METHOD FOR TREATMENT OF A PRODUCT CONTAINING ASBESTOS

Abstract

The present invention relates to a process for treating a product containing asbestos comprising grinding the product, which is preferably asbestos waste, and incubating the ground product with whey inoculated with lactic acid bacteria.

Description

Title of the invention: METHOD FOR TREATMENT OF A PRODUCT CONTAINING ASBESTOS INTRODUCTION

[0001] The present invention falls within the field of biological processes for treating products containing asbestos and, in particular, asbestos waste.

[0002] Asbestos is a fibrous mineral of the magnesium phyllosilicate type that was widely used for its numerous properties, particularly its insulating properties, and its chemical and mechanical resistance. Its use has been banned in France since 1997 due to its harmful effects on human health. Currently, the removal of asbestos from numerous sites generates significant quantities of waste that society must manage. One of the major concerns is finding an environmentally friendly, economical, rapid, and industrially applicable solution for disposing of or recovering the different types of asbestos waste. Chrysotile (Mg6Si4O10(OH)8), the only asbestos-like mineral species in the serpentine group, accounts for 95% of industrial asbestos use.The main asbestos-based products come primarily from the construction sector (buildings and public works) and include, in particular, asbestos cement, representing approximately 80% of global asbestos production, and raw bulk asbestos used in spraying processes.

[0003] To date, there is no satisfactory treatment for asbestos. The most common method of asbestos removal in France is landfilling in specialized centers. Although economical, it requires significant storage space for the waste. Furthermore, it does not address the hazardous nature of asbestos (Damien, 2016). Plasma fusion vitrification is also used to treat asbestos-containing products (Spasiano and Pirozzi, 2017). However, while effective, this method of asbestos removal is extremely expensive, particularly due to its energy consumption.

[0004] Chemical or thermochemical treatments are also considered, some of which generate a valuable treatment product with high added value. However, some limitations remain. In particular, chemical treatments are based on the acid attack of chrysotile and require the use of strong acids (for example, hydrochloric, nitric, sulfuric, or hydrofluoric acids), which raises concerns related to the hazardous nature of these acids.

[0005] In addition to the treatment methods mentioned above, biological treatments are also envisaged, using in particular by-products and waste from The food industry. For example, application WO 2015 / 166359 describes a process for treating asbestos comprising preparing an acidic solution by subjecting food industry waste to mixed fungal and bacterial proliferation and / or fermentation (Saccharomyces cerevisiae and Acinetobacter acetii), and treating asbestos-containing material with the acidic solution / suspension obtained from the mixed fermentation at a temperature of 120 to 170 °C and a pressure of 2 to 10 bar. A process using whey from the dairy industry has, for example, been developed to treat asbestos cement waste. Indeed, whey is an acidic waste product, composed in particular of lactic acid, which allows the asbestos fibers to be released from this waste by dissolving the cement matrix. The fibers are then treated by a hydrothermal attack to obtain an inert waste (EP2428254B1).Although these biological processes have the advantage of being more environmentally friendly and less hazardous than the treatments mentioned above, their effectiveness needs improvement in terms of asbestos removal and cost. Specifically, the process described in EP2428254B1 relies on the high extraction of iron and magnesium, reflecting the alteration of the asbestos. This extraction is linked to the acidic pH of the whey; however, this pH increases progressively during the reaction due to the dissolution of magnesium oxide, leading to a rapid reduction in the process's effectiveness. Therefore, it is necessary to add a hydrothermal treatment step to achieve more effective asbestos alteration.

[0006] Other authors describe the use of microorganisms whose metabolism would allow them to alter asbestos. For example, Stanik et al. (2006) describe the use of Lactobacillus casei and Lactobacillus plantarum in the destruction of chrysotile in asbestos. However, the sole use of metabolites (mainly acids), products of the activity of these bacteria, does not succeed in altering asbestos very effectively (only 7.5% of Mg and 1.3% of Fe are extracted after 10 days of culture).

[0007] From the foregoing, it appears that biological methods for altering asbestos in products containing it are the most promising from an ecological standpoint, and particularly from a cost perspective, as they allow for the recovery of waste from the agri-food industry. However, the efficiency of these processes must be further improved so that the asbestos contained in the products, especially waste, is almost entirely, or even entirely, altered by the biological process.

[0008] There is therefore still a need for an environmentally friendly and efficient process for treating asbestos waste.

[0009] While the prior art recommends using hydrothermal treatment to improve the alteration of asbestos in whey, it advises against using microorganisms because of the low rate of asbestos alteration (paragraph

[0016] of (EP2428254), the present inventors have surprisingly found that inoculating whey with lactic acid bacteria, and in particular with Lactobacillus plantarum, maintains the acidic pH of the whey necessary for the deterioration of asbestos (see Table 1 in the experimental part of this application) through the lactic acid fermentation induced by these bacteria during the deterioration process. This deterioration of asbestos in whey inoculated with lactic acid bacteria is confirmed by the high extraction of iron and magnesium (see [Fig. 7] of this application).

[0010] The present inventors have also surprisingly discovered that the rate of asbestos deterioration is increased by a prior grinding step of the asbestos-containing product. The authors have thus shown that the extraction of iron and / or magnesium is greater in ground asbestos cement waste than in unground flocking waste (see [Fig. 7] of this application).

[0011] The present application therefore relates to a process for treating a product containing asbestos, said process comprising the following steps:

[0012] a) the grinding of the product containing asbestos,

[0013] b) the incubation of said ground product in step a) with whey inoculated with lactic acid bacteria.

