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ENST 510 exam 1 > Solid Waste Exam 1 Lecture 3 > Flashcards

Solid Waste Exam 1 Lecture 3 Flashcards

1
Q

What is integrated solid waste management?

A

Hierarchical approach to waste management to manage increasing volumes of MSW

  • source Reduction
  • recycling / composting
  • combustion / incineration
  • landfill
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2
Q

What is source Reduction?

A

Altering products or materials to reduce amount of toxicity of what gets thrown away

  • requires manufactures and consumers to take active role in reducing amount of waste produced
  • increases the useful life of manufactured products
  • pollution prevention and not producing waste in the beginning
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3
Q

Examples of Source Reduction

A
  • Decrease packaging
  • decrease toxicity by use of alternative materials (heavy metals : Cd, Pb, Hg)
  • design products to last longer
  • reduce paper waste via e-communication
  • purchase selectively
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4
Q

Definition of recycling

A

A resource recovery method
- involves the collection and treatment of waste product for use as raw material in the manufacture of the same or another product

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5
Q

Benefits of recycling?

A
  • Conserve natural resources
  • Decrease toxicity
  • Less dependence on landfill
  • Use less energy (90-95%)
  • Community / consumer pride
  • Job development : 5 times more jobs than taking straight to landfill
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6
Q

Barriers to recycling ?

A
  • convince factor
  • price : plastics, cheaper to buy chemicals and make it new
  • labor intensive (who is going to sort it out)
  • consumer attitude (quality of recycled goods product)
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7
Q

Recycling collection methods

A
  • drop off : voluntary, least amount of involvement
  • buy back : take it there, get dollars for it
  • curbside : pick up, they come to you
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8
Q

Three phases to recycling

A
  • collecting secondary materials
  • preparing materials for market : crushing cans, break glass, plastics shredded, paper baled, etc. very labor intensive / expensive
  • Remanufacturing new products with recycled materials : selling , post consumer products
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9
Q

Recyclable markets

A
  • Paper / cardboard ( 30% of MSW) : grade of paper and color, price fluctuates
  • Glass (5% of MSW) : process driven, heavy , breaks, different colors, require separation
  • Aluminum (9% of MSW)
  • Plastics (12% of MSW) : difficult to crush, degrades and breaks down easily, cheaper to make new plastic, 1% gets recycled
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10
Q

What is composting?

A

Controlled biological decomposition of organic solid waste under aerobic conditions

  • organic waste materials are transformed into soil amendments/ mulch
  • decrease volume by 75%
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11
Q

Environmental conditions for composting

A
  • control the environment, right mixture for odor free compost
  • Biological
  • Chemical
  • Physical
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12
Q

Composting - Biological properties

A

Bacteria , fungi, insects : produce CO2 , heat, water
- Pathogen Reduction : Density of fecal coliform LESS than 1,000 MPN (most probable number) . Density of Salmonella LESS than 3 MPN

  • MPN is a technique used to estimate microbial populations in soil water and agriculture products
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13
Q

Composting - Pathogen reduction

A

Enclosed or within- vessel composting : temp of 131F or higher for pathogen reduction period of THREE days.

Windrow composting : aerobic conditions, 131F or higher for a parthenogenesis Reduction period of FIFTEEN days or longer, minimum of FIVE turnings

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14
Q

Composting - Chemical properties

A

N, P, K are nutrients that must be managed
-Heavy metal content must not exceed the maximum acceptable concentrations

  • Gardeners use a lot of nutrients on a square foot basis for fertilizers, composts, and organic materials. So they must be managed.
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15
Q

Composting - physical properties

A
  • Water
  • Oxygen level
  • pH 6-8 (neutral )
  • particle size
  • temp of 130F for optimal temp. Too high = fire possibility, too low = support bacterial growth
  • Eliminate toxics and pesticide
  • Pile size : conserve energy, mixing
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16
Q

3 steps in composting

A
  • Process waste : shred it, uniform size
  • Compost using a technology : Windrow (long piles) , Static pile (uses pipes to control air supply, no turning necessary, control temp) , In vessel : container ,throw everything into it , drums, silos, tunnels
  • Post processing : cured, screened, sold
17
Q

Operational issues with composting?

