WO1998030514A1

WO1998030514A1 - Method and compound to convert urban and/or special waste into inert material and material so obtained

Info

Publication number: WO1998030514A1
Application number: PCT/IB1998/000045
Authority: WO
Inventors: Giampaolo Mantovani
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-01-14
Filing date: 1998-01-14
Publication date: 1998-07-16
Anticipated expiration: 1999-07-14
Also published as: AU5336198A; IT1290639B1; ITBO970016A1; ITBO970016A0

Abstract

A method to convert into inactive material contaminated toxic water and/or noxious mud, and/or urban and special, dangerous and not dangerous waste by using a compound mainly including pozzolan, calcium oxide, silver oxide, diatomite, zeolite, silver nitrate, iron oxide, aluminium oxide, aluminium, activated micro-carbon, includes the following steps: mixing the compound with the waste to be treated, waiting a first predetermined time interval for activating the compound; maintaining the reaction temperature under the boiling temperature by adding a predetermined water quantity; stirring for a second predetermined time interval; settling until solidification into inactive material.

Description

METHOD AND COMPOUND TO CONVERT URBAN AND/OR SPECIAL WASTE INTO INERT MATERIAL AND MATERIAL SO OBTAINED

BACKGROUND OF THE INVENTION

The present invention relates to the methods used for urban and/or special waste disposal.

Particularly the present invention refers to a compound and a method for converting contaminated toxic water and urban and/or special waste, of dangerous or not dangerous kind, into inert material, and refers to the inert material so obtained.

DESCRIPTION OF THE PRIOR ART

It is nowadays known how many problems have the disposal of the urban, industrial, special (either toxic or not) waste, coming from different civil and industrial activities.

The process for disposing the organic, and not, waste, mainly consists in the attempt to make inert the enclosed active elements which can be toxic and not, or better classified like dangerous and not dangerous according to the new Italian Legislative Decree approved on December 30, 1996 implementing the European Directives no. 91/156, 91/689 and 94/62.

Inside the known methods applied for making inert any waste material, it is known the method based on mixing waste with calcium oxide. Such a method normally includes the grinding of the waste to be treated, therefore their mixing with pre-determined quantity of calcium oxide and finally the reaction between such components so that this latter dispatches its "disinfectant" action towards the waste submitted to treatment. Using this method a percentage reduction of the toxic elements, contained in the waste before the treatment, is obtained.

The relatively small amounts of such reduction are the main disadvantage of this method for making inert the waste because this is really made inert only partially.

Other disadvantage introduced by the known method consists in using an enormous quantities of calcium oxide to produce a sufficient inert system in comparison with both the waste amount to be treated and the usage of high energy consumption means for promoting the mixing and therefore the intimate contact between calcium oxide and waste to be treated.

In fact, the mixing is typically performed in an open environment by means of mechanical shovels designed to mix the waste with the calcium oxide. However, it is often necessary the treatment in circumscribed environment, that is in basins, for innermost mixing by using a stirring system with low numbers of revolution.

Further disadvantage introduced by such known method for making inert any waste consists in the elevated consumption, both of calcium oxide and energy, and therefore with consequent high cost, for carrying out the mixing process if it is wished to get an enough action for rendering inert the treated waste.

SUMMARY OF THE INVENTION

The main object of the present invention is to propose a compound for making inert any waste and a method to render inert the contaminated toxic water and the urban and/or special organic waste which is able to reduce notably, or completely reduce to zero, the percentage of active toxic elements contained in the same waste.

Further object is to propose a method avoiding the dispersion in the environment of any noxious element produced during both the implementation of the method and the obtained final product.

Other object consists in proposing a method for making inert any waste with an optimal quantitative and economic relationship between the used waste to be treated and the used compound.

Other object consists in using the final product for making manufactured articles or predominantly usable elements like building material.

The above mentioned purpose are reached according with the content of the claims .

BEST MODE OF CARRYING OUT THE INVENTION

The compound for making inert any waste (hereinafter briefly called only "compound") used for converting the contaminated toxic water and the urban and special, dangerous and not dangerous, waste into inactive material, (according to the classification listed in the article 7 of the Italian Legislative Decree approved on December 30, 1996 implementing the European directives no. 91/156, 91/689 and 94/62) , mainly consist of pozzolan, calcium oxide and silver oxide.

The pozzolan essentially includes diatomite, zeolite, pumice and metallic elements.