[0014] The term "asbestos" as used here refers to varieties of hydrated silicates, magnesium or calcium, formed naturally during the metamorphism of rocks, which can be transformed into mineral fibers. There are various categories of asbestos corresponding to several mineral varieties:

[0015] serpentines, which are hydrated magnesium phyllosilicates with a lamellar structure, the most common fibrous form of which is "chrysotile" or "white asbestos"; -

[0016] amphiboles, double-chain silicates which can comprise five distinct fibrous varieties, namely: anthophyllites, actinolites, tremolites, amosites known as "brown asbestos", and crocidolites known as "blue asbestos", each differing from the other in its chemical composition.

[0017] According to one embodiment of the process, the product containing asbestos is asbestos-containing waste. Several types of asbestos waste are distinguished:

[0018] - loose asbestos waste, in friable form, originating from spraying waste or thermal insulation,

[0019] - bonded asbestos waste, in non-friable form, also known as "asbestos- "cement or fiber cement."

[0020] Generally, flocking or thermal insulation waste is preferably chrysotile of formula [Mg3(Si2O5)(OH)4].

[0021] Chrysotile does not contain internalized iron in its chemical composition. Theoretically, however, iron may be present due to magnesium and silicon substitutions in the layers. Furthermore, chrysotile contains magnesium in its crystalline structure, which can be extracted to alter this asbestos waste.

[0022] Generally, fiber cement waste is amphibole-type asbestos waste, preferably amosite with the formula [(Fe2+Mg)7Si8O22(OH)2] or cro-cidolite with the formula [Na2Fe2+3(Fe2+Mg)3 Si8O22(OH)2]. Both of these types of amphiboles contain both magnesium and iron in their crystal structure.

[0023] These asbestos wastes can be of "native" or "heterogeneous" compositions.

[0024] Herein, "native" asbestos waste means "homogeneous" waste containing pure asbestos, that is, the pure mineral without any additional material in its structure. "Homogeneous" asbestos waste contains natural crystallized asbestos fibers.

[0025] The term "heterogeneous" asbestos waste is understood here to mean waste containing asbestos and other compounds, such as metals, gypsum, carbonates, particularly calcium carbonates found especially in cement. In sprayed coating materials, which are particularly friable and dangerous, asbestos is mixed with gypsum.

[0026] According to a particular embodiment, the asbestos-containing product is chosen from the group comprising flocking or thermal insulation waste or fiber cement waste.

[0027] According to another particular embodiment, the product comprising the asbestos may be a homogeneous asbestos waste or a heterogeneous asbestos waste.

[0028] More specifically, asbestos waste can be flocking waste, vinyl tiles, fiber cement containing mainly chrysotile and possibly containing amphiboles.

[0029] According to a preferred embodiment, the asbestos-containing product treated by the process described herein is asbestos-containing waste preferably chosen from the group consisting of flocking or thermal insulation waste or fiber cement, having a homogeneous or heterogeneous composition.

[0030] The process described herein makes it possible to transform asbestos waste, in particular by reducing the concentration of magnesium and / or iron until an altered waste consisting of a solid phase and a liquid phase is obtained. These two phases can be separated by any techniques known to those skilled in the art, in particular for the purpose of recovering value from each of them.

[0031] The solid phase of the altered waste, referred to as "solid altered waste," can subsequently serve as a base material for the manufacture of zeolite. Similarly, the liquid phase of the altered waste, referred to as "liquid altered waste," can be recovered, in particular through the recovery of iron and / or magnesium.

[0032] Herein, "altered solid waste" means asbestos waste whose crystalline structure is modified and disrupted because it is depleted or free of iron and / or magnesium following total or partial extraction by contacting the ground product containing asbestos, preferably the asbestos waste, with whey inoculated with lactic acid bacteria.

[0033] Herein, "altered liquid waste" means the liquid phase comprising the whey obtained after step b) of incubation in which the iron and / or magnesium extracted from the asbestos waste are found.

[0034] In other words, the altered waste obtained will contain a lower, or even zero, quantity of asbestos fiber compared to the quantity initially present in the asbestos waste before the implementation of the present process.

[0035] As mentioned above, the alteration of the product containing asbestos and preferably of the waste containing asbestos is obtained by grinding it and incubating the ground product with whey inoculated with lactic acid bacteria.

[0036] The term "grinding" as used herein refers to a mechanical treatment capable of transmitting mechanical energy to the ground asbestos-containing product. The grinding in step a) of the process could be carried out in any type of mill having the dimensions and mechanical characteristics necessary to safely grind the asbestos-containing product by reducing the fiber length and increasing the specific surface area. In particular, the grinding is carried out in a planetary ball mill (FRITSCH PULVERISETTE 6) or in a Retsch PM 100 planetary mill. Preferably, the mill is a Retsch PM 100 planetary mill.

[0037] Preferably, the grinding in step a) of the process is carried out in a planetary mill which grinds the asbestos-containing product for 10 minutes at 500 rpm. Those skilled in the art can adjust the grinding time and speed according to the type of asbestos-containing product being ground, its size, and its other physical characteristics.

[0038] When a product containing asbestos is ground, particularly when that product is fiber cement, the grinding preferably takes place in a liquid medium to prevent the dispersal of asbestos fibers and dust. Any liquid medium suitable for this purpose may be used. For example, this liquid medium may be water or a liquid waste from the food industry that allows the growth of lactic acid bacteria, such as sauerkraut juice or whey. Preferably, the liquid medium is whey.

[0039] Thus, according to a particular embodiment, the grinding in step a) is carried out by liquid medium, preferably in whey.

