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Disposing Of Plastic

In this post you can read about the many ways we dispose of plastic.
Most plastics are made from oil and most plastics do not biodegrade. See how and why here…
which  makes it difficult to dispose of.

There are no natural processes in place that can absorb non biodegradable  plastic back into the biological cycle. It cannot be composted or left to rot where it is dropped or dumped like organic rubbish. Read more about the plastic lifespan here.

Most plastic lasts  for decades, maybe centuries, possibly for ever.

WHICH MEANS that every bit of plastic created has to be collected up and specially treated. All of these processes are time-consuming and so expensive.

Main methods are
Landfill
Recycling and Reusing
Incineration & Waste to Energy –
Gasification
Pyrolysis
Thermal depolymerization

Landfill

Just A big hole that we fill with rubbish. The theory was that waste would slowly biodegrade. Plastics do not biodegrade so once in a landfill it will sit there forever. That said turns out that a lot of rubbish in landfill sites do not biodegrade. William Rathje, of the University of Arizona, excavates landfill sites and  has found  newspapers printed in the 1950s that could still be read. Consequently the landfill is rapidly filling up.

Recycling and Reusing 

Let’s be clear about this recycling is just a more responsible form of waste management. That stuff in your recycle bin is still rubbish and has to be dealt with the attendant environmental and financial costs. While recycling may offset these costs it is still expensive. Moreover recycling does not address the main issue of misusing plastic and stupidly using it to make one use throwaway items.

With that in mind lets look at plastic recycling.

Incineration & Waste to Energy –

Incinerating plastic which means burning it.  At best this adds to global warming and at worst releases dioxins on of the most carcinogens known.  Sometimes using the heat created is used to generate electricity which offsets the cost of waste disposal.
N.B. only offsets!

Other Plastic To Energy Processes

Technofix – updates on the latest ways to sort it out

 

Plastic Waste & The Poor

As noted all the above are expensive. They require special treatment facilities, a decent infrastructure of roads and a reliable rubbish collection service. Theses facilities are often not available to poorer communities, certainly not those based in the more remote parts of the world.  They have two methods of plastic waste disposal

Burning plastic – On open fires could be safe or it could kill you – depends on the plastic  Find out more here

Dumping  –  on the outskirts of town, a major cause of plastic pollution and potential death for  animals who forage there.
Read about plastic and animals here

And more about the other problems with plastic here….

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Incineration

Incineration is to dispose of waste materials by burning them. The end results are heat, ash and gases.
High-temperature waste treatment systems are described as “thermal treatment”.
Incinerating reduces the need for landfill but does not eliminate it. It reduces the soid mass of waste by 80–85% . The reamaining ashes still have to be disposed of.

The Process of Incineration

A dump truck drops the municipal waste into a warehouse-sized pit. Then a giant claw (much like one that picks up loot in an arcade game) grabs nearly a truckload of garbage and dumps it into an incinerator.

The incinerator is initially fired up with gas or other combustible material.

The process is then sustained by the waste itself. Complete waste combustion requires a temperature of 850º C for at least two seconds but most plants raise it to higher temperatures to reduce organic substances containing chlorine. Flue gases are then sent to scrubbers which remove all dangerous chemicals from them. To reduce dioxin in the chimneys where they are normally formed, cooling systems are introduced in the chimneys. Chimneys are required to be at least 9 meters above existing structures.

Technology developed in Europe mixes the waste at temperatures of up to 2,000 degrees Fahrenheit. The heat then makes steam, which runs a turbine and produces electricity.

sources

http://www.brighthubengineering.com/structural-engineering/89810-pros-and-cons-of-incineration-for-landfill-relief/

https://www.scientificamerican.com/article/does-burning-garbage-to-produce-energy-make-sense/

The Advantages Of Incineration & Waste To Energy

Pathogens and toxins can be destroyed by high temperatures making incineration a very good choice for certain kinds of waste.

Unlike  landfill  there is no release of methane. Every ton of MSW incinerated, prevents about one ton of carbon dioxide equivalents from being released to the atmosphere.

The leachates that are produced in landfills by waste are totally eliminated.

By reducing waste it reduces the pressure on landfill space.

