WO2011074007A2

WO2011074007A2 - Process and composition for bioremediation of oily sludge

Info

Publication number: WO2011074007A2
Application number: PCT/IN2010/000816
Authority: WO
Inventors: Shalini Gupta; Peddy Venkat Chalapathi Rao; Banwari Lal; Venkateswarlu Nettem Choudary
Original assignee: Bharat Petroleum Corp Ltd
Current assignee: Bharat Petroleum Corp Ltd
Priority date: 2009-12-18
Filing date: 2010-12-16
Publication date: 2011-06-23
Anticipated expiration: 2012-06-18
Also published as: WO2011074007A3

Abstract

A process and composition for bioremediation of an oily sludge is provided herein. The process disclosed herein is an improved process which shows 97% degradation of oily sludge. The process of the present invention is time and cost effective process for enhanced bioremediation of petroleum sludge in environmentally safe manner. The composition provided herein comprises bacterial consortia and poultry manure along with the nutrient mixture immobilized with corm powder.

Description

PROCESS AND COMPOSITION FOR BIOREMEDIATION OF OILY SLUDGE

FIELD OF INVENTION

The present invention relates to a process for bioremediation of oily sludge particularly petroleum sludge.

BACKGROUND OF THE INVENTION

Over the past several decades world wide production, processing and storage of petroleum sludge, transportation and utilization of synthetic and naturally occurring chemical substances has led to the introduction of significant quantities of hazardous material into the environment. Unintentional spillage of petroleum sludge and petroleum distillates, industrial solvents and other chemicals has resulted in large numbers of polluted sites. Many of these compounds are both toxic and persistent in terrestrial and aquatic environments. The contamination of soil, surface and groundwater is simply the result of the accumulation of these toxic compounds in excess of permissible levels. Oil spills are a major menace to the environment as they severely damage the surrounding eco systems. Since petroleum sludge is lighter than water, it floats on the sea surface and result in a swift - spreading fire.

Apart from accidental spills of petroleum sludge, oily sludge, a hydrocarbon waste generated in huge quantities by oil refineries creates enormous environment pollution. Due to side effects on humans, public pressure, regulatory or legislative requirements, and enlightened behaviour; there is a growing realization and movement to clean up such environment messes. Oil refineries need a well planned sludge management strategy to manage oily sludge and there is a need to have more cost effective alternative traditional physical and chemical methods of remediation.

Today, hydrocarbon sludge is a major problem faced by all the petroleum industries, be it producers, refiners, or the distributors. The severity of the problem depends on the nature of petroleum sludge, the processing capacity, the downstream capacities, and the design of the effluent treatment plant. The cause of sludge accumulation in refineries are usually pump failures, desalter failure, oil draining from tanks and operation units, periodic cleaning of storage tanks and pipeline ruptures.

Crude oil sludge varies greatly in appearance depending on its composition. It is usually black or dark brown (although it may be yellowish or even greenish). In the reservoir it is usually found in association with natural gas, which being lighter forms a gas cap over the petroleum, and with saline water, which being heavier generally floats underneath it. The storage and processing of petroleum sludge produces sludge which is to be disposed off in an environmentally acceptable manner. It is estimated that each refinery produces 30,000 tones of oily sludge each year (USEPA 1991).

Sludge disposal is a worldwide problem and a wide variety of disposal methods have been adopted. The dramatic increase in the volumes of wastewater treated has resulted in the generation of large volumes of sludge. Also due to more restrictive government or legislative regulations for disposal of sludge, and growing awareness of the public towards environmental hazards, there is greater need for disposal of sludge in a cost-effective and more environmental friendly manner. This legislation regulates the future use of land disposal for hazardous wastes and mandates a reduction of the volume and toxicity of the wastes.

The techniques for disposal of oily sludge are limited. These techniques are based on physical, chemical, thermal and biological approaches. Land filling which is a physical method involves burying of sludge in specially constructed pits. These pits are difficult to construct, costly, wastes large area of land, and thus environmentally unacceptable. Since the sludge generated in refineries is huge and the space near the vicinity of refineries is limited, this method is unsuitable.

Sludge farming is spreading and mixing of sludge on soil. This method uses the natural nutrients of soil which are in a very less quantity for degradation to occur at a faster rate, thus the process requires long time duration. Also the process is suitable only for certain types of soil and depends on climatic conditions at the site. Incineration which is the controlled burning of sludge is totally unacceptable, as it causes serious air pollution.

