WO2007053961A1

WO2007053961A1 - Composition and process for bioremediation of water contaminated with hydrocarbons

Info

Publication number: WO2007053961A1
Application number: PCT/CH2005/000658
Authority: WO
Inventors: Werner Kroh
Original assignee: Swisstech Holding Ag
Priority date: 2005-11-08
Filing date: 2005-11-08
Publication date: 2007-05-18

Abstract

A novel composition and a novel process are proposed for in situ bioremediation of water contaminated with hydrocarbons, in particular with oil. For removal of, for example, an oil slick floating on the surface of a body of water, it is sufficient to scatter the novel composition in powder form over the oil slick. The composition of the invention binds to the oil virtually spontaneously and falls away from the water surface together with the oil, in order finally to settle on the bottom as fine sediment. The water is freed in this case from toxic hydrocarbons within a few hours, in such a manner that in the case of fresh water even drinking water quality can be restored. The microbiological degradation proceeds in situ. The composition contains silicon carbide in powder form and also preferably additives of granite meal, siliceous limestone meal and calcium. The novel composition permits bioremediation of oil contamination of surfaces of bodies of water in a simple and inexpensive manner. Especially in developing countries and countries on the verge of economic development, by this means, to the benefit of humans and the environment, oil contamination can now be combated which was previously neglected for reasons of cost.

Description

COMPOSITION AND METHOD FOR BIOREMEDIATION OF HYDROCARBONIZED WATER

Technical Field The present invention relates to a composition for bioremediation of water contaminated with hydrocarbons, particularly crude oil. The invention also relates to a method for the bioremediation of hydrocarbons polluted with hydrocarbons, in particular crude oil.

PRIOR ART The transport of crude oil or its various fractions from the production sites or from the production centers to the consumer is a high-risk enterprise and takes place over long distances by tankers or via pipelines. With recurring tanker accidents, millions of tons of crude oil can be released. Even in the case of leaks or attacks on pipelines, large quantities of oil get into oceans or inland waters, where they develop their devastating effects on the ecosystems. But even for oil spills of less catastrophic extent, as they are unfortunately, for example, by the illegal flushing of oil tanks at sea everywhere found to cause serious damage to the environment. Especially in coastal areas, oil spills are causing serious economic and social consequences.

It is not just about getting rid of the Ölversch mutzte water from the oil, as z. B. in the known suction is the case; Rather, the goal is simple, final and environmentally sound disposal of the oil and the toxic hydrocarbons it contains. In order to eliminate the floating oil on the polluted water, so far mainly the following measures apply: 1. Suction or mechanical picking up of spilled oil by specialized ships and subsequent removal and disposal

2. Binding and / or stabilization of the free-floating oil with oleophilic or hydrophobized powder or fiber mixtures on the surface of the water and subsequent absorption, removal and subsequent disposal.

In practice, however, only a small part of the oil can be sucked off, transported away and possibly landfilled or incinerated. In addition, storage or incineration is often carried out without regard to the ecological compatibility, so that these measures encounter in turn violent public resistance. In the meantime, landfill space for such critical waste is also lacking in most of the 0 countries, and in many countries such elimination of free-floating oils is prohibited by law.

There are a number of means and methods for binding oil spills on water surfaces known. In the description of these binders in the prior art, the terms adsorption and absorption are often not clearly different from each other. In the following, the adsorption of a sorptive on the surface of the sorbent and the absorption of a sorptive in the interior of the sorbent will be referred to as absorption. The substance to be sorbed is referred to as sorbent, the sorbent as sorbent or sorbent, and the absorbed or bound substance as sorbate

0 Absorbents are currently proposed for binding oil contaminants on water, which can absorb the largest possible volume of oil per volume of binder and can be extracted from the water surface in the fully absorbed state. Since most of the known agents with large internal surfaces are hydro- or amphiphilic, they must first oleophil and / or with considerable effort be made hydrophobic. Such absorbents based on expanded and subsequent siliconized perlite or vermiculite granules are already known from DE-2845975 from 1980 for use as oil suction agents. In DE-2314616 is suggested to use crumbs of a cellular polystyrene foam having a density of 2.24 x 10 ^"2 and 21.3 x ^{10 -2} g / cm ² as an absorbent for oily liquid hydrocarbons. Also known from US-3,756,948 is the use of Numerous absorbents are known from the literature which contain a wide variety of organic base and aggregates, for example US-3630891 describes hyrdophobized wood fibers and US-3591524 describes a cellulose-based composition which is impregnated with an oil in water, a In US-4172039, porous coconut fiber material treated with an oleophilic and hydrophobic substance is used to bind oil spills to water, and it is also proposed to fill containers with this material drifting the surface of the water and thereby absorbing the oil. US-6087301 discloses a granular Läres absorbent described in addition to a perlite-gypsum aggregate, corn starch and baking powder.