A 
Permitting
Inspections
Odors
Leachates
Pathogens
18
Q

Properties of Waste Disposal?

A
  1. Resource Recovery

2. Incineration

19
Q

Properties of a Transfer Station

A
  • Receive , handle, separate, convert, process materials
  • Transfer solid waste directly from one container to another or from one vehicle to another for transport
  • Store solid waste
  • Contain a material recovery facility where recyclables are sorted out and recovered
20
Q

Minimum standards of Transfer Stations

A

No Off site of litter
Load checking program
Dust and odor control
Permit compliance : daily tonnage maximum, record keeping requirements

21
Q

What is a material recovery facility?

A

Mechanical and manual separation of recyclables from MSW and Source Separated Recyclables
( were developed and implemented in order to help meet AB 939 landfill diversion goals)

22
Q

Benefits of (MRF) Material Recovery Facility?

A

Reduces overall community truck traffic by consolidating
Reduces air pollution , fuel consumption, and road wear
Allows for screening of waste for special handling
Reduces traffic at the disposal facility

23
Q

Concerns of a Material Recovery Facility (MRF?)

A

Vector control : rodents and birds

Air emissions: unloading dry dust waste, driving over unpaved surfaces, loaders and other equipment
Litter
Traffic
Noise : heavy truck traffic and operation of heavy duty facility equipment
Odor

24
Q

MRF Process

A

Collection : mixed refuse collection (no separation) , recyclables collection ( co-mingled or separated)

Tipping : unloading of the materials from the collection vehicles , move the deposited material onto conveyors to the separation systems

Processing : sorting , baling

25
Q

What is Combustion / incineration ?

A

Controlled burning process to decrease the volume of SW

Decrease volume by 60-90%

Recover energy from the waste burning process to produce steam and electricity

26
Q

Factors affecting incineration?

A

Public opposition : does not understand risks, decrease property values, doesn’t want o accept more environmental risk

Cost of setting up system : $500 million , size of facility, land cost, systems to install, engineering control devices, labor personnel training - (medical , PPE )

Meeting regulatory standards : hazardous constituents, extra processing /handling , hazardous air pollutants must be controlled (emission components : NOX, SOX, PM . Plastics (dioxins, furans, toxic materials )

Ash Disposal and reuse : stabilizer (road base), landfill monofill (only accept incinerator ash)

27
Q

Properties of waste to energy incineration

A

Generate steam or electricity
Heat value : 4500 btu/lb (US) :
- 8000 btu / lb : coal
- 1000 to 1100 btu/cubic feet : natural gas
- 500 btu / cubic feet :landfill methane gas

28
Q

Advantages of WTE incineration (waste to energy)

A

Generates electricity and heat to run the facility as well as sell electricity to power companies

Toxins safely captured

Sterile ash

Volume of combusted material is reduced by 90% and weight by 70%

29
Q

Disadvantages to incineration

A

Air pollution = toxic metals released into atmosphere

May produced hazardous waste / ash which need to buried in hazardous landfill. Ash needs to be tested for heavy metals before disposal

Cost = major. Large initial investment and more expensive than landfill (twice as expensive to dispose via incineration )

30
Q

Sanitary landfill considerations

A
  • prevent groundwater and surface water contamination and air polllution
  • prevent spread of disease : vector control (rats, fleas, birds, dogs)
31
Q

Sanitary landfills advantages

A
  • no open burning, little odor, low groundwater pollution, constructed quickly , low operating costs, large capacity, closed landfill can be reuse
32
Q

Sanitary landfill disadvantages

A
  • Noise and traffic, dust, air pollution, GHG releases, potential groundwater contamination, slow waste decomposition, discourages reuse recycling and Reduction.
33
Q

State of a Landfill

A

Aerobic state : 4 to 60 days

Anaerobic state : after 60 days . Produces methane, CO2 and hydrogen sulfide gases as anaerobic decomposition products.

In a well run landfill : methane / carbon dioxide ratio is between 65% and 35% . Hydrogen sulfide is <1%

ENST 510 exam 1 (4 decks)

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