Chemical treatment is just the encapsulation of the sludge in an inert sealant; therefore the contaminants are not eliminated but simply entrapped in a matrix. In the chemical treatment, chemical properties of the soil and the contaminants such as acidity and precipitation potential are exploited, which leaves hazardous byproducts. The chemical stabilization increases the volume by adding a binding material, thus fixing and diluting the toxic components. But the chemical treatment is costly and often the fate of contaminants is not known.

In recent decades bioremediation has emerged as the most eco-friendly and cost effective than all other remediation options, but bioremediation technique differs depending upon regulatory provisions, site characteristics, type of sludge, and the resources available. Bioremediation technique also referred to as 'Biorestoration' has been proven to be able to reclaim contaminated land, reduce the threat of groundwater pollution and enhance the degradation rate of oil's constituents. Tillage and turning of the soil distributes carbon, nitrogen and water and reduces spatial distribution with in the soil. It also serves to bring the bacteria and hydrocarbons in contact under conditions in which the bacteria will act to metabolize the hydrocarbons. Tilling of the land at regular intervals facilitates faster degradation and watering maintains proper aeration and moisture levels. Bioremediation involves establishing the conditions in contaminated environment so that appropriate micro-organisms flourish and carry out the metabolic activities to detoxify the contaminants. During bioremediation micro-organisms may use the contaminants (hazardous chemicals) as nutrients or energy source or it may be degraded by co-metabolism. Bioremediation is preferably carried out using indigenous micro flora. Generally it is the consortia that are active and biodegradation by monoculture is slow. Bioremediation harnesses natural biogeochemical processes and removes toxic chemicals from the environment. It is a cost effective alternative since it involves low capital expenditure and energy as compared to other technologies also requires less manual supervision. It has high public acceptance and can often be carried out on site.

US Pat. No. 415,662 describes the use of a fungus Actinomucor elegans (Ediam) Benj. and Hasselt. Strain no TC-405, ATCC20613, or an enzymatic active material, a broth comprising it, or a carrier and for detergent for the degradation of crude and petroleum products.

US Pat. No. 5,059,252 relates to a method for onsite bioremediation of hydrocarbon soils. This method includes mixing of soil with cationic ion exchange resin to promote growth of organism capable of degrading the alkanes and other petroleum derived hydrocarbons.

US Pat. No. 5,81 1,290 discloses a method and a composition suitable for enhancing the biodegradation of hydrocarbon contaminated soil, water and sludge using urea non-ionic surfactant clathrates, preferably in combination with a phosphorous source.

US Pat. No. 5,039,415 describes a method for treating hydrocarbon contaminated soil using naturally occurring bacteria by excavating the soil, forming the soil into a flowing particulate stream forming an aqueous liquid mixture of water and treating substances that reacts with hydrocarbon to form C0₂ and water.

US Pat. No. 5,609,667 discloses a process for the absorption and removal of hydrocarbon contaminated soil using powered cellulose containing essentially 3- 8% of ammonium sulphate creates a biologically active media which preferentially absorbs hydrocarbons in the presence of water and which supports the growth of naturally occurring hydrocarbon reducing bacterial forms.

US Pat. No. 3,871 ,957 discloses different methods of applying different micro organism for rapid dispersal of oil spills. The micro organism employed include a wide variety of bacteria, yeast, fungi, ion exchange resins, silica gel, clays such as kaolin or zeolites as carriers for such organism. US Pat. No. 6,057, 147 is directed to an apparatus and method for enhanced bio remediation of hydrocarbons removed from contaminated objects such as car and aero plane parts using recyclable bioremediating clearing solution.

US Pat. No. 6,319,328 B l discloses an in situ method for treating of contaminants in soil and for groundwater using an oxidizing agent that generated free radicals e.g. hydroxyl radicals (peroxide, ozone) and neutral agent comprising an effective amount of metal catalyst to maintain pH from about 5 to 8. e.g., iron (II) and iron (III), copper (II) salts etc.

US patent application 20030150801 A l relates to a method for biodegradation of an oil based sludge consisting of a mixture of petroleum hydrocarbons. This method comprises forming an aqueous solution of oil based sludge, bacterial culture and nutrients for bacterial growth.

US Pat. No. 7, 160,459 B l provides a specific in situ bioremediation for petroleum contaminated soil and groundwater.

US Pat. No. 3,871 ,956 describes a process for the microbial degradation of petroleum or oily waste materials using particular hydrocarbon utilizing bacteria.

The US Pat. Application US 20020187545 discloses a process for bioremediation of hydrocarbon-contaminated waste using corn material. The hydro carbonaceous contaminant is contacted with the corn material in the presence of nutrients and bacteria effective for bioremediation.

