IL266925A - Stabilization of waste containing brominated organics for landfilling - Google Patents

Description

38725/19 STABILIZATION OF WASTE CONTAINING BROMINATED ORGANICS FOR LANDFILLING The present invention relates to processing bromine-rich waste, and particularly to an environmentally friendly process for handling waste containing brominated organic compounds, resulting in a stable solid waste suitable for environmentally safe landfilling.

Background of the Invention Tons of bromine-containing waste accumulate from chemical industries around the world every year. One of the sources of such waste, for example, is the production of flame retardants, which are added to numerous industrial and consumer products, including plastics, textiles, furniture, insulation, surface finishes, building products – as required by fire safety standards. Controlled burial of the bromine-rich waste is necessary in order to prevent the formation and spreading of dangerous components, particularly in view of the still stricter environmental and safety regulations.

Brominated organic compounds pose serious ecological dangers. Some belong to potent greenhouse agents, but the main negative effects of the brominated materials are felt in the ecological environment, where some polybrominated molecules accumulate and increase due to their low biodegradation profile, appearing even in human milk, showing a great variety of biological effects, and generally acting as potential endocrine disrupters in terrestrial and marine life.

The existing systems do not enable to easily convert bromine-rich waste to stable material for landfilling. It is therefore an object of this invention to provide an environmentally safe method of converting bromine-containing waste to a material which can be economically and safely buried by landfilling.

It is another object of this invention to provide an environmentally friendly industrial process for handling bromine-containing waste and for converting said waste to a material which may be landfilled, while complying with the valid land filling regulations. 38725/19 Other objects and advantages of present invention will appear as the description proceeds.

Summary of the Invention This invention provides a method for safe landfilling of waste containing brominated organic materials, comprising steps of i) mixing 1 weight part (wp) of said waste with water in an amount of from 0.2 to 0.6 wp; ii) adding, to said waste of step i), calcium hydroxide (Ca(OH) ) in an amount of from 0.02 to 0.20, and homogenizing the waste 2 mixture; iii) adding, to the waste mixture with Ca(OH) of step ii), ferric chloride (FeCl ) 2 3 in an amount of 0.075 to 0.150, said FeCl being in an aqueous solution, and 3 homogenizing; iv) adding, to the waste mixture with FeCl of step iii), a cement material 3 in an amount of 0.4 to 1.2 wp, and homogenizing; v) adding, to the waste mixture with said cement of step iv), 0.025 to 0.05 wp of calcium nitrate (Ca(NO ) ), and 3 2 homogenizing; vi) optionally adjusting the water content, of the waste mixture with Ca(NO ) of step v), by adding more water to reach a well blendable mixture, while not 3 2 exceeding the total amount of water of 0.6 wp water; and vi) transferring said mixture to the site of landfill. In a preferred embodiment, the method of the invention comprises steps of i) mixing 1 weight part (wp) of said waste with water in an amount of at least 0.25 wp; ii) adding, to said waste of step i), 0.05-0.1 wp calcium hydroxide (Ca(OH) ), and homogenizing the waste mixture; iii) adding, to the waste mixture with 2 Ca(OH) of step ii), 0.2 to 0.3 wp of an aqueous solution of FeCl , the concentration of 2 3 the solution being between 30 and 40 wt%, and homogenizing; iv) adding, to the waste mixture with FeCl of step iii), cement in an amount of 0.9 to 1.1, and homogenizing; v) 3 adding, to the waste mixture with said cement of step iv), 0.1 wp of an aqueous solution of Ca(NO ) , the concentration of the solution being between 35 and 45 wt%, 3 2 and homogenizing; vi) optionally adjusting the water content, of the waste mixture with Ca(NO ) of step v), by adding up to 0.25 wp more water; and vi) transferring said 3 2 mixture to the site of landfill in a continuous or batch mode; thereby obtaining stabilized and solidified bromine-containing waste mixture exhibiting after seven days a compression strength of at least 1 MPa, such as at least 2 MPa, for example at least 3 38725/19 MPa, for example at least 4 MPa, for example at least 5 MPa, for example at least 6 MPa, for example at least 7 MPa or more. Water may be added during all stages according to the need of good blending. Said step i) of mixing preferably includes crushing the waste to obtain particles or grains smaller in average than 100 mm, such as grains having in average maximal dimensions of up to 40 mm. Said cement material employed in the method of the invention comprises available cements, slag cement, clinker, coal fly ash, and shale fly ash. Said available cement is usually a hydraulic cement, such as Portland cement. In a preferred embodiment of the method according to the invention, a part of said available cement is replaced with one or more components selected from the group consisting of slag cement, clinker, carbonates of alkaline metals, carbonates of alkaline earth metals, silicates, side product materials obtained in burning fossil fuels, bottom, ash, crushed ash, coal fly ash, shale fly ash, or a mixture thereof. Said part of the hydraulic cement to be replaced may constitute between 0.2 and 0.8 weight parts of said hydraulic cement. Water employed in processing the waste according to the invention may comprise industrial or municipal or other waste water, such as treated industrial, municipal or agricultural waste water, wherein water is admixed to the bromine-containing waste in an amount necessary for obtaining a blendable and homogenizable mixture. Usually, the homogenized mixture is transferred to the site of landfill, where it hardens and results in stable waste safely embedded in a hardened matter, the waste being chemically and mechanically stabilized.

