Reagent for treating a contaminated waste material and method for same

A reagent material useful for converting a contaminated waste material, which is environmentally unacceptable, to a relatively harmless granular substance which is environmentally acceptable. The reagent material is comprised of an effective amount of alumina, silica, a hydroxide, or hydroxide precursor, of an alkali metal, calcium oxide, and a medium to large pore zeolitic material. The method involves blending an effective amount of the reagent material with the waste material and allowing it to dry without setting, thereby resulting in an environmentally acceptable particulate substance.

FIELD OF THE INVENTION 
The present invention relates to a reagent material useful for converting a 
contaminated waste material, which is environmentally unacceptable, to a 
relatively harmless granular substance which is environmentally 
acceptable. The reagent material is comprised of an effective amount of 
alumina, silica, a hydroxide, or hydroxide precursor, of an alkali metal, 
calcium oxide, and a zeolitic material. The method involves blending an 
effective amount of said reagent material with said waste material and 
allowing it to dry without setting, thereby resulting in an 
environmentally acceptable particulate substance. 
BACKGROUND OF THE INVENTION 
All industrial societies are faced with significant environmental problems 
associated with industrial waste materials, many of which are hazardous to 
both animal and plant life. Examples of such waste materials include 
sludges which settle as sedimentation layers at the bottom of the sea, 
lakes, and rivers; effluent sludges discharged from various industries 
including pharmaceutical, tanning, paper and pulp manufacturing, wool 
washing, fermenting, food processing, metal surface processing, plating, 
ore dressing, coal washing, and fume desulfurizing; as well as other 
wastes such as sewage sludges discharged from sewage processing stations, 
and those resulting from the refining of petroleum products. Such wastes 
are often contaminated with substances which can have an adverse effect on 
the ecological system. Contaminants found in such wastes often include 
unacceptable levels of heavy metals such as copper, lead, cadmium, 
arsenic, mercury, hexavalent chromium. Also found are other chronically 
toxic compounds such as PCB, PCP, DDT, 2-BHC, Dieldrin, Chlordecone, 
Mirex, Parathion, cyanic compounds, alkyl-mercury compounds, dioxins, 
furans; and the like. These waste materials are sometimes referred to 
herein as environmentally unacceptable. 
The treatment and handling of such contaminated waste materials, many of 
which can be classified as hazardous, is strictly regulated by one or more 
governmental agencies because of their potential harm to the public 
welfare. As such, a great deal of work has been done in recent years in 
developing methods for safely handling these materials and for 
neutralizing their troublesome characteristics so they can be safely 
discarded. 
Non-limiting examples of methods which have been developed and which have 
met with varying degrees of success, include sorption, adsorption, 
volatilization, biodegradation, chemisorption, passivation, ion-exchange, 
encapsulation, and embedment through solidification into a monolith 
structure, as well as stabilization of chemical constituents. Sorption 
involves adding a solid to the hazardous waste material to soak-up any 
liquid which is present. Non-biodegradable materials are typically used as 
the sorbent. Such materials include activated carbon, anhydrous sodium 
silicate, various forms of gypsum, celite, clays, bottom ash, fly ash, fly 
dust, kiln ash, and cement kiln dust. Biodegradable materials can also be 
used, such as peat moss, rice hulls, sawdust, and the like. These 
treatments primarily use biodegradation for reducing organic constituents 
of the waste material. The sorbent may interact chemically with the waste 
material, or it may simply be wetted by the liquid portion which is 
retained in the sorbent as a capillary liquid. Sorption generally cannot 
be used with many types of hazardous waste, such as those which contain 
potentially hazardous components, because they can often be easily leached 
from the sorbent. This is because sorption typically only requires that it 
be mixed with the waste. Further, as governmental regulations become ever 
stricter, sorption becomes less and less attractive for meeting such 
regulations. 
Another method for treating hazardous waste involves the consolidation and 
solidification of the waste into a solid block of material that has 
relatively high structural integrity. The resulting block is often called 
a monolith. The monolith can be as small as the contents of a steel drum, 
or it can encompass the entire waste disposal site, called a monofill. The 
components of the monolith do not necessarily interact chemically with the 
reagents, but are usually mechanically locked within a solidified matrix, 
called microencapsulation. Contaminant loss is primarily limited by 
decreasing the surface area which is exposed to the environment and/or 
isolating the contaminants from environmental influences by encapsulating 
the waste particles. Wastes can also be microencapsulated. That is, bonded 
to, or surrounded by, an impervious coating. 
