Environment and Waste disposal 15.9.23.pptx

Waste disposal

1. Solid waste, human excreta & sewage disposal Dr. Neelam Kumar Professor & Unit Head Department of Community Medicine Pt. B.D Sharma, PGIMS, Rohtak

2. SOLID WASTE

3. The definition………… Produced by the United Nations Statistics Division (U.N.S.D.): " Wastes are materials that are not prime products (that is products produced for the market) for which the generator has no further use in terms of his/her own purposes of production, transformation or consumption, and of which he/she wants to dispose. Wastes may be generated during the extraction of raw materials, the processing of raw materials into intermediate and final products, the consumption of final products, and other human activities. Residuals recycled or reused at the place of generation are excluded."

4. Kinds of Wastes Solid wastes : wastes in solid forms, domestic, commercial and industrial wastes Examples: plastics, styrofoam containers, bottles, cans, papers, scrap iron, and other trash Liquid Wastes : wastes in liquid form Examples: domestic washings, chemicals, oils, waste water from ponds, manufacturing industries and other sources

5. Classification of Wastes according to their Properties Bio-degradable can be degraded (paper, wood, fruits and others) Non-biodegradable cannot be degraded (plastics, bottles, old machines, cans, Styrofoam containers and others)

6. Classification of Wastes according to their Effects on Human Health and the Environment Hazardous wastes Substances unsafe to use commercially, industrially, agriculturally, or economically and have any of the following properties- ignitability, corrosivity, reactivity & toxicity. Non-hazardous Substances safe to use commercially, industrially, agriculturally, or economically and do not have any of those properties mentioned above. These substances usually create disposal problems.

7. Classification of wastes according to their origin and type Municipal Solid wastes: Solid wastes that include household garbage, rubbish, construction & demolition debris, sanitation residues, packaging materials, trade refuges etc. are managed by any municipality. Bio-medical wastes: Solid or liquid wastes including containers, intermediate or end products generated during diagnosis, treatment & research activities of medical sciences. Industrial wastes: Liquid and solid wastes that are generated by manufacturing & processing units of various industries like chemical, petroleum, coal, metal gas, sanitary & paper etc. Agricultural wastes: Wastes generated from farming activities. These substances are mostly biodegradable.

8. Classification of wastes according to their origin and type Fishery wastes: Wastes generated due to fishery activities. These are extensively found in coastal & estuarine areas. Radioactive wastes: Waste containing radioactive materials. Usually these are byproducts of nuclear processes. Sometimes industries that are not directly involved in nuclear activities, may also produce some radioactive wastes, e.g. radio-isotopes, chemical sludge etc. E-wastes: Electronic wastes generated from any modern establishments. They may be described as discarded electrical or electronic devices. Some electronic scrap components, such as CRTs, may contain contaminants such as Pb , Cd , Be or brominated flame retardants.

9. Global Solid Waste Generation Around the world : waste generation rates are rising. In 2012, the worlds’ cities generated 1.3 billion tonnes  of solid waste per year, amounting to a footprint of 1.2 kilograms per person per day. With rapid population growth and urbanization, municipal waste generation is expected to rise to 2.2 billion tonnes by 2025. Reference: www. worldbank.org

10. SOLID WASTE MANAGEMENT RULES

11. 5 R of Solid Waste Management

12. EXCRETA DISPOSAL

13. Public Health Importance Human excreta is a source of infection Important cause of environment pollution Responsibility of society to dispose it safely Failure to dispose safely leads to severe threat to public health

14. Health hazards Improper excreta disposal causes Soil pollution Water pollution Contamination of foods Propagation of flies Burden to community in terms of sickness, mortality & low expectation of life Deterrent to social & economic progress

15. Diseases-improper disposal Bacterial: typhoid, dysenteries Viral: hepatitis, diarrhoeas Helminths: hook worm, ascariasis

16. Extent of problem-India 74% of population is rural and majority of them go to fields for defecation Situation in urban area is equally worse The solution to the problem is only through hygienic disposal of human excreta which is a corner stone of all public health services

17. HOW THE DISEASE IS CARRIED FROM EXCRETA FAECES FINGERS FLUID/WATER FLIES FIELD/SOIL FOOD NEW HOST

18. Transmission of diseases to the human host is prevented by segregation of faeces, protection of food, personal hygiene, control of flies. Transmission of faecal born diseases

19. FAECES FINGERS W A T E R FLIES SOIL FOOD PROTECTED HOST S A N I T A T I O N B A R R I E R Sanitation barrier – transmission of faecal-borne diseases

20. SANITATION BARRIER Segregation of excreta by imposing a barrier is called Sanitation barrier. This is the most effective step so that the disease agent can not reach the new host directly or indirectly

21. METHODS OF EXCREATA DISPOSAL

22. Unsewered areas Service type (conservative) Non service type (sanitary latrine) Bore hole latrine Dug well or pit latrine Water-seal type of latrines PRAI RCA SULABH Septic tank Aqua privy Latrine suitable for camps & temporary use Shallow trench/deep trench/pit/bore hole latrines

23. Sewered areas

24. Water carriage system & sewage treatment Primary treatment Screening/removal of grit/plain sedimentation Secondary treatment Trickling filters/activated sludge process Other methods Sea outfall River outfall Sewage farming Oxidation pond

25. SERVICE TYPE Night soil is collected from pail or bucket type of latrines by human agency, and later disposed by burying or composting.

