EP0663948A1

EP0663948A1 - Novel biodegradation additive

Info

Publication number: EP0663948A1
Application number: EP93919407A
Authority: EP
Inventors: Anne Basseres; Patrick Chemin Du Pont-Long Eyraud; Alain Ladousse
Original assignee: Societe National Elf Aquitaine
Current assignee: Societe National Elf Aquitaine
Priority date: 1992-08-31
Filing date: 1993-08-27
Publication date: 1995-07-26
Also published as: AU4964993A; JPH08501935A; WO1994005773A1; US5618725A; FR2695138A1; CA2143624A1

Abstract

Biodegradation additive characterized in that it consists of a mixture of (i) at least one assimilable nitrogen source composed of at least one unsubstituted or substituted amino acid; (ii) at least one phosphorus source, the ratio of nitrogen to phosphorus ranging from 2 to 100, said additive being subjected to a treatment to make it oleophilic. The invention also concerns an additive in accordance with any of the foregoing claims for the biodegradation of hydrocarbons.

Description

NEW BIODEGRADATION ADDITIVE

The present invention relates to a new biodegradation additive and its application for the treatment of environments soiled by hydrocarbons, by acceleration of natural biodegradation.

There are many methods using cultures of microorganisms, which are developed under controlled conditions (in reactors for example) and then applied to the medium to be treated. But these methods are not effective when it comes to working in an open environment. There are indeed problems related to the dilution of microorganisms in the natural environment, and competition problems with native microorganisms much better suited to the environment considered. This is why we turned to the solution in which we stimulate the native micro-organisms by providing them with nutrients necessary for their development and which are limiting in the natural environment. Also, we have proposed nutritional additives which are added to the medium to be treated. These additives can be fertilizers of the type used in agriculture, or synthetic protein products, or even bacterial lyophilisates with the nutrient. These products meet the carbon, nitrogen and phosphorus needs of bacteria. The particular needs of microorganisms for nitrogen and phosphorus correspond to a variable N / P molar ratio to a large extent, without appreciable alteration in efficiency. In addition to nitrogen and phosphorus, these additives contain assimilable carbon. This assimilable carbon is contained in hydrocarbon molecules whose chain is similar to a chain aliphatic which one meets in hydrocarbons. Furthermore, these products serve as a "starter", that is to say that they promote the reaction in the first moments.

The availability of nutrients is also an important problem, since this conditions the kinetics of degradation of hydrocarbons. In order to accelerate this kinetics, various solutions have been proposed, which consist in mixing the nutrients with various additives and in forming suspen¬ sions, and especially emulsions. FR-A-2 490 672 describes microemulsions in which the nutritive substances are in an aqueous solution which is microemulsified in a lipomiscible liquid. However, this technique involves the step of forming the microemulsion and requires the presence of additives such as surfactants and the like, which are expensive. FR-A-2,512,057 describes an improvement to the solution proposed in the aforementioned patent, which consists in providing the source of nitrogen in the form of a dual system comprising two chemically different kinds of nitrogenous compounds. A preferred system is a system consisting of urea and amino acids. Furthermore, this patent teaches that amino acids alone are not as effective as the dual system. This dual system is also a microemulsion, it suffers from the same drawbacks as any (micro) emulsion.

However, these synthetic additives present toxicity problems, due to the presence of derivatives, such as for example butoxyethanol, and other similar products.

So we are looking for natural products as additives; but the problem is that these products do not contain carbon in a form close to an aliphatic group of the type of those present in hydrocarbons and, therefore, are not liable to lead to a choke effect. Furthermore, additives are sought which can be used without requiring a (micro) emulsion or the use of expensive additives. O is also aware of the use of animal meal as a nutrient for microorganisms, these being in aqueous solution or suspension.

Biosis Previews Databan. Philidelphia, Biosis Number: 83042449, GA Kochkina et al .: "Development of a Nutrient Médium for Cultivating Ntomophthora-Thaxteriana"& Biotekhno- logiya, vol. 4, 1986, pages 46-51, describes the use of fishmeal as a nutrient for the culture of a microorganism, for example Entomophthora-Thaxteriana fungi.

