The document discusses re-refining of used lubricating oil. It begins by defining lubricating oil and its functions. It then discusses the production and demand for lubricating oil worldwide and in India. It describes the types of lubricating oils and their hydrocarbon composition. The document outlines the additives used in lubricating oils and contaminants that are present in used lubricating oil. It discusses the environmental impacts of improper disposal of used lubricating oil. Finally, it summarizes different methods for re-refining used lubricating oil including physical, physiochemical, and sulfuric acid refining methods.

1. RE-REFINING OF USED LUBRICATING OIL
Presented By -
Manoj Praharaj Bhatnagar
Roll no. 03
Avadhut Palekar
Roll no. 52
Pravin Panaskar
Roll no. 53
SEMESTER VII
DEPARTMENT OF
CHEMICAL
ENGINEERING
BHARATI VIDYAPEETH
COLLEGE OF
ENGINEERING,

2. Definition:
Lubricating oils are viscous liquids used for lubricating moving part of
engines and machines. Ex. engine oils, gear oils, hydraulic oils,
turbine oils, grease etc.
Functions:
 Used to reduce friction between moving surfaces.
 Remove heat from working parts in machinery.
 Remove wear debris created by moving surfaces.
 Provide a protective layering on the metal surfaces to avoid corrosion.
 Removing contaminants from the engine.
Production & Demand:
 Worldwide production of lubricating oil is estimated at 4.3x107 m3/year
(11.2x1010 gal/year). Of these volumes, automotive lubricants and
industrial/process lubricants each represent approximately one-half.
 The current lube oil demand in India is of the order of 10 lakh tonnes
per year. Out of this, almost 60% accounts for automotive and the rest
of 40% for industrial lubricants.
 In India, entire lube oil production is based upon imported Base oil as
Indian crude is predominantly waxy, hence, not suitable for lubricating
Base oil production.

3.  Lubricants today are classified into two major groups: automotive
lubricants and industrial lubricants.
 Industrial lubricants can be sub-divided into industrial oils and
industrial specialties; i.e., greases, metalworking lubricants, and
solid lubricant films.
 The industrial lubricants category includes the following types:
hydraulic, quenching, cutting, metalworking, electrical, and process
oils.
 Lubricating oils from petroleum consists essentially of complex
mixtures of hydrocarbon molecules.
 They are mostly composed of isoalkanes having slightly longer
branches and the monocycloalkanes and monoaromatics which
have several short branches on the ring.
 These hydrocarbon molecules generally range from low viscosity
oils having molecular weights as low as 250, up to very viscous
lubricants with molecular weight as high as 1000.

4.  Detergents
They hold acid-neutralising compounds in solution in the oil.
They are alkaline and react with the strong acids which form
during the combustion of fuel and can cause corrosion. Neutral
detergents are also used to impart anti-wear and extreme
pressure properties to an oil.
Ex. Phenaltes, Sulphonates, Naphthenates.
 Dispersants
Dispersants keep soot and combustion products in suspension
in the body of the oil charge and therefore prevent deposition as
sludge or lacquer.
Ex. PBI (Polyisobutylene) Succinimides.
 Antioxidants
Antioxidants inhibit the processes of decomposition that occur
naturally in lubricants as they oxidise in the presence of air.
These oxidation processes give rise to formation of sludge
resulting in an increase in acidity and viscosity.

5.  Anti-Foam Additives
They are substances that prevent foaming. Air entrapment in
lubricating oil can cause oil starvation due to the presence of air
bubbles at the contacting surfaces.
Ex. Silicone Polymers (very low concentrations)
 Pour Point Depressants
Mineral oils contain paraffin waxes that start crystallising at low
temperatures. This rapidly increases the viscosity of the oil and
leads to faster crystallisation as the temperature lowers. Pour point
depressants prevent this rapid viscosity increase.
Ex. Polymethylacrylate
 Polymer Thickeners
These additives are used if the viscosity characteristic of an oil at
different temperatures needs to be altered.
Ex. Didodecyl hydrogen phosphate
 Corrosion Protection
Included to protect vulnerable metal surfaces from atmospheric
corrosion. especially when machinery is idle or during overhaul.
Ex. Sulphates, Thiourea type chemicals