While solidification can be very effective for treating some hazardous 
wastes, recently passed governmental regulations are placing greater 
demands on this technology. This is because of the ever stricter 
limitations relating to acceptable levels of leachates from the solidified 
block. Also, the block must withstand ever greater physical pressures 
without cracking and exposing contaminants to environmental influences. 
Other methods of hazardous waste treatment include inorganic and organic 
stabilization. Unlike solidification processes which convert wastes into a 
solid mass, stabilization processes can reduce the solubility or chemical 
reactivity of the waste. Stabilization processes typically include 
adjusting pH, converting metals to hydroxides, and/or establishing 
oxidation-reduction conditions to prevent solubilization or leaching of 
contaminants into ground water. The most commonly used inorganic 
stabilization processes include mixing the waste product with inorganic 
materials such as fly ash, cement kiln dust, lime kiln dust, hydrated 
lime, Portland cement, or other pozzolanic materials. Stabilization 
processes, like solidification, are being pushed to meet the stricter 
governmental regulations. 
A typical stabilization process is taught in U.S. Pat. Nos. 4,781,842 and 
4,902,431 wherein a sewage sludge is stabilized and converted to 
fertilizer by mixing the sludge with an alkaline material which is 
sufficient to raise the pH to at least 12. The mixture is then allowed to 
dry for at least one day. The alkaline material is selected from cement, 
kiln dust, and lime dust, to achieve chemical stabilization. Bulking 
materials, such as slag fines, fly ash, gypsum, etc. may also be added. 
Such a process is primarily a drying process to eliminate offensive odors 
and pathogenic microorganisms. The process is not capable of generating a 
substantial amount of heat to destroy many of the contaminants. 
Also, U.S. Pat. No. 4,859,367 teaches a waste solidification method wherein 
toxic mine tailings are incorporated into a cement mixture which contains 
a mineral binder selected from the class of alkali-activated 
silico-aluminate geopolymers which is stated to be related to natural and 
synthetic zeolites and feldspathoids. 
Although a significant amount of work has already been done to treat 
contaminated waste materials, there is still a considerable need in the 
art for improved methods for treating and neutralizing such materials. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided a reagent 
material for treating environmentally unacceptable waste materials, which 
reagent material, by weight, is comprised of: 
(i) 1 part alumina; (ii) 1 to 3 parts of a silica having a surface area of 
at least about 10 m.sup.2 /g; (iii) 0.5 to 3 parts of a hydroxide, or 
hydroxide precursor, of an alkali metal; (iv) 2 to 5 parts of CaO; (v) 2 
to 5 parts of a zeolitic material having a pore diameter equal to or 
greater than 4 .ANG., and an SiO.sub.2 to Al.sub.2 O.sub.3 ratio greater 
than or equal to 2.5. 
Also in accordance with the present invention is an innocuous solid waste 
mixture which may be safely disposed of in a landfill comprising: 
(a) a reagent material comprised of: (i) 1 part alumina; (ii) 1 to 3 parts 
of a silica having a surface area of at least about 10 m.sup.2 /g; (iii) 
0.5 to 3 parts of a hydroxide, or hydroxide precursor of an alkali metal; 
(iv) 2 to 5 parts of CaO; and (v) 2 to 5 parts of a zeolitic material 
having a pore diameter equal to or greater than 4 .ANG., and an SiO.sub.2 
to Al.sub.2 O.sub.3 ratio greater than or equal to 2.5; and 
(b) a waste material, which prior to a reaction with said reagent material, 
contains unacceptable levels of one or more contaminants selected from the 
group consisting of heavy metals and organic components. 
