EO 012.01 TP1a.-d.

INSPECT HUMAN WASTE DISPOSAL SYSTEMS

REFERENCES

• Environmental Engineering 5th Edition, pgs 755 - 872

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

SOLID WASTE MANAGEMENT

• Disciplines essential include:– Administrative– Financial– Legal– Architectural– Planning– Environmental– Engineering functions

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

IWM

SOURCE REDUCTION• Focuses on reducing

the volume and/or toxicity of generated waste– Reusable products and

packaging– Mulching of grass

clippings

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

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

INCINERATION

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

LANDFILL

IWM

IMPLEMENTING IWM• Typically involves the use of several

technologies and all management options

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

CHARACTERISTICS OF SOLID WASTE

COMPOSITION• See Table 5-2, pg 767• Averages subject to several factorsQUANTITIES• 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

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

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

SPECIAL WASTES

MEDICAL WASTES• Infectious waste, regulated medical wasteANIMAL WASTES• May contain pathogens causing diseaseWASTE OIL• Contain toxic metals and additivesUSED TIRES• Fires release hazardous chemicals including oil;

provide harbourage and breeding sites for vermin and pests

QUESTIONS

EO 012.01 TPj.(1)-j.(6)

SANITARY LANDFILL PLANNING, DESIGN & OPERATION

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

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

LANDFILL METHODS

• Trench Method

• Area or Ramp Method

• Valley or Ravine Method

LANDFILL METHODS

LANDFILL METHODS

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

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

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

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

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

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

LEACHATE GENERATION

LANDFILL GASES

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

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

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

LANDFILL GAS COLLECTION

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

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

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

LANDFILL DESIGN

QUESTIONS

EO 012.01 TP1k.

INCINERATION

INCINERATION

• 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

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

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

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

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

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

INCINERATOR STACKS

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

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

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

PUBLIC HEALTH ISSUES

QUESTIONS