6.  Used lube oil is defined as the petroleum-derived or synthetic oil
which remains after applications in lubrication, cutting purposes
etc.
 After a certain period of useful life, the lubricating oil loses its
properties and cannot be used as such in machinery.
 Build up of temperature degrade the lubricating oils, thus leading
to reduction in properties such as: viscosity, specific gravity, etc.
 Dirt and metal parts worn out from the surfaces are also deposited
into the lubricating oils.
 With increased time of usage, the lubricating oil loses its
lubricating properties as a result of over-reduction of desired
properties, and thus must be replaced with a fresh one.
The Hydrocarbon Composition of Used Lube Oil
 The hydrocarbon composition of new or used automotive
lubricating oil sludge consists primarily of saturated compounds
such as linear and branched chain, paraffins, which have at least
twice as many naphthenes.
 Aromatics generally comprise about 10 to 15 weight percent of the
hydrocarbon base material.
 Composition of used oil consists of four major groups, which have
average values of 76.7% saturates, 13.2% monoaromatics, 3.7%
diaromatics and 6.5% polyaromatic-polar material.

8. The automotive lubricating oil loses its effectiveness during operation due to the presence of certain types of
contaminants. These contaminants can be divided into:
 Extraneous Contaminants

 Extraneous contaminants are introduced from the surrounding air and by metallic particles from the engine.
Contaminants from the air are dust, dirt, and moisture. Air itself may be considered as a contaminant since
it might cause foaming of the oil. The contaminants from the engine are:
 Metallic particles resulting from wear of the engine,
 Carbonaceous particles due to incomplete fuel combustion,
 Metallic oxides present as corrosion products of metals,
 Water from leakage of the cooling system,
 Water as a product of fuel combustion and
 Fuel or fuel additives or their byproducts, which might enter the crankcase of engines.
 Halogenated compounds, originated from solvents and glycols, resulting from anti-freezing
compounds, used in engine cooling systems.
 Products of Oil Deterioration



Many products are formed during oil deterioration. Some of these important products are:
 Sludge: A mixture of oil, water, dust, dirt, and carbon particles that results from the incomplete combustion
of the fuels. Sludge may deposit on various parts of the engine or remain in colloidal dispersion in the oil.
 Lacquer: A hard or gummy substance that deposits on engine parts as a result of subjecting sludge in the
oil to high temperature operation.
 Oil-soluble products: The result of oil oxidation products that remain in the oil and cannot be filtered out
and deposit on the engine parts. The quantity and distribution of engine deposits vary widely depending on
the conditions at which the engine is operated. At low crankcase temperatures, carbonaceous deposits
originate mainly from incomplete combustion products of the fuel and not from the lubricating oil. While, at
high temperature, the increase in lacquer and sludge deposits may be caused by the lubricating oil.

11.  Used oils themselves are not toxic. Contaminants
such as additives, degradation products, para chloro
benzene (PCB) and poly nuclear aromatics (PNA)
make them so hazardous.
 They have high potential to cause damage to the
environment by virtue of their persistent nature and
potential to spread over large surface areas on land
and water.
 Films of oil prevent light and air from reaching to life
forms of all types on land and water.
 As per the data, one litre of oil can render one million

12.  Oil, in any form, is potentially harmful to the environment. Post-
studies of oil spills indicate that it takes up to twenty years for an
aquatic environment to return to a healthy condition.
 Once it has been used by industry or the DIYer, it has even more
potential for environmental damage.
 In aquatic community oil residue tends to settle on the bottom,
coating the substrate and whatever organisms live there.
 When poured on the ground, oil can rapidly migrate through the
soil.
 In both instances bacteria, plants, invertebrates and vertebrates
experience physiological stress.
 Oil film on water can reduce the penetration of light into the water
and, consequently, reduce the rate of photosynthesis. When
photosynthesis is reduced, oxygen production is also reduced.
 The oil film may also inhibit the movement of oxygen from the air
through the surface of the water. The reduction of dissolved
oxygen in the water stresses animals living in the water.

13.  Generally speaking, there are 3 categories for waste oil disposal:
1- Reuse , including re-refining
2- Thermal cracking
3- Incineration / Use as a fuel
 The first one , is the best one and is the subject of this study .
The second one – although produces acceptable (cracked)
products , but is not as good as re-refining. The third one
produces a lot of ash, which contains heavy metals and pollutes
the environment.
 In disposing used oil, many people use it as a dust cure; that is,
for dust prevention. This method of disposal is in many ways
unsatisfactory as the lead-bearing dust and run-off, constitute air
and water pollution.
 Another method by which used oil is being disposed is by
incineration. This method represents another poor use of such a
valuable product, and the attendant emission of probably
carcinogenous products, contribute to environmental pollution.

