Chapter 29: Waste Management

Early Concepts of Waste Disposal

• Start of Industrial Revolution, the volume of waste produced in the US was relatively small.– Managed through the concept of “dilute and disperse.”

• Factories located near water. – Easy transport of materials by boat– Sufficient water for processing and cooling – Easy disposal of waste into the river

• Few factories and a sparse population– Method was sufficient to remove the waste from the

immediate environment.

Early Concepts of Waste Disposal

• As industrial and urban areas expanded, the concept became “concentrate and contain”– Containment not always achieved.

– Containers leak or break and allow waste to escape.

• People are facing a serious solid-waste disposal problem. – We are producing a great deal of waste and the

acceptable space for permanent disposal is limited.

– Difficult to site new landfills (NIMBY).

Modern Trends

• Environmentally correct concept is to consider wastes as resources out of place.– Waste would be a resource to be used again.

– Referred to as the “zero waste” movement.

• Industrial ecology– Study of relationships among industrial systems and

their links to natural systems.

– Waste from one part of the system would be a resource for another part.

Modern Trends

• Countries have moved to cut waste by imposing taxes.– Taxation of waste in all its various forms, from

emissions from smokestacks to solids delivered to landfills.

– As taxes increase people produce less waste.

• Landfills produce methane gas which can be burned as fuel.

Integrated Waste Management

• A set of management alternatives that includes:– Reuse– Source reduction– Recycling– Composting– Landfill– Incineration

Reduce, Reuse, Recycle

• Ultimate objective of the three R’s is to reduce.• Study of the waste stream in areas that utilize

IWM technology suggests that the amount of refuse disposed of in landfills or incinerated can be reduced by at least 50%

• Reduction facilitated by– Better design of packaging to reduce waste, an element

of source reduction (10% reduction).– Large-scale composting programs (10% reduction).– Establishment of recycling programs (30% reduction).

Reduce, Reuse, Recycle

• Recycling is a major player in the reduction of urban waste stream.– Estimated that as much as 80-90% of the US

waste stream might be recovered through intense recycling.

– Partial recycling can provide a significant reduction ~50%.

– Simplified by single stream recycling.

Public Support for Recycling

• Encouraging signs– An increase in the willingness of industry and

business to support recycling on a variety of scales.

– People are now more likely to purchase products that can be recycled or that come in containers that are more easily recycled or composted.

Markets for Recycled Products

• In communities where recycling has been successfully implemented, it has resulted in glutted markets for the recycled products.

• If recycling is to be successful,– markets and processing facilities will also have

to be developed to ensure that recycling is a sound financial venture.

Recycling of Human Waste

• The use of human waste or “night soil” on croplands is an ancient practice. – Early uses of human waste for agriculture occasionally

spread infectious diseases.

– One of the major problems of recycling human waste today is that thousands of chemicals and metals flow through our waste stream.

– Because many toxic materials are likely to be present with the waste, we must be very skeptical of utilizing sewage sludge for land application.

Materials Management

• Futuristic waste management has the goal of zero production of waste.– Consistent with the ideals of industrial ecology.– Goal will require more sustainable use of

materials combined with resource conservation in what is being termed materials management.


• The goal could be pursued in the following ways:– Eliminate subsidies for extraction of virgin

materials.– Establish “green building” incentives that

encourage the use of recycled-content materials and products in new construction.

– Assess financial penalties for production that uses negative materials management practices.


– Provide financial incentives for industrial practices and products that benefit the environment by enhancing sustainability.

– Increase the number of new jobs in the technology of reuse and recycling of resources.

Solid-Waste Management

• Continues to be a problem in many parts of the world.– Many practices inadequate.

• Open dumps, illegal roadside dumping

– Social problem as much as a physical one, because many people are simply disposing of their waste as inexpensively and as quickly as possible.

Composition of Solid Waste

• Paper is by far the most abundant content.

• Excavations into modern landfills using archeological tools have cleared up some misconceptions concerning other items. – Fast-food packaging accounts for about 0.25%

of the average landfill– Disposable diapers, approximately 0.8%– Polystyrene products, about 0.9%

On-Site Disposal

• A common on-site disposal method in urban areas is the mechanical grinding of kitchen food waste. – Garbage-disposal devices are installed at the

kitchen sink, and the garbage is ground and flushed into the sewer system.

Composting

• Biochemical process in which organic materials decompose to a rich, soil-like material. – The process involves rapid partial decomposition of

moist solid organic waste by aerobic organisms.

• As a waste management option, large-scale composting is generally carried out in the controlled environment of mechanical digesters.

Incineration

• Combustible waste is burned at temperatures high enough (900°–1,000°C, or 1,650°–1,830°F) to consume all combustible material.– Leaving only ash and non-combustibles to dispose of in

a landfill.

• Process of incineration can be used to supplement other fuels and generate electrical power.

• In modern incineration facilities, smokestacks are fitted with special devices to trap pollutants.

Open Dumps

• In the past, solid waste was often disposed of in open dumps, where the refuse was piled up without being covered or otherwise protected.– Located wherever land is available, without regard to

safety, health hazards, or aesthetic degradation.