Also in accordance with the present invention, there is provided a method 
for treating an environmentally unacceptable contaminated waste material 
to convert it to an environmentally acceptable material, which method 
comprises mixing said contaminated waste material with an effective amount 
of a reagent material comprised of: (i) 1 part alumina; (ii) 1 to 3 parts 
of a silica having a surface area of at least about 10 m.sup.2 /g; (iii) 
0.5 to 3 parts of a hydroxide, or hydroxide precursor, of an alkali metal; 
(iv) 2 to 5 parts of CaO; and (v) 2 to 5 parts of a zeolitic material 
having a pore diameter equal to or greater than 4 .ANG., and an SiO.sub.2 
to Al.sub.2 O.sub.3 ratio greater than or equal to 2.5. 
In a preferred embodiment of the present invention, the alkali metal 
hydroxide is NaOH, and the zeolite is a zeolite material which is 
iso-structural to a zeolite selected from clinoptilolite and chabazite. 
In other preferred embodiments of the present invention, the reagent 
material is comprised of: (i) 1 part alumina; (ii) 1.5 to 2.5 parts of a 
silica having a surface area of at least about 10 m.sup.2 /g; (iii) 0.5 to 
1.5 parts of a hydroxide of an alkali metal; (iv) 2.5 to 3.5 parts of CaO; 
and (v) 2.5 to 3.5 parts of a zeolitic material having a pore diameter 
equal to or greater than 4 .ANG., and an SiO.sub.2 to Al.sub.2 O.sub.3 
ratio greater than or equal to 2.5. 
In yet other preferred embodiments of the present invention, the 
contaminated waste material is selected from the group consisting of 
sewage sludge; a biologic organic waste material; a non-biologic waste 
material; waste resulting from the drilling, production, and processing of 
petroleum, such as tanker bottoms; and waste contaminated with a naturally 
occurring radioactive material.

DESCRIPTION OF THE INVENTION 
Any contaminated waste material may be treated in accordance with the 
present invention so long as it is a solid a liquid, or combination 
thereof. A typical waste stream which can be treated in accordance with 
the present invention is in the form of a sludge. The term "sludge" as 
used herein, means a material which is flowable at ordinary temperatures 
and at about atmospheric pressure, but which has a relatively high solids 
content, and which can typically be pumped by conventional pumping means. 
Non-limiting examples of such wastes included sludges which settle as 
sedimentation layers at the bottom of the sea, lakes, and rivers; effluent 
sludges discharged from various industries including pharmaceutical, 
tanning, paper and pulp manufacturing, wool washing, fermenting, food 
processing, metal surface processing, plating, ore dressing, coal washing, 
and fume desulfurizing; and still other wastes, such as sewage sludges 
discharged from sewage processing stations, and those resulting from the 
drilling, production, and processing of petroleum. Such wastes are often 
contaminated with substances which have an adverse affect on the 
ecological system. Non-limiting examples of such substances include heavy 
metals, such as copper, lead, cadmium, arsenic, mercury, hexavalent 
chromium; and other chronically toxic compounds such as PCB, PCP, DDT, 
2-BHC, Dieldrin, Chlordecone, Mirex, Parathion, cyanic compounds, 
alkyl-mercury compounds, dioxins, furans; and the like. It is also within 
the scope of the present invention to treat a waste material which is 
contaminated with naturally occurring radioactive materials. 
The term "contaminated waste" as used herein, means any waste material 
which is environmentally unacceptable. By "environmentally unacceptable" 
we mean those materials which governmental regulations define as being 
harmful, or potentially harmful, to the ecological system pertaining to 
the environment and which must be disposed of in accordance with 
governmental laws and/or regulations. 
In accordance with the present invention, the contaminated waste material 
to be treated, will typically not meet environmental laws and/or 
regulations. After treatment, the waste is converted to a relatively 
innocuous granular substance. That is, a substance which will meet such 
regulations, and which will thus be environmentally acceptable. The 
resulting innocuous material is a granulated, or particulate substance, 
which when mixed with soil, will support the growth of vegetation. 
Furthermore, the method of the present invention can be performed on-site; 
thus, not requiring the transportation of contaminated substances which 
may be subject to even more restrictive regulations. 
The waste material to be treated is placed into a containing means. Any 
suitable containing means may be used. Non-limiting examples of suitable 
containing means include earthen pits, barges, drums, as well as any 
relatively large metal container, such as those used to haul trash and 
soil. The particular containing means used will depend on such things as 
economics of the job, the waste to be treated, and the amount of waste to 
be treated. 