US patent application US 200201 87545 discloses use of corn materials including shredded corn cobs, for bioremeditating hydrocarbon contaminated waste. The document further discloses the use of an impervious plastic coating.

WIPO application WO/2008/121079 discloses a sludge hydrocarbon bed with HDPE base and covering for bioremediation. It is¹ also directed towards , a bioremediation process that enables direct and on-site treatment of hydrocarbon sludge process comprising step of contacting the sludge with a biofilm comprising at least one of the following microorganisms OBJECTS OF THE INVENTION

The primary object of the invention is to provide a microbial process for remediation of oily sludge particularly petroleum sludge which is time and cost effective.

Another object of the present invention is to provide for a sludge degrading composition comprising of Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, s -30 strains along with suitable nutrients.

Another object of the invention is to enhance the rate of degradation of petroleum sludge through different compositions of nutrients and microbial culture.

Yet another object of the invention is to restrict the ground water contamination using polythene films thus ensuring that the contaminants are not merely moved from one place to another.

Yet another object of the invention is to provide the improved process for the bio remediation of petroleum sludge.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; spreading oily sludge over the soil; and contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1.

Another aspect of the present invention provides a composition for biodegradation of an oily sludge comprising Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, and s-30, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3 : 1.

DETAILED DESCRIPTION OF THE INVENTION

The term "Bioaugmentation", "bioremediation" and "remediation" used herein can be used interchangeably. The term "Bioaugmentation" "bioremediation" and "remediation" refers to adding natural or genetically engineered micro flora to contaminated soil or water for biodegradation of contaminants. Bioaugmentation is proposed when rapid clean-up is required and competent indigenous flora may not be present for intended biodegradation. Total Petroleum Hydrocarbons (TPH) is the parameter used to indicate the level of contamination present in the environment.

The crude oil sludge comprises of 26.5% of total petroleum hydrocarbon and 13 % water; and diesel oil sludge comprises of 19% of total petroleum hydrocarbon and 10.9 % water (Table 1 ).

The term "Oil zapper" used herein refers to a consortium of five bacterial strains which could degrade aliphatic, aromatic, nitrogen, sulphur, and oxygen containing compounds. The product is mixed along with nutrients and poultry manure is also a microbial consortium which further catalyzes and accelerating the degradation of oily sludge.

The present invention provides a process and composition for bioremediation of oily sludge. The process disclosed in the present invention is quick and cost effective. In addition the composition provided in the present invention degrades the contaminants present in oily sludge in less time as compared to the composition known in the art.

The rate of degradation of contaminants using the bioremediation technologies available in the prior art is poor in natural environmental conditions. It takes days to months for degradation of the contaminants. Further, heavy metals can not be removed by using the techniques.

Deficiency of carbon, nitrogen nutrients and of P and K is responsible for low rate of degradation. Also exhaustion of nutrients, depletion of oxygen, small number of useful hydrocarbon degrading micro-organisms, difficulty in keeping organisms in contact with oil and poor survival of externally added micro-organisms in new environment is some of the problems. The present invention provides a process for bioremediation of oily sludge particularly petroleum sludge using oil zapper comprising microbial consortium comprising various micro-organisms capable of degrading hydrocarbons, microbial nutrient mixture and poultry manure.

The oil zapper in particular comprises of microbial consortia and microbial nutrient mixture, wherein the microbial consortia comprises bacterial strains Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, s- 30 in equal proportions and the microbial nutrient mixture comprise nutrients immobilized on corn cob powder in the ratio of 3: 1. The oil zapper is used at the concentration of lx 10⁹cell /per gm of oil.

Process for preparation of microbial nutrient mixture comprises mixing 0.1 % - 0.3% K2HPO4, 0.1% - 0.3% KH2PO4, 0.05% - 0.1 % MgS0₄7H₂0, 0.5% - 1 % NaCl, 0.05% - 0.1 % KN0₃, 0.1% - 0.3% yeast extract powder, 0.05% - 1% NH4CI, 1 % - 2% (v/v) trace element solution, 0.1 % - 0.5% (v/v) vitamin solution and 1000 ml Reverse Osmosis (RO) water adjusting the pH of the mixture preferably to 6.5%-7.5% autoclaving the nutrient mixture at the temperature of around 121±5°C at the pressure of 10-20 pond for a period of 15-25 minutes, cooling the mixture and immobilizing the same with the corn cob powder in the ratio of 3: 1.