Detailed Description of the Invention It has now been found that the known problem of handling bromine-rich organic waste can be handled by employing a process which stabilizes bromine-containing particles by embedding them in a stable matrix created from said waste and a bonding agent.

Flame retardant production was the main source of the waste rich in bromine which was processed during the development of the method according to the invention. The treated waste contained tetrabromobisphenol A (TBBPA) and decabromodiphenyl ether (DBDPE). 38725/19 Burying of harmful waste in the ground, known as landfilling, must comply with regulations aiming to prevent or reduce as much as possible any negative impact from landfilling on surface water, groundwater, soil, air or human health. For example, EU legislation introduced stringent technical requirements, and in 2014 it was adopted to strengthen the quality of the environmental impact procedure set out in Directive 2011/92/EU; Decision 2003/33/EC lays down the criteria and procedures for the acceptance of waste at landfills. The method of the invention complies with the regulations as outlined in the mentioned EU documents. Accordingly, the bromine- containing waste must be processed before depositing or landfilling; however, previous attempts to stabilize the waste by solidifying with cements failed.

The organic bromine-containing waste for landfilling turned out i) to contain too much solvents interfering with the cement-solidifying process, ii) to include organic components whose concentrations pass the allowed limits, iii) to exhibit too high solubility of harmful components to be immobilized. The existing methods, or methods suggested by commercial providers of landfilling technologies, necessitated the use of relatively expensive materials and procedures which, moreover, differed for different waste types, thus precluding the use of a generally applicable, cost-effective and universal method. The invention now provides a generally applicable, cost-effective method for landfilling organic bromine-containing waste, complying with the landfilling regulations, and enabling to co-process waste of various compositions and origins.

The invention aims at avoiding the known problems and at stabilizing the bromine-rich waste, while enabling its safe earth deposition, in accordance with the regulations, including 2003/33/EC. The present invention, beside limiting the contents of certain components in the deposited mixture, predominantly aims at immobilizing the brominated organic compounds. In order to achieve said aims, the brominated agents are either coated with a cement components or intimately contacted with them. The landfilling system according to the invention enables to employ the existing landfilling sites without need of allocating new sites for this purpose, and without necessitating to obtain further permissions required by the regulations relating to starting new sites. 38725/19 Stabilization by solidification aims at preventing the leakage of dangerous materials and their seeping out of the controlled area where it may be inadvertently drunk or otherwise contacted by members of the ecologic chains. Physical and chemical steps may neutralize and/or immobilize the dangerous components. The system and the method of the invention reduce the mobility of the dangerous components by entrapping them within a stable matrix, by reducing their volatility via lowering the content of fine particles, and by enhancing the long-term stability of the processed waste, while employing relatively low-cost means. The stabilization in the process of the invention may include chemical steps modifying some of the components of the processed mixture, reducing the components' volatility and/or toxicity, for example by converting the fluid phase to a solid phase or from a solubilized phase to a solid phase.