Biosis Previews Databank, Philadelphia, Biosis Number: 70050436, M. Rusan et al .: "Influence of Animal Proteins on the Fermentation of Antibiotics" & Bol Soc Broteriana 52, vol. 0, 1978, (Recd. 1979), pages 29-36, describes the use of meat and blood meal as a source of nitrogen for the production of antibiotics from fungi-type microorganisms.

Biosis Previews Databank, Philadelphia, Biosis Number: 70043472, 0. Yagi et al .: "Degradation of Poly Chlorinated Bi Phenyls by Microorganisms" & J. ater Pollut Control Fed 52, vol. 5, 1980, pages 1035-1043, describes the use of micro¬ organisms for combating pollution, the meat extract being added to the culture medium.

However, there is no indication that these same flours can also be used in a medium contaminated by a hydrocarbon, that is to say as different as a simple aqueous medium.

Surprisingly, the Applicant has found that the additive according to the present invention meets all the requirements stated above.

Thus, the subject of the present invention is a biodegradation additive characterized in that it consists of a mixture comprising:

(i) at least one assimilable nitrogen source consisting of at least one amino acid, unsubstituted or substituted; (ii) at least one source of phosphorus; according to an N / P ratio of between 2 and 100; said additive having been subjected to a treatment aimed at making it oleophilic. By biodegradation, is meant degradation by a microorganism, present in situ or reported. This application can therefore be carried out in an open environment in the presence of an indigenous bacterial flora, or on soils in the presence of a specific bacterial flora added, if that in presence is judged insufficient.

The microorganism used can be a yeast, a fungus, a bacterium; in fact any micro-organism capable of degrading a hydrocarbon is appropriate. By way of non-limiting example, mention may be made of Pseudomonas, Acitenobacter, Flavobacterium, Artrobacter, Corynebacterium.

By assimilable nitrogen is meant the nitrogen effectively metabolized by the micro-organism during degradation. This treatment, aimed at making the additive oleophilic, can be a conventional treatment. By way of example, mention may be made of: acylation, esterification, grafting of a long radical onto different groups, transformation by Schiff base, formation of carbamate. in the presence of isocyanate and the like. Preferably, the treatment consists of acylation. The carbon chain of the acyl group is preferably a fatty chain; advantageously, an acid chloride, in particular laurylic acid, is used.

The amino acids which can be used within the framework of the present invention can be any amino acid, natural or close synthetic acids such as ornitine, and the like. These amino acids can be unsubstituted or substituted. When substituted, the substituent is an alkyl, lower alkoxy, hydroxy and the like. Preferably, the amino acid is chosen from the group consisting of: lysine, methionine, cystine, threonine, tryptophane, hydroxylysine, hydroxyproline, and mixtures thereof.

Preferably, the assimilable nitrogen source represents at least 5% by weight of the total weight of said biodegradation additive.

According to an embodiment of the present invention, the assimilable nitrogen source is found in proteins representing at least 50% by weight of the total weight of said additive.

Any source of phosphorus, both natural and synthetic, is appropriate.

Preferably, the source of phosphorus is an inorganic salt of phosphorus.

Advantageously, said N / P ratio is between 4 and 40, preferably is equal to about 16.

According to an embodiment of the present invention, the additive consists of animal meal.

Alternatively, the flour is fish meal. According to another variant, the flour is a meat meal. Fish or meat meal is obtained by any conventional manufacturing process. By way of example, mention may be made of the following process for meat meal: skinning of corpses, grinding of the latter, calibration, preheating, draining, drying, press and final grinding. By way of example for fishmeal, the following process may be cited: shredding, cooking, press, mixing with a concentrated press juice, drying, sieving, and final grinding. The composition of these flours can vary to a large extent; as a representative but non-limiting example, compositions for various flours are given below. Fishmeal: proteins: 60 to 85% of which main amino acids: lysine, methionine, threonine. fat: 3 to 25%. mineral matter (phosphorus, calcium, chlorides): 5 to 24%, Meat meal: protein: 60 to 85% of which main amino acids: lysine, threonine, hydroxy-proline. fat: 2 to 7%. mineral matter (phosphorus, calcium, chlorides): 7 to 28%,

