=======================Electronic Edition========================
RACHEL’S HAZARDOUS WASTE NEWS #92
—August 29, 1988—
News and resources for environmental justice.
——
Environmental Research Foundation
P.O. Box 5036, Annapolis, MD 21403
Fax (410) 263-8944; Internet: erf@igc.apc.org
==========
The Back issues and Index are available
here.
The official RACHEL archive is here.
It’s updated constantly.
To subscribe, send E-mail to rachel-weekly-
request@world.std.com
with the single word SUBSCRIBE in the message. It’s free.
===Previous issue==========================================Next issue===
NEW STUDY SHOWS INCINERATOR ASH MORE DANGEROUS THAN WE REALIZED.
A new study by a team of engineers at Rutgers, the state
university of New Jersey, shows that municipal incinerator ash is
more dangerous than previously realized.
When household garbage burns, the resulting ash has two parts:
fly ash, most of which is captured from the smoke stack by an air
pollution control system, and the heavier “bottom ash” which
falls through the grate of the combustion chamber into an ash
pit; both types of ash must be carted away. Both types of ash
contain toxic heavy metals (chromium, cadmium, lead, arsenic,
zinc, and other metals) as well as organic compounds (PCBs,
dioxins, benzene, and other cancer-causing organics). Here we
will discuss only the metals.
When the ash is thrown away, the metals in the ash become
available to the environment. Currently, such ash is typically
heaped on the ground somewhere, or is dumped in a municipal
landfill. Then rainwater seeps into the ash and begins to
dissolve the metals and carry them into the general environment.
Chemical engineers at Rutgers have released a new study showing
that toxic metals in municipal incinerator ash are more abundant
and more soluble, and therefore more dangerous, than previously
thought.
The Rutgers team took samples of household solid waste from three
locales (Pennsauken, NJ, Magnolia, NJ, and Somerset County, NJ)
and burned them in a small (50 ton per day) solid waste
incinerator. They captured the fly ash and the bottom ash. The
solid waste samples did not include substantial quantities of
industrial trash but were restricted to household wastes.
The actual composition of the ash is shown in Table 1. There
were, of course, other elements and compounds in the ash, but the
Rutgers team did not measure these because they are not regulated
under federal law. As is obvious from these numbers (which are
all given as parts per million, or ppm) there are large
quantities of metals in the ash.
Table 2 shows how many pounds of metal are found in each ton of
ash, using the “average” values given at the bottom of Table 1.
(We, not the Rutgers group, did the averaging in Table 1.)
The numbers are quite astonishing. Take lead, for example. If a
2000 ton-per day incinerator produces 500 tons of ash per day,
and if 10% is fly ash and 90% is bottom ash, the total daily ash
will contain 2935 pounds of lead. That’s a ton and a half of
lead per day. The same arithmetic tells us that one day’s ash
will contain 48 pounds of chromium, 61 pounds of cadmium, and 97
pounds of arsenic. In a year’s time (operating 5 days a week, 52
weeks a year), such an incinerator will put out 12,610 pounds of
chromium, 15,990 pounds of cadmium, 25,246 pounds of arsenic, and
three quarters of a million pounds of lead (763,256, actually).
These are all metals that are toxic in microgram quantities
(there are 454 million micrograms in one pound).
ALL of this metal will most likely leach into the environment
sooner or later. But the law does not view it that way. The law
requires that the ash be tested for toxicity using something
called the “extraction procedure” toxicity test (EP Tox Test for
short). The EP tox test asks, “If we mix the ash with a dilute
solution of acetic acid and then test the dilute solution, how
much metal do we find has dissolved into the solution?” If we
find more than 100 times as much metal as is allowed in drinking
water, then the ash is declared a “hazardous waste.” If the
metals are not present at levels 100 times the drinking water
standard, the ash is declared “nonhazardous” no matter how many
tons of dangerous metals it may contain. (This system clearly
does not protect the public, but it’s what the EPA [U.S.
Environmental Protection Agency] has set, so it’s what we’ve got.)
Many scientists have criticized the EP Tox Test for a variety of
reasons. So the EPA has proposed a new test, which will soon
replace the EP Tox test. The new one is called the TCLP
extraction test (short for Toxicity Characteristic Leaching
Procedure). The details of the TCLP are different from the EP
Tox test, but the basic idea is the same.
The Rutgers team tested the ash from the three locales with the
EP Tox Test, and the Pennsauken sample was given the TCLP test.
All the fly ash samples were deemed “hazardous” for both lead and
cadmium by the EP Tox test. The TCLP results showed that THE
TCLP LEACHED EVEN MORE METALS THAN THE EP TOX TEST. Lessons from
the work at Rutgers: (1) The amount of metal in solid waste ash
varies from place to place with socio-economic status, geographic
location, season, collection patterns, and recycling practices.
Your local waste stream should be sampled every 2 weeks for a
year to see what it really contains; some consulting firm’s
“estimate” of what’s in your local waste is most likely off; (2)
the quantity of toxic metals in your waste may be very high and
the toxicity will endure forever; ask how long the landfill
liners are guaranteed. (3) The EP tox test may show that the ash
is legally “hazardous” but the TCLP test is even more likely to
show that the ash is legally hazardous. Get T.L. Clapp and
others, “Municipal Solid Waste Composition and the Behavior of
Metals in Incinerator Ashes,” ENVIRONMENTAL PROGRESS, Vol. 7
(Feb., 1988), pgs. 22-30. Dr. Clapp ‘s address is: Department of
Chemical and Biochemical Engineering, College of Engineering,
Rutgers, P.O. 909, Piscataway, NJ 08854; phone (201) 932-3047 or
932-2213.
TABLE 1– Metals in ash resulting from combustion of
household wastes
============================================
| Waste Source | Metal | Fly ash (ppm) | Bottom ash (ppm) |
|---|---|---|---|
| Pennsauken | Chromium | 30 | 40 |
| Cadmium | 490 | 100 | |
| Lead | 4990 | 6970 | |
| Arsenic | 47 | 118 | |
| Zinc | 4700 | 4400 | |
| Magnolia | Chromium | 50 | 73 |
| Cadmium | 130 | 5 | |
| Lead | 2838 | 650 | |
| Arsenic | 80 | 71 | |
| Somerset | Chromium | 52 | 35 |
| Cadmium | 227 | 8 | |
| Lead | 3993 | 852 | |
| Arsenic | 87 | 112 | |
| Average | Chromium | 44 | 49 |
| Cadmium | 282 | 37 | |
| Lead | 3940 | 2824 | |
| Arsenic | 71 | 100 |
============================================
============================================
TABLE 2 — Pounds of metal in each ton of ash
| Metal | Fly ash (lbs.) | Bottom ash (lbs.) |
|---|---|---|
| Chromium | 0.09 | 0.1 |
| Cadmium | 0.56 | 0.07 |
| Lead | 7.9 | 5.6 |
| Arsenic | 0.14 | 0.2 |
============================================
–Peter Montague, Ph.D.
Descriptor terms: incineration; ash; studies; findings; rutgers;
ep toxicity; msw; landfilling; heavy metals; cancer; disease
statistics; risk assessment; leachate; groundwater; nj; lead;
chromium; cadmium; arsenic; monitoring; drinking water; hazardous
waste industry; epa; tclp extraction test; t.l. clapp;