An effective amount of reagent material is mixed with the waste to be 
treated. An effective amount will typically be that minimum amount needed 
to contact an effective amount of the waste material to an innocuous 
material. That is, enough which will contact at least that fraction of the 
waste material which must be treated to render the entire volume of 
treated waste material environmentally acceptable. Of course, it is most 
preferred to contact substantially all of the waste. For typical 
treatments and wastes, a preferred ratio of reagent material to waste 
material will range from about 10/1 to 1/10, more preferably from about 
5/1 to 1/5, most preferably 2/1 to 1/2, particularly about 1/1. Of course, 
the level of contamination of the waste, the treating environment, and 
equipment used, will have an effect on the degree of mixing of reagent 
material and waste which can be achieved. It is especially preferred to 
achieve a substantially homogeneous mixture. Of course, water may be added 
to enhance mixing. 
The reagent material of the present invention is comprised of: (i) 1 part 
alumina; (ii) 1 to 3 parts, preferably 1.5 to 2.5 parts silica; (iii) 0.5 
to 3 parts, preferably 1 to 2 parts of a hydroxide, or hydroxide 
precursor, of an alkali metal; (iv) 2 to 5 parts, preferably from about 
2.5 to 3.5 parts of CaO; (v) and 2 to 5 parts, preferably from about 2.5 
to 3.5 parts of a zeolitic material. It is also preferred that the silica 
material have a surface area of at least about 10 m.sup.2 /g, preferably 
at least about 50 m.sup.2 /g. The preferred hydroxide is NaOH. It is 
understood that hydroxide precursor materials may also be used. None 
limiting examples of NaOH precursors include Na.sub.2 O, NaAlO.sub.2, and 
Na.sub.2 O.(SiO.sub.2).sub.x. Preferred zeolitic materials are those 
having an average pore diameter equal to or greater than 4 .ANG., 
preferably equal to or greater than 5 .ANG.. The more preferred are 
zeolitic materials which are iso-structural to a zeolite selected from 
clinoptilolite and chabazite. It is also understood that precursors of 
both alumina and silica may be used. For example, bauxite, kaolin, 
NaAlO.sub.2, and Al.sub.2 O.sub.3.3H.sub.2 O are preferred materials for 
the alumina component of the reagent material of this invention. Preferred 
silica materials include: silica gel, silica smoke, volcanic ash, kaolin, 
and sodium silicate (water glass). 
The reagent material of the present invention, which will typically be in 
particulate or granular form, is used by mixing an effective amount of it 
with the waste material. As previously stated, it is preferred that the 
two be mixed as homogeneously as possible. The mixture of waste material 
and particulate reagent material will need to reach an effective 
temperature in order to initiate a chemical reaction between the reagent 
mixture and some of the contaminants in the waste material. An effective 
temperature can often be reached by merely mixing the reagent material 
with the waste material, particularly if the waste material contains 
water, thereby causing an exothermic reaction. If necessary, the mixture 
can be heated by an external heating means to achieve the effective 
temperature. It will be understood that the temperature of the mixture 
should not be allowed to reach a temperature at which undesirable, or 
toxic, gases evolve. Acceptable temperatures for most waste materials will 
range from about 50.degree. C. to about 250.degree. C., preferably from 
about 100.degree. C. to about 200.degree. C. 
After the desired temperature is reached, and held there for an effective 
amount of time, the mixture is allowed to dry without setting. This 
ensures that a granular, or particulate, product is produced. Such a 
product can be mixed with soil and used to support the growth of 
vegetation. 
The following examples are presently for illustrative purposes only and 
should not be taken as limiting the present invention in any way. 
EXAMPLE 1 
A sample (236 gm) of a soil/sludge from a contaminated site near Manvel, 
Tex., was treated with 236 gm of a reagent mixture of the present 
invention having the composition set forth in Table I below. Mixing was 
conducted by use of a mortar and pestle and the resulting mixture was held 
at 175.degree. C. in an oven for 24 hours. After this treatment, the 
resulting dry sample was found to have lost 58 gm, which was assumed to be 
water because neither odor nor smoke was observed during heating. The 
texture of the treated material was observed to be a fine powder 
containing a few friable lumps. Analyses of the treated and untreated 
materials are given in Table II below. 