The solidification according to the invention includes a step of stirring waste with bonding components, such as cements, in order to form a solid by a chemical reaction between the bonding component and other components in the waste mixture, whereas mechanical means support the process, including an efficient homogenizing step. The process advantageously provides uniform blocks, or ceramic or clay-like grains or other solidified objects.

The stabilized waste product has a reduced surface/volume ratio compared to the original waste; the penetrability of the contaminants substantially decreases, as well as the their horizontal flow. Preferably, the free liquid content of the stabilized waste decreases, and its mechanical strength increases. Water, such as rain, incidentally contacting the processed waste do not solubilize or substantially move the contaminants. The stabilization by solidification in accordance with the invention aims at utilizing reactions between bonding agents and water with other components in the waste in order to at least one of: precipitate, immobilize, encapsulate, neutralize, detoxify, absorb, or adsorb the dangerous materials. The process according to the invention preferably employs inorganic, cost-effective, bonding agents, including cements, fly ash, lime, or silicates. Preferably, cement as an important binding agent undergoes hydration and solidifies, optionally including cheap bonding agents obtained as side products in industrial processes, such as for example fly ash, preferably 38725/19 substituting at least a part of more expensive bonding components. In most cases, the cement with waste provides a solid that has sufficient strength to safely hold also the soil above the deposited processed waste. In preferred modifications, the cement is partially substituted or enriched with lime, slag, ash, such as coal ash, or others.

The system and process according to the preferred embodiment of the invention aims at stabilizing a bromine-enriched waste, such as waste comprising 10% or more bromine, for example at least 15% or at least 20%, or even up to 40% or more, while complying with the regulations, including 2003/33/EC. The processed and stabilized waste complies with the leakage test. In an important embodiment, the bromine-rich waste is combined with other waste types, sometimes acting synergistically, and sometimes assisting in disposal of other waste types at landfilling sites. In pilot experiments, batches of a hundred kilogram of bromine-rich waste were processed, aiming at handling 1000 ton or more waste in the landfilling site per year.

The process of the invention, aiming at stabilizing bromine-rich waste for landfilling, comprises a solidification step stabilizing the particles comprising brominated organic compounds against leaching and moving, and also against combining smaller particles to bigger ones, the stabilization being achieved by occluding the particles and entrapping them within a heat stable matrix. The matrix is formed from cement and/or components selected, among others, from lime, ash, blast furnace slag, and silicates, the strength of the matrix depending on several factors, including the degree of hydration and the character of the porous structure which is formed during the process. The process of the invention minimizes the negative effects of the bromine- rich waste on the final advantageous physical and chemical properties of the processed waste mixture.

The invention will be further described and illustrated by the following examples. 38725/19 Examples Materials Waste containing 1%-80% bromine from flame retardant production industries were employed. The analyzed samples of said waste showed non-compliance with 2003/33/EC in regard to landfilling.

In some tests, waste form the production of tetrabromobisphenol A (TBBPA) was employed. TBBPA has a large market as a frequently employs flame retardants, being admixed, for example, in epoxy resins making printed circuit boards, where the bromine content may be about 20 wt%. TBBPA is produced by bromination of bisphenol A in the presence of various solvents and reagents, such as halocarbons, methanol, and others.

In other tests, waste from the production of decabromodiphenyl ether (DBDPE) was employed. The waste taken to the tests had between 20 and 40 wt % bromine.

Cement class CEM II and cement class CEM III were employed, as well as other pozzolanic materials (for example burnt shell oil ash).

Tap water or waste water was used.

The following chemicals of technical grade were used: calcium hydroxide, ferric chloride as 40 or 30% aqueous solution, ferrous sulfate heptahydrate, calcium nitrate as 40% aqueous solution.

Methods Processing waste In many test batches, the method of processing bromine-rich organic waste for landfilling included the following steps: * 1 weight part (wp) of waste was mixed with about 0.25 wp water, and 0.05 wp calcium hydroxide, and homogenized; 38725/19 * 0.19 wp of 40% FeCl3 was added and mixed; * 0.25 wp cement CEM IIA and 0.75 wp of cement CEM IIB were added and mixed; * 0.1 wp of 40% calcium nitrate was added and mixed; * water was added to reach a well homogenizable mixture, possibly comprising up to 0.6 wp, but usually not more than 0.45 wp totally, whereas water may be added during all stages according to need, while the homogenization may include crushing when the consistency of the waste necessitates that.

