This was originally published as a five
part series in the Nation newspaper in March 1997.
It examined the advantages and disadvantages of incineration for Barbados
and came against the background
of a raging debate on where to put the island's next landfill or whether
there should be some other method of disposal
From waste to what?
Byline: Terry Ally
WHAT'S COMES NEXT? More landfilling or incineration?
Some observers believe that incineration is inevitable in Barbados because
of the dwindling availability of land for landfills and the fact that the
two major political parties are committed to incineration.
Government officials said they had received about 40 proposals from local
and foreign private companies seeking to build a number of alternate waste
disposal systems, including incinerators, pyrolysis and thermolysis.
This article looks at some of the major issues that are likely to surface,
should the greenlight be given for the construction of a national
incinerator. Some of these issues include the cost to build and to operate
it, as well as the impact it can have on human health and the recycling
industry.
Abroad, environmentalists have been waging a strong battle against this
method of disposal, pointing particularly to the health impacts, such as
pollution by dioxin - an unwanted by-product of chlorine - formed in
incinerators and which causes cancer, affects the functioning of hormones,
and damages the immune system.
Types
Incinerators today include
generation of electricity. These are known as Waste-To-Energy (WTE) or
Energy-From-Waste (EFW) facilities. The incinerator is lit by regular fuel
and the fire kept going by the garbage which burns 24-hours daily, reducing
the need for imported fuel. A 250-tonne per day incinerator can generate
about 6.5 megawatts of electricity daily (about one-tenth of what the
Barbados Light and Power generated last year), and can save about $3 million
to $5 million in fuel annually.
It can cover capital and operating costs by selling electricity and by
charging a tipping fee, similar to what will be done at Greenland. The cost
to build the incinerator is far higher than a landfill and was therefore
disqualified by the consultants who were hired to come up with a least cost
solution to Barbados' solid waste management problems.
Proponents argue that incineration is cheaper in the long term.
An incinerator can last 20 to 40 years as compared to Mangrove Pond which is
being closed after five years and Greenland which is projected between ten
and 20 years.
There are two types of incinerators, one which burns everything up front and
takes out recyclables afterwards (metals would not be in good shape). The
other removes the recycables before incineration which reduces wear and tear
on the furnace, but more expensive because it requires more manual labour.
In both designs, the garbage is stored in a pit. A crane then picks it up
and dumps it into a furnace. As it is incinerated "bottom ash"
falls into a receptacle to be transported to the landfill. This ash is
usually non-toxic, if temperatures, at which chemicals are destroyed, are
maintained, though the World Health Organisation has reported instances of
traces of toxic chemicals in bottom ash.
Flue gases (air emissions) from the furnace passes through a scrubber where
it is sprayed with lime to remove sulphur dioxide and hydrogen chloride. The
flue gas is then channelled to a baghouse, where "fly ash" which
contains the pollutants is trapped, before being released through the smoke
stack into the atmosphere. The final emissions are virtually invisible but
small quantities of pollutants may still be released. This method
drastically improves the quality of the emissions with 99.9 per cent
efficiency.
Incineration reduces the volume of garbage by about 90 per cent. The ten per
cent of ash is usually buried in a landfill, though some countries are doing
revolutionary things with the ash, such as vitrifying it for creation of
artificial reefs or mixing it with clinker to make cement.
World turning to
burning
Incineration of regular garbage has been
routine for over a century in Europe, Japan and the United States.
In the 1950s, when energy costs skyrocketed, countries on both sides of the
Atlantic went in different directions. Europe and Japan used energy recovery
in their incinerators and incorporated them as part of their central heating
systems for cities and located them near population centres. Today, 50 per
cent of solid waste incinerated in Sweden produces eight per cent of the
country's heating needs. This is projected to rise to ten per cent using 70
per cent of their solid waste.
The US, on the other hand, started closing down incinerators in the 1950s
and 1960s mainly because of polluted flue gas emissions. The cost of
installing pollution control devices was too high, and at any rate, it was
not a priority because there was an abundance of land to use for landfilling.
In addition, they were not aware, at that time, of the negative impact of
landfills on the environment. Also, energy recovery was not a priority
because the cost of energy was low in the US. However, when the global oil
crisis of the 1970s struck, the US was back into the incineration market
with emphasis on energy recovery.
Today, Europe is moving away from landfills towards recycling and
incineration. Many members of the European Union are either prohibiting the
dumping of incinerable materials in a landfill; imposing levies on top of
tipping fees to encourage recycling, reuse and incineration; banning compost
material from landfills by the year 2000; permitting disposal of materials
with only three per cent or less carbon; or, passing laws to encourage the
construction of incinerators.