15. Recycling of used lubricants is now attracting more attention because of the
fear of dwindling of world oil reserves and more as a result of the environment
concern which it posses.
The following three distinctive reasons explain the interest in the re-cycling of
waste lubricating oils:
 The need to conserve crude reserves.
 Minimizing unemployment through the building/construction of used
lubricating oil recycling plant.
 The elimination of environment pollution source of used lubricant.
Recycling efforts can no doubt minimize non-discriminatory disposal of waste
oils into landfills and surface waters other benefits include:
 Reduce dependence on Base oil imports saving foreign exchange.
 Prevent ground water contamination and pollution of surface waters.
 Preserve natural resources such as coal and crude oil.
 Reduce sewage treatment costs.
 Reduce future remedial costs for landfills and disposal sites.
 Reduce safety risks and hazards associated with extensive stockpiling.
 Eliminate improper burning of waste oil as fuel, which generates toxic fumes
and air pollution.

16.  The re-refining of used oils to lube base oils started in 1935. The principal
reasons why re-refining was unable to find acceptance were:
- high process costs
- and therefore high selling prices compared to relatively low virgin oil
prices,
- Inadequate removal of carcinogenic polycyclic aromatics.
 By mid-1960's there were more than 150 small companies re-refining over
three hundred million gallons of used oil annually employing the "acid/clay"
re-refining process, wherein large amounts of sulfuric acid and clay were
used to treat the used oil.
 The technology produced acceptable, although sub-standard, base oil. It
also created substantial hazardous waste by-products, including acid tar
and oil saturated clay.
 In late 1970s, alternative processes were developed to treat the used oil in a
more environmentally friendly manner. The first of the "next-generation"
technologies was the Phillips' Re-Refined Oil Process (PROP). This
technology was developed during the energy crisis of the 1970s
 That process was capable of producing low quality base oils; however, there
were still several environmental concerns that arose due to the need to
dispose of large quantities of heavy metal laden precipitate and filter media

17. Physical Method
Mechanical Filtration: Mechanical Filtration is widely used method
of re-cycling. Here contaminants are separated mechanically or by
absorption or adsorption by passing through materials of controlled
porosity.
Vacuums Dehydration: It is a well-known oil-recycling method.
Water and oil, for all practical purpose, are immiscible liquids. If not
agitated, water introduced into lubricating oil separates readily by
gravity.
Centrifugal Separation: It is efficiently used in some commercial oil
purifying equipment to separate solids and free water from the oil.
The method involves whirling the dirty oil to separate it into layer of
insoluble contaminants, water and clean oil.
Magnetic Separation: Several types of magnetic filters are used
principally for the removable of ferrous metal contaminants from
low viscosity oils and water-soluble oil coolants.

18. Physio-Chemical Method
These methods have been developed for those oils, which are heavily
contaminated and re-refining is not possible only by physical methods.
Re-refining of the used oils has been practiced over the past fifty years.
Among the first commercial approached for this, the ACID/CLAY
refining had been widely adopted in the past. With the ever-increasing
awareness towards the cleaner environment, following new ECO
friendly process producing higher yields of re-refining oils have been
developed which totally eliminates ACID SLUDGE.
Step 1 - Dehydration
The oil is boiled in a closed container to remove the water that has been
mixed into it.
Step 2 - Diesel stripping
The dehydrated oil is then fed continuously into a vacuum distillation
plant for fractionation. Lighter oils boil off first and are removed,
followed by the lubricating oil itself. Other heavier components do not
boil in the conditions used.
Step 3 - Lube oil distillation and condensation
A liquid extraction process then removes any aromatic components
from the oil.
By this stage, the oil is identical to refined virgin oil. It is then tested,
appropriate

19.  This is the core process for lube oil re-refining. In
India, the general practice is to refine waste oil in a
batch process.
 The de-watered oil is heated in a kettle under vacuum.
As the temperature in the kettle rises, various cuts are
liberated and rise as vapours, to be condensed in a
condenser.
 The condenser, along with the heating kettle, is
maintained under vacuum by a vacuum pumping
system. The condensed products are available as
different products corresponding to various kettle
temperatures as mentioned below.
 Finally, the process ends when the residual material in
the kettle does not vapourise, even at a temperature of
around 320°Celcius. At this point, the heating in the