Emmisions (Copied from Slate)

As for carbon dioxide—the big class of emissions that isn’t yet regulated—WTE actually performs quite well compared with other methods of electricity generation. On its face, WTE appears to be very carbon-intensive. The EPA reports that incinerating garbage releases 2,988 pounds of CO2 per megawatt hour of electricity produced. That compares unfavorably with coal (2,249 pounds/megawatt hour) and natural gas (1,135 pounds/megawatt hour). But most of the stuff burned in WTE processes—such as paper, food, wood, and other stuff created of biomass—would have released the CO2 embedded in it over time, aspart of the Earth’s natural carbon cycle.” As a result, the EPA notes, only about one-third of the CO2 emissions associated with waste-to-energy can be ascribed to fossil fuels, i.e., burning the coal or natural gas necessary to incinerate the garbage. In other words, WTE really only produces 986 pounds of carbon dioxide per megawatt hour. “So we’re roughly equivalent to natural gas, and half of coal,” Michaels says. “But coal and natural gas don’t manage solid waste.”

However not all good news….

The ashes are toxic and so need further treatment. As such they were cause for concern  however “Ash from modern incinerators is vitrified at temperatures of 1,000 °C (1,830 °F) to 1,100 °C (2,010 °F), reducing the leachability and toxicity of residue. As a result, special landfills are generally no longer required for incinerator ash from municipal waste streams”

The gases too need to be “cleaned” of pollutants before they are dispersed into the atmosphere. proponents of the technology claim that the flue scrubbers are up to the job while many others feel there is cause for concern.

Waste To Energy Systems

The heat created when incinerating the waste is used to make electricity which seems like a good idea.

It is important to remember that waste to energy systems do not make money or even cover the cost of waste incineration but they do offset it.

The plants  are very expensive to build and once built need a lot of fuel (waste) to run them. They need to be kept running. This means that alternatives forms of waste disposal like recycling are no longer promoted.

Here are some figures from 2009 for  Spokane County

WASTE TO ENERGY FACILITY

Mandatory service area: Spokane County / 430,000 ratepayers
Type of contract: Full service/Operate Wheelabrator / Waste Management
Ownership: City of Spokane 
Financing ($110 million): Revenue Bonds – Mandatory debt to entire County
Department of Ecology Grant ($60 million)
Start-up: 1991
Expenses and Revenues for 2009:
   Cost of Operation   $17.2 million  ($62 per ton)
   Cost of Ash Disposal   $4.1 million ($47 per ton)
   Cost of Debt  $9 million
TOTAL COSTS   $30.3 million
   Electricity Revenue   $11.4 million
Materials Recovery  
$0.1 million
NET COST OF OPERATIONS  
$18.8million ($68 per ton)

Refuse Combustion:

Operation: 24-hours per day, 7 days per week
Process Lines: 2 @ 400 tons-per-day
Plant maximum daily capacity: 800 tons
Average thru-put: 720 tons per day (365 days per year)
Feed system: 2 overhead refuse cranes with ram feeder
Grate design: Von Roll reciprocating
Combustion temperature: 2500° F
Auxiliary fuel: Natural gas
Waste weight reduction: 65%
Annual Greenhouse Gas Production 600,000,000 Pounds CO2
CO2 per MWH 4480 pounds of total CO2 per Megawatt Hour:
1580 pounds of fossil CO2 / MWh plus,
2900 pounds of bio CO2 / MWh
BTU values:
Garbage = 4,800/pound
Coal = 12,000/pound
Plastic = 14,000/pound
Tires = 16,000/pound

The Friends Of The Earth worries about the waste of resources.  The Following was taken from the website

Resource efficiency: Incineration wastes valuable resources such as metals, plastics, wood or biodegradable materials that could otherwise be salvaged through recycling. Every tonne of incinerated materials has to be extracted and processed again, increasing environmental damage and the European economy’s dependence on expensive imports. More energy is saved through recycling than is extracted by burning most waste

Climate change: Incineration produces greenhouse gas emissions – a typical incinerator converting waste to electricity produces around 33 percent more fossil fuel-derived carbon dioxide than a gas-fired power station. In contrast, recycling saves greenhouse gas emissions by avoiding the need to extract and process primary resources.

Jobs: Recycling creates jobs. Recycling 10,000 tonnes of waste creates up to 250 jobs, compared to 20 to 40 jobs if the waste is incinerated, and about 10 if it is landfilled.

Laura Haight, senior environmental associate at New York Public Interest Research Group (NYPIRG), says that if the petition passes, waste will take incentives away from more sustainable technologies like wind and solar. She also says that presenting the issue as though incineration offsets landfill emissions is the wrong approach.

“In framing this whole debate as incineration versus landfills, they’re pushing the needle back 20 years,” said Haight. “Twenty years ago, people used to say we need to do more recycling; now we’re talking about more burying or burning. No, we need to be doing more recycling.”