EXAMPLE 2 
A sample (200 gm) of a soil/tar from a contaminated site near Mayfield, 
Tex., was treated with 200 gm of the same reagent material which was used 
in Example 1 above. Mixing was again achieved by use of a mortar and 
pestle and the resulting mixture was heated at 175.degree. C. in an oven 
for 24 hours. After this treatment, the dried sample was found to have 
lost 151 gm, which was assumed to have been water because neither odor nor 
smoke was observed during heating. The texture of the treated material was 
also found to be a fine powder containing a few friable lumps. Analyses of 
the treated and untreated materials are set forth in Table II below. 
TABLE I 
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Composition of the Reagent Material 
Component Wt. % Parts 
______________________________________ 
alumina trihydrate 
8.7 1.00 
sodium hydroxide 10.0 1.15 
silica 20.0 2.30 
zeolite* 28.0 3.22 
dolomite oxide 33.3 3.83 
Total 100.0 11.50 
______________________________________ 
*Clinoptilolite comprised of 84 wt. % clinoptilolite, 12 wt. % volcanic 
glass, 3 wt. % feldspar, and 1 wt. % hematite. 
TABLE II 
______________________________________ 
Example 1 Example 2 
Analysis As received 
Treated As Received 
Treated 
______________________________________ 
Aromatic 
volatile org. 
(micrograms/ 
Kg) 
xylenes 3570 BDL 3820 BDL 
acetone BDL 920 10,000 8900 
toluene BDL BDL 3830 BDL 
2-butanone 
BDL 1300 BDL 680 
Base neut./ 
Acid Extract 
2-methyl- 
25,700 BDL BDL BDL 
naphthalene 
phenanthrene 
BDL BDL 91 BDL 
______________________________________ 
BDL = below detectable limit 
EXAMPLE 3 
A sample (100 gm) of contaminated soil from a site near Mexico City was 
mixed with 100 gm of the reagent material used in the previous two 
examples. The two were mixed with a spatula in a stainless steel bowl. 
Water (61 gm) was added and blended into the sample resulting in a 
relatively stiff mud-like substance. After treating the mixture for 24 hr. 
at 175.degree. C., the sample appeared to be powdery with only a few soft 
granules being present. There was no smoke or vapor evolution during 
heating, thus it was assumed that the weight loss was due to loss of 
water. The dry weight was found to be 174 gm. Analyses of the treated and 
untreated samples are given in Table III below. 
TABLE III 
______________________________________ 
Analysis As received Treated 
______________________________________ 
Total volatile petroleum 
3600 &lt;5 
hydrocarbons (mg/Kg) 
Total Extractable Petro- 
32,000 25 
leum hydrocarbons (mg/Kg) 
BTEX Analysis (.mu.g/Kg) 
benzene &lt;500 26 
toluene 570 67 
ethylbenzene 10,000 5.3 
xylenes 68,000 28 
Organic Lead (mg/Kg) 
1.0 &lt;0.3 
______________________________________ 
EXAMPLE 4 
A sample (100 gm) of contaminated soil from Chemical Pollution Control of 
New York, N.Y., was treated with 100 gm of the reagent material of Example 
1 above. The waste and reagent material were mixed with a mortar and 
pestle and placed in a 175.degree. C. oven for 24 hr. The resulting dry 
sample appeared to be a powder and had a dry weight of 180 gm. The weight 
loss was assumed to be water because no odor or smoke was observed during 
heating. Analyses of the treated and untreated materials are given in 
Table IV below. 
TABLE IV 
______________________________________ 
Analysis As received 
Treated 
______________________________________ 
Total volatile petroleum 
22,000 23 
hydrocarbons (mg/Kg) 
Total Extractable Petro- 
23,000 410 
leum hydrocarbons (mg/Kg) 
BTEX Analysis (.mu.g/Kg) 
benzene 47,000 &lt;50 
toluene 1,100,000 820 
ethylbenzene 370,000 350 
xylenes 2,700,000 2,500 
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