waste management a brief history of waste disposal: the early years: “dilute and disperse”...
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Waste ManagementA Brief History of Waste Disposal:
The Early Years: “Dilute and Disperse”
-Waste production was taken care of by dumping,either into unused land areas (“swamps”) or intorivers.
Many cities have areas that once were “dumps”,and are now covered by parks or buildings.
Most trash or waste was either buried loose, orin barrels.
Big Problem: Early trash dumps were used foreverything, and unregulated. Many toxins weredumped with no thought as to the repercussions.
In Delaware, several sites that were formerly sand and gravel pits were used as dumps.
EX: Army Creek Landfill, Tybouts Corner Landfill,Delaware Sand and Gravel Landfill
Most of these dumps were “open pit” dumps, withno effort made to cover up the trash and waste.
In some instances, the waste was periodicallyburned, to provide more space. Sanitary Landfills
Later designs were not open pit, because the waste was covered with a layer of soil. Landfillstoday use this method of covering the trash.
The layer of soil prevents access to the waste bybirds, insects and rodents.
Sanitary Landfills have distinct alternating layersof compacted trash and soil.
Soil Layer
Layer of Compacted Trash
Problems Associated with Landfills
1) Landfill space is very limited
Ex: Philadelphia is out of landfill space (it used to be near the airport), and now has to ship itstrash elsewhere (very costly!)
In Delaware: The Cherry Island Landfill is nearcapacity, and studies are underway to determineif the hill of trash can be made even higher.
Understandably, people living near the landfillare quite upset about the prospects of more trash.
2) Creating newer, safer landfills is an uphill battle.
NIMBY Syndrome
The sites chosen for landfills often are located near poor, politically disconnected populations.
3) Leachate from the Landfill
Probably the biggest environmental problem withlandfills, leachate is the movement of water through the waste, into the groundwater or a nearby body of water.
The nature of the leachate depends on the nature of the waste,the quantity of water, and the time it takes to percolate through the pile.
4) Atmospheric Pollution
Since the waste is cut off from the air, it degradesanaerobically.
Rather than decomposing into CO2, the trash decomposes into CH4, methane gas.
Anaerobic degredation takes longer, and producesdifferent products.
The Composition of Our Solid Waste
Solid waste varies in composition dependingon its source.
Paper is the largest component of the wastestream, at about 38%.
The single largest item is newspaper, which accounts for over 18% of solid waste.
The CompositionOf the Solid Waste Stream
Waste Management, or “What Do We DO With All This Stuff”?
Integrated Waste Management (IWM)“a set of management alternatives that includereuse, source reduction, recycling, composting, landfills, and incineration”
1)Reduce, Reuse, Recycle: the ultimate goal of waste management is to reduce the amount of waste that must be dealt with in the first place.
But HOW?-Reduction in packaging wastes
-Reusable packages, deposits on containers
Studies have indicated that waste could be reduced by as much as 70%.
-Packages made of easily recycled materials
-Increased markets for recycled materials
-Increased public support for recycling
2) Composting
Composting is a biochemical process that breaks down organic materials into rich soil-like material.
It involves microscopic aerobic organisms, so the compost must be aerated to keep them alive.
Piles of compost may be turned over periodically,allowing air to penetrate the pile.
Large “digesters” continually turn the compost, making a very efficient system.
Problems with Composting:
Compost having left over pesticides may kill plantsthat it is applied to. (herbicides)
Compost can only be made when the organic material is collected separately from other trash.(plastics/metals, etc..)
Composting does have a good future, because itcan be done on a small scale, in yards andgardens.
3) Sanitary Landfill (improved designs):
Sanitary landfills are not going to be eliminated from any integrated system. There is always goingto be a need for them.
Improved designs will better handle leaching, andprevent contamination of air and groundwater.
Landfills by design, not by accident, built to takespecific types of waste.
Built in monitoring systems, wells, liners, and leachate collection pipes.
An Idealized Sanitary Landfill
4)Incineration: also known as “trash to steam”, has an advantage that the energy in the trash can be converted to heat energy.
Also reduces the volume of trash up to 95%.
Problems with Incineration
-Creates air pollution, including SO2, NOx andall kinds of heavy metals (mercury, lead, etc…)-can be lowered with specialized equipment ($$)
-The ash produced is very toxic, and needs to be handled as toxic waste.
Human Waste DisposalSince the dawn of human evolution, solid human waste has posed a problem as to its disposal.
For thousands of years in China and India, waste was used on crops as fertilizer.
Wherever large populations of people lived, the waste became a big problem.
By the early 20th century, land application was taking place in many places, including the U.S.