[0040] Here, "whey" (also called "lactoserum") refers to the residual liquid portion after milk coagulation. Whey is a yellowish-green liquid composed of approximately 94% water, sugar (lactose), protein, and very little fat. At the beginning of the cheesemaking process, milk is coagulated by the addition of rennet, by the acidifying action of lactic acid bacteria, or by chemical acidification. This results in the aggregation of the milk's casein micelles, forming a gel (or curd or coagulum). An aqueous liquid, called "whey," separates from the curd.This curdling step consists of separating the total milk proteins into two protein phases: the aqueous phase containing the whey or water-soluble milk proteins ([3-lactoglobulin, α-lactalbumin, serum albumin, lactoferrin, caseinomacropeptide) and the solid phase in which the hydrophobic casein has been retained (α-casein, [3-casein, para-K-casein). The whey used in the process described here is acidic whey with a pH generally between 3.5 and 4.5. In particular, the inventors used whey supplied by the company Alsace Lait.

[0041] The term "lactic acid bacteria" as used herein refers to unicellular, prokaryotic, heterotrophic, and chemoorganotrophic microorganisms. Lactic acid bacteria tolerate acidic pH and possess a strictly anaerobic or aerotolerant metabolism. Lactic acid bacteria, as understood here, have a fermentative metabolism. In particular, they produce lactic acid as the main metabolic product by fermenting sugars (glucose, fructose, mannose, galactose, sucrose, and lactose) in homofermentative bacteria, in addition to ethanol and CO2 in heterofermentative bacteria.

[0042] The term "lactic acid bacteria" refers in particular to bacteria from the families Aerococcaceae, Camobacteriaceae, Lactobacillaceae, Streptoccaceae, Enterococcaceae, Leuconostocaceae, and Bifidobacteriaceae. Preferably, the main lactic acid bacteria used here belong to the genera Lactobacillus, Lactococcus, Streptococcus, and Bifidobacterium, which are indigenous lactic acid bacteria found in the human digestive tract. More preferably, the lactic acid bacteria used in the present process belong to the genus Lactobacillus or Lactococcus. Even more preferably, these bacteria belong to the genus Lactobacillus. Even more preferably, the lactic acid bacteria used in the present process are Lactobacillus casei, Lactobacillus acidophilus, and Lactobacillus delbrueckii subsp.bulgaricus, Lactobacillus rhamnosus, Lactobacillus helveticus, Lactobacillus para-plantarum, Lactobacillus pentosus or Lactobacillus plantarum, preferably Lactobacillus plantarum. .

[0043] Thus, according to a preferred embodiment, the lactic acid bacteria used in the present process are bacteria with fermentative metabolism, in particular lactobacilli or lactococci, preferably Lactobacillus casei or Lactobacillus plantarum and more preferably Lactobacillus plantarum.

[0044] According to another embodiment, the process described here may include, prior to step b), a step of seeding (or inoculating) the whey with lactic acid bacteria.

[0045] This seeding (inoculation) step can be carried out before, in parallel or after step a) of grinding the product containing asbestos.

[0046] The inoculation step is carried out by culturing the lactic acid bacteria in a culture medium suitable for bacterial growth, in particular a culture medium that promotes the growth of lactic acid bacteria. Those skilled in the art will be able to select any suitable medium for the growth of lactic acid bacteria. Preferably, the culture medium is chosen from an MRS (Man, Rogosa, Sharpe Agar) medium, a rich medium of the LB (Luria Broth) type, or a minimal medium (MOPS), supplemented or not with glucose. More preferably, the culture medium is an MRS (Man, Rogosa, Sharpe Agar) medium.

[0047] The culture of lactic acid bacteria in the culture medium is carried out for a period of 20 to 30 hours, preferably 22 to 28 hours, more preferably 24 to 26 hours and even more preferably 24 hours.

[0048] The culture temperature of the lactic acid bacteria in the culture medium is a temperature favorable to bacterial growth. Preferably, this temperature is between 20°C and 40°C, more preferably between 25°C and 37°C, more preferably between 30°C and 35°C, and even more preferably, the incubation temperature is 30°C.

[0049] According to a preferred embodiment, the culture of lactic acid bacteria is carried out in an MRS medium, for 24 to 26 hours, preferably for 24 hours at a temperature between 30°C and 35°C, preferably at 30°C.

[0050] At the end of the culture period, the bacterial culture is centrifuged for a period of 3 to 10 minutes, preferably 5 to 7 minutes and more preferably for a period of 5 minutes.

[0051] The centrifugation speed can be between 1000 and 20000 g, preferably between 5000 and 10000 g and more preferably between 8000 and 10000 g.

[0052] According to a particularly preferred embodiment, the lactic acid bacteria are cultured in an MRS culture medium for 24 hours at 30°C and the culture is then centrifuged for 5 minutes.

[0053] After centrifugation, the pellet is washed, preferably in whey, and returned to suspension in whey. Washing, preferably washing in whey, can be carried out at least once, preferably 2 to 10 times, more preferably 2 to 8 times, and even more preferably 2 to 4 times.

[0054] The concentration of lactic acid bacteria in the whey inoculated with these bacteria is then adjusted by diluting the bacterial culture in whey and the optical density (OD) of the bacteria at a wavelength of 600 nm (OD600) was measured.

[0055] The term "optical density at 600 nm (OD600)" as used here refers to the measurement of bacterial growth by optical density at 600 nm. This measurement is based on the absorbance detection mode and essentially determines how much light passes through a sample of bacteria. Particles in solution scatter light, and the more particles (bacteria) there are in a suspension, the more light they scatter. Therefore, a replicating bacterial population increases light scattering and the measured absorbance values. At the same time, this means that the absorbance mode is used only to determine the extent of light scattering rather than measuring the physical absorbance of light energy by absorbing molecules. Thus, light scattering and the OD600 value can be directly related to the number of bacteria.

[0056] According to one embodiment of the process described herein, the optical density at 600 nm (OD600) of the lactic acid bacteria in the whey at the end of the seeding (inoculation) step is between 0.5 and 2, preferably between 1 and 1.5 and preferably is 1.

