WO2006126057A1

WO2006126057A1 - A bioremediation product for use in the biodegradation of liquid hydrocarbons

Info

Publication number: WO2006126057A1
Application number: PCT/IB2006/001337
Authority: WO
Inventors: Raymond John Long
Original assignee: Van Der Vijver, Brian
Priority date: 2005-05-23
Filing date: 2006-05-23
Publication date: 2006-11-30

Abstract

A bioremediation product for use in the biodegradation of liquid hydrocarbons in an environment containing microorganisms which have an affinity for consuming and thereby decomposing liquid hydrocarbons. The bioremediation product comprises a mixture a sphagnum peat moss (32) which absorbs the hydrocarbons and a nutrient solution for providing nutrition for the microorganisms. The nutrient solution includes a culture of microorganisms which have an affinity for consuming the hydrocarbons. The invention extends to a method of biodegrading liquid hydrocarbons by mixing the bioremediation product together with the liquid hydrocarbon to be treated, into soil in a soil landfill and allowing time for microorganisms occurring naturally in the soil to consume and thereby decompose the hydrocarbon. The invention extends also to method of producing the bioremediation product by spraying the nutrient solution through spray nozzles (29) onto the moss.

Description

A BIOREMEDIATION PRODUCT FOR USE IN THE BIODEGRADATION OF

LIQUID HYDROCARBONS

FIELD OF INVENTION

THIS INVENTION relates to a bioremediation product for use in the biodegradation of liquid hydrocarbons. It relates also to a method of producing the bioremediation product and to a method of biodegrading liquid hydrocarbons using the bioremediation product.

BACKGROUND TO INVENTION

In a conventional bioremediation process, the peat moss is used to absorb liquid hydrocarbons by encapsulating the hydrocarbons in its cell structure. The moss and the absorbed liquid hydrocarbon is then gathered and typically placed in a land fill where the moss and absorbed liquid hydrocarbon is mixed with soil. Bacteria and other microorganisms occurring naturally in the soil and any bacteria residing in the liquid hydrocarbon act on the liquid hydrocarbon to decompose the liquid hydrocarbon to its base elements by breaking the complex hydrocarbon chains, assisted by humic acid which occurs naturally in the moss. The humic acid contains free radicals which are capable of interacting with anthropogenic organic compounds such as polycyclic aromatic hydrocarbons, increasing the reactivity of these substances.

In order to accelerate the biodegrading process, nutrients such as phosphate and nitrate, for the microorganisms occurring naturally in the soil and possibly also in the liquid hydrocarbon, are added to the soil / moss / liquid hydrocarbon mixture. Water is then added to assist the biodegradation process and enhance the mobility of the microorganisms. When adding the phosphates and nitrates to the moss / soil mixture, the absorption of the phosphates and nitrates into the cell structure of the moss in which the liquid hydrocarbon is encapsulated, is difficult to achieve due to the presence of the soil. Furthermore, the phosphate / nitrate nutrients are often lost due to leaching into the soil without providing any nutrition to microorganisms which are able to decompose the liquid hydrocarbon and which can cause further contamination of the soil.

Any reference herein to a "liquid hydrocarbon" must be interpreted to mean a hydrocarbon which is flowable and includes hydrocarbons such as tar and the like.

It is an object of the present invention to ameliorate the abovementioned problems associated with existing conventional bioremediation processes.

SUMMARY OF INVENTION

According to a first aspect of the invention there is provided a bioremediation product for use in the biodegradation of liquid hydrocarbons in an environment containing microorganisms which have an affinity for consuming and thereby decomposing the liquid hydrocarbon, the bioremediation product comprising a mixture of sphagnum peat moss and a nutrient solution for providing nutrition for the microorganisms.

The moss may be pre-treated by heating the moss to change the moss from a hydrophilic state to a hydrophobic state. The moss may have a moisture content of between 12 % and 20 %.

The moss may have a Van Post grade of between 1 and 4.

The nutrient solution may include water as the solvent and nutrients in the form of phosphates and nitrates dissolved therein. More particularly, the nutrient solution may include phosphate and nitrate in a weight ratio of 1 part phosphate to 5 parts nitrate.

The nutrient solution may include an emulsifying agent. More particularly, the emulsifying agent may be in the form of a biodegradable, non-ionic surfactant. In use, the surfactant is effective to reduce the surface tension of the water solvent thereby to assist in the absorption of the nutrient solution into the cell structure of the hydrophobic moss.

The nutrient solution may include hydrogen peroxide. More particularly, the nutrient solution may include 3 % to 6 % by weight hydrogen peroxide. In use, 3 % to 6 % by weight hydrogen peroxide is effective to release oxygen which is required by aerobic bacteria acting on the liquid hydrocarbons during the biodegradation thereof.

The nutrient solution may include a culture containing microorganisms which have an affinity to consuming the liquid hydrocarbons.