The use of additives according to the present invention, in particular animal meal, such as meat or fish meal, is therefore useful for the biodegradation of hydrocarbons on soils, sediments and on the surface of water. The sediments contaminated by hydrocarbons can come from accidental discharges of hydrocarbons or not, such as cleaning of basins, pavement, grounds, ... This use is just as adapted and profitable, in the case of treatment in closed environments, such as reactors, quagmire, storage of hydrocarbons and others.

The proportion of additive relative to the hydrocarbon is variable. The mass ratio [additive] / [hydrocarbons] is generally between 3 and 30. Preferably, the mass ratio is equal to approximately 10.

The present invention also relates to the use of the present additives for the biodegradation of hydrocarbons. The following examples illustrate the invention in more detail. EXAMPLES COMPOSITION OF ADDITIVES

The composition of the biodegradation additives is given in the table below.

Products% Nitrogen% Phosphorus N / P% Carbon ⁽ P ⁾

. fish meal ₅ (Solatlante G)

. meat meal 60% .... (from Viandor extraction)

. meat meal 70%

(Viandor extraction creton

. meat meal 80% Q (Viandor extraction creton)

These flours have the following average analytical characteristics.

5

0

5

The present invention is illustrated in more detail in the following examples given by way of illustration but not limitation.

Figures 1 and 2 show the evolution of the ammonia nitrogen contents in tanks and reactors with acylated flour or not.

Figures 3 and 4 show the evolution of orthophosphate contents in tanks and reactors with acylated flour or not. Figures 5 and 6 show the release of nitrogen in the reactors with acylated flour or not.

Figures 7 and 8 show the release of phos¬ phore in the reactors with acylated flour or not.

FIGS. 9 and 10 represent the temporal evolution of the total bacterial flora and specific hydrocarbon in the presence of non-acylated flour and acylated flour.

FIG. 11 represents the evolution of the indices of bio-degradation of the alkanes for the two experiments: in the presence of acylated flour or not. Figures 12 and 13 represent the temporal evolution of total bacterial flora and specific hydrocarbons in the three basins: control, with non-acylated flour and with acylated flour.

FIG. 14 represents the composition of the crude samples recovered in the 3 basins, at TO, and at 42 days: alkane, aromatic, asphaltene and resin fraction.

Figures 15 to 18 are the alkane fraction chromatograms for, respectively, the BAL 150 at 0 days, the control basin at 42 days, the basin treated with non-acylated flour at 42 days, the basin treated with flour rolled at 42 days. EXAMPLE 1

Biodegradation of hydrocarbons in the presence of acylated animal meal In order to make animal meal more oleophilic, the raw meal was subjected to an acylation reaction. Synthesis of acylated flour

The synthesis of acylated flour was obtained under the conditions described below.

This synthesis is carried out in a solvent medium. The principle of the reaction is to bring the animal meal (fish meal) into contact with an acid chloride (lauroyl chloride C ₁₂ H ₂₃ C10) in the presence of solvent (dichloromethane CH C1 ~). middle a proton sensor which is triethylamine [C ^ HJ _^ N], In a reactor, the mixture [lauroyl chloride + fishmeal + dichloromethane + triethylamine] is stirred (mechanical agitator) for 24 hours at 30 ° C.

The amount of acid chloride is put in excess (+ 20%) relative to that necessary to react on the amine groups of lysine. Lysine accounts for 5% of the protein in fishmeal. The amount of triethylamine is added in the same proportions.

After 24 hours of reaction, the acylated flour is washed on a solvent filter (dichloromethane) to remove the excess acid chloride. The cake is then taken up in water, then filtered to remove the excess of triethylamine and the salt formed. The cake consisting of acylated flour is then dried in an oven. First test (degree of oleophilicity of acylated flour) The degree of oleophilia of raw flour or acylated flour is measured by means of a partition coefficient test.