[0057] After the step of inoculating the whey with lactic acid bacteria, the inoculated whey is brought into contact with the asbestos-containing product. Preferably, this contact is made in whey so as to obtain a mixture containing the whey inoculated with lactic acid bacteria, the whey, and the ground asbestos-containing product. In this mixture, the ratio of the whey inoculated with lactic acid bacteria to the whey can be between 1 and 1000, preferably between 2 and 1000, and the quantity of asbestos waste can be between 0.1% and 10% of the total quantity of said mixture, preferably between 1% and 8% of the total quantity of said mixture. According to a particular embodiment, one part of inoculated whey is mixed with nine parts of whey and 1% of the ground asbestos-containing product.

[0058] According to a preferred embodiment, the concentration of lactic acid bacteria in the whey inoculated with lactic acid bacteria containing the ground product containing asbestos before incubation in step b) (i.e., at time T0 as shown in [Fig. 1]) is between 1105 and 1109 CFU / ml, preferably between 1106 and 1108 CFU / ml, and more preferably, is 1108 CFU / ml. Thus, the optical density of bacteria before step b) of incubation at DO600 is between 0.0001 and 1, preferably between 0.001 and 0.5, more preferably between 0.01 and 0.3, even more preferably between 0.05 and 0.1 and is more preferably 0.1.

[0059] The whey inoculated with lactic acid bacteria and comprising the ground product containing asbestos is then incubated in step b) of the process described herein.

[0060] According to a particular embodiment, the incubation in step b) is carried out for a period of 24 to 96 hours, preferably 30 to 80 hours and more preferably 72 hours. Preferably, this incubation is carried out at a temperature between 20°C and 40°C, preferably between 25°C and 37°C, more preferably between 30°C and 35°C and even more preferably, the incubation temperature is 30°C.

[0061] According to a preferred embodiment, the incubation step b) is carried out for a period of 30 to 80 hours at a temperature between 30°C and 35°C, preferably, the incubation step b) is carried out for a period of 72 hours at 30°C.

[0062] According to one embodiment, the incubation in step b) is carried out under agitation at a speed between 10 and 600 rpm and preferably between 100 and 400 rpm.

[0063] The incubation step b) can be carried out in a bioreactor, preferably in a Global Process Concept, Laval Lab or AD Biotec type bioreactor.

[0064] As stated above, the present inventors have demonstrated that the products of lactic acid bacteria metabolism lower and stabilize the pH of whey, which is increased following the dissolution of magnesium oxides during asbestos alteration, thereby reducing the alteration. Consequently, maintaining a strongly acidic pH during step b) of incubation improves the efficiency of asbestos alteration in the product containing it.

[0065] Thus, according to a particular embodiment, the pH of the whey containing the lactic bacteria and the ground product containing asbestos in step b) is between 2.5 and 4.5, preferably between 3 and 4 and even more preferably, the pH is 3.7.

[0066] At the end of step b) of incubation which is in particular a bacterial growth step, the concentration of bacteria is at least 1xlO9 CFU / rnl.

[0067] The incubation step b) can be repeated to improve the efficiency of asbestos alteration. Preferably, step b) is repeated at least once, at least twice, at least three times, at least four times, at least five times, at least six times, at least seven times, at least eight times, at least nine times, at least ten times; more preferably, the incubation step b) is repeated between 2 and 10 times, and more preferably between 4 and 6 times.

[0068] In the event that the incubation step is to be repeated at least once, it is preferable, before the new incubation step, to dilute the whey obtained at the end of the The first incubation stage. In fact, this whey contains lactic acid bacteria at a higher concentration than that in the whey before incubation, dissolved iron and magnesium resulting from the deterioration of the asbestos, and may also contain traces of the unaltered asbestos-containing product. To prevent saturation of the whey due to the increased bacterial concentration during incubation stage b) and the increased concentration of dissolved iron and magnesium, it is necessary to dilute the whey obtained at the end of incubation stage b) before subjecting it to any further incubation. This dilution is necessary because it prevents the whey inoculated with lactic acid bacteria at the end of incubation stage b) from becoming saturated and thus reduces its capacity to deteriorate unaltered asbestos.The purpose of this dilution is, in particular, to reduce the concentration of lactic acid bacteria and thus avoid a phase of bacterial lysis which would lead to a decrease in the products synthesized during bacterial metabolism, especially organic acids, and consequently, to an increase in the pH of the whey.

[0069] The dilution prior to the next incubation step is carried out by gentle centrifugation for approximately 3 to 10 minutes, preferably 5 minutes, of the whey obtained at the end of incubation step b). This centrifugation aims to separate the asbestos from the lactic acid bacteria and thus release them for a new growth cycle during the next incubation step. After this centrifugation, a portion of the supernatant is recovered and whey is added to the remaining fraction. The step of separating the bacteria from the asbestos by centrifugation can be repeated at least once more, preferably between 1 and 4 times under the same centrifugation conditions. Each time, a portion of the supernatant is recovered and whey is added to the remaining fraction.After this (these) centrifugation(s), the remaining fraction (containing the whey, lactic acid bacteria, and unaltered asbestos residues) and the most recently added whey are subjected to a further centrifugation step lasting between 20 and 40 minutes, more preferably between 25 and 35 minutes, and even more preferably 30 minutes. At the end of this further centrifugation step, the supernatant is completely removed, and whey is added to the pellet to obtain a mixture of whey inoculated with lactic acid bacteria and unaltered asbestos residues ([Fig. 2]). The concentration of lactic acid bacteria in this mixture is the same as that described above for the bacteria in the whey inoculated with lactic acid bacteria comprising the ground-up product containing asbestos before being subjected to the first incubation in step b).

[0070] Thus, according to one embodiment, step b) of the process is repeated at least once, preferably between 2 and 10 times, and more preferably between 4 and 6 times, said process optionally comprising one or more steps of dilution of whey containing lactic acid bacteria and the product containing crushed asbestos.