According to a second aspect of the invention, there is provided a method of producing the bioremediation product as defined in accordance with the first aspect of the invention, the method including mixing the sphagnum peat moss and the nutrient solution for providing nutrition for said microorganisms.

The method may include mixing the moss and the nutrient solution by supporting the moss on a support surface, agitating the moss on the support surface thereby the spread the moss out on the support surface, allowing the moss to fall from the support surface under the influence of gravity and spraying the nutrient solution onto the moss after it has fallen from the support surface thereby to coat exposed surfaces of the moss with the nutrient solution.

According to a third aspect of the invention, there is provided a method of biodegrading liquid hydrocarbons which includes providing the bioremediation product as defined hereinabove in accordance with the first aspect of the invention; and mixing the bioremediation product with the liquid hydrocarbon to be treated and locating the bioremediation product/liquid hydrocarbon mixture in an environment containing microorganisms which have an affinity for consuming and thereby decomposing the liquid hydrocarbon.

The method may include mixing the bioremediation product together with the liquid hydrocarbon, into soil in a soil landfill and allowing time for microorganisms occurring naturally in the soil to consume and thereby decompose the liquid hydrocarbon.

BRIEF DESCRIPTION OF DRAWING

Further features of the invention are described hereinafter by way of a non- limiting example of the invention, with reference to and as illustrated in the accompanying diagrammatic drawings:

Figure 1 shows a schematic side elevation of equipment used to prepare a bioremediation product in accordance with the first aspect of the invention; and

Figure 2 shows a fragmentary schematic perspective view of the spray nozzle of the equipment of Figure 1.

DESCRIPTION OF PREFERRED EMBODIMENTS

The bioremediation product in accordance with the first aspect of the invention is adapted for use in the biodegradation of liquid hydrocarbons, for example, hydrocarbon oils such as petroleum-based oils. The bioremediation product comprises a mixture of sphagnum peat moss and a microorganism nutrient solution.

The moss is in the form of "heat activated" sphagnum peat moss which has been heat-treated to change the moss from a hydrophilic state to a hydrophobic state. After heat treatment, the moss preferably has a moisture content of between 12 % and 20 %. In order to be used effectively in the biodegradation of liquid hydrocarbons, the cell structure of the moss needs to be intact and as such, the moss preferably has a Van Post grade of between 1 and 4.

The nutrient solution includes water as the solvent and microorganism nutrients in the form of phosphate and nitrate dissolved therein. More particularly, the nutrient solution includes phosphate and nitrate in a weight ratio of 1 part phosphate to 5 parts nitrate. An emulsifying agent in the form of a biodegradable, non-ionic surfactant (the non-ionic surfact "NP9" supplied by Protea Chemicals in South Africa, has been found to be suitable) is added to the nutrient solution in order to reduce the surface tension of the water solvent thereby to assist in the absorption of the nutrient solution into the cell structure of the hydrophobic moss.

The nutrient solution includes between 3 % and 6 % by weight hydrogen peroxide which is effective to release oxygen which is required by an aerobic bacteria acting on the liquid hydrocarbon during the biodegradation of the liquid hydrocarbon, in use.

In a particular embodiment, the nutrient solution includes a culture containing microorganisms which have an affinity for consuming and thereby decomposing the liquid hydrocarbon. More particularly, the culture includes microorganisms in the form of bacteria and/or fungi which have an affinity for consuming petroleum-based oils. Typically, the heat-activated moss has a pH of between 4 and 6, whereas the microorganism culture will typically have a pH of between 5,5 and 7, As a result, the Applicant envisages that a basic substance will be added to the heat-activated moss to raise the pH thereof prior to adding the nutrient solution, thereby to create a compatible pH environment for the microorganism culture.

With reference to the drawings, equipment used in a process for preparing the bioremediation product, is illustrated. The equipment includes a storage hopper 10 in which heat-activated sphagnum peat moss is stored. The moss is introduced into the storage hopper via an opening 12 at the top end of the hopper. The base 13 of the hopper is funnel-shaped and defines a discharge opening 14 through which the moss is discharged from the hopper. In order to prevent coagulation of the moss when being discharged from the hopper, a vibrating cone agitator 16 is provided in the hopper near the discharge opening 14 for agitating and loosening the moss. The agitator 16 is connected to a vibrating unit 18 which is caused to vibrate by a vibrator motor 20. As the moss is discharged from the hopper, it is deposited onto a support surface in the form of a downwardly-sloping support tray 22 which is also caused to vibrate by the vibrator motor 20. The nutrient solution is stored in a nutrient tank 24 and is piped to a spray nozzle arrangement 26 via a nutrient supply pipe 28. Air is supplied to the spray nozzle at a pressure of 7 bar via an air supply line 30.