The mixture is stirred for 5 minutes in a separatory funnel with a mixture of artificial seawater without nitrogen (700 ml) + hydrocarbons (BAL 150: 28 g) and a known quantity of animal flour on the surface of the hydrocarbons. After stirring, the mixture is left to settle for 12 hours and the nitrogen content of the aqueous phase is assayed. This nitrogen content is representative of a passage of the nitrogen contained in the flour to the aqueous phase. We can thus calculate the degree of oleophilia. The results obtained are listed in Table I. TABLE I

Degree of oleophilia of animal meal

(HC: hydrocarbons, N: nitrogen)

Quantity Quantity

Flour% weight% N in nitrogen nitrogen% animal nitrogen Flour / HC flour introduced into water in water

Raw flour 3.54% 12.1% 120 mg 123.9 mg 100.0% Acylated flour 3.54% 12.1% 120 mg 3.5 mg 2, ⁽

It can therefore be seen that the treatment of animal flour by acylation makes the flour oleophilic and that the release of nitrogen decreases markedly when the flour has been acylated. Second test (biodegradation of hydrocarbons in the presence of acylated or non-acylated flour)

To test the efficiency of animal meal in the biodegradation of hydrocarbons, we use a scintillometry technique in which a hydrocarbon model

(Hexadecane) is radioactive. Its biodegradation is followed by the release of 14CO- according to the following principle:

In order to follow the kinetics of degradation of the labeled substrate, the 14C0 ~ observed by a bacterial culture is observed. For this, a technique is used in which a mini-reactor (5 ml) containing a bacterial culture (nutrient medium: 1 ml and inoculum: 0.1 ml) is enclosed in a scintillation vial containing 2.5 ml of molar soda. After incubation at 20 ° C in the dark and without shaking, the 14C0- trapped in soda is analyzed after acidification of the culture medium and after addition of the scintillation liquid (Hionic fluorine). It is the same for the marked substrate remaining in the vial. Radioactivity is read in a BECMANN scintillation counter

LS 3801.

The results obtained are given in Table II. TABLE II

Biodegradation (%) of hexadecane in the presence or not of acylated animal meal or not

The rate of biodegradation of hexadecane alone remains zero. The bacteria present are therefore not capable of degrading as is hexadecane. On the other hand, in the presence of animal meal, an acceleration of the biodegradation of hexadecane is observed. This acceleration is all the stronger as the flour is acylated. EXAMPLE 2

Biodegradation of hydrocarbons in the presence of animal flour, acylated or not, in an open environment In order to demonstrate the interest of making animal meal oleophilic, an experiment was carried out in an open environment, this in order to check whether the oleophilicity of the flour keeps nutrients (nitrogen and phosphorus) in contact with hydrocarbons and thus make biodegradation faster.

Fish meal acylation

The animal meals used for Examples 2 and 3 are fish meals. The modifications made to the chemical synthesis, compared to that described previously in Example 1, are:

the reaction temperature, which is of the order of 50 ° C., which corresponds to the reflux temperature of the solvent,

- the duration of the reaction is 17 hours,

the acid chloride is in excess of 300%, which corresponds to the parameter which has undergone the most significant modification compared to the synthesis according to Example 1. The other parameters and protocols are unchanged. Test:

The pilot used for this experiment is composed of a reactor containing 100 ml of sea water polluted by hydrocarbons (2.5 ml of light Arabic). Animal flour, acylated or non-acylated, was applied to the surface of the hydrocarbons at a rate of 10% by weight relative to the hydrocarbons present. This reactor is continuously stirred and aerated. The reactor water is continuously renewed for 15 days with sea water, contained in a tank, at the rate of 8 renewals per day. The effluent is collected at the outlet of the reactor,

3_ in which physico-chemical (NH., NO, -, PO., Hydrocarbons) and bacteriological (total and specific bacteria) analyzes are carried out. The same analyzes are carried out in the reservoir water. At the end of the test, the entire reactor is sacrificed and the remaining hydrocarbons are extracted with chloroform.