The corn cob powder is prepared by grinding the corn cob into the powder form. The corn cob powder so obtained is autoclaved (in dry cycle autoclave) at a temperature of 121± 5°C at the pressure of 10-20 pond for a period of 45-90 minutes for three times in consecutive days. The autoclaved corn cob material is ready to mix with autoclaved nutrient mixture. The corn cob powder is mixed with the nutrient mixture in the ratio of preferably 1 :3. The bacterial strains Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer are mixed with the powder and the mixture so obtained is packed into poly bags for use as a biodegrading agent for biodegrading oily sludge/refinery waste.

Poultry manure contains microbial species including various aerobic heterotrophs e.g. Bacillus species, Micrococcus species, Pseudomonas species, Acinetobacter species, Entreobacteria and Proteus bacteria. Contribution of these microbes sourced from the poultry manure may be aiding in accelerating the bioremediation process. Poultry manure contains: nitrogen 4%, phosphorus 6%, potassium 4% and organic material 86%.

Surprisingly, it was found that poultry manure was effective when used with the oil zapper for degradation of Diesel oil sludge and other petroleum sludges. Growth and activity of Oil zapper microbial culture was not hindered by the use of poultry manure as nutrient and additional source of bacteria. These materials, when mixed with soils increase soil permeability and cause soils to have finer texture which increases surface area and aeration. Thus use of poultry manure in oil zapper makes the remediation of sludge generated in refineries more economical and faster and practical.

Natural, lipophilic, cheap and easily available nutrients like, poultry manure is easily soluble in product tank sludge therefore availability of the nutrients to the microbes increases resulting in overall increase in degradation efficiency. Poultry manure has increased degradation efficiency manifold and thus oil zapper could degrade various types of product tank sludge e.g.: crude oil tank sludge, diesel tank sludge, motor spirit tank sludge, furnace oil tank sludge, ETP sludge etc. Use of poultry manure as a component on nutrient mixture has resulted in elimination of chemical nutrients in bioremediation of diesel sludge contaminated soil; hence overall cost of bioremediation process is reduced.

Different type of hydrocarbon wastes which can be remediated using the process and composition disclosed in the present invention includes but not limited to petroleum sludge, crude oil tank sludge, diesel tank sludge, motor spirit tank sludge, furnace oil tank sludge and ETP sludge.

The present invention provides an improved bioremediation process using externally added microbial consortium which is supplemented by addition of various nutrients to support their growth. Combined with tillage and watering which ensures an adequate aeration and moisture content the process thus facilitates rapid bioremediation. Use of HDPE sheet prevents leaching of heavy metals to ground water and serves to retain moisture content and nutrients within the sludge.

Plots were excavated to the depth of one meter below ground level and covered from all four sides by polythene film. After placing the HDPE sheet at the bottom of soil bed, soil is again filled in the plots up to depth of one foot below the ground level and 30-50 kg oily sludge was spread uniformly.

The bioremediation of petroleum sludge in soil was carried out in-situ by introducing an inoculum ranging from 100-600 g of a mixture of bacterial culture of five species along with nutrients which were taken in the range of 5-50 litres. This was followed by tilling, watering and ploughing of the plots to supply the optimum moisture and oxygen to the oil degrading bacteria's for degradation of the same. The sampling was done at different time intervals viz; zero days, 18^th day and at 38^th days from the start of the bioremediation process to monitor the soil and sludge parameters.

Surprisingly, the bioremediation process as disclosed in the present invention leads to a reduction of total petroleum hydrocarbons which was 19% in the oily sludge to 0.5% after 38 days i.e. approximately 97% petroleum hydrocarbons gets degraded when the composition provided in the present invention was used in the process, whereas the % degradation claimed in prior art after 30-60 days is 30-40% depending upon the TPH of sludge as compared to the accelerated degradation in the present invention.

In one of the embodiment of the present invention, the bioremediation process as disclosed in the present invention leads to a 63% reduction of total petroleum hydrocarbon after 18 days and 97 % reduction in 38 days (Table 2), when the composition provided in the present invention was used in the process, on the other hand it takes 6 months for degradation of approximately 95% crud oil sludge using the oil zapper technology known in the prior art (Table 3).

One embodiment of the present invention provides a process for bioremediation of oily sludge said process comprising: spreading oil zapper comprising of the sludge degrading microbial consortium and microbial nutrients; tilling of the site to mix the oily sludge uniformly with the soil and oil zapper applied onto it.

Further embodiment of the present invention provides a process, wherein the said microbial consortium comprises of Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, s-30.