In practical use, it has been shown that the bound oil-absorbent mass floating on the surface of the water is extremely difficult to handle and that the absorbed oil can usually only be desorbed from the absorbent with considerable effort.

An adsorbent on TiO ₂ -BaSJs is disclosed in US Pat. No. 6,030,536, which is said to be used after removal of oil contamination from the water surface. In the laboratory or in suitable industrial facilities, the TiO ₂ -containing adsorbent is used to separate the highly viscous water / crude oil mixture, which contains up to 90% of seawater. The crude oil is deposited on the adsorbent, which is finally recycled in a multi-stage process. The patent mentions ZrO ₂ and Al ₂ O ₃ as further adsorbents.

Since an effective removal of oil spills, as well as the subsequent treatment and disposal of the often toxic binder-crude oil-Cemischen is complex and costly, is deliberately omitted in many regions of the earth. As a result, the initial pollution on a surface of the water, with all its negative effects on the marine or limnic ecosystems, also delays the contamination of vast coastal areas with enormous human and environmental costs. Especially in developing and emerging countries, there is an enormous need for new, inexpensive and effective means and methods for controlling oil spills on water surfaces.

It is therefore the object of the present invention to provide a composition and a method for the bioremediation of water polluted with hydrocarbons, in particular with crude oil, which does not have the abovementioned disadvantages.

Presentation of the invention

By the present invention, as characterized in the claims, a new solution for the aforementioned problem and the task derived therefrom is given. The new composition and procedure enable in situ bioremediation. This means that the crude oil is not only bound, but the local biological degradation is not only accelerated, but often even made possible.

To eliminate an oil slick floating on the surface of a body of water, it is sufficient to spread the composition according to the invention above the oil slick. In fact, the composition according to the invention has the advantageous and surprising property that it combines spontaneously with the oil and the sorbate without the formation of larger lumps sink from the water surface to the bottom of the water and settle there as fine sediment. Within a few hours or days, when sufficient quantities of the composition according to the invention are used, practically no toxic hydrocarbons are detectable in the treated water. Laboratory tests have shown that even drinking water quality can be achieved.

Due to the novel composition according to the invention in powder form, the oil is broken down into microscopically smallest parts. The powder particles adsorb the oil particles by arranging themselves around the oil droplets. As a result of the higher specific weight of the powder according to the invention, which is preferably between 2.5 and 3.5, more preferably around 3.0, the parts of the oil-powder complex sink completely to the bottom of the respective body of water. The present invention utilizes physisorption, a special form of adsorption in which the sorbent is bound to the sorbent by physical forces rather than the formation of chemical bonds. The physical forces acting here are usually undirected and have the advantage that the bonds are reversible. The sorptive can thus be released again from the sorbent, which supports the microbial degradation of the oil.

Even by violent water turbulence, the sunken oil can not be separated again from the inventive composition and thus no longer aufschreiben to the surface of the water.

As the crude oil is adsorbed to the particles of the composition, the effective surface area available to the oil-degrading microorganisms to attack is greatly increased. The degradation of the oil is thereby enormously accelerated until complete decomposition of the oil. The microscopic oil droplets serve as a substrate for the abundant development of the microorganisms involved in the degradation. Depending on the geological region On the basis of the prevailing environmental conditions, the oil is completely decomposed within 3 to 4 months. The biodegradation, respectively the remediation, therefore preferably takes place in situ. The inventive in situ degradation of the toxic hydrocarbon compound eliminates the difficult and costly extraction of oil binder mixtures from the water surface and the subsequent disposal, landfill or processing of this highly problematic waste, which, as mentioned above, often cause no oil spills Measures for cleaning are taken.

Microorganisms suitable for degrading crude oil or other hydrocarbon contaminants are added to the composition and, in an advantageous embodiment, form an important constituent of the product. The microorganisms are formulated to ensure their ability to be stored and their fluidity. The formulation is preferably in the form of pellets or capsules.

The exact composition of the product in powder form and the grain size of the components is preferably adapted to the nature of the oil to be removed.