Recycling
The impact on the recycling
industry depends on whether recyclable material is taken out before or after
incineration.
In virtually all cases, glass and metals will be recovered and those
industries will remain untouched.
The plastics and paper products are another matter. On the world market, the
price of paper and plastics for recycling has plummeted. Paper, for example,
which in the early days used to fetch US$270 per tonne is now attracting no
more than US$40 per tonne which barely pays for local collection.
At least two local companies which deal in paper and plastics are feeling
the crunch and are in danger of closing operations. If they close, it will
mean that thousands of tonnes of paper and plastics will be headed for
Greenland, increasing the volume of garbage than what was envisioned and
shortening the lifespan of that facility. One of the companies is expected
to pull out of Barbados to a neighbouring Caribbean island where the
Government has offered generous concessions for a paper recycling operation.
'Dumps pollute
more than burning'
The problem with landfills is that they can
pollute the underground water by leaching toxic substances from certain
types of garbage, into the ground. The situation is worsened when rain falls
on the landfill and quickens the flow.
Engineers have since designed impermeable landfill liners and leachate
collection tanks to deal with this, but in 1994 the United States
Environmental Protection Agency revealed that landfills posed a bigger
threat to air quality than to ground water.
In England, the Royal Commission on Environmental Pollution 17th report,
Incineration of Waste , studying emissions of greenhouse gases, confirmed
that landfills were responsible for much more air emissions with adverse
global consequences than incineration. This has led to many European
governments favouring incineration over landfilling.
In addition, findings from a 1994 lawsuit in the United States showed that a
WTE facility was more environmentally friendly than a landfill. The study,
which compared a 1 500 ton-per-day (TPD) WTE facility with a 1 500 TPD
landfill, measured higher emissions of hydrocarbons, non-methane organic
compounds, hazardous air pollutants, nitrogen oxides and dioxin and furans
from the landfill than from the incinerator.
The only gas that the incinerator spew more than a landfill was carbon
monoxide - 1 290 tons over the WTEs 30 year lifespan compared to 3 094 tons
during the 130 year lifespan of the landfill. (The lifespan of the landfill
was 30 years with another 100 years given to biodegradation of garbage after
closure.)
The 1995 Stanley Environmental Impact Assessment for the Greenland landfill
did not identify the potential gases which Greenland or Mangrove Pond would
emit, but said that three major typical landfill gases were methane (47.5
per cent), carbon dioxide (47.5 per cent) and nitrogen (3.7 per cent). It
did not mention dioxin as a landfill gas. Other gases mentioned included
oxygen, aromatic and alkane hydrocarbons, hydrogen, carbon monoxide,
hydrogen sulphide, ammonia and various volatile organic compounds.
The three major gases are normally present in the atmosphere and not a
problem to human health, however a methane build-up can be explosive when
mixed with air. The report recommended methods for monitoring and minimising
production of landfill gases for Greenland.
Dioxin - cancer-causing
pollutant
The chemical dioxin was first discovered in an
old incinerator in the United States in 1978 and later at other incinerators
throughout the country.
Countless studies were launched to determine the health and environmental
impact of dioxin, and in the last 20 years it became one of the most studied
chemicals in the United States. It is one of the several pollutants produced
by an incinerator, and by far the most fearful because it is a
cancer-causing, hormone altering chemical.
There is a great debate about the quantities of dioxin that are produced,
whether there are "safe limits" and what these limits should be.
Dioxin is made up of a family of 210 compounds (75 dioxin and 135 furans)
which are accidental by-products of the chlorine industry. Compounds related
to dioxin, and believed to be as harmful, are chlorinated dibenzodioxins (CDD),
chlorinated dibenzofurans (CDF) and polychlorinated biphenyl (PCB). They are
collectively called dioxin (polychlorinated dibenzo-para-dioxin or PCDD).
Dioxin is created in many different processes, such as in incinerators which
burn regular household garbage or medical waste, as well as power companies
that burn fuel to produce electricity. A forest fire can produce large
quantities of the chemical, which is also formed during chlorine bleaching
of wood pulp that is used to make paper or it can be found in vehicle
exhaust emissions. In addition, the toxin can also be produced during the
process of treating sewage sludge with chlorine to kill bacteria. It can
also be produced by landfills.
Dioxin is formed through molecular re-arrangement. During combustion, when
the chlorine molecules in chlorinated materials, such as paper, wood and
plastics, split apart and interact with organic material, dioxin forms.
