ES2293864A1 - Method for fungal biodegradation of shredded tires, involves using fungus and crushed tire is washed to eliminate interfering contamination - Google Patents

Abstract

The method involves using a fungus Paecilomyces lilacinus. The crushed tire is washed to eliminate the interfering contamination. The fungus is grown in the presence of liquid medium under agitated conditions. The excess liquid medium is eliminated and the incubation period shows growth of the fungus that demonstrates their biodegradation.

Description

Fungal biodegradation procedure of Tire crushing

Technical sector to which the invention relates

Tire industry, Tire management used, Degradation of used tires.

Exhibition of the state of the art

In recent years they have come developing bioremediation procedures consisting of use of microorganisms for the recovery of environments contaminated Efforts in this field have been mainly aimed at the restoration of soils contaminated with products toxic or dangerous chemicals using microorganisms; thus The concept of bioremediation has been implemented. Additionally, processes have been developed in recent times of biodegradation applied to polluting materials with a view to subsequent use and reuse of its components, this being the object of the procedure that covers this patent.

The study of the biodegradation of rubber has also been carried out for years. The majority of the works are of basic research and essentially involve the participation of bacteria, mainly isolated from soils, hot springs and the remains of decomposing tires. Actinomycetes have been considered the most important bacteria in the degradation of natural and vulcanized rubber products, especially Nocardia . It has also been described, although to a lesser extent, the use of wood rot fungi and their enzymes for the decomposition of vulcanized rubber.

The vulcanization process suffered by the natural rubber in tires and other products realizes their desirable mechanical and thermal properties, but it is at the same time responsible for its reuse is complex. Through this process disulfide bridges are formed between the chains of the polymers, both natural and synthetic rubbers. They have described various chemical, physical and chemical devulcanization processes microbial Also, degradation processes have been documented that they involve only the breakage of the polymer chains.

As already said, so far the Vulcanized microbiological treatments used mean mainly the use of bacteria, which appears reflected in several patent documents. For example, the patent Japanese JP2004313031 refers to the desulfurization of rubber crushed vulcanized (natural rubber, or butadiene rubbers) by Gram-positive bacilli isolated from ground.

In US patent US6479558, they are used bacteria isolated from sulfur-containing hot springs, for rubber devulcanization, so as to improve your ability to be recycling. According to WO01 / 74933, said biotreatment can be completed for a microwave treatment.

German patent DE4220623 raises the devulcanization of crushed tires used with bacteria such as Thiobacillus oxidans, Thiobacillus ferrooxidans and the like. In Spanish patent ES2086468, Thiobacillus ferrooxidans, Thiobacillus thiooxidans and / or Thiobacillus thioparis are used .

The international patent WO2004 / 087799 discloses the surface activation and / or surface devulcanization of rubber particles, by the action of mesophilic bacteria or enzymes derived therefrom. These are bacteria that use and / or reduce sulfur, namely Desulfuromonas thiophila, Desulfuromonas palmitatis, Sulfurospirillum deleyianum or Desulfuromonas acetoxidans . US5597851 refers to the use of thiophilic microbes or enzymes derived therefrom, for the surface devulcanization of rubber. Bacteria are selected from Thiobacillus ferrooxidans, Thiobacillus thiooxidans, Rhodococcus rhodochrous and Sulfolobus acidocaldarius .

In DE19728036, Thiobacillus ferrooxidans, Thiobacillus thiooxidans, Thiobacillus thioparus, Thiobacillus novellus, Sulfolobus acidocaldarius, Sulfolobus brierley, Acidanus acidaus, Rhodococcus rhodochrous or Pseudomonas vulcanized surface area and rubber modulation.

In JP2003250526 a new bacterium ( Enterobacter cloacae MOE-1) is proposed for the decomposition of natural rubber or styrene-butadiene. In JP1096230 Xanthomonas NR-35Y (FERM 9640) is used.

In JP2004131643 the decomposition of products containing natural rubber, such as used tires, is proposed by actinomycetes of the genus Nocardia . JP2006182952 refers to obtaining rubber powder suitable for reuse, which is obtained by treating the surface of rubber crushed with Nocardia actinomyces strain BS-HA1 (FERM P-19378). This strain is also described in JP2006180822. JP2006180794 describes the Nocardia strain BS-TAI (FERM P-19379) and its usefulness for degrading rubber. According to JP11060793, the biodegradation of hard rubber, such as that derived from tires, is carried out with actinomycetes of the genus Nocardia , preferably of the strain Rd-Cm or a variant, specifically deposited as FERM P-16338. In US5854058 the genus Nocardia , strain NR-35A is also used. That same strain of Nocardia and Rhodococcus NR-26S, are used in JP61085193 and JP60072934 to degrade isoprene polymers, natural or synthetic. Nocardia (NR-35A) and Rhodococcus are also used in JP2076575 for rubber decomposition. JP54055778 proposes the use of Pseudomonas strain AT-S-1 and Nocardia strain AT-S-3.

European application EP1454942 employs a WU-YSO5 strain of Pseudonocardiaceae to produce surface roughness of powdered rubber. This bacterium is also used in JP2003231118. Rhodococcus rhodochrous ATCC 53968 is used in EPO441462 for the rupture of carbon-sulfur bonds, for example in rubber recycling. That bacterium and / or Bacillus sphaericus ATCC 53969 can be used according to EP0562313 and US5358869, for the same purpose.