Analytical tests The processed waste was tested for leaching and for compress strength in various time periods. Leaching was characterized by dissolve organic carbon (DOC, in mg/kg) and the strength by compress strength coefficient (in MPa).

Example 1 In one series of experiments, 400-500 g waste from TBBPA production was mixed with various amounts of water (108-255 g), calcium hydroxide (20-80 g), 30% or 40% ferric chloride (0-135 g), 40% calcium nitrate (20-40 g), and cement (200-500 g), whereas the solidified samples were checked for leaching and strength during five months. All samples prepared in accordance with the invention complied with the requirements.

While the invention has been described using some specific examples, many modifications and variations are possible. It is therefore understood that the invention is not intended to be limited in any way, other than by the scope of the appended claims.

Claims (6)

IL 266925/2 -9- CLAIMS

1. A method for safe landfilling waste containing brominated organics, comprising steps of i) mixing 1 weight part (wp) of said waste with water in an amount of from 0.2 to 0.6 wp; ii) adding, to said waste of step i), calcium hydroxide (Ca(OH) ) in an amount of 2 from 0.02 to 0.20, and homogenizing the waste mixture; iii) adding, to the waste mixture with Ca(OH) of step ii), ferric chloride (FeCl ) 2 3 in an amount of 0.075 to 0.150, said FeCl being in an aqueous solution, and 3 homogenizing; iv) adding, to the waste mixture with FeCl of step iii), a cement material in an 3 amount of 0.4 to 1.2 wp, and homogenizing; v) adding, to the waste mixture with said cement of step iv), 0.025 to 0.05 wp of calcium nitrate (Ca(NO ) ), and homogenizing; 3 2 vi) optionally adjusting the water content, of the waste mixture with Ca(NO ) 3 2 of step v), by adding more water to reach a well blendable mixture, while not exceeding the total amount of water of 0.6 wp water; and vii) transferring said mixture to the site of landfill.

2. The method of claim 1, wherein: said mixing comprises mixing 1 weight part (wp) of said waste with water in an amount of at least 0.25 wp; said adding, to said waste of step i), comprises adding 0.05-0.1 wp calcium hydroxide (Ca(OH) ); 2 said adding, to the waste mixture with Ca(OH) of step ii) comprises adding 2 0.2 to 0.3 wp of FeCl , as an aqueous solution of 30% to 40 wt%; 3 said adding, to the waste mixture with FeCl of step iii), comprises adding 3 cement in an amount of 0.9 to 1.1 wp; said adding, to the waste mixture with said cement of step iv), comprises adding 0.1 wp of Ca(NO ) as an aqueous solution of between 35% and 45 3 2 wt%;IL 266925/2 -10- said optionally adjusting the water content, of the waste mixture with Ca(NO ) of step v), comprises adding up to 0.25 wp more water; and 3 2 said transferring is conducted in in a continuous mode or batch mode; thereby obtaining stabilized and solidified bromine-containing waste mixture exhibiting after seven days a compression strength of at least 1 MPa.

3. The method of any one of claims 1 to 2, wherein water may be added during all stages according to the need of good blending, and wherein said step i) of mixing includes crushing the waste to obtain particles or grains having in average a maximal dimension of up to 40 mm.

4. The method of any one of claims 1 to 3, wherein said cement material comprises cement, slag cement, clinker, coal fly ash, or shale fly ash.

5. The method of any one of claims 1 to 4, wherein said cement is a hydraulic cement, such as Portland cement, of which a part is replaced with one or more components selected from the group consisting of slag cement, clinker, carbonates of alkaline metals, carbonates of alkaline earth metals, silicates, coal fly ash, and shale fly ash.

6. The method of claim 5, wherein said part of hydraulic cement to be replaced is between 0.2 and 0.8 wp of said replacing component for 1 wp part of said hydraulic cement.