|Title of Invention||
A BIOTECHNOLOGICAL PROCESS FOR RECOVERY OF HYDROCARBONS FROM OILY SLUDGE
|Abstract||The present invention provides a biotechnological process for recovery of hydrocarbons from oily sludge using Bacillus subtilis which comprises carrying out homogenization of oily sludge by treating the said oily sludge by agitation with kerosene-water mixture or with diesel - water mixture in a ratio ranging 1:5.1 to 1:6.2 at a temperature ranging between 30-55°C; growing culture of Bacillus subtilis ATCC 21331 in about 1% glucose as carbon source for about 18 hours to obtain fermented broth containing acetoin acting as de-emulsifying agent to provide de-emulsified sludge; separating hydrocarbons from the de-emulsified sludge by centrifugation .|
|Full Text||This invention relates to a biotechnological process for the treatment of oily sludge for the recovery of hydrocarbons. More particularly, the invention relates to a biotechnological process for the treatment of oily sludge for the recovery of hydrocarbons using B.;subtilis
A major environmental problem associated with crude oil refineries is the generation of oily sludge at various stages. These oily sludge pose serious disposal problems due to their hazardous nature. Oily sludge is produced at the steps of oil cracking process at crude oil processing refineries. Because of the non-availability of economical sludge management technologies, the weathered oily sludge get accumulated over the decades and is also found at the refinery premises. The hitherto known conventional methods for hydrocarbon recovery use chemicals, which cause problem due to their environmental unfriendly properties. The sludge from the refinery premises can be treated for recovery of hydrocarbons by the present invention. In the process of this invention a physico-chemical homogenization approach has been developed for sludge dispersion using kerosene or diesel and water, which acts as a organic homogoniser for dispersion of sludge. This process also leads in the reduction in viscosity, which can be further effected by the addition of the fermentation broth resulting the sludge into a more fluid matrix.
The prior art related to the invention, is mostly specific to the the origin of waste and does not address wide range of oily sludges from various origin. The processes tilM990 focused on removal of solids from oily wastes (generated as cutting oil, rolling mill oil or petroleum based cleaning solvents ). There are few reports which target the oily sludges generated at
refinery premises where it involves series of voltilizing and condensing steps. The method fractions the sludge on the basis of the boiling points and extraction properties giving a higher energy demanding option. There are no reports which uses the biotechnological route for recovery of hydrocarbons from oily sludges. The technology available to process the oily sludge which was reported uses the combination of volatilization and condensation steps. The process uses the low temperature volatilization to remove the emulsified water in the sludge as a first step. The de-watered sludge was subjected to 400-1150°F temperature to vaporize the hydrocarbon content of the sludge. The extracted hydrocarbons were condensed through series of distillation columns for recovery of hydrocarbons (Reynolds, V. R. et al, US patent 5,269,906). There are no direct technologies available to address the problem of cleaning and processing of tank bottom sludge. This invention gives an approach with potential for the cleaning of crude storage tank by making the sludge pumpable vis-a-vis the recovery of hydrocarbons.
The main object of the invention is to provide a biotechnological process for Recovery of Hydrocarbons from Oily Sludge which comprises treating the sludge by agitation with kerosene - water or diesel water mixture at a temperature range of 30 to 55°C for homogenization of oily sludge. The dispersed sludge is affected by treating the acetoin prepared by the process of fermentation of glucose.
In order to meet the above object, the invention described herein can process the oily sludge of different physico-chemical characteristics. The process can also be used for making tank-bottom oily sludge more
pumpable so that the crude oil storage tanks can be cleaned efficiently. The invention describes a two step process, wherein the sludge from any stage of processing at refinery premises; can be homogenized with kerosene or diesel and water mixture. The process uses bacterial de-emulsifier for de-stabilization of the homogenized oily sludge.
Description of Figures: The explanations of the enclosed figures are as
Fig. 1 (a) depicts the relative viscosity of the oily sludge after
homogenization with the varying volumes of kerosene or diesel in
fig (1b) depicts the change in fluidity of sludge using fermented broth.