• Common sites – Abandoned mines and quarries, natural low areas, such

as swamps or floodplains; and hillside areas above or below towns.

Sanitary Landfills

• Designed to concentrate and contain refuse w/o creating a nuisance or hazard to public health or safety. – Confined to the smallest practical area– Reduced to the smallest practical volume – Covered with a layer of compacted soil at the

end of each day of operation.

Leachate

• The most significant hazard from a sanitary landfill is pollution of groundwater or surface water. – If waste comes into contact with water, leachate

is produced.• noxious, mineralized liquid capable of transporting

bacterial pollutants

Site Selection

• A number of factors must be taken into consideration when selecting a site, including:– Topography

– Location of the groundwater table

– Amount of precipitation

– Type of soil and rock

– Location of the disposal zone in the surface water and groundwater flow system.

• Best sites are arid sites

Site Selection

• The waste is buried above the water table in relatively impermeable clay and silt soils.– Leachate produced remains in the vicinity of the site

and degrades by natural filtering action.

• Site selection also involves important social considerations. – Chosen where they expect local resistance to be

minimal or where they perceive land to have little value.

– Frequently located in areas of low socioeconomic status

Monitoring Pollution in Sanitary Landfills

• Once a site is chosen for a sanitary landfill and before filling starts, monitoring the movement of groundwater should begin. – Accomplished by periodically taking samples

of water and gas from specially designed monitoring wells.

– Monitoring the movement of leachate and gases should continue as long as there is any possibility of pollution.

How Pollutants Can Enter the Environment from Sanitary Landfills

1. Methane, ammonia, hydrogen sulfide, and nitrogen gases can be produced from compounds in the soil and the waste and can enter the atmosphere.

2. Heavy metals, such as lead, chromium, and iron, can be retained in the soil.

3. Soluble materials, such as chloride, nitrate, and sulfate, can readily pass through the waste and soil to the groundwater system.

4. Overland runoff can pick up leachate and transport it into streams and rivers.



5. Plants growing in the disposal area can selectively take up heavy metals and other toxic materials. Passed up the food chain as

people and animals eat the plants.

6. If plant residue return toxic substances to the soil.


7. Streams and rivers may become contaminated by waste from groundwater seeping into the channel (3) or by surface runoff (4).

8. Toxic materials can be transported to other areas by the wind.


• Modern sanitary landfills are engineered to include multiple barriers: – Clay and plastic liners to limit the movement of

leachate– Surface and subsurface drainage to collect

leachate– Systems to collect methane gas – Groundwater monitoring to detect leaks of

leachate below and adjacent to the landfill.

Federal Legislation for Sanitary Landfills

• Resource Conservation and Recovery Act of 1980. – Legislation intended to strengthen and standardize

design, operation, and monitoring of sanitary landfills.

• Landfills that cannot comply with regulations face closure.

• States may choose between two options:– 1. Comply with federal standards.

– 2. Seek EPA approval of solid-waste management plans, which allows greater flexibility.


• Provisions of federal standards include the following:– Landfills may not be sited on floodplains, wetlands,

earthquake zones, unstable land, or near airports.– Landfills must have liners.– Landfills must have a leachate collection system.– Landfill operators must monitor groundwater for many

specified toxic chemicals.– Landfill operators must meet financial assurance

criteria to ensure that monitoring continues for 30 years after the landfill is closed.


• EPA approval of its landfill program:– Groundwater monitoring may be suspended.– Alternative types of daily cover over the waste.– Alternative groundwater protection standards

and schedules for documentation are allowed.– Under certain circumstances, landfills in

wetlands and fault zones are allowed.– Alternative financial assurance mechanisms are

allowed.

Reducing the Waste You Produce

Hazardous Waste

• In the US, approximately 1,000 new chemicals are marketed each year, and about 70,000 chemicals are currently on the market. – 35,000 chemicals used are classified as definitely or

potentially hazardous to the health of people or ecosystems.

• The US currently produces about 700 million metric tons of hazardous chemical waste per year, referred to more commonly as hazardous waste.

Hazardous Waste

• Uncontrolled dumping of chemical waste has polluted soil and groundwater in several ways:– Chemical waste may be stored in barrels.The barrels

eventually corrode and leak.

– When liquid chemical waste is dumped into an unlined lagoon, contaminated water may percolate through soil and rock to the groundwater table.

– Liquid chemical waste may be illegally dumped in deserted fields or even along roads.

Resource Conservation and Recovery act

• Passed in 1976– Identification of hazardous wastes and their life cycles.– “Cradle to grave” management

• The act classifies hazardous wastes in several categories: – Materials highly toxic to people and other living things; – Wastes that may ignite when exposed to air;– Extremely corrosive wastes– Reactive unstable wastes that are explosive or generate

toxic gases or fumes when mixed with water.

Comprehensive Environmental Response, Compensation, and Liability Act

• Passed in 1980– Act defined policies and procedures for release of

hazardous substances into the environment.

– Mandated development of a list of the sites where hazardous substances were likely to or already had produced the most serious environmental problems

– Established a revolving fund (Superfund) to clean up the worst abandoned hazardous-waste sites.