[0071] According to a particular embodiment, the process for treating the asbestos-containing product results in the reduction of iron and / or magnesium contained in the asbestos. This reduction consists of extracting at least some of the iron and / or magnesium that are present on the surface of the asbestos product or that are internalized in its crystalline structure. Advantageously, all of the iron and / or magnesium is extracted from said asbestos product.

[0072] According to another embodiment of the process, the quantity of iron and / or magnesium in the asbestos-containing product can be determined before the process is carried out using various methods (ICP-AES, atomic absorption spectrometry). This determination gives the "initial quantity" of iron and / or magnesium present in the asbestos product before the process described herein is carried out.

[0073] After completion of step b) of incubation of the whey inoculated with lactic acid bacteria and of the ground product containing asbestos, the amount of iron and / or magnesium possibly remaining in the product containing asbestos can be determined by determining the amount of iron and / or magnesium in the whey. The measurement of this amount is generally carried out in the supernatant obtained after centrifugation of the whey at the end of incubation step b).

[0074] The quantities of iron and / or magnesium can be measured after a single incubation step, after each incubation step if incubation step b) is repeated more than once, or after two or more successive incubation steps.

[0075] Preferably, the concentration (quantity) of iron and / or magnesium is measured in real time. As understood here, "measure in real time" means that several measurements of the same sample are taken over a predetermined period of time (measurement period) in order to provide a record of the change in concentration over time with temporal resolution. This measurement period can last from 20 min to 180 min, preferably from 20 min to 60 min, and more preferably from 15 min to 40 min. Depending on the length of the measurement period, each sample can be measured 20 to 200 times, more preferably 20 to 75 times, and more preferably 15 to 50 times.

[0076] Thus, according to a particular embodiment, the process may further include a step c) of real-time determination of the concentration of iron and / or magnesium released by the asbestos-containing product in the whey of step b).

[0077] The difference in the concentration of iron and / or magnesium measured before implementation of the process and after step b) of incubation will account for the amount of iron / and / or magnesium reduced in the asbestos-containing product during implementation of the process.

[0078] According to a particularly preferred embodiment, the process described in this application is a process for treating a product containing asbestos comprising the following steps:

[0079] a) the grinding of the product containing asbestos,

[0080] b) the incubation of said ground product in step a) with whey inoculated with lactic acid bacteria, in which process:

[0081] - the grinding in step a) is carried out in a liquid medium, preferably in whey;

[0082] - prior to step b), a step of inoculating the whey with lactic acid bacteria is produced;

[0083] - the concentration of lactic acid bacteria in the whey containing the crushed product containing asbestos before incubation in step b) is between IxlO5 and IxlO9 CFU / ml, preferably between IxlO6 and IxlO8 CFU / ml and more preferably is IxlO8 CFU / ml;

[0084] - the pH of the whey containing the lactic acid bacteria and the crushed product containing the asbestos at step b) is between 2.5 and 4.5, preferably between 3 and 4 and even more preferably, the pH is 3.7;

[0085] - the incubation period in step b) is 24 to 96 hours, preferably 30 to 80 hours and, more preferably, 72 hours;

[0086] - step b) is repeated at least once, preferably between 2 and 10 times, and in a way more preferred between 4 and 6 times, the said process may also optionally include one or more steps of dilution of the whey containing lactic bacteria and the ground product containing asbestos;

[0087] - a step c) of real-time determination of the concentration of iron and / or magnesium released by the ground product containing asbestos in the whey of step b) is carried out;

[0088] - the ground product containing asbestos is a selected asbestos-containing waste preferably from the group consisting of flocking or insulation waste or fiber cement, having a homogeneous or heterogeneous composition, and

[0089] - lactic acid bacteria are bacteria with fermentative metabolism, in particular lactobacilli or lactococci, preferably Lactobacillus casei or Lactobacillus plantarum and more preferably Lactobacillus plantarum.

[0090] The present process will be described in more detail by means of the examples and figures below. These examples are provided here by way of illustration and are not, unless otherwise indicated, intended to be limiting. FIGURE CAPTIONS

[0091] [Fig. 1]: Diagram of the experimental protocol used for the preparation of the bacterial inoculum.

[0092] [Fig.2]: Schematic of the sample treatment including lactic acid bacteria, the whey and the product containing asbestos, after a 72-hour bacterial growth cycle.

[0093] [Fig. 3]: Kinetics of iron and magnesium extraction from flocsing waste during 96 h in the presence of whey with or without the addition of Lactobacillus plantarum. Error bars are standard errors on the mean of 3 replicates.

[0094] [Fig. 4]: Extraction of iron and magnesium from flocsing waste after 72-hour cycles in the presence of whey with the addition of Lactobacillus plantarum. Error bars are standard errors on the mean of 3 replicates.

[0095] [Fig. 5]: Kinetics of iron and magnesium extraction from ground fiber cement roof tile waste over 96 h in the presence of whey with or without the addition of Lactobacillus plantarum. Error bars are standard errors on the mean of 3 replicates.

[0096] [Fig. 6]: Extraction of iron and magnesium from crushed fiber cement roof tile waste after 72-hour cycles in the presence of whey with the addition of Lactobacillus plantarum. Error bars are standard errors on the mean of 3 replicates.

[0097] [Fig.7]: Percentage of iron and magnesium extracted from flocking waste (A) and crushed fiber cement roof tiles (B) after 4 cycles of 72 h in the presence of whey incubated in the presence of Lactobacillus plantarum.