Fig. 2 depicts the schematic diagram of the two step process for the
recovery of tank bottom sludge wherein numerals 1-9 represent the
1.Media; 2.Culture; S.Fermentor; 4.Kerosene; 5.Water; 6.Crude Oil Storage
Tank; 7.Hydrocarbon Separator/Centrifuge; S.Stirrer; 9.Pump
Accordingly, the present invention provides a biotechnological process for recovery of hydrocarbons from oily sludge which comprises: carrying out homogenization of oily sludge by treating the said oily sludge by agitation with kerosene-water mixture or with diesel - water mixture in a ratio ranging 1:5.1 to 1:6.2 at a temperature ranging between 30-55°C;
growing culture of Bacillus subtilis ATCC 21331 in about 1% glucose as carbon source for about 18 hours to obtain fermented broth containing acetoin said acetoin acting as a de-emulsifying agent to provide de-emulsified sludge;separating of hydrocarbons from the de-emulsified sludge obtained from step (c) above by centrifugation.
In an embodiment of the invention, the acetoin used is produced by fermentation of 18hr culture of B.subtilis, the said strain having characteristics equivalent to ATCC 21331, grown on 1% glucose as a carbon source.
In another embodiment of the invention, acetoin produced acts as a de-emulsifying agent.
In yet another embodiment of the invention, the de-emulsified hydrocarbons are recovered by centrifugation.
In a further embodiment of the invention, the acetoin facilitates the reduction of the viscosity of the homogenized sludge.
In a feature of the invention, the pumpable sludge helps in the process of cleaning of the crude oil storage tank.
In yet another feature of the invention, the sludge developed at various processes such as API separator, spills, heat exchanger sludge and slop oil
sludge can be used as a matrix for homogenization at the Kerosene-water dispersion step.
Recovery of oil from sludge is economically feasible through a biotechnological route as evidenced by the present invention. The process uses simple physico-chemical treatment for dispersion of sludge matrix followed by de-stabilization of the homogenized oily sludge using fermented broth containing the acetoin produced from the fermentation of sugar. The de-emulsified hydrocarbons are finally recovered using centrifugation and can be recycled through the routine refining process. The waste-water generated in the process can be recycled and the de-oiled sludge is disposed in the conventional way. The resulting pumpable sludge is centrifuged so that the de-emulsified hydrocarbons can be collected separately. The recovery of hydrocarbons depends on the quality and age of the sludge, but in most of the sludge samples, there was 75-85% recovery of hydrocarbons has been observed. The major portion of the wastewater generated in the process can be recycled; the excess quantity of remaining water having very low chemical oxygen demand (COD) with insignificant levels of inorganic which can be treated using conventional wastewater treatment such as trickling filtration. The solids after treatment with low levels of hydrocarbons now can be safely disposed via conventional land filling guidelines.
The invention is described with the help of following examples, which are only illustrative in the nature and should not be construed to limit the scope of the invention.
Thick, non-fluid hazardous oily sludge with 62% of hydrocarbons ( hexane extractable ), 22% of non hydrocarbon residue and 16% moisture and others has been homogenized. The process involves a aqueous mixture of diesel or kerosene for homogenization of sludge. 50g of sludge was agitated with 5-20ml of kerosene or diesel in 250ml of water for SOmin at 200rpm.The process results in dispersion of sludge matrix into a solvent-water mixture with some emulsification. The process results in lowering of the relative viscosity of the sludge as represented in terms of relative viscosity to glycerol as shown in Figure 1A. The addition of 5-20 ml of fermented broth ( overnight culture of Bacillus subtilis grown on 1% glucose as carbon source ) having the de-stabilizing principle when added to same homogenized sludge the relative viscosity reduce to even lower than that of glycerol as shown in Figure 1B. When the same amount of water or the uninoculated broth was added there was no reduction in viscosity.