Further embodiment of the present invention provides a process, wherein the said microbial nutrients comprise of microbial nutrients immobilized with corn cob powder in a ratio of 3 : 1.

Further embodiment of the present invention provides a process, wherein the microbial nutrients comprise of Luria broth, NO3 and poultry manure.

Further embodiment of the present invention provides a process, wherein the oil sludge is used in a quantity of 30-50 kg and has a TPH of 19.

Further embodiment of the present invention provides a process wherein, wherein total petroleum hydrocarbons are reduced from 19% to 0.5% after 38 days.

Further embodiment of the present invention provides a process wherein, the excavated plots are covered with the polythene films from all four sides at a depth of -1 -2 meters.

Further embodiment of the present invention provides a process microbial, wherein consortium for bioremediation of oily sludge comprises Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, and s-30. Yet another embodiment of the present invention provides a kit for enhanced bioremediation of oily sludge / refinery waste, the kit comprises a composition comprising microbial consortium along with microbial nutrients.

Further embodiment of the present invention provides a composition wherein, the quantity of microbial consortium varies from 100-600g.

Further embodiment of the present invention provides a composition wherein, quantity of microbial nutrient varies from 5-20 litres. Yet another embodiment of the present invention provides the microbial nutrients wherein, microbial nutrients are immobilized with corn cob powder in a ratio of 3: 1.

Further embodiment of the present invention provides the microbial nutrients wherein, microbial nutrients comprise of Luria broth, KNO₃ and poultry manure. Yet another embodiment of the present invention provides a sludge hydrocarbon bed comprising of plots with HDPE base containing oily sludge to which oil zapper is added for bioremediation.

Further embodiment of the present invention provides a sludge hydrocarbon bed wherein, the oil zapper comprises of Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginos and s-30.

Further embodiment of the present invention provides a sludge hydrocarbon bed wherein, the oily sludge is augmented with nutrients.

Further embodiment of the present invention provides a sludge hydrocarbon bed wherein, the nutrients comprise of Luria broth, KNO₃ and poultry manure.

The bioremediation process disclosed herein enables in situ treatment of oily sludge with sludge degrading microbial consortium.

The process parameters and the consortium of micro-organism species may be tailored for the treatment of different composition of petroleum sludge and oil waste.

According to one aspect of the present invention the process may be implemented in biotreatment facility, which may comprise means for controlling aeration and moisture levels within the oily sludge.

Still another embodiment of the present provides tillage and watering of the sludge, oil zapper and soil in order to fasten the bioremediation process.

In yet another embodiment of the present invention the excavated plots are covered with the polythene films from all sides at a depth of -1-2 meters. Another embodiment of the present invention provides a process wherein the initial sludge quantity is 30-50 kg and has a TPH of 19.

Still another embodiment of the present invention provides a composition for enhanced bioremediation which comprises of the sludge degrading microbial consortium along with nutrients.

In general, the rate and extent of microbial utilization of petroleum hydrocarbons is limited by the concentration of microbial nutrients. Therefore, microbial nutrients, especially nitrogen containing nutrients have been added to contaminated soil or water as a method for enhancing the biodegradation of the petroleum contaminants.

The present invention relates to a sludge treatment process wherein bioaugmentation of oily sludge is done with Luria broth, N0₃ and poultry manure. Luria broth contains nitrogen and other necessary components needed for growth of micro-organism. It also possesses other components that may facilitate the bioremediation of homocyclic hydrocarbons.

Poultry manure is used successfully for the enhancement of bioremediation process and it mainly contains organic material and small percentage of nutrients such as nitrogen, phosphorus, and potassium which are needed by microbes for their growth and synthesis/bioremediation of their food/carbon source.

Yet another embodiment of the present invention provides a monitoring process wherein sampling at different time intervals viz; zero days, 18^th day and at 38^th day from the start of the bioremediation process to monitor the soil and sludge parameters.

Yet another embodiment of the present invention provides a time and cost effective bioremediation process wherein total petroleum hydrocarbons are reduced from 19% to 0.5% after 38 days.

According to another aspect there is provided a bed of oily sludge which comprises of the microbial consortium and can be additionally supplemented with additives and nutrients to further promote the growth of the consortium. In accordance with the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; spreading oily sludge over the soil; and contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3 : 1.

In another embodiment of the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; spreading oily sludge over the soil; and contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1 , wherein the impervious lining is polythene film.

In yet another embodiment of the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; spreading oily sludge over the soil; and contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1, wherein the bacterial consortia comprises Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, and s-30.

In still yet another embodiment of the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; spreading oily sludge over the soil; and contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1 , wherein the bacterial consortia is present at the rate of l x 10⁹cell /per gm of the soil.