[0098] [Fig.8]: Transmission electron microscopy (TEM-EDX) mapping of chrysotile fibers present in untreated (A) or altered fiber cement waste after 4 cycles of 72 h in the presence of whey inoculated with Lactobacillus plantarum (B). Mg / Si ratio of the different zones (entire zone and zones 1, 2 and 3 (chosen to allow a better representation of the analyzed sample) of the sample) of the mapping (C). EXAMPLES I. Materials and methods 1.1. Preparation of asbestos waste

[0099] For the implementation of the process, the following asbestos waste was used: - flocking waste and fiber cement pipe waste: obtained from an asbestos removal site at the University of Paris-Jussieu and supplied by the company SOMEZ, and - Fiber cement roof tile waste: supplied by the company CEFASC Environnement.

[0100] The asbestos waste was ground up (with the exception of flocking waste) and sterilized.

[0101] The grinding of the fiber cement samples was carried out for 10 min at 500 rpm The material was ground in a Retsch PM 100 planetary ball mill (grinding carried out at the Charles Gerhardt Institute in Montpellier). Next, 0.2 g of asbestos sample—either ground fiber cement or sprayed-on waste—was collected. The samples were then autoclaved for 20 minutes at 121°C and subsequently incubated for 14 days at 70°C to sterilize them.

[0102] 1.2. Preparation of the starting bacterial inoculum and the sample to be tested

[0103] Lactobacillus plantarum lactic acid bacteria (accession number in the National Collection of Microorganism Cultures (CNCM) no. ATCC 14917) and bovine whey (provided free of charge by the company Alsace Lait) were used.

[0104] First, the lactic acid bacteria were cultured in MRS (Man, Rogosa, Sharpe) agar for 24 hours at 30°C. Next, the bacterial culture was centrifuged (5 min / 9871 g) and washed twice in 5 ml of whey. After washing, the pellet was resuspended in 10 ml of whey and then diluted 1 / 10 in whey to measure the optical density (OD) of the bacteria at a wavelength of 600 nm. After this measurement, the OD600 was adjusted to 1.

[0105] Once the bacterial culture was obtained, 2 ml of it were mixed with 18 ml of whey and 0.2 g of asbestos. The bacterial concentration in this mixture was 0.1 OD600 (or approximately 1108 CFU / ml). This mixture (comprising the whey inoculated with lactic acid bacteria + the added whey and the asbestos waste) was incubated at 30°C with shaking (220 rpm).

[0106] Fig. 1 schematically illustrates the steps described above. 1.3. Iron dosage

[0107] After 72 hours of incubation (time required for the growth cycles of the lactic acid bacterium Lactobacillus plantarum) of the mixture containing the lactic acid bacteria, whey and asbestos waste, a colorimetric determination of iron was carried out from this mixture (sample).

[0108] To this end, 40 pL of saturated sodium acetate (Sigma) (5.5 M) were added to 20 µL of sample (3 replicates per sample). Then, at room temperature, 80 pL of double-distilled water and 10 pL of thioglycolic acid diluted 10 times in distilled water were added. The resulting mixture was then stirred, and 10 pL of 0.5% bathophenantroline in double-distilled water were added, followed by further stirring. The final mixture was left to stand overnight at 4°C, protected from light, and then placed in a microplate. The reading was performed at 535 nm in a Tecan Infinité M200 microplate reader. 1.4. Magnesium dosage

[0109] As with the iron assay, after 72 hours of incubation of the mixture containing the lactic acid bacteria, whey and asbestos waste, a colori- The metric of magnesium was made from this mixture (sample).

[0110] To do this, 300 pL of a mixture consisting of the following were added to 3 µL of sample (3 replicates per sample): - 1 volume of reagent 1 (1 mol / L 2-methyl-2-Amino-l-Propanol and 215 pmol / L EGTA), and - 1 volume of reagent 2 (300 pmol / L calmagite).

[0111] This mixture is left to stand for 30 seconds before being deposited onto a reading microplate. The reading is performed at 500 nm in a Tecan Infinité M200 microplate reader. 1.5. pH Measurement

[0112] In addition to iron and magnesium concentrations, the pH of samples containing lactic acid bacteria, asbestos waste, and whey was measured after 72 hours of incubation to determine whether bacterial metabolism maintains or even increases the acidity of the sample. The pH was measured using a pHenomenal® IS 2100L pH meter.

[0113] 1.6. Bacterial growth cycle and asbestos deterioration

[0114] The inventors performed several determinations of iron and magnesium concentrations by repeating the bacterial growth cycles approximately 4 times. At each growth cycle, an iron and magnesium concentration was determined and the pH of the sample was measured.

[0115] Before repeating a growth cycle, the whey obtained at the end of the incubation step was centrifuged (30 min / 9871 g). All of the supernatant was used for iron and magnesium determination, and 40 ml of whey was added to the remaining pellet, which was then subjected to a new incubation (growth cycle). Before starting the incubation step, the mixture was subjected to gentle centrifugation (5 min / 67 g) to separate the asbestos and lactic acid bacteria, thus releasing them for a new growth cycle. After this centrifugation, 30 ml of the supernatant was collected and discarded, and then 30 ml of the whey was added to the remaining mixture. This step of separating the bacteria from the asbestos was repeated once more under the same centrifugation conditions.Next, 30 ml of the supernatant were collected and discarded, and the remaining mixture was subjected to a further, faster and longer centrifugation step (30 min / 9871 g) than the previous one. At the end of this centrifugation, the supernatant was completely removed, and 20 ml of whey were added to obtain a mixture that was then subjected to a new bacterial growth cycle.

[0116] After a 72-hour growth cycle, the organic acids produced during the alteration of asbestos waste were quantified by the AERIAL technology resource center using the Nuclear Magnetic Resonance technique. (NMR).

[0117] The treatment of the sample after a growth cycle is schematically illustrated in [Fig.2].

[0118] 1.7. Alteration kinetics of asbestos waste in the presence of whey with or without the addition of lactic bacteria

[0119] The inventors monitored the alteration kinetics of asbestos waste in the presence of whey with Lactobacillus plantarum. To do this, the same operational scheme as that shown in [Fig. 1] was followed to obtain a sample comprising a mixture of whey, whey-inoculating bacteria, and asbestos waste.