The same compound can also include further diatomite and/or zeolite, and/or silver nitrate, and/or iron oxide, and/or aluminium oxide and/or aluminium, and/or activated micro-carbon.

Both the weight ratio between the different components of the compound and their kinds are established both by the main composition of the pozzolan used and by the composition of the waste to be treated.

In other words, there are the cases in which the compound contains a higher quantity of calcium oxide and silver oxide, when it is desired to accelerate the action for making inert any waste, or the percentage of the compound is reduced in comparison with the quantity of waste to be treated.

Other cases include the addition of diatomite to the compound, if it contains little pozzolan, and so for the zeolite, and the addition of the iron oxides, silver and aluminium, if these are poorly present in the waste to be treated or in the same pozzolan. The method for converting contaminated water, and/or toxic mud, and/or urban and/or special, dangerous or not, waste into inert material, normally includes the initial grinding of the waste, or the mud, therefore the following steps.

Mixing the waste with the compound in such a way to constitute a compost thereof.

Waiting a first predefined time interval for activating the compound amalgamated with said compound, ranging from 1 second to 10 minutes depending on the environmental conditions, however preferably with environmental temperature higher than -10°C, and on the speed of the compost innermost mixing.

This first time interval is 3 seconds at the environmental temperature of about 10-12°C and with enough mixing between the compound and the waste to be treated: that is in 3 seconds the compost is already deactivated even if it is not completely inert .

in this phase, an intense catalysis takes place inside the compost without any direct energy supply external to the same catalytic process.

Stirring the compost (compound and waste) for a second predetermined time interval, up to its transformation into a kind of "magma", varying from 3 to 60 minutes.

The following settling of such magma involves the reduction of the so treated waste into an inactive material including the same component of the compost resulting from compound and waste combination which can contain, for instance, harmful elements such as arsenic, cadmium, hexavalent chrome, mercury, lead, copper, antimony, aluminium, iron, selenium, nickel, zinc .

Therefore the compost components are deactivated and made inert and no element included in the compound is delivered in the environment, particularly no noxious or toxic element is released to the environment after the activation of the compound, that is after 3 second from the realization of the compost (compound and mixed waste) with optimal environmental conditions (temperature of 10-12°C) .

The preferred implementation of the above mentioned method includes besides, after the compound activation, the maintenance of the reaction temperature under the boiling temperature of the compound by adding thereto a predetermined water quantity.

This reaction temperature ranges from 100°C to 125°C, and it is preferably of 105°C so the second time interval is 35 minutes: this is the time in which the magma is maintained in mechanical stirring by means of shovel stirrer (normally during the waste treatment inside the basin) or self moving mechanical shovel apparatuses (during the waste treatment in the open environment) .

The water addition is necessary to "cool" the reaction, maintaining it to 105°C so that, after such settling, the magma becomes inactive material of the fossil type. The only emission into the surrounding environment of the reaction is therefore the aqueous vapour caused by the boiling of water added to the waste reacting with the compound.

If this doesn't happen, the compost during the reaction reaches temperatures around 400 °C, so that at the end of the reaction it is obtained an inactive, but not completely fossil, material.

Water is added to the compost during the reaction in such quantity to reach the maximum weight ratio of 8 : 1 with the same compost .

The compound is mixed with the waste to be treated in a ratio varying from 0,1:1 to 0,3:1 between weight parts of the compound and weight parts of the waste: in the preferred embodiment the ratio is 0,2:1.

It needs to be underlined that the waste to be treated can be of any kind and any physical state: it can be then at solid and/or liquid and/or gaseous state .

It is notable that the compound activation rises both in open and defined environment (basin) .

An advantageous use of this fossil material consists in its pouring, when it is still in the magmatic state, into suitable die shaped as a manufactured article to be realized, for instance a brick, a block, a floor-tile, a tile, a garden table etc. Then the magma is left to be hardened without any mechanical treatment so that the fossil inactive material takes the die shape carrying out the desired article.

It will follow two examples related to the treatment of special and urban waste with the compound.

Example 1

A sample of mud taken from industrial special waste contains the following elements mainly in the weight ratio with the sample mass:

Elements Uni _t of Values

Arsenic mg/kg 219,5

Cadmium g/kg 77,3

Chrome mg/kg 28, 5

Mercury mg/kg 134, 5

Lead mg/kg 155,6

Soluble Copper mg/kg 95

Then a transfer test is implemented in the acetic acid 0,5 M according to the CNR IRSA method, without subjecting the sample to any treatment. Then the obtained values are compared with the values of the Table A, of Italian Law Merli no. 319/76, under which the noxious elements must be maintained according to the waste to be disposed.