PCT application WO2004 / 076492 proposes to use actinomycetes, e.g. ex. of the genera Corynebacterium, Rhodococcus, Nocardia, Gordonia, Tsukamurella, Dietzia and Mycobacterium . In particular, Gordonia desulfuricans SG213E is used for biotreatment of natural or synthetic rubber.

Patents that refer to the use of fungi for the treatment of rubbers, natural or vulcanized, are much scarcer. Only JP2004099738 proposes to treat natural or synthetic vulcanized rubber with wood rot fungi, such as p. ex. Ceriporiopsis subvermispora (FP 90081) and Dichomitus squalens (CBS 482.84). On the other hand, JP2006152237 and JP2005232347 use enzymes isolated from fungi of wood rot, for the decomposition of vulcanized rubber.

With the procedure presented in this patent, the biodegradation of a heterogeneous crushing of commercial tires used by means of the Paecilomyces lilacinus IMI 117109 fungus is achieved.

Explanation of the invention.

To carry out the aforementioned degradation previously of the crushing of used tire has been devised a biodegradation procedure in which the fungus is grown in a liquid medium of mineral salts in which the crushed material It is the only source of carbon for the microorganism.

Prior to the crushing incubation of pneumatic with the fungus, a crushing wash is carried out in certain conditions of crushing weight / volume ratio of sterile water used, temperature, agitation and time. This washing allows the elimination of organic remains and microorganisms contaminants that could interfere or displace the reaction of biodegradation

Cultures of the fungus are then carried out in a liquid medium of mineral salts and without carbon sources. From This way ensures that the only nutrients that can be metabolized by the fungus are the polymeric compounds that form mostly tire crushing.

Cultivation of the fungus in the crushing of pneumatic with the mineral salts medium is carried out in two phases: in the first one a culture is carried out in liquid medium, with an excess of medium and agitation. This phase is necessary for activation and correct distribution of the fungus in the crushed. In the second phase excess liquid medium is removed, leaving a culture solid-wet static, in which it continues developing the fungus on the crushed.

Fungal development is an unequivocal signal of the biodegradation process that is taking place in the crushed tire

The procedure described can also be possibly applied to other microorganisms, such as other fungi and even bacteria as long as they possess metabolic abilities necessary for tire crushing degradation, and adapting the process conditions to the particular physiology of The microorganisms to consider.

Detailed statement of at least one embodiment of the invention

The tire crushing used for the Performing this procedure is granulometry 3 <x < 4 mm, from various used tires of composition commercial, all based on a polymer matrix of rubber natural or synthetic crosslinked by disulfide bridges in its vulcanization.

The first part of the procedure consists of tire crushing preparation to be used as biodegradation substrate. A washing of the crushed under the following conditions: weight ratio of crushed / used volume of sterile water of 0.25 (50 g of crushed for every 200 mL of water) in 250 Erlenmeyer flasks mL These are incubated at 50 ° C and 140 rpm for 24 hours on a shaker orbital (Lab-Line® Orbit Environ-Shaker Lab-Line Instruments, Inc., Melrose Park, ILL, USA). This is done process twice.

Through this procedure they are performed 250 mL Erlenmeyer flask cultures. Culture medium used is MSB (Mineral Salts Broth; Zaborski et al., 2006, Polimery, 51 (7-8): 534-538). How inoculum 6 tacos extracted with Tranfertubes® (Spectrum) are used Laboratories, Inc., Rancho Dominguez, CA, USA) of a Petri dish with the fungus grown for 4 weeks. The weight ratio of Crushed / volume of medium used is 0.4 (10 g of crushed pneumatic per 25 mL of medium).

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The flasks are incubated for a week in a orbital shaker at 25 ° C and with a stirring of 100 rpm. One time after this time, the excess medium is removed and, in sterile conditions, wet crushing is placed on plates Petri These plates are sealed with paraffin tape (Parafilm®. Pechiney Plastic Packaging, Menasha, WI, USA) and incubate at 25 ° C for 1 week After this time is observed visually a clear development of the mycelium of the fungus on the crushed wet tire, in which they are clearly appreciable, by scanning electron microscopy at low temperature, the grooves on the surface of the material and the galleries inside, created by the hyphae of the fungus in its increase.

Claims (4)

1. Fungic biodegradation process of tire crushing, characterized in that it comprises two phases or stages of incubation of at least one degradative fungus: in the first one a culture is carried out under agitation with at least one liquid medium of mineral salts, and in the second The excess liquid medium phase is removed, leaving a static solid-wet culture where the fungus development on the crushing continues. 2. The fungal biodegradation process for crushing tires according to claim 1, characterized in that, prior to the two phases, washing under agitation with sterile hot water is carried out. 3. The fungal biodegradation process for crushing tires according to claims 1 and 2, characterized in that the degradative fungus used is Paecilomyces lilacinus IMI 117109. 4. Use of the procedure defined according to claims 1 to 3 for the degradation of crushing of tires and subsequent use of products Biodegradation obtained.