[0120] A second sample containing only whey and asbestos waste was also prepared.

[0121] 400 pl of each of these two samples were taken every 24, 48, 72 and 96 hours. The collected samples were then filtered with a Millex filter (0.22 µm) and iron and magnesium were measured. The pH was measured at the end of the kinetic analysis. II. Results

[0122] II. 1. Alteration of flocking waste by whey inoculated with Lactobacillus plantarum

[0123] An extraction kinetics study comparing the alteration efficiency of flocsing waste in the presence of whey with or without L. plantarum was performed ([Fig. 3]). The results show a significant increase in iron and magnesium extraction between 24 and 96 h in the presence of L. plantarum (3.48 to 8.93 mg / L for iron and 68 to 132 mg / L for magnesium) compared to the test without bacteria (1.78 to 2.64 mg / L for iron and 32 to 52 mg / L for magnesium). After 96 h of incubation in the presence of L. plantarum, iron and magnesium extraction is approximately three times greater than with whey without bacteria. This strong extraction measured during the kinetics is linked to a strong decrease in pH in the presence of L. plantarum (pH=3.85) whereas in the presence of whey without bacteria the pH increases (pH=5.28).

[0124] The optimum duration of whey extraction in the presence of L. plantarum is approximately 96 h.

[0125] To confirm the effectiveness of the whey-lactic acid bacteria mixture, the inventors carried out four 72-hour bacterial growth cycles with whey renewal to allow the growth of L. plantarum in each cycle. The results in [Fig. 4] show a strong extraction of iron (9.22 to 1.17 mg / L) and magnesium (91 to 19 mg / L), which decreases from T72-1 to T72-4. The decrease in dissolution is progressive during the alteration cycles in the presence of L. plantarum, linked to the acidic and stable pH during the experiment, which homogeneously and progressively alters the asbestos fibers. Table 1 below presents the pH measurements after each growth cycle of Lactobacillus plantarum in whey in the presence or absence of asbestos waste.

[0126] [Tables 1] pH Whey + Lactobacillus Fiber cement + whey + Lactobacillus plantarum Flocking + whey + Lactobacillus plantarum T72HI 3.58 3.86 3.69 T72H II 3.72 3.49 3.48 T72H III 4.02 3.72 3.68 T72H IV 4.03 3.80 3.75

[0127] Although the four bacterial growth cycles carried out allow the extraction of significant quantities of iron and magnesium, additional cycles can be carried out to obtain a complete extraction of these elements and thus an optimal alteration of the flocking waste.

[0128] n.2. Alteration of fiber cement roof tile waste by whey inoculated with Lactobacillus plantarum

[0129] Fiber cements were altered with whey in the presence of L. plantarum to verify whether the sharp increase in pH could be compensated by the addition of this bacterium. This method was therefore tested on samples of fiber cement roof tiles composed of chrysotile fibers and a cementitious matrix.

[0130] The inventors initially compared whey extraction with and without L. plantarum ([Fig. 5]). After 96 h of incubation, the presence of L. plantarum resulted in the extraction of 200 times more iron and 30 times more magnesium than in the absence of bacteria. As before, this high extraction rate is linked to a significant decrease in pH in the presence of L. plantarum (pH=3.7), whereas in the presence of whey without bacteria, the pH increases (pH=5.7).

[0131] Between 24 and 96 h of incubation, the amount of iron and magnesium extracted increases in the presence of L. plantarum (22 to 59 mg / L for iron and 57 to 93 mg / L for magnesium), while in the presence of whey without bacteria, the extraction tends to decrease (1.37 to 0.26 mg / L for iron and 4 to 3 mg / L for magnesium) over time. This decrease could be due to precipitation of the elements linked to the increase in pH during the kinetics. After 72 h of incubation, a plateau is reached, indicating that the optimal extraction time is 72 h.

[0132] In order to determine the extraction limit of this pathway on fiber cement roof tile waste, four 72-h renewal cycles were carried out in the presence of whey and L. plantarum ([Fig. 6]). After the first 72-h cycle, a high extraction of iron (68 mg / L) and magnesium (299 mg / L) was observed. This extraction The concentration drops sharply during the cycles, reaching 2.3 mg / L for iron and 14 mg / L for magnesium at T72-4. Iron and magnesium extraction drops abruptly after the first cycle, T72-1, for asbestos cement. With flocking waste, this extraction decreases more gradually. The inventors concluded that this is due to the fact that the asbestos cement waste was ground before biological treatment. These results thus demonstrate the importance of grinding in the efficiency of asbestos waste alteration.

[0133] The results discussed above show that inoculation of whey with L. plantarum leads to high iron and magnesium extraction for both waste materials, flocculants and asbestos cement. After long-term alteration, very high extraction yields were obtained for asbestos cement waste, with 86% iron and 100% magnesium extracted ([Fig. 7]), which is extremely interesting given that asbestos cement represents 80% of the asbestos waste to be managed.

[0134] To validate the degradation, transmission electron microscopy (TEM-EDX) mapping of the altered fibers showed a magnesium / silica ratio of 0 to 0.5, whereas it is 1 to 1.5 in untreated fibers ([Fig. 8]). This significant difference in the Mg / Si ratio is a key parameter that demonstrates the dissolution of the elements present in the chrysotile fiber. Regarding the flocking waste, extraction yields of 47% for iron and 34% for magnesium were obtained, lower yields that could be improved by grinding this waste and / or continuing the alteration cycles.

[0135] II.3. Production of organic acids by Lactobacillus plantarum in the presence asbestos waste

[0136] The results presented above showed that the pH of the whey decreased and remained stable in the presence of L. plantarum and asbestos waste. The solutions after treatment were analyzed by the AERIAL technology resource center, which used Nuclear Magnetic Resonance (NMR) to determine and quantify the organic acids produced.