Elements Unit of mi Values Table A

Arsenic mg/kg 0,6 0,5

Cadmium mg/kg 0,07 0,02

Chrome mg/kg <0, 05 0,2

Mercury mg/kg <0, 005 0, 005

Lead mg/kg 2,1 0,2

Soluble Copper mg/kg 0, 12 0,1 The comparative analysis between the values of each sample elements and the corresponding values of Table A, shows that the eluate exceeds 10 times the limit values for which the waste is defined toxic and noxious waste only disposable into a dump classified as 2B.

A quantity of 8 kilograms of the same sample is mixed for around 7 minutes with a quantity of 2 kilograms of compound including pozzolan, diatomite, zeolite, calcium oxide, silver oxide, iron and aluminium oxide and silver nitrate.

When the compost (compound and mud sample) reaches the reaction temperature of 105°C, this latter is maintained by adding water.

Such a compost, now at magma state, is continuously stirred for 35 minutes to finish the reaction. In this phase 56 litres of water are added.

After the settling of the magma and its cooling, a block of inactive fossil material is obtained whose spectrographic analysis shows the presence of the same elements of the mud sample remained still active in the followings proportions:

Elements Unit of measure Values

Arsenic mg/kg 8,5

Cadmium mg/kg 24,2

Chrome mg/kg 16,9

Mercury mg/kg <1

Lead mg/kg <1

Soluble Copper mg/kg 18,6 The treated sample according to the method of the present invention has been therefore submitted to the transfer test in acetic acid 0,5 M (CNR IRSA) showing the values in the following compared with the corresponding values of the Table A (Merli Law no. 319/76) .

Elements Unit of mi Values Table A

Arsenic mg/kg <0, 05 0,5

Cadmium mg/kg 0, 02 0, 02

Chrome mg/kg <0, 05 0,2

Mercury mg/kg <0, 005 0, 005

Lead mg/kg <0, 01 0,2

Soluble Copper mg/kg <0, 01 0,1

Then, the eluate shows values not exceeding 10 times the limits of the Table A of the Law no. 319/76 and that, on such results, the waste of the analyzed sample is considered as inactive waste according to all current Laws.

Example 2

The analysis of sample of an urban organic waste, essentially including a common kitchen waste, shows the presence of the following elements :

Synthetic fibres;

Plastic subjects of the type PVC and Polyester;

Organic Resins (polyurethane, cyanoacrylates) ; Paper and Cardboard;

Fat and vegetable and animals oils;

Carbon Hydrates ;

Different organic residual product;

Leftovers of biological material (vegetables, meat, fish) ; Vegetable fibres, different vegetables, cotton.

The analysis of such sample has not been performed because this sample is a standard urban solid waste (USW) .

A sample of 4 kilograms of such waste has been mixed to 1 kilogram of compound and then the reaction has been maintained to 110°C by adding water in quantity equal to about 16 litres. The continuous stirring of the so obtained magma was maintained for about 28 minutes was carried out by means of a shovel with low number of revolutions.

After 33 minutes from the reaction start, the magma is settled for cooling, so obtaining the reduction of the waste to inactive material of the fossil kind.

The analysis of such sample has shown the following values :

Elements Unit of measure Values

Residual at 105°C % 98,0 Residual at 600°C % 94,0

Total Cyanides mg/kg <1

Total Phenols mg/kg <1

Arsenic mg/kg 2,5

Cadmium mg/kg 0 , 4 Chrome hexavalent mg/kg 11,5

Mercury mg/kg <0,1

Lead mg/kg 128

Soluble Copper mg/kg 10

Asbestos mg/kg 1,5 Aromatic solvents: Benzene mg/kg <1

Toluene mg/kg <1

Xylenes mg/kg <1

Chlorinated Solvents mg/kg <1

From the transfer test in acetic acid 0,5 M according to the CNR IRSA method, without subjecting the sample to any treatment, the following values are taken.

Elements Unit of measure Values Table A

Total Cyanides mg/kg <0, 01 0,5

Total Phenols mg/kg <0, 01 0,5

Arsenic mg/kg <0,01 0,5

Cadmium mg/kg 0,004 0,02

Chrome hexavalent mg/kg 0, 006 0,2

Mercury mg/kg <0, 001 0,005

Lead mg/kg 0,07 0,2

Copper mg/kg 0,005 0,1

Aromatic solvents:

Benzene mg/kg <0, 001 0,2

Toluene mg/kg <0, 001 0,2

Xylenes mg/kg <0,001 0,2

Chlorinated Solvents mg/kg <0,001 1

The USW sample values compared with the corresponding in the Table A they show that the active toxic or noxious elements have not exceeded the law limit .