In still yet another embodiment of the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; spreading oily sludge over the soil; and contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1 , wherein the nutrient mixture comprises 0.1 % - 0.3% K₂HP0₄, 0.1 % - 0.3% KH₂P0₄, 0.05% - 0.1% MgS0₄7H₂0, 0.5% - 1% NaCl, 0.05% - 0.1% KN0₃, 0.1% - 0.3% yeast extract powder, 0.05% - 1% NH^Cl, 1% - 2% (v/v) trace element solution and 0.1% - 0.5% (v/v) vitamin solution.

In still yet another embodiment of the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; -spreading oily sludge over the soil; and contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1 , wherein pH of the nutrient mixture is in the range of 6.5%-7.5%.

In still yet another embodiment of the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; spreading oily sludge over the soil; contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1 ; and tilling, watering and ploughing of the pit.

In still yet another embodiment of the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; spreading oily sludge over the soil; contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1 ; and tilling, watering and ploughing of the pit, wherein the tilling is repeated after every 15 days. In still yet another embodiment of the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; spreading oily sludge over the soil; contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1 , wherein total petroleum hydrocarbons in the oily sludge reduces from 19% to 0.49% in 35 to 40 days preferably in 38 days.

In another embodiment of the present invention there is provided a process for biodegradation of an oily sludge, the process comprising providing a pit having a substantially impervious lining; adding soil having at least 10% of moisture content into the pit; _, spreading oily sludge over the soil; and contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1 , wherein 97% of the oily sludge gets biodegraded in 38 days.

In a further embodiment of the present invention there is provided a composition for biodegradation of an oi!y sludge comprising Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, and s-30, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1 .

In a another embodiment of the present invention there is provided a composition for biodegradation of an oily sludge comprising Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, and s-30, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1, wherein the nutrient mixture comprises 0.1% - 0.3% K₂HP0₄, 0.1% - 0.3% KH₂P0₄, 0.05% - 0.1% MgS0₄7H₂0, 0.5% - 1% NaCl, 0.05% - 0.1 % KN0₃, 0.1% - 0.3% yeast extract powder, 0.05% - 1 % NH₄C1, 1% - 2% (v/v) trace element solution and 0.1% - 0.5% (v/v) vitamin solution.

Advantages of the present invention The process and composition for bioremediation of oily sludge disclosed in the present invention shows 97% degradation efficiency when applied on hydrocarbon contaminated oil especially petroleum sludge.

Further, the process comprising treating the plots with nitrogen source e.g. Luria broth, potassium Nitrate as a nutrient show maximum degradation of oily sludge after 38 days of bioremediation. Also the plots with poultry manure as nutrient have comparable degradation efficiency with nitrogen source. Poultry manure was effective when used with oil zapper for degradation of petroleum oily sludge. Growth and activity of Oil zapper microbial culture was not hindered by the use of poultry manure as nutrient. Thus use poultry manure with oil zapper would make the remediation of sludge generated in refineries less costly and practical.

Use of polythene films in the plots during excavation at the depth of 3-6 feet or 1- 1.5 meters enhanced the overall degradation efficiency of petroleum sludge. Nutrients may get leached out with water in the lower layers of soil during tilling or during heavy rains, resulted in nutrient loss. Due to loss of nutrients, microbial growth and their activity may get reduced and this in turn may slow down the degradation process which ultimately increases the time and cost of bioremediation study. Furthermore there may be possibility of leaching of heavy metals into the groundwater which is very harmful to the humans as well as crops. This behaviour shows that placing of polythene film not only enhances the biodegradation rate but also prevents groundwater contamination, thus use of polythene film should be preferred in bio remediation process.

With the developed novel approach of bioremediation, the degradation efficiency increased, economics improved, ground water contamination reduced and reduction in time taken for bioremediation has also been observed.

As the time taken for bioremediation of oily sludge has reduced to half, the labour charges for tilling, watering and cost for maintaining the nutrient levels in soil also decreased.

It should be understood that the following examples described herein are only for illustrative purposes and all the possible modifications or changes suggested to a person skilled in the art are included within the scope and purview of this application and appended claims.

EXAMPLES

It should be understood that the following examples described herein are for illustrative purposes only and that various modifications or changes in light of the specification will be suggestive to person skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims.

Example 1

Preparation of Oil Zapper

The oil zapper was prepared by mixing microbial consortia comprising Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, s-30 in equal proportions and microbial nutrient mixture comprising nutrients immobilized on corn cob powder in the ratio of 3: 1. The oil zapper thus prepared was used at the concentration of lx 10⁹cell /per gm of oil.