The sludge sample as used in example 1, was treated for recovery of hydrocarbons. 50g of tank-bottom sludge was agitated with 20ml of kerosene in 250ml of water for SOmin at 200rpm. The variation in temperature of 30 ± 50°C has no effect on the results. To this homogenized sludge 35ml of fermented broth from overnight culture of Bacillus subtilis grown on 1% glucose as carbon source has been added. The mixture was
agitated for 30min at 200rpm followed by centrifugation at 5000g for 10 min. This process resulted in the de-stabilization homogenate with recovery of 80% hexane extractable hydrocarbons.
The tank-bottom sludge as used in example 1 and 2 was homogenized with diesel as dispersent. 50g of sludge was mixed with 20ml of diesel and kept at 55°C for 30min with intermittent mixing every 5min for 30 sec at 200rpm. To this mixture 250ml water at 55°C was added and agitated for 10min at 55°C. The resultant homogenate was de-stabilized using fermented broth as described in example 2 for recovery of hydrocarbons. This process resulted recovery of 85% of hydrocarbons.
The process has been developed for recovery of waxy or weathered sludge from refinery premises. The sludge has 40% hexane extractable hydrocarbons with remaining the waxy material and inorganic and solids. 50g of sludge was mixed with 50ml of kerosene and agitated at 200rpm for 30min. The mix was then treated with 40ml of 1% triton solution in water for 10min. The resultant dispersed and homogenized sludge was treated for hydrocarbon recovery as described in example 2 and 3. The process resulted in 60% hexane extractable hydrocarbon.
The process has been developed for treatment of weathered sludge using diesel as homogenizing agent. 50g of sludge as has been used in example 4 is mixed with 60ml of diesel and kept at 55°C for SOmin with intermittent mixing every 5min for 30 sec at 200rpm. 40ml of 1% triton solution in water was added and the mixture was agitated at 55°C for 15min. 250ml of water at 55°C was added to finally homogenized the mixture by shaking at 200rpm for 10min. The homogenate then treated for recovery of hydrocarbons by addition of 350ml of fermented broth as described in example 2 and 3 and kept at 55°C for 15min. The de-stabilized hydrocarbons were recovered by centrifugation at 5000g for 15min. The process gave 80% hydrocarbon recovery.
1. The petrochemical industries are the prime clients for the technology
to enable environmental friendly treatment of various kinds of the oil
sludge with hydrocarbon recovery.
2. The process is less energy demanding considering the available
chemical technology options.
3. The process doesn't demand the down-processing of bacterial
metabolite to use as de-emulsifier
4. It allows recovery of value added product.
5. The process not only provides a solution for recovery of hydrocarbons
from oily sludges but also can be used for cleaning of crude oil
6. The developed protocol is flexible enough to accomodate different
types of oily sludges.
1. A biotechnological process for recovery of hydrocarbons from oily sludge using
a) carrying out homogenization of oily sludge by treating the said oily
sludge by agitation with kerosene-water mixture or with diesel - water
mixture in a ratio ranging 1:5.1 to 1:6.2 at a temperature ranging
b) growing culture of Bacillus subtilis ATCC 21331 in about 1% glucose as
carbon source for about 18 hours to obtain fermented broth containing
c) treating the homogenized sludge obtained from step(a) above with
fermented broth containing acetion obtained in step b) wherein the said
acetoin acting as a de-emulsifying agent to provide de-emulsified sludge:
d) separating of hydrocarbons from the de-emulsified sludge obtained from
step (c) above by centrifugation.
2. A process as claimed in claim 1, wherein the acetoin used is produced by
fermentation for about 18hr of the culture of Bacillus subtilis grown on 1%
glucose as a carbon source for the reduction of the viscosity to make sludge
pumpable in the process of cleaning of the crude oil tank.
3. A biotechnological process for recovery of hydrocarbons from oily sludge using
Bacillus subtilis substantially as herein described with reference to the examples
accompanying the specification.
|Indian Patent Application Number||2879/DEL/1998|
|PG Journal Number||10/2008|
|Date of Filing||25-Sep-1998|
|Name of Patentee||COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH|
|Applicant Address||RAFI MARG, NEW DELHI - 110 001, INDIA|
|PCT International Classification Number||C12N 1/20|
|PCT International Application Number||N/A|
|PCT International Filing date|