26. DRAWBACKS Water pollution Soil pollution Access to flies Corrosion of buckets and pans Recruitment of staff is difficult, should be replaced by sanitary latrine

27. Sanitary latrine Excreta should not contaminate the ground or surface water Excreta should not pollute the soil Excreta should not be accessible to flies, rodents, animals & other vehicles of transmission Excreta should not create a nuisance due to odour or unsightly appearance

28. WATER SEAL LATRINES It has water seal which prevent access to flies and escape of odour. There are two types P.R.A.I evolved by planning research and action institute lucknow. R.C.A. type by research cum action projects in environmental sanitation of ministry of health.

29. FE A TUR E S LOCATION: It should be away from source of water supply to prevent contamination. SQUATTING PLATE or SLAB: It is made up of an impervious material to keep it clean and dry. So that it will not facilitate the growth of hook warm larva. Dimensions 90cms square, 5cms thickness, slop ½ inch for drainage of water with footrests

30. SEPTIC TANK It is a water tight masonry tank used for individual dwelling, small groups of houses and institutions. DESIGN: Single chambered or double chambered. CAPACITY: 20 to 30 gallons per person for household with a minimum of 500 gallons.

31. SEWAGE

32. Introduction Sewage is a waste water from a community, containing solid and liquid excreta, derived from houses, streets, factories and industries. ‘Dry weather flow’ : average amount of sewage which flows through the sewerage system in 24 hours

33. Composition of Sewage Sewage contains 99.9 percent water and 0.1 percent solids (partly organic and partly inorganic). Th e strengt h o f th e sewage ma y b e expresse d in terms of: Biochemical oxygen demand, Chemical oxygen demand and Suspended solids.

34. Biochemical Oxygen Demand (BOD) The amount of oxygen absorbed by a sample of sewage during a specified period (generally 5 days) at a specified temperature (usually 20°C) for aerobic digestion. The most important test carried out on sewage. Sewage with a BOD value of: 300 mg/l (300 ppm) or above is termed as strong 100 mg/l (100 ppm) or below is termed as weak.

35. Chemical Oxygen Demand (COD) The amount of oxygen required to oxidize the organic matter by use of dichromate in an acid solution and to convert it to carbon dioxide and water. The value of COD is always higher than the BOD many organic substances can be oxidized chemically but not biologically. COD is used to test the strength of wastewater that is either non biodegradable or contains compounds that inhibit activities of microorganisms. Commonly, BOD is used to test the strength of untreated and treated municipal and biodegradable industrial waste waters.

36. Sewage Purification The aim of sewage treatment is: to convert an offensive and potentially dangerous mixture into an inoffensive effluent and sludge which can be disposed off safely and without causing nuisance into river, sea or on land. The conversion of complex organic matter in the sewage to simpler substances takes place by two processes: aerobic and anaerobic.

37. The aerobic process: requires a continuous supply of free dissolved oxygen for the aerobic microorganisms to break the organic matter into simpler substances such as carbon dioxide, ammonia, water, nitrite, nitrate, sulphate etc. The anaerobic process more effective where the sewage is highly concentrated and contains plenty of solids. Hence, this metho d is usuall y gainfully utilize d for digestion of sludge in sewage works. The end product s o f anaerobic decompositio n are methane, ammonia, carbon dioxide, hydrogen etc.

38. Modern Sewage Treatment Th e sewage treatmen t undergoe s throug h many stages. Primary, secondary and tertiary treatment stages. Primary treatment : The first stage is the physical treatment to remove solids (from the liquid). Secondary treatment : The primary treatment is followed by biological treatment brought about by aerobic and anaerobic bacteria.

39. Tertiary treatment : – Treatment rendered in addition to the conventional secondary treatment for improving further the quality of effluent is termed ‘tertiary treatment’ or advanced waste treatment process. Chemical treatment by the addition of coagulants may be used to assist sedimentation and sludge treatment.

40. Flow diagram of a Modern Sewage Treatment Plant

41. Activated Sludge Process

42. Sludge Treatment The sludge from primary or final sedimentation tanks contains 90 to 95 percent water. This high water content needs to be reduced for converting the sludge to a solid condition in which it may be used or disposed off harmlessly. Anaerobic digestion is the most preferred sludge treatment method.

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