Microbial nutrient mixture was prepared by mixing 0.1% - 0.3% K2HPO4, 0.1% - 0.3% KH₂P0₄, 0.05% - 0.1% MgS0₄7H₂0, 0.5% - 1% NaCl, 0.05% - 0.1% KN0₃, 0.1%) - 0.3% yeast extract powder, 0.05% - 1% NH₄C1, 1% - 2% (v/v) trace element solution, 0.1 % - 0.5% (v/v) vitamin solution and 1000 ml Reverse Osmosis (RO) water adjusting the pH of the mixture preferably to 6.5%-7.5%. The nutrient mixture was sterilized in an autoclave at a temperature of around 121±5°C at the pressure of 10-20 pound for a period of 15-25 minutes. The autoclaved mixture was cooled and immobilized with the corn cob powder in the ratio of 3: 1.

The corn cob powder was prepared by grinding the corn cob into the powder form. The corn cob powder so obtained was autoclaved (in dry cycle autoclave) at a temperature of 121± 5°C at the pressure of 10-20 pound for a period of 45-90 minutes for three times in consecutive days.

The autoclaved corn cob material was mixed with autoclaved nutrient mixture as described above. The corn cob powder was mixed with the nutrient mixture in the ratio of preferably 1 :3. To this the bacterial strains Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer were mixed and the mixture so obtained was packed into poly bags for use as a biodegrading agent for biodegrading oily sludge/refinery waste.

Example 2

Degradation of Petroleum Sludge in Soil

A plot of 2 x 1 meters was marked and excavated to the depth of one meter below ground level and covered from all four sides by polythene film for enhancing the overall degradation efficiency of petroleum sludge due to complete retention of the oil zapper material and the nutrients in the pit which prevented heavy metal contamination to the ground water. After placing the polythene film at the bottom of soil bed, soil was again filled in the plots up to depth of one foot below the ground level and 30-50 kg oily sludge was spread uniformly.

The bioremediation of petroleum sludge in soil was carried out in situ by introducing an inoculum (100-300g) comprising of a mixture of bacterial culture of five species along with nutrients (5-10 litre) containing a nitrogen source for sustaining the growth of the bacteria.

All the treatments were applied on the petroleum sludge contaminated soil. Tilling, watering and ploughing of the plots were done manually to supply the optimum moisture and oxygen to the oil degrading bacteria's for degradation of the same. Tilling is done at the start of bioremediation process, and it was repeated after every 15 days.

The sampling was done at different time intervals viz; zero days, 18^th day and at 38^th days from the start of the bioremediation process to monitor the soil and sludge parameters.

Petroleum sludge degradation was monitored at different time intervals and different properties were analyzed for different samples collected at different time intervals to check the degradation of sludge. Table 4 clearly shows the degradation of total petroleum h¾|bc#r&){i§ ttfl petroleum sludge from 19% to 0.53% in 38 days in environmentally safe manner.

Example 3

A plot of 2 x 1 meters was marked and excavated to the depth of one meter below ground level and covered from all four sides by polythene film for enhancing the overall degradation efficiency of petroleum sludge due to complete retention of the oil zapper material and the nutrients in the pit which prevented heavy metal contamination to the ground water. After placing the polythene film at the bottom of soil bed, soil is again filled in the plots up to depth of one foot below the ground level and 30-50 kg oily sludge was spread uniformly.

The bioremediation of petroleum sludge in soil was carried out in situ by introducing an inoculum (200-600g) comprising of a mixture of bacterial culture of five species along with nutrients (5-10 litre) containing a nitrogen source for sustaining the growth of the bacteria.

All the treatments were applied on the petroleum oil contaminated soil. Tilling, watering and ploughing of the plots were done manually to supply the optimum moisture and oxygen to the oil degrading bacteria's for degradation of the same. Tillage alters soil physical and chemical properties such as stimulates microbial activity. Tilling is done at the start of bioremediation process, and then it is repeated after every 15 days.

Petroleum sludge degradation was monitored at different time intervals and different properties were analyzed for different samples collected at different time intervals to check the degradation of sludge.

