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Presentation on theme: "EO 012.01 TP1a.-d. INSPECT HUMAN WASTE DISPOSAL SYSTEMS."— Presentation transcript:


2 REFERENCES Environmental Engineering 5 th Edition, pgs 755 - 872

3 SOLID WASTE MANAGEMENT INTRODUCTION a complex process involving many technologies –Generation and source reduction –On-site handling and disposal –Collection –Transfer and transportation – Processing –Disposal of solid wastes

4 SOLID WASTE MANAGEMENT Disciplines essential include: –Administrative –Financial –Legal –Architectural –Planning –Environmental –Engineering functions

5 IWM INTEGRATED WASTE MANAGEMENT (IWM) The selection and application of suitable techniques, technologies, and management programs to achieve specific waste management objectives and goals Subject to all provincial and federal laws

6 IWM SOURCE REDUCTION Focuses on reducing the volume and/or toxicity of generated waste –Reusable products and packaging –Mulching of grass clippings

7 IWM RECYLCING AND COMPOSTING Most positively perceived and achievable of all waste management practices Returns raw materials to market by separating reusable products from the rest of the municipal waste stream Saves resources, reduces environmental impact, reduces energy consumption, improves efficiency of incinerators

8 IWM COMBUSTION (WASTE-TO-ENERGY) Incineration attractive because it dramatically reduces the volume of waste Recovers useful energy in the form of steam or electricity Smaller physical footprint than full landfill Constraints include high cost $ and public perception of emission toxicity and safety


10 IWM LANDFILLS No combination of waste management techniques that do not require landfills to make them work Technology and operation can assure protection of human health and environment Requires proper design and monitoring once closed


12 IWM IMPLEMENTING IWM Typically involves the use of several technologies and all management options

13 SOURCES OF SOLID WASTE Sources of solid waste generally related to land use and zoning General categories of solid waste –Residential –Commercial –Institutional –Construction and demolition –Municipal services –Treatment plant sites –Industrial –Agricultural

14 CHARACTERISTICS OF SOLID WASTE COMPOSITION See Table 5-2, pg 767 Averages subject to several factors QUANTITIES See Table 5-3, pg 768 Estimates of quantity of solid wastes generated and collected (lbs/capita/day) SPECIFIC WEIGHT Volume occupied by solid waste and associated infrastructure

15 COMMERCIAL & HOUSEHOLD HAZARDOUS WASTE Contribute to contamination of ordinary municipal waste Exacerbate problems associated with waste disposal by landfill, incineration and composting 0.5% of total waste generated by households is estimated to be hazardous waste

16 CONSTRUCTION & DEMOLITION DEBRIS Consists of uncontaminated solid waste resulting from the construction, renovation, repair, and demolition of structures and roads; also includes vegetation from land clearing, grubbing, utility line maintenance and seasonal and storm-related clean- up Includes masonry materials, soil, wood, plaster, drywall, plumbing fixtures, roofing materials, non- hazardous electrical components, etc. Not included is asbestos waste, electrical fixtures containing hazardous liquids, garbage, furniture, appliances, drums, fuel tanks, etc. Not included is processed construction debris

17 SPECIAL WASTES MEDICAL WASTES Infectious waste, regulated medical waste ANIMAL WASTES May contain pathogens causing disease WASTE OIL Contain toxic metals and additives USED TIRES Fires release hazardous chemicals including oil; provide harbourage and breeding sites for vermin and pests



20 INTRODUCTION A sanitary landfill is a controlled method of solid waste disposal Sites chosen must be geologically, hydrologically and environmentally suitable must prevent groundwater pollution, provide gas (methane) venting or recovery, have a leachate collection and treatment system, provide gas and leachate monitoring wells, and be located above the 100-year flood level

21 PLANNING Key elements in the planning and implementation of a landfill –Meeting all legal requirements –Engaging in inter-municipal cooperation –Meeting long-term planning objectives –Social and political factors Educating the public Financial support from government

22 LANDFILL METHODS Trench Method Area or Ramp Method Valley or Ravine Method



25 LANDFILL DESIGN ISSUES LOCATION Proximity to waste will directly affect $cost ACCESSIBILITY Near major highways away from residential areas LAND AREA (VOLUME) REQUIRED Dependant on population served Should be sufficient for 20-40-year period

26 LEACHATE GENERATION LEACHATE – liquid resulting from precipitation percolating through landfills containing water, decomposed waste, and bacteria desirable to prevent the development of leachate; however, it cannot in practice be entirely avoided Precipitation minus runoff, transpiration and evaporation will determine the amount of infiltration which, along with percolation, will determine amount of leachate

27 LEACHATE CONTROL If all infiltration is excluded and solid wastes kept dry, biodegradation by microorganisms will cease and solid waste will be preserved in initial state <14-16% moisture content = cessation of bacterial activity Optimal amount of moisture necessary for biodegradation, methane production, final stabilization and possible recycling of solid waste or reuse of the site

28 LEACHATE CONTROL Landfill liners are designed to minimize or eliminate the infiltration of leachate into subsurface soils below the landfill in order to eliminate the potential for groundwater contamination