The composition having a specific gravity of slightly above 3 g / cm ³ is a composition of various rocks or naturally occurring minerals in powder form. The particle size of the individual components or components of the composition according to the invention is preferably between 100 and 600 micrometers. At a minimum, more than 50% of the powdered composition should be below 400 microns.

As favorable or possible, the following percentage proportions have been found for the individual abovementioned constituents (in percent by weight): 20-60% silicon carbide (SiC) 25-40% granite flour 5-40% silica lime powder

2 to! 4% by weight of calcium (CaCO ₃ ) may be added as optional components to preferred embodiments of the composition.

Within the aforementioned limits, the following composition is preferred:

40% SiC 40% Granitmehl 15% Kieselkalkmehl 5% CaCO ₃

The agent indicated by the invention according to a preferred embodiment contains silicon carbide having a hexagonal crystal structure.

The addition of granite powder or SiO ₂ makes it possible above all to save or replace a percentage of silicon carbide and, above all, the affinity of the agent according to the invention to oil is increased by the silica lime powder.

Within the aforementioned limits, the following composition is therefore proposed as a further preferred embodiment:

20% silicon carbide 20% quartz sand (SiO ₂ ) 40% granite flour

15% Kieselkalkmehl 5% CaCO ₃ As mentioned above, the grain size of the silicon carbide as well as that of the other materials used should preferably be between 60 and 600 micrometers. Preferably, more than 50% of all particles should be in a size range below 400 microns.

The components described above are in turn composed as follows:

Component silica lime

Minerals content Share in% by weight Chemical formula

Quartz / silicon 25 SiO ₂

Calcite 65 CaCO ₃ dolomite 1 CaCO ₃ MgCO ₃

Pyrite 1 FeS

Clay (montmorillonite) 5 (Na ₁ Ca) (Al ₁ Mg) ₂ Si ₄ O ₁₀ (OH) ₂ 4H ₂ O

Organic substances 3 complex (C _x H _y S _z ) compounds

Component silicon carbide

Minerals content Share in% by weight Chemical formula

Silicon 50 Si carbon 50 C Component granite

Minerals content Share in Cew-% Chemical formula

Quartz / silicon 40 SiO ₂

Feldspar series (plagioclase / orthoclase) 50 (K ₁ Na ₁ Ca) (Al _x SIyO ₂ )

Mica series (Muskowit / Biotit) 10 (K, Alχ, Mg _y ) (F ₁ OH) ₂ (AlSi ₃ 01 ₀ )

In further embodiments, the following optional components may be used:

Component garnet sand

Minerals content Share in% by weight Chemical formula

Almandine 100 (Fe ₁ Ca ₁ Mg) _x Al ₂ (Si0 ₄ ) ₃

In an advantageous embodiment, 10 to 15% of the granite meal was replaced by garnet sand.

test example

Normal tap water (fresh water) was adjusted to the usual salt content of seawater by adding sea salt. In a test vessel, 20 ml of crude oil (so-called Curde oil) were added to one liter of the salt water thus obtained with gentle stirring.

On the substantially floating on the surface of the salt water oil (a part of the oil was also distributed in the form of small droplets in the water) was just spilled by the inventive agent in the above-mentioned preferred composition so much that the whole on the Water surface floating oil layer was covered with an approximately uniformly thin layer of the inventive composition.

Only a few seconds after the spreading of the agent according to the invention, this compound entered into a connection with the oil, disappeared from the water surface and subsequently slowly settled as a fine sediment on the bottom of the test vessel. The water cleared up quickly and after about one day, no oil was visible in the water either visually or due to the smell. The oil was completely bound in the sediment. After 2 days, a sample (500 ml) of the water treated with the agent according to the invention was taken.

The water sample was washed on a C18 column and an aliquot of the eluent was analyzed by instrumental analysis for oil traces. This was done using a gas chromatograph mass spectrometer system from Hewlett-Packard. After capillary gas chromatographic separation, masses 43 and 57 were detected in an ion-selective manner. There were only 0.05 mg / liter of these masses in the tested water sample, i. H. at hydrocarbon or oil residues,

In a salt water reference sample to which no oil and, correspondingly, none of the agent according to the invention had been added, 0.02 mg / liter of hydrocarbons were detected. According to the regulations currently in force in Switzerland concerning the maximum permissible hydrocarbon content in water, the limit values for discharge water into public sewers are 20 mg / liter, for discharge water into open waters such as rivers or lakes 10 mg / liter and for river water and river ice 0.05 mg / liter Liter. For drinking water a value of 0.01 -0.05 is assumed. After only 0.05 mg / liter of hydrocarbons were found in the sample, this is comparable to the quality targets for drinking water.