The spray nozzle arrangement 26 is in the form of a pipe 27 having a "horseshoe" shape when viewed in top plan view and a number of spray nozzles 29 located along an inner side of the pipe 27. The nutrient solution is sprayed onto the moss (designated by reference numeral 32 in Figure 2) after the moss has fallen from the support tray 22 under the influence of gravity, as the moss passes through a spray curtain of the nutrient solution provided by the spray nozzle 29, in a spray area within the horseshoe-shaped pipe 27. Exposed surfaces of the moss are thus coated by the nutrient solution. The horseshoe shape of the spray pipe 27 provides for effective coating of all exposed sides of the moss as it falls through the spray area. The moss after having been sprayed is then conveyed to a packing press wherein the moss containing the nutrient solution is compressed and packaged. The flow path of the moss through the process described above, is shown by the solid line arrows in the drawings.

In another embodiment of the invention, the Applicant envisages that the microorganism-containing culture may be added to the moss at a later stage, i.e. the nutrient solution (without the microorganism culture) may be mixed with the moss and microorganisms added to the moss at a later stage closer to the time when the moss is to be used in a bioremediation process.

It will be appreciated that by adding the nutrient solution to the sphagnum moss prior to its use in the bioremediation of liquid hydrocarbons, effective absorption of a controlled amount of the nutrients into the cell structure of the moss can be achieved. When liquid hydrocarbons are absorbed into the cells of the moss, the nutrients, already present within the cells, can immediately be used to provide nutrition for the bacteria which acts on the liquid hydrocarbons which are absorbed into the cells.

In use, sphagnum peat moss treated with the nutrient solution in the manner described hereinabove, is mixed with liquid hydrocarbon to be treated thereby absorbing the hydrocarbon and coating the surfaces of the moss and in particular, encapsulating the liquid hydrocarbon within the cell structure of the moss. The moss/liquid hydrocarbon mixture is then mixed into soil in a soil landfill where microorganisms such as bacteria occurring naturally in the soil, are allowed to consume and thereby decompose the liquid hydrocarbon. In instances where microorganisms such as bacteria, are present in the liquid hydrocarbon, such microorganisms also assist with the biodegradation of the liquid hydrocarbon. These microorganisms occurring within the hydrocarbon, together with the microorganisms occurring naturally in the soil and the microorganisms added to the nutrient solution , provide a nutrient-rich environment in which the microorganisms can multiply and metabolise the liquid hydrocarbon.

Claims

CLAIMS:

1. A bioremediation product for use in the biodegradation of liquid hydrocarbons in an environment containing microorganisms which have an affinity for consuming and thereby decomposing the liquid hydrocarbons, the bioremediation product comprising a mixture of sphagnum peat moss and a nutrient solution for providing nutrition for the microorganisms.

2. The bioremediation product as claimed in claim 1 , wherein the moss has been pre-treated by heating the moss to change the moss from a hydrophilic state to a hydrophobic state.

3. The bioremediation product as claimed in claim 2, wherein the moss has a moisture content of between 12 % and 20 %.

4. The bioremediation product as claimed in claim 3, wherein the moss has a Van Post grade of between 1 and 4.

5. The bioremediation product as claimed in claim 4, wherein the nutrient solution includes water as the solvent and nutrients in the form of phosphates and nitrates dissolved therein.

6. The bioremediation product as claimed in claim 5, wherein the nutrient solution includes phosphate and nitrate in a weight ratio of 1 part phosphate to 5 parts nitrate.

7. The bioremediation product as claimed in claim 5 or claim 6, wherein the nutrient solution includes an emulsifying agent.

8. The bioremediation product as claimed in claim 7, wherein the emulsifying agent is in the form of a biodegradable, non-ionic surfactant.

9. The bioremediation product as claimed in any one of claims 1 to 8, wherein the nutrient solution includes hydrogen peroxide.

10. The bioremediation product as claimed in claim 9, wherein the nutrient solution includes 3 % to 6 % by weight hydrogen peroxide.

11. The bioremediation product as claimed in any one of claims 1 to 10, wherein the nutrient solution includes a culture containing microorganisms which have an affinity for consuming the liquid hydrocarbons.

12. A method of producing the bioremediation product as claimed in any one of claims 1 to 11 , the method including mixing the sphagnum peat moss and the nutrient solution of the bioremediation product.

13. The method of claim 12, which includes mixing the moss and the nutrient solution by supporting the moss on a support surface, agitating the moss on the support surface thereby the spread the moss out on the support surface, allowing the moss to fall from the support surface under the influence of gravity and spraying the nutrient solution onto the moss after it has fallen from the support surface thereby to coat exposed surfaces of the moss with the nutrient solution.

14. A method of biodegrading liquid hydrocarbons includes providing the bioremediation product as claimed in any one of claims 1 to 11 ; and mixing the bioremediation product with a liquid hydrocarbon to be treated and thereafter locating the bioremediation product/liquid hydrocarbon mixture in an environment containing microorganisms which have an affinity for consuming and thereby decomposing the liquid hydrocarbons.

15. The method as claimed in claim 14, which includes mixing the bioremediation product together with the liquid hydrocarbon into soil in a soil landfill and allowing time for microorganisms occurring naturally in the soil to consume and thereby decompose the liquid hydrocarbon.