The physico-chemical analyzes are carried out in accordance with the standards in force: ammoniacal nitrogen: AFNOR NF T90-015; nitrogen in nitrate form: Standard methods 4500-NO3-E; orthophosphate: standard method 4500-PC-Vn Acid Col. Meth.

Total bacteria are counted according to the most probable number technique, in liquid medium (Marine Broth 2216). The specific hydrocarbon bacteria are also counted by the technique of the most probable number, in a liquid medium, in which the hydrocarbons represent the only source of carbon. Hydrocarbons are analyzed by gas chromatography.

Two experiments were carried out: one with non-acylated animal meal, the other with the same acylated animal meal. Each experiment lasts 15 days.

The results obtained are presented below. Evolution

3_ mineral elements (NH.; PO.) Is given in Tables III and IV and Figures 1, 2, 3 and 4. TABLE III Evolution of the ammoniacal nitrogen contents in the two experiments: with acylated flour or not

TABLE IV Evolution of the orthophosphate contents in the two experiments: with acylated flour or not

The results obtained are different for acylated flour from non-acylated flour. It is observed that the acylated flour causes less salting out of nitrogen and phosphorus. It is necessary to take into account the comparison with the nitrogen and phosphorus concentrations in the reservoir water, which change, because it is living sea water (plankton, bacteria ...). Obtaining these results therefore made it possible to estimate what quantity of nutrients was leached by subtraction with the concentrations measured in the reservoirs. The results are given in Table V and in Figures 5, 6, 7 and 8.

TABLE V Release of nutrients: nitrogen and phosphorus in each reactor: with acylated flour or not.

These results clearly show that the salting out is much less important for the flour made oleophilic by acylation. This treatment therefore makes it possible to obtain a product which remains in contact with the hydrocarbons for a longer time. Thus the nutrients: nitrogen and phosphorus, essential for the development of specific hydrocarbon bacteria are present at the place of biodegradation: at the water-hydrocarbon interface.

The results concerning the evolution of the bacterial flora are presented in Tables VI and VII and in Figures 9 and 10. TABLE VI Evolution of the total and specific hydrocarbon bacterial flora in the reactor with non-acylated flour

Evolution of the total and specific hydrocarbon bacterial flora in the reactor with non-acylated flour

The bacterial counts carried out during the two experiments make it possible to demonstrate that in the case of acylated flour, the bacterial development is faster, but above all, than the difference between the bacteria in the reservoir (which enters the reactor every days), is more important in the presence of this flour. It therefore more favorably stimulates total and specific hydrocarbon bacteria, since the nutrients are more available.

The quantification of the biodegradation of hydrocarbons is carried out by the estimation of biodegradation indices calculated from gas chromatography. These indices are the C17 / pristane and C18 / phytane ratios. The decrease in these ratios is correlated with the biodegradation of alphatic hydrocarbons. They are reported in table VIII.

TABLE VIII Biodegradation indices obtained after 15 days of experimentation

The results, in particular, the evolution of the biodegradation indices, show that acylated flour gives better results than non-acylated flour.

The results show that acylation of animal flour leads to a product which remains in contact with the hydrocarbons: there is the presence of nitrogen and phosphorus at the water-hydrocarbon interface, this therefore stimulates the bacterial flora. , both specific and total, and the resulting biodegradation of hydrocarbons is also stimulated.

Acylated animal flour therefore has more advantages than non-acylated flour for the acceleration of hydrocarbons. the

EXAMPLE 3

Biodegradation of hydrocarbons in the presence of acylated animal meal or not, in an open environment, on a large scale

Given the results obtained in the laboratory, which show the advantage of using acylated animal meal, a larger-scale test was carried out. This experiment was carried out in three 400-liter tanks fed continuously with fresh sea water, pumped into the lagoon located next to the tanks. The renewal rate of these tanks is 4 times the volume of the pool per day. Petroleum (arabian light topped at 150 ° C) was put in each tank (1 liter). A container, in which there was no addition, served as a witness; non-acylated flour (5% / gross) was added to the second tank; acylated flour (5% / raw) was added to the third tank. The non-acylated flour and the acylated flour are identical to those used in Example 2.