“Sewage Sludge”
Major Problems with Human Waste Disposal-Contamination with infectious agents, and theirspread to waterways and treated crops
Ex: Chi-Chi’s green onion problem (e-coli bacteria)
-Pollution with heavy metals, industrial solvents, and pesticides.Industrial contributors could pre-treat their sewage,thereby eliminating many pollutants. ($$$)If the price of oil continues to climb, making man-made fertilizers more expensive,the use of human waste as fertilizer may gain favor again.
Ocean Dumping Types of things that get dumped into theoceans of the world:Dredge spoils: solid materials, generally silt,sandand pollutants dug up as navigation channels are deepened.
Industrial wastes:acids, pesticide wastes, allmatter of solvents, heavy metals
Sewage SludgeConstruction Debris
Radioactive waste, explosives, garbage
Ocean Dumping Laws (U.S.)1972: Ocean Dumping Act:Prohibited the dumping of chemical weapons, high level radioactive waste, biological warfare agents.
1988: Expanded to include sewage sludge, industrial waste, and medical waste.
1992: Provisions for a coastal water qualitymonitoring program were added
Permitted dumpingArticle 4 states that Contracting Parties "shall prohibit the dumping of any wastes or other matter with the exception of those listed in Annex 1."1. Dredged material
2. Sewage sludge
3. Fish waste, or material resulting from industrial fish processing operations
Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972
4. Vessels and platforms or other man-made structures at sea
5. Inert, inorganic geological material
6. Organic material of natural origin
7. Bulky items primarily comprising iron, steel, concrete and similar unharmful materials for which the concern is physical impact and limited to those circumstances, where such wastes are generated at locations, such as small islands with isolated communities, having no practicable access to disposal options other than dumping.
Hazardous Waste and its Disposal
In the U.S., over 35,000 chemicals are classified as hazardous to the health of people or to ecosystems (Table 28.1 in textbook)
The U.S. produces an average of 700 MILLION metric tons of hazardous waste annually.
Most is generated by the chemical industry, followed closely by the electronics industry, and oil/petroleum industries.
Another great source of hazardous waste is US!
Almost every household has used pesticides, oil,solvents, paints, batteries, etc.
When these get thrown into the “regular” trash,they end up in a landfill not designed for hazmat,or, even worse, incinerated in a plant not madefor burning hazmat.
In the U.S., there are an estimated 2000 sitespolluted with hazmat, and the number keeps going up as new sites are found.
Love Canal
In 1976, toxic chemicals began oozing out of thesoil covering what once had been a toxic dumpingground.
Chemicals had been dumped by a company that produced pesticides, such as DDT, as well as lotsof chlorinated solvents.
The company sold the land to the city of Niagara,NY for $1 (it was pressured by the city to do so)
Studies in the late 70’s suggested high rates of
cancer and birth defects among the residents of Love Canal, although results were debated.
Homes and a school were eventually built over the buried waste.
Efforts were made to clean and neutralize the siteand the homes were eventually sold again to newowners.
By 1990, $275 million had been spent on cleanup and relocation costs.
Hazmat Disposal
There are several methods of dealing with hazmat disposal (Table 28.2 in textbook)
1)Secure Landfill: similar to a sanitary landfill, butwith more durable liners, closer inspection of wells, etc.
Secure landfills also usually have a leachatepond, which collects the liquid as it runs through the pile. The leachate is then sent to a treatmentfacility designed for hazmat.
Hazardous Waste Landfill
2) Surface Impoundments: natural or man-madeholes, in which liquid waste is held
May include a plastic liner but not all do. Some rely on clay, rock or “impermeable soil”.
Big Problems with Impoundments
1)They are open to the air, so evaporation takesplace, especially of solvents, etc..
2) They can be flooded with heavy rain, and overflow into a nearby waterway or groundwater
3) Deep Well Injection: drilled to a depth that is below any underground aquifers, and the liquidwaste is injected under high pressure into the Earth.
The well has to be sited so that it penetrates a permeable rock layer far underground, but is under an impermeable layer
Well
Impermeable Rock
Porous Rock
Problems with Deep Well Disposal
There have been instances where deep wellinjection has been implicated in causing earthquakes deep underground.
The high pressure liquid lubricates rocklayers, allowing them to slide. (Rocky Mtn. Arsenal, 1980’s)
There is no guarantee that the waste will not find its way into a water system at sometime. (no way to monitor the waste)
4) Incineration
Destruction by high temperatures
Is considered a treatment, rather than disposal, because the leftover ash must stillbe disposed of in a landfill
Is the chosen method for treatment of chemical weapon stocks (Johnston atoll)
Also conducted on ships that are purpose built for incineration (very controversial)
Incinerators for hazmat are designed to reduce waste as much as is possible.
Hazardous Waste Legislation
Ultimately, it would be far better to reducethe amount of waste, rather than disposeof or treat it.
Resource Conservation and Recovery Act (RCRA): Identification of hazardous productsand regulations regarding their disposal.
“Cradle to Grave” regulation
Promotes recycling, re-use of chemicals