Table 5 clearly shows the degradation of total petroleum hydrocarbons in petroleum sludge from 19% to 0.49% in 38 days in environmentally safe manner. Example 4

A plot of 2 x 1 meters was marked and excavated to the depth of one meter below ground level and covered from all four sides by polythene film for enhancing the overall degradation efficiency of petroleum sludge due to complete retention of the oil zapper material and the nutrients in the pit which prevented heavy metal contamination to the ground water. After placing the polythene film at the bottom of soil bed, soil is again filled in the plots up to depth of one foot below the ground level and 30-50 kg oily sludge was spread uniformly

The bioremediation of petroleum sludge in soil was carried out in situ by introducing an inoculum (100-300g) comprising of a mixture of bacterial culture of five species along with nutrients (10-15 litre) containing a organic material for sustaining the growth of the bacteria.

Table 6 clearly shows the degradation of total petroleum hydrocarbons in petroleum sludge from 19% to 1% in 38 days in environmentally safe manner.

Example 5

The bioremediation of petroleum sludge in soil was carried out in situ by introducing an inoculum (100-300g) comprising of a mixture of bacterial culture of five species along with nutrients (12-20 kg) containing a organic material for sustaining the growth of the bacteria.

All the treatments were applied on the petroleum contaminated soil. Tilling, watering and ploughing of the plots were done manually to supply the optimum moisture and oxygen to the oil degrading bacteria's for degradation of the same. Tillage alters physical and chemical properties of soil. It stimulates microbial activity. Tilling is done at the start of bioremediation process, and then it is repeated after every 15 days.

Table 7 clearly shows the degradation of total petroleum hydrocarbons in petroleum sludge from 19% to 1.05% in 38 days in environmentally safe manner.

Table 1 : Composition of Diesel oil Sludge

Table 2: Degradation efficiency of various fractions of Diesel sludge at bioremediation site (using poultry manure)

Table 3: Degradation efficiency of various fractions of crude oil sludge at bioremediation site (using oil zapper technology known in the prior art at BPCL site)

Table 4: Soil characteristics and TPH degradation at zero days, 18 & 38 days

Table 5: Soil characteristics and TPH degradation at zero days, 18 & 38 days

Table 6: Soil characteristics and TPH degradation at zero days, 18 & 38 days

Table 7: Soil characteristics and TPH degradation at zero days, 18 & 38 day

Claims

What is claimed is:

1. A process for biodegradation of an oily sludge, the process comprising

a. providing a pit having a substantially impervious lining;

b. adding soil having at least 10% of moisture content into the pit;

c. spreading oily sludge over the soil; and

d. Contacting the sludge with oil zapper comprising bacterial consortia, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3 : 1.

2. The process as claimed in claim 1 , wherein the impervious lining is polythene film.

3. The process as claimed in claim 1 , wherein the bacterial consortia comprises Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, and s-30.

4. The process as claimed in claim 1 , wherein the bacterial consortia is present at the rate of lx 10⁹cell /per gm of the soil.

5. The process as claimed in claim 1 , wherein the nutrient mixture comprises 0.1% - 0.3% K₂HP0₄, 0.1% - 0.3% KH₂P0₄, 0.05% - 0.1% MgS0₄7H₂0, 0.5% - 1 % NaCl, 0.05% - 0.1% KN0₃, 0.1% - 0.3% yeast extract powder, 0.05% - 1% NH₄C1, 1 % - 2% (v/v) trace element solution and 0.1 % - 0.5% (v/v) vitamin solution.

6. The process as claimed in claim 1 , wherein pH of the nutrient mixture is in the range of 6.5%-7.5%.

7. The process as claimed in claim 1 , wherein the process further comprises tilling, watering and ploughing of the pit.

8. The process as claimed in claim 7, wherein the tilling is repeated after every 1 5 days.

9. The process as claimed in claim 1 , wherein total petroleum hydrocarbons in the oily sludge reduces from 19% to 0.49% in 35 to 40 days.

10. The process as claimed in claim 1, wherein 97% of the oily sludge gets biodegraded in 38 days.

1 1. A composition for biodegradation of an oily sludge comprising Acinetobacter bauminii, Alcaligene odorans, Bukhardica cepacer, Pseudomonas aeruginosa, and s-30, poultry manure and nutrient mixture immobilized with the corn cob powder in the ratio of 3: 1.

12. The composition as claimed in claim 1 1, wherein the nutrient mixture comprises 0.1% - 0.3% K₂HP0₄, 0.1% - 0.3% KH₂P0₄, 0.05% - 0.1%

MgS0₄7H₂0, 0.5% - 1% NaCl, 0.05% - 0.1% KN0₃, 0.1% - 0.3% yeast extract powder, 0.05% - 1% NH₄C1, 1 % - 2% (v/v) trace element solution and 0.1% - 0.5% (v/v) vitamin solution.