alkaline wastes are neutralized by mineral acid. eg . H2SO4 or HCl or with CO2.

21. Removal of metals is done by ion exchange, membrane technique, reverse osmosis, electrodialysis , activated carbon absorption & precipitation.

22. Physical treatment Physical treatments tie up or isolate substances. Charcoal or resins filters absorb toxins. Distillation separates hazardous components from aqueous solutions. Precipitation and immobilization in ceramics, glass, or cement isolate toxins from the environment.

23. Biological treatment Specific bacterial strains capable of degrading the wastes breaking down into CO2 & water are used. By using recombinant DNA technology new microorganisms could be developed to feed on specific hazardous wastes.

24. Disposal of hazardous wastes

25. Finally after treatment the hazardous wastes are disposed by the following methods. 1. Landfilling 2. Incineration 3. Deep well injection

26. Lanfilling Guidelines: The site must be located higher than 100 year flood plain. Impermeable lines be installed to collect the leachates . Any leachate that is collected should be pumped out and treated. Monitoring wells are required to check the quality of ground waters in the area.

27. Common wastes which can be disposed are: Sludge from cyanide bearing wastes, Sludge from phenol treatment, Heavy metal containing wastes, Ash from various treatment categories of wastes, Discarded containers.

28. incineration A high temperature thermal oxidation, which converts wastes into gases and combustible substances. This method is used to dispose combustible liquids and solid hazardous wastes and pesticides and petroleum refineries wastes. It destroys pathogens & decomposes organic compounds into CO2, H2O, etc., This process is adopted for wastes that cannot be recycled or reused.

29. Deep well injection Developed in late 1800’s. A specific kind of geological formation must be needed for disposal. The formation must be deep, providing space & sandwiched between impermeable layers of rock. This method is very expensive and risky, hence not followed in routine practice.

30. Deep well injection

31. Hospital (or) biomedical wastes

32. Biomedical wastes are wastes which are generated during diagnosis, treatment or immunization or in the research and testing biologicals . Hospital wastes are needles, syringes, surgical gloves, bottles, blood and body fluid, placenta and other body parts, radioactive substances, cytotoxic drugs , chemicals, etc.,

33. Transmitable infections AIDS, Hepatitis, Meningitis, Gastroenteric , respiratory, ocular, genital & skin infections Anthrax, etc.,

34. Management & disposal The wastes are disposed by burning it in incinerator at 1200ºC . Other methods by using autoclave, microwave, hydro wave, etc., Wastes burnt below 1200ºC release toxic pollutants like dioxins, furans which are carcinogenic & suppress immune and reproductive systems

35. Necessary awareness Launching mass awareness campaign through electronic and print media to inform clinics and dispensaries to undertake proper management of biomedical wastes. Training of staffs towards proper segregation of biomedical wastes is also necessary.

36. Thank you