Haight points out that more energy is saved by reusing materials instead of destroying them. Also, rather than being burned, biomass could be composted and used for energy recovery, she said.

More information on waste to energy can be found here

Plastic to Energy

Burning Plastic On Open Fires 

NB Burning plastic on open fires can release carcinogens and toxins…

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Dioxins & Burning plastic

So, is it safe to burn plastic? Well most plastics don’t  burn easily – it melts and bubbles.  It will burn eventually but you have to keep heating it. And, when you do set fire to plastic it gives off a terrible smell.

But is it bad for you? It could be lethal.

The smell according to the naked scientist could be anything. They say

“There are lots of different plastics, and they will give off lots of different vapours when they decompose.

It could be just a simple hydrocarbon, or it could contain cyanides, or PCB’s, or lots of other substances.  Without knowing what the plastic was …..it would be difficult to know what are the likely volatiles it would create…. volatiles given off from plastics in house fires are a major cause of death.”

So, to conclude, it depends on the plastic then. PLA plastic is it is claimed non toxic and safe to burn. Some oil based plastics like polythene are an efficient fuel and burns in the same way oil does. Not pleasant exactly but not exactly dangerous either. PCBs? – thats a dioxin and dioxins are nasty!

It’s a big NO if its a halogenated plastics, i.e one of those  made from chlorine or fluorine

Halogenated plastics include:
Chlorine based plastics:
Chlorinated polyethylene (CPE)
Chlorinated polyvinyl chloride (CPVC)
Chlorosulfonated polyethylene (CSPE)
Polychloroprene (CR or chloroprene rubber, marketed under the brand name of Neoprene)
PVC
Fluorine based plastics:
Fluorinated ethylene propylene (FEP)

Burning these plastics can release dioxins. Dioxins are unintentionally, but unavoidably produced during the manufacture of materials containing chlorine, including PVC and other chlorinated plastic feedstocks.
Dioxin is a known human carcinogen and the most potent synthetic carcinogen ever tested in laboratory animals. A characterization by the National Institute of Standards and Technology of cancer causing potential evaluated dioxin as over 10,000 times more potent than the next highest chemical (diethanol amine), half a million times more than arsenic and a million or more times greater than all others.

The World Health Organisation said “Once dioxins have entered the environment or body, they are there to stay due to their uncanny ability to dissolve in fats and to their rock-solid chemical stability.”

That is because dioxins are classed as one of the persistant organic pollutants, POPs, also known as  as PBTs (Persistent, Bioaccumulative and Toxic) or TOMPs (Toxic Organic Micro Pollutants.)
POPs are a small set of toxic chemicals that remain intact in the environment for long periods and accumulate in the fatty tissues of animals. They are extremely toxic and cause all manner of illnesses. You can find out more about POPS here

The Uk Government states on their website “Burning plastic, rubber or painted materials creates poisonous fumes and can have damaging health effects for people who have asthmatic or heart conditions. This is covered under the Environmental Protection Act 1990

And in America Burn barrels have this to say… “Burning trash in a 55 gallon drum or in just a pile, often in the backyard, is a common method of solid waste disposal in some rural areas. Surveys have revealed between 25 and 50 percent of rural residences and farms may do backyard burning. Backyard burning is by definition “uncontrolled” burning and results in very high levels of toxic chemicals emitted in the smoke. Compared to municipal incinerators it takes place at much lower temperatures, with virtually no combustion air control, and with none of the very expensive high-tech pollution filtering apparatus required before the incinerator stack. Very high levels of toxic chemicals and particulates are present in the smoke from open burning of waste. These may cause acute respiratory and other health problems in those breathing the smoke. Burning plastics can be especially problematic, with PVC plastic in particular contributing to high emissions of dioxin.

SO, IN CONCLUSION, don’t burn plastic on open fires unless you know exactly what it is made up of..Identifying plastic is not always possible so while there are some plastics that are supposed to be safe to burn, I won’t be burning any on my bonfire.

And If you have been sniffing burning plastic fumes and are now feeling worried,  find out what kind of plastic it was and then track down the Material Safety Data Sheet. This will tell you everything you need to know.

Is it safe to burn plastic in my local waste disposal plant incinerator?

It is claimed that all plastics can be burnt safely  in the modern industrial incinerators – but only those built to high specifications. Opinions vary wildly as to wether this is the case with environmentalists saying we are poisoning the very air that we breathe.

Many of these plants generate electricity from the heat produced so in effect the plastic is recycled.

The resulting ash from incineration plants has to be disposed of and so presnets yet another waste disposal challenge.

You can read more about incinerating plastics and waste to energy plants here