From said examples it is clear that the implementation of such a method allows an eluate in which the still "active" noxious elements are greatly inferior to the limits admitted by the Table A of the Law no. 319/76 (law Merli) .

Then, the reported experimental data underline that the principal advantage reached by implementing such method is the inert action which perform the reduction of the organic, urban and special, waste into inert material and is able to reduce notably, if not to completely zero, the percentage of toxic elements contained in the same waste.

Further advantage consists in supplying an implementing method for avoiding any emission, into environment, of some noxious element during the method implementation and the realization of the final product, with the possible release of water vapour .

Other advantage consists in providing a method with an optimal quantitative relationship between waste to be treated and compound used so providing a very good energetic and consequently economic saving.

Claims

1) Method to convert into inactive material contaminated toxic water and urban and/or special, dangerous and not dangerous, waste, said method being characterized in that includes:

- mixing said waste with a compound for making inert any of said waste, essentially including a mixture of pozzolan, silver oxide and calcium oxide, in such a way to constitute a compost;

- waiting a first predetermined time interval for activating said compound inside said compost;

- stirring said compost for a second predetermined time interval up to its transformation into magma; - settling said magma up to its solidification into inactive material.

2) Method according to claim 1, characterized in that further includes the addition to said compound of zeolite mixed with silver nitrate, and/or iron oxide, and/or aluminium oxide, and/or aluminium, and/or activated micro-carbon.

3) Method according to claims 1 or 2 , characterized in that further includes the addition of diatomite to said compound.

4) Method according to any of the preceding claims characterized in that it further includes, after the activation of said compound, the maintenance of the reaction temperature under the boiling temperature of said compost by adding a predetermined water quantity thereto.

5) Method according to claim 4, characterized in that said reaction temperature ranges from 100°C to 125°C, and it is preferably 105°C.

6) Method according to claim 4, characterized in that said predetermined water quantity reaches at most the ratio 8:1 with the total quantity of said compost .

7) Method according to claim 4, characterized in that said settling of said magma it occurs until said inactive material becomes inactive fossil material .

8) Method according to claim 1, characterized in that , after said settling, said inactive material includes all the elements inside said waste.

9) Method according to claim 1 or 4 , characterized in that said first predetermined time interval varies from 1 second to 10 minutes, and it is preferably 3 seconds at the environment temperature of 10-12°C.

10) Method according to claim 1 or 4 , characterized in that said second predetermined time interval ranges from 3 to 60 minutes, preferably is 35 minutes .

11) Method according to claim 1 or 4 , characterized in that said waste mainly includes noxious elements as arsenic, cadmium, hexavalent chrome, mercury, lead, copper, antimony, aluminium, iron, selenium, nickel, zinc.

12) Method according to claim 1, characterized in that said waste is at solid and/or liquid and/or gaseous state .

13) Method according to claim 1, characterized in that said activation of said compound occurs in the open environment .

14) Method according to claim 1, characterized in that said compound is mixed with said waste in a variable ratio ranging from 0,1:1 to 0,3:1 between weight parts of said compound and weight parts of said waste, preferably said ratio being 0,2:1.

15) Compound for converting, into inactive material, contaminated toxic water and/or noxious mud, and/or urban and special, dangerous and not dangerous, waste, said compound being characterized in that mainly includes pozzolan, calcium oxide and silver oxide .

16) Compound according to claim 15 characterized in that further includes diatomite.

17) Compound according to claim 15 or 16 characterized in that further includes zeolite, and/or silver nitrate, and/or iron oxide, and/or aluminium oxide, and/or aluminium, and/or activated micro-carbon.

18) Compound according to claim 15 characterized in that said pozzolan mainly includes diatomite, zeolite, pumice and metallic elements.

19) Use of the compound according to claim 15, for converting, into inactive material, contaminated toxic water and/or noxious mud, and/or urban and special, dangerous and not dangerous waste.

20) Product constituted by inactive fossil material derived from contaminated toxic water and/or noxious mud, and/or urban and special, dangerous and not dangerous waste made reactive with the compound according to the method claim 1 or 4.