[0137] The production of organic acids was verified under the following different conditions: i) whey before treatment ii) whey in the presence of L. plantarum after 72 h of incubation iii) whey in the presence of L. plantarum with flocking waste or fiber cement (roof tile) after 72 h of incubation. The results are presented in Table 2 below.

[0138] [Tables2] Concentration (mM) lactate acetate succinate citrate Whey 85.5 4.9 0.72 10.7 Whey + L. plantarum 130 11.4 0.71 6.8 Whey + L. plantarum + CHR-GY 199.8 11.4 1.11 nd Whey + L. plantarum + Fibro 261.9 10.9 2.20 ndnd: not determined; CHR-GY: chrysotile + gypsum; Fibro: fiber cement roof tile.

[0139] These results show that a higher concentration of lactate (130 mM) and acetate (11.4 mM) is found in whey in the presence of L. plantarum, without asbestos, compared to the concentrations found in whey before treatment (85.5 mM lactate and 4.9 mM acetate). In the presence of L. plantarum and asbestos, lactate, acetate, and succinate are found in greater quantities compared to whey alone. In the presence or absence of asbestos, the solutions have the same amounts of acetate (10.9 to 11.4 mM).

[0140] The concentration of lactate and succinate is, however, higher in the presence of asbestos, with differences depending on the type of waste. In the presence of sprayed asbestos waste, 199.8 mM of lactate and 1.11 mM of succinate are measured, while in the presence of asbestos cement, the concentrations are 261.9 mM and 2.20 mM of lactate and succinate, respectively. The presence of asbestos therefore stimulates the production of organic acids by L. plantarum, but differently depending on the type of waste. This can be explained by the release of magnesium present in this waste. Since a greater quantity of magnesium is released in the presence of asbestos cement, the production of organic acids is thus stimulated more strongly than in the presence of sprayed asbestos waste.

[0141] In conclusion, it appears from the experimental results presented below that the process described here does indeed alter asbestos in a product containing it, particularly because the metabolic action of the lactic acid bacteria inoculating the whey maintains its acidic pH throughout the alteration process, a process which is further facilitated by grinding the asbestos-containing product. BIBLIOGRAPHICAL REFERENCES

[0142] Amouzou, K.-S., Prévost, H., and Divies, C. (1985) Influence of supplementation Magnesium in milk affects lactic fermentation carried out by S. lactis and S. thermophilus. Le Lait 65: 21-34.

[0143] Damien, A. (2016) Guide to waste treatment - 7th ed.: Regulations and choice of processes, Dunod.

[0144] Spasiano, D., Luongo, V., Petrella, A., Alfè, M., Pirozzi, F., Fratino, U., and Piccinni, A.F. (2017) Preliminary study on the adoption of dark fermentation as pre-treatment for a sustainable hydrothermal dénaturation of cement-asbestos composites. J CleanProd 166: 172-180.

[0145] Stanik et al (2006) : “Destruction of the chrysotile asbestos structure with a population of bacteria Lactobacillus casei and Lactobacillus plantarum”, FEB, Volume 15 -No 7, 2006

[0146] Weber, K.A., Achenbach, L.A., and Coates, J.D. (2006) Microorganisms pumping iron: anaérobie microbial iron oxidation and réduction. Nat Rev Microbiol 4: 752.

[0147] Werner, A.J., Hochella, M.F., Guthrie, G.D., Hardy, J.A., Aust, A.E., and Rimstidt (1995) Asbestiform riebeckite (crocidolite) dissolution in the presence of Fe chelators: Implications for mineral-induced disease. Am Minerai 80: 1093-1103.

[0148] EP2428254

[0149] WO2015 / 166359

Claims

Claims

1. A method of treating a product containing asbestos, characterized in that it comprises the following steps: a) grinding the product containing asbestos, b1) seeding the whey with lactic acid bacteria b) incubating said product ground in step a) with whey seeded with lactic acid bacteria.

2. Method according to claim 1, characterized in that the grinding in step a) is carried out in a liquid medium, preferably in whey.

3. Method according to any one of claims 1 or 2, characterized in that the concentration of lactic acid bacteria in the whey containing the ground product containing asbestos before incubation in step b) is between IxlO5 and IxlO9 CFU / ml, preferably between IxlO6 and IxlO8 CFU / ml and more preferably is IxlO8 CFU / ml.

4. Method according to any one of claims 1 to 3, characterized in that the pH of the whey containing the lactic bacteria and the ground product containing asbestos in step b) is between 2.5 and 4.5, preferably between 3 and 4 and even more preferably, the pH is 2.7

5. 3, / . Method according to any one of claims 1 to 4, characterized in that the incubation time in step b) is 24 to 96 hours, preferably 30 to 80 hours and more preferably 72 hours.

6. Method according to any one of claims 1 to 7, characterized in that step b) is repeated at least once, preferably between 2 and 10 times, and more preferably between 4 and 6 times, said method possibly further comprising optionally one or more steps of dilution of the whey containing lactic bacteria and the ground product containing asbestos.

7. Method according to any one of claims 1 to 6, characterized in that it further comprises a step c) of real-time measurement of the concentration of iron and / or magnesium released by the ground product containing asbestos in the whey of step b).

8. A method according to any one of claims 1 to 7, characterized in that the ground product containing asbestos is a waste containing asbestos preferably chosen from the group consisting of flocking or insulation waste or fiber cement, having a com-

9. homogeneous or heterogeneous position. Method according to any one of claims 1 to 8, characterized in that the lactic acid bacteria are bacteria with fermentative metabolism, in particular lactobacilli or lactococci, preferably Lactobacillus casei or Lactobacillus plantarum and more preferably Lactobacillus plantarum.

Images