Tests on the effectiveness of bioremediation

Bound with the inventive composition, the environmentally harmful hydrocarbons can be degraded in a short time by natural means. The observations made in the above-described internal experiments suggest that the natural degradation of the hydrocarbons using the composition of this invention is accelerated. In a Bioremediation Effectiveness Test according to the US Environmental Protection Agency (EPA) protocol (according to 40 CFR Chapter 1 (7-1-99) Pt.300 Appendix C, Item 4.o) was issued by the independent certified testing laboratory Bio-Aquatic Testing in Carrollton, TX ₁ USA demonstrated that treatment with the composition according to the invention of crude water contaminated with crude oil within 28 days led to a 46.6% reduction of the alkanes compared to untreated control samples. The reduction of the aromatic compounds was even 86.6% above the value of the untreated controls in the case of the oil-contaminated seawater samples treated with the composition according to the invention. The treated samples had a 52.7% reduction in oil mass compared to the untreated controls. The oil used in the trials is Alaska's North Slope 521 as it can be sourced from EPA Environmental Monitoring to the Support Laboratory in Cincinnati, Ohio, USA. The composition according to the invention is applied in the form of a powder with suitable equipment to the oil surfaces to be treated. In experiments, blowers have proven to be useful, such as those used in sandblasting. Depending on the type and nature of the oil, the individual components of the composition according to the invention can thus be varied on site. That is to say, the composition is not premixed to the site of use, but is mixed together from the individual components on site, preferably by the sandblast blower.

It is understood that the mixture may be put together differently for the particular application and taking into account the nature of the oil to be removed. Apart from the lowering and binding of oil floating on a water surface by spreading over the oil, the agent according to the invention can, of course, also be used for other specific purposes or in ways other than that described due to its advantageous properties. For example, the agent may also be used to contaminate soil with oil or hydrocarbons, to reduce oil or hydrocarbons in water of any kind, or more generally to improve water quality.

Claims

claims

1 composition for the bioremediation of hydrocarbons, in particular oil contaminated water, characterized in that it contains silicon carbide (SiC) in powder form.

Composition according to Claim 1, characterized in that it contains a mineral powder selected from the group: SiO ₂ , (K ₁ Na ₁ Ca) (Al _x Si _y θ 2) and / or (K, Al _x , Mg _y ) (F ₁ OH) ₂ (AISi ₃ O ₁₀ ]

A composition according to claim 2, characterized in that the mineral powder is granite flour

4 A composition according to any one of claims 1 to 3, characterized in that it is a mineral powder selected from the group: SiO ₂ , CaCO ₃ , CaCO ₃ MgCO ₃ , FeS and / or (Na ₁ Ca) (Al ₁ Mg) ₂ Si ₄ Oi ₀ (OH) ₂ 4H ₂ O includes

A composition according to claim 4, characterized in that the mineral powder is silica lime flour,

Composition according to any one of Claims 1 to 5, characterized in that it comprises 20-60% by weight of silicon carbide, 25-40% by weight of granite flour and 5-40% by weight of silica-limestone powder.

A composition according to claim 6, characterized in that it comprises 40% by weight of silicon carbide, 40% by weight of granite flour, 15% by weight of lime powder and 5% by weight. Composition according to Claim 6, characterized in that it comprises 20% by weight of silicon carbide, 20% by weight of SiO ₂ , 40% by weight of granite flour, 15% by weight of lime powder and 5% by weight.

Composition according to one of claims 3 to 8, characterized in that 10 to 15% of Graπitmehls are replaced by garnet sand.

A composition according to any one of claims 1 to 9, characterized in that the grain size of the individual components is between 60 and 600 micrometers, preferably more than 50% of the individual particles are in the range below 400 micrometers.

Composition according to one of claims 1 to TO _1, characterized in that oil-degrading microorganisms are added in the form of pellets or capsules.

A method for the bioremediation of hydrocarbons contaminated with hydrocarbons, in particular crude oil, with a composition according to any one of claims 1 to 9, wherein the composition is applied as sorbent directly to the contaminant to be removed, so that the hydrocarbons are adsorbed and fall with the sorbent , whereby the water is almost completely removed from the pollution.

A method according to claim 12, characterized in that the adsorbed hydrocarbons, in particular the adsorbed crude oil is degraded in situ.