Throughout the experiment, which lasted 2 months, there was monitoring of the total bacterial flora and specific hydrocarbons according to the same protocol as that described in Example 2. Monitoring of the hydrocarbons was also carried out.

The results of the bacteriological monitoring are given in Table IX and Figures 12 and 13.

TABLE IX Enumeration of total and specific hydrocarbon bacteria

In treaties basins with flour acylated and non-acylated, the development of bacterial flora ^is' greater than in the control. Animal meal therefore stimulates native bacterial flora. It is observed that the development is greater in the basin treated with acylated flour than with non-acylated flour. The acylation of the flour keeps the product near the oil slick and thus promotes the development of bacterial flora. The results obtained on the hydrocarbon analyzes are presented in FIG. 14 and in the chromatograms given in FIGS. 15 to 18.

The interpretation of the evolution of the different crude fractions makes it possible to estimate whether there has been biodegradation. Thus, in the case where the oil has been biodegraded, there is a decrease in the alkane and aromatic fraction and an increase in the asphaltene and resin fractions.

In FIG. 14, it is observed that there has been a decrease in the alkane fractions in the 3 basins after 42 days, but the increase in the asphaltene + resin fraction is most significant in the basin treated with acylated flour. This result, which shows that biodegradation is the most important in the basin treated with acylated flour, is corroborated by the chromatograms presented below. Indeed, a clear decrease in the alkane fraction is observed between 0 and 42 days; this decrease is greater for the basin treated with acuylée flour.

All of these results obtained at 42 days show that the presence of acylated flour promotes the biodegradation of hydrocarbons. The results are even more significant after a longer period, 42 days being a short enough period of time to observe the biodegradation of the hydrocarbons.

In addition, visual observations make it possible to say that the acylated flour does not cause the pouring of the hydrocarbons in the bottom of the basin. This experiment makes it possible to highlight the advantage of treating a sheet of hydrocarbons with acylated animal flour. This is all the more interesting since there are no or few biodegradation additives for treating floating oil slicks.

Claims

1.- Biodegradation additive characterized in that it consists of a mixture comprising:

(i) at least one assimilable nitrogen source consisting of at least one amino acid, unsubstituted or substituted; (ii) at least one source of phosphorus; according to an N / P ratio of between 2 and 100; said additive having been subjected to a treatment aimed at making it oleophilic. 2.- Additive according to claim 1, characterized in that said treatment consists of an acylation.

3.- Additive according to claim 2, characterized in that one acylation is carried out with a laurylic acid chloride. AT . - Additive according to claim 1, 2 or 3, characterized in that the amino acid is chosen from the group consisting of: lysine, methionine, cystine, threonine, tryptophan, hydroxylysine, hydroxyproline, and mixtures thereof.

I.. - Additive according to any one of claims 1 to 4, characterized in that the assimilable nitrogen source re¬ presents at least 5% by weight of the total weight of said additive.

6.- Additive according to any one of claims 1 to 5, characterized in that the assimilable nitrogen source is found in proteins representing at least 50% by weight of the total weight of said additive.

7.- Additive according to any one of claims 1 to 6, characterized in that the source of phosphorus is an inorganic salt of phosphorus.

8.- Additive according to any one of claims 1 to 7, characterized in that said N / P ratio is between 4 and 40, preferably is equal to about 16.

9.- Additive according to any one of claims 1 to 8, characterized in that said additive is present in a mass ratio [additive] / [hydrocarbons] between 3 and 30, and preferably equal to about 10.

10.- Additive according to any one of claims 1 to 9, characterized in that it consists of an animal meal. 11.- Additive according to claim 10, characterized in that said meal is a fish meal.

12.- Additive according to claim 10, characterized in that said flour is a meat meal. 13.- Use of an additive according to any one of the preceding claims for the biodegradation of hydrocarbons.