29 LEACHATE RECIRCULATION Waste biodegradation and stabilization of organic matter can be accelerated by leachate recirculation Controlled recirculation, including nutrient addition to maintain optimum moisture and pH, can enhance anaerobic microbial activity, break down organics and convert them to methane and carbon dioxide Complete biological stabilization in 4-5 years

30 LEACHATE TREATMENT Treatment required may be physicochemical - addition of chemicals such as lime followed by settling, or biological - addition of activated sludge determined by the composition of the fill material, leachate volume and characteristics, and water pollution control standards


32 LANDFILL GASES Gases found in landfills include: –Methane –Carbon dioxide –Nitrogen –Oxygen –Hydrogen sulphide –Ammonia –Hydrogen –Carbon monoxide

33 CONTROL OF LANDFILL GASES Methane (CH4) explosive in air at concentrations of 5 – 15% Because low levels of O2 present in landfills when CH4 concentrations reach this critical level, little danger landfill will explode Explosive CH4 mixtures can form if gas migrates off site and mixes with air Controlled by cutoff walls, barriers, or ventilation system such as gravel-filled trenches around perimeter of landfill

34 CH4 RECOVERY AND UTILIZATION CH4 production quite variable depending on the amount of decomposable material, moisture content, temperature and rate of decomposition CH4 extracted using plastic tube wells with perforations, well screens connected to a vacuum pump, or a series of horizontal gravel trenches connected to a pipe collection system


36 SURFACE WATER MANAGEMENT Runoff from drainage areas to the landfill site must ensure that surface water drainage systems such as ditches, dikes, berms, and culverts are properly designed and flows diverted from the site to prevent flooding, erosion, infiltration, and surface/ground water pollution Examine topography and soil cover for obstructions – floods, erode cover material

37 COVER MATERIAL Final cover of a completed landfill should be soil that is easily worked yet minimizes infiltration Four feet of cover recommended if area to be landscaped, less if grass to be planted Vegetation will prevent wind and water erosion and contribute to transpiration and evaporation

38 LANDFILL MINING Excavation and recycling of landfill waste may be feasible where there has been adequate moisture to permit decomposition and stabilization of the waste Factors such as landfill design, type of cover material, waste composition and age of the landfill must also be evaluated and regulatory approval granted




42 involves the conversion of solid wastes into gaseous, liquid, and solid conversion products with concurrent or subsequent release of energy implemented to reduce the volume of solid waste and, to the extent possible, recover energy Not recommended for small scale Landfill required for disposal of residue

43 MUNICIPAL SOLID WASTE INCINERATOR 1.Solid waste is unloaded from trucks 2.Waste storage pit 3.Overhead crane batch load wastes 4.Charging chute 5.Furnace 6.Grates 7.Combustion chamber 8. Boiler 9.Turbine generator 10. NO controls 11. Dry Scrubber 12. Bag House 13. Induced draft fan 14. Stack 15. Residue hopper 16. Ash to landfill

44 COMBUSTION PRODUCTS / RESIDUES COMBUSTION ESSENTIALS: Time, temperature and turbulence (including sufficient O2) GASEOUS COMBUSTION PRODUCTS: CO2, H2O, O2, N2, SO2 COMBUSTION RESIDUES: Bottom ash, fly ash, and non-combusted organic and inorganic materials

45 TYPES OF INCINERATORS Mass-fired Combustor Minimal processing prior to combustion Refuse-derived Fuel-fired Combustors Produced from organic fraction of MSW Modular Combustion Units For capacities of <700 lb/hr or 250 tons/day On-site Commercial / Industrial Incinerators Hospitals, schools, industry

46 CAPACITY AND STACK HEIGHTS Incinerators are rated in terms of tons of burnable waste per day Incinerator with capacity of 600 tons/day can theoretically handles that much solid waste in a 24-hour period or burn 400 tons in 16 hours Stacks or chimneys 150 – 200 ft above ground are constructed to provide natural draft and air supply for combustion

47 CAPACITY AND STACK HEIGHTS Heights of 300 – 600 ft are not uncommon. Discharging gases at these heights also facilitates dilution and gas dispersal Considerations in stack height include prevailing meteorological conditions, topography, adjacent land use, and air pollution standards


49 OPERATION A properly designed and operated incinerator requires control instrumentation for: –Temperature –Draft pressures –Smoke emission –Weights of solid wastes entering/leaving the plant –Air pollution control equipment

50 RESIDUE MANAGEMENT Incinerator ash and fly ash leaving the furnace may contain various concentrations of hazardous materials Dioxin, cadmium and lead in ash are the contaminants of major concern ash can be solidified by cementing, vitrification, or asphalting Recycling preferred option Ash must be disposed of in a properly constructed landfill

51 PUBLIC HEALTH ISSUES Emissions from modern, properly designed and operated incinerators are considered to be of minimal health significance. However, they are perceived to be a serious health hazard. Evidence is inconclusive as incinerator emissions are widely dispersed and their effects difficult to evaluate. Pollution controls to prevent accidental emissions must be ensured Health effects from exposure to contaminants such as dioxin, cadmium and lead are well documented Further study required




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