Solid Waste Exam 1 Lecture 3 Flashcards
What is integrated solid waste management?
Hierarchical approach to waste management to manage increasing volumes of MSW
- source Reduction
- recycling / composting
- combustion / incineration
- landfill
What is source Reduction?
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
Examples of Source Reduction
- 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
Definition of recycling
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
Benefits of recycling?
- 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
Barriers to recycling ?
- 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)
Recycling collection methods
- drop off : voluntary, least amount of involvement
- buy back : take it there, get dollars for it
- curbside : pick up, they come to you
Three phases to recycling
- 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
Recyclable markets
- 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
What is composting?
Controlled biological decomposition of organic solid waste under aerobic conditions
- organic waste materials are transformed into soil amendments/ mulch
- decrease volume by 75%
Environmental conditions for composting
- control the environment, right mixture for odor free compost
- Biological
- Chemical
- Physical
Composting - Biological properties
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
Composting - Pathogen reduction
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
Composting - Chemical properties
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.
Composting - physical properties
- 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
3 steps in composting
- 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
Operational issues with composting?
Permitting Inspections Odors Leachates Pathogens
Properties of Waste Disposal?
- Resource Recovery
2. Incineration
Properties of a Transfer Station
- 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
Minimum standards of Transfer Stations
No Off site of litter
Load checking program
Dust and odor control
Permit compliance : daily tonnage maximum, record keeping requirements
What is a material recovery facility?
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)
Benefits of (MRF) Material Recovery Facility?
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
Concerns of a Material Recovery Facility (MRF?)
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
MRF Process
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
What is Combustion / incineration ?
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
Factors affecting incineration?
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)
Properties of waste to energy incineration
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
Advantages of WTE incineration (waste to energy)
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%
Disadvantages to incineration
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 )
Sanitary landfill considerations
- prevent groundwater and surface water contamination and air polllution
- prevent spread of disease : vector control (rats, fleas, birds, dogs)
Sanitary landfills advantages
- no open burning, little odor, low groundwater pollution, constructed quickly , low operating costs, large capacity, closed landfill can be reuse
Sanitary landfill disadvantages
- Noise and traffic, dust, air pollution, GHG releases, potential groundwater contamination, slow waste decomposition, discourages reuse recycling and Reduction.
State of a Landfill
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%