Greater amounts of dioxin will be formed if a heavy metal, such as copper or
zinc is present. If temperatures higher than 1500°F are achieved throughout
the furnace for at least half a second, organic compounds in the gases will
be destroyed, preventing the formation of dioxin.
In modern incinerators, even with a 99.9 per cent efficiency, trace amounts
of organics do escape, leading to the formation of dioxin. The chemical is
actually formed in the smoke stack, between 650°F to 300°F, when the flue
gases (emissions) are being cooled. Modern WTE incinerators use a cooling
device in the smoke stack and under ideal conditions, the temperature would
change instantly and no dioxin would be formed. However, dioxin is formed as
those ideal conditions are not always achieved.
Dioxin is hydrophobic, meaning that it will not dissolve in water, and
therefore has to piggyback on various materials to be transported. This is
why scientists call it a "stable" material, because it cannot
easily be washed away.
Modern incinerators much
safer
Since the discovery of dioxin in an
incinerator in 1978 in the United States, there was much hysteria about the
potential health impact of the chemical family, one member of which is a
Class 1 human carcinogen (cancer-causing) and a proven teratogen (causes
deformation in foetuses).
In animals, it disrupts hormones and affects the immune system and it is
believed that the same might occur in humans, but there is no evidence, yet.
There were two well-documented cases in which people ingested the chemical
along with a few other incidents involving accidental exposure, which
resulted in short-term health effects but no deaths (see box).
The World Health Organisation (WHO) in 1989, after examining several cases
of exposure, was unable to reach a decision on the impact on human health.
It said that the uncertainties were too great but recommended that
"exposure should be reduced to levels as low as are reasonably
practicable".
On February 14, 1997, the International Agency for Research on Cancer
announced that it was declaring the most potent form of dioxin
(2,3,7,8-tetrachlorodibenzo-para-dioxin or TCDD) to be a Class 1 human
carcinogen. All the examples, however, of the health impact to people in
Missouri, Nitro, Seveso, Yucho and Yu-cheng were extreme cases where they
were exposed to levels in far greater concentrations than what a modern
incinerator was likely to emit.
Levels
An incinerator today, equipped
with proper environmental controls, will emit mere specks of dioxin compared
to what these people were exposed - as much as one pound of TCDD.
"Safe" limits vary from country to country and even from agency to
agency in the United States, but in each case, they are all equivalent to
mere specks of dust. Sweden has the toughest regulations, limiting dioxin
emissions to 0.1 nanogram per cubic metre (one billionth of a gram). In the
US, the Environmental Protection Agency set a standard of 0.006 picogram
(trillionth of a gram) per kilogram of body weight while the Food and Drug
Administration's limit is 167 times higher. Canada accepts 10 picograms per
kilogram of body weight, which is 1 667 times greater than the USEPA limit.
There are two schools of thought on whether there is a "safe
limit" for exposure to a toxic chemical.
Environmental activists, such as Greenpeace, argue that as long as the
chemical is toxic, there is no safe limit. But regulatory health and
environmental agencies say that despite how toxic the chemical is, the
health impact depends on the quantities, the length of time and the
frequency that people are exposed to it. For example, the chemical atropine
is extremely poisonous, a mere 10 milligrams can kill a child but a smaller
dose is an antidote to treat people poisoned by certain pesticides or nerve
gas.
In Barbados one also has to place incineration in context of what already
happens in the environment. Is dioxin being spewed from the incinerators at
the Queen Elizabeth Hospital or the Bridgetown Port or from the Barbados
Light and Power smoke stacks at its Spring Garden generating plant? How much
dioxin billows into the sky and lodges in the surrounding plants, trees and
grass every time a wooden house goes up in smoke? How much dioxin has
covered Arch Hall, Bennetts and surrounding villages when the Mangrove Pond
landfill was on fire? Is there any dioxin continuously being produced by the
landfill? Does a cane fire produce dioxin? Do these things spew more dioxin
into the air than a modern incinerator will emit in its 30 or 40 year
lifespan?
Studies suggest that a modern incinerator, (which removes 99.9 per cent
dioxins and other pollutants), burning 416 000 tonnes of garbage per year
(four and a half times what Barbados is likely to burn) will produce about
0.431 grams of dioxin per year.
Though the research seems to favour incineration in developed countries, the
data must be carefully assembled and studied to determine the level of
dioxin that already exists in the local environment, how much higher an
incinerator will push it or whether it must first be reduced from all
sources before incineration.
If incineration is chosen, it will have to be a policy decision, just like
Greenland was, and then attention will have to be turned to ensuring that
the levels of dioxin and other pollutants are kept to negligible quantities.