Comprehensive Environmental Response, Compensation, and Liability Act

• Strengthened by amendments that made the following changes:– Improved and tightened standards for disposal and

cleanup of hazardous waste.

– Banned land disposal of certain hazardous chemicals.

– Initiated a timetable for phasing out disposal of all untreated liquid hazardous waste in landfills or surface impoundments.

– Increased the size of the Superfund.

Hazardous-Waste Management Land Disposal

• Management of hazardous chemical waste involves several options, including:– Recycling– On-site processing to recover by-products with

commercial value– Microbial breakdown– Chemical stabilization– High-temperature decomposition– Incineration– Disposal by secure landfill or deep-well injection

Secure Landfill

• A secure landfill for hazardous waste is designed to:– Confine the waste to a particular location– Control the leachate that drains from the waste– Collect and treat the leachate– Detect possible leaks

• This type of landfill is similar to the modern sanitary landfill.

Land Application: Microbial Breakdown

• Intention application of waste materials to surface soil.– May be a desirable method of treatment for

certain biodegradable industrial wastes.– A good indicator of the usefulness of land

application for a particular waste is the biopersistence of the waste.

• How long the material remains in the biosphere.• Greater the biopersistence, the less suitable for land

application

Land Application: Microbial Breakdown

• Land application of biodegradable waste works because, – when materials are added to the soil, they are

attacked by microflora that decompose the waste material in a process known as microbial breakdown.

Surface Impoundment

• Both natural topographic depressions and human-made excavations formed primarily of soil or other surface materials but lined with manufactured materials such as plastic. – Examples include aeration pits and lagoons at

hazardous-waste facilities.– Prone to seepage, resulting in pollution of soil and

groundwater.– Evaporation from surface impoundments can also

produce an air pollution problem.

Deep Well Disposal

• A deep well penetrates to a depth below and completely isolated from all freshwater aquifers.– Waste is injected into a permeable rock layer

several thousand meters below the surface in geologic basins.

– Capped by relatively impervious, fracture-resistant rock such as shale or salt deposits.

Deep Well Disposal

• Important control of water pollution in oil fields.– Injection of oil field brine.

• Should not be viewed as a quick and easy solution to industrial waste problems.

Alternatives to Land Disposal of Hazardous Wastes

• Advantages to source reduction, recycling, treatment, and incineration include the following:– Useful chemicals can be reclaimed and reused.– Treatment of wastes may make them less toxic and

therefore less likely to cause problems in landfills.– The actual waste that must eventually be disposed of is

reduced to a much smaller volume.– Because a reduced volume of waste is finally disposed

of, there is less stress on the dwindling capacity of waste-disposal sites.


• Source Reduction– The object is to reduce the amount of hazardous

waste generated by manufacturing or other processes.

• Recycling and resource Recovery– May contain materials that can be recovered for

future use.


• Treatment– Waste can be treated by a variety of processes to

change the physical or chemical composition of the waste and so to reduce its toxic or hazardous characteristics.

• Incineration– Destroyed by high-temperature incineration. – Incineration is considered a waste treatment rather than

a disposal method because the process produces an ash residue, which must then be disposed of in a landfill.

Ocean Dumping

• Oceans have long been dumping grounds for many types of waste, including industrial waste, construction debris, urban sewage, and plastics

• Many locations in the world’s oceans are– Accumulating pollution continuously

– Have intermittent pollution problems

– Or have potential for pollution from ships in the major shipping lanes

Ocean Dumping

• Marine pollution has a variety of specific effects on oceanic life, including the following:– Death or retarded growth, vitality, and reproductivity of

marine organisms.– Reduction in the dissolved oxygen content necessary

for marine life because of increased BOD.– Eutrophication caused by nutrient-rich waste in shallow

waters of estuaries, bays, and parts of the continental shelf.

– Habitat change caused by waste-disposal practices that subtly or drastically change entire marine ecosystems.

Ocean Dumping

• Microlayer– The upper 3 mm of ocean water.– Planktonic life abundant (base of the marine food

chain)– Home to young fish and shellfish in the early stages of

their life.

• Microlayer also tends to concentrate pollutants, such as toxic chemicals and heavy metals.

• Fear that disproportionate pollution will have especially serious effects on marine organisms.

Ocean Dumping

• Marine pollution can have major impacts on people and society.– Contaminated marine organisms may transmit

toxic elements or diseases to people who eat them.

– When beaches and harbors become polluted there may be damage to marine life as well as a loss of visual appeal and other amenities.

– Economic loss is considerable.• Tourism and fishing industry

Pollution Prevention

• Involves identifying ways to prevent the generation of waste rather than finding ways to dispose of it.

• Approaches include:– Purchasing the proper amount of raw materials

so that no excess remains to be disposed of.– Exercising better control of materials used in

manufacturing processes so that less waste is produced.

Pollution Prevention

– Substituting nontoxic chemicals for hazardous or toxic materials currently in use.

– Improving engineering and design of manufacturing processes so that less waste is produced.

Chapter 29: Waste Management

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