21. Sulfuric Acid Refining (Meinken Process)
 The sulfuric acid refining process was mostly developed by Meinken.
Compared to older acid based methods, various process stages reduce
the amount of acidic sludge and used bleaching clay generated as well as
increasing the lube oil yield. Due to the acidic sludge problem, acid
refining has largely been replaced by other methods.
 It is a process based on chemical pretreatment. Before the used oil flows
into the waste oil storage tanks, it passes through the filters to remove
solid impurities.
 The dewatered oil is treated with sulfuric acid (96%) and the acid refined
oil is vacuum distilled to separate lube base oil from the low boiling
spindle oil and gas oil. A block flow diagram of re-refining process is
shown below.
 Clay is added to reduce viscosity of oil during acid treatment. However,
the sulfuric acid treatment and clay addition produce waste streams like
acid tar and spent clay resulting in a problem of waste disposal.
 In spite of the disposal problem associated with Meinken process, the
Meinken technology appears to be very popular. At present, there are
about 60 such refiners around the world using the same system.

23.  The principle of this processing step, developed by the Institut Francais du
Petrole (IFP), also known as the Selectopropane Process, is the use of propane
to extract selectively all base oil components from waste oil. In this process,
water-free waste oil from atmospheric distillation is put in an extraction column
with liquid propane at 75-95°C. Dirt and insoluble sludge settle out. After
extraction, the oil-containing propane is removed from the extractor.
 Snamprogetti (Italy) has further developed the IFP process by including a
propane extraction step before and after vacuum distillation, and by adding a
hydrofinishing step which changes the technology to a four-stage process,
without clay treatment.
 The IFP vacuum/distillation and propane/deasphalting plus hydrogenation
technology includes:
1. atmospheric distillation to remove water and light ends;
2. vacuum distillation to recover light and medium base oil cuts;
3. hydrofinishing of the vacuum distillates to produce finished base oils;
4. propane deasphalting of the vacuum residue to recover the bright stock
fraction; and hydrogenation of the brightstock fraction.
The hydrogenation reactor for bright stock includes two catalytic beds. The first
one ensures demetallisation, and the second hydrofinishing of the bright stock. In
the first stage of the Snamprogetti technology, the light hydrocarbons and water are
removed by atmospheric distillation. In the second stage, all the impurities picked
up by the engine oil, including the additives and partly degraded polymers, are
removed by extraction with propane. In the next stage, the extracted oil is
fractionated by vacuum distillation. The vacuum residue is then submitted to a
second extraction stage in which metal content and resinous/asphaltic components
are further reduced. The base oil cuts from the vacuum residue (bright stock) are

25.  The Mohawk Process (subsequently CEP – Mohawk) using high
pressure hydrogenating was introduced in the USA at the end of
the 1980s.
 The first stage of the process removes water from the feedstock.
 The second stage of the process is thin-film vacuum distillation ,
at this step light hydrocarbons are removed resulting in a
marketable fuel by-product.
 The third stage, evaporation, vaporizes the base oil, separating it
from the additives, leaving behind a by-product called residue.
This residue is used in asphalt industry.
 This is followed by hydrogenation of the distillate at 6900 kPa
over a standard catalyst. Special steps realized catalyst life of 8
to 12 months, which was essential for the economy of the
process.
 The Mohawk process features continuous operation, low
maintenance, longer catalyst life span, reduced corrosion, and
proven technology. A marked reduction in the amount of water
which must be treated as effluent as well as the cheaper

27.  The KTI (Kinetics Technology International) process combines
vacuum distillation and hydrofinishing to remove most of the
contamination and additives.
 The key to the process is the thin-film vacuum distillation to
minimize thermal stress through mild temperatures not
exceeding 250 ◦C.
 The hydrofinisher then removes sulfur, nitrogen and oxygen. The
yield of finished base oils is high (82% on a dry waste oil basis).
 The KTI waste lube oil re-refining process involves a series of
proprietary engineering technologies that affords high economic
returns without resulting in environmental loads. The main
features of the KTI process include:
1. high recovery yield up to 95% of the contained lube oil;
2. excellent product quality;
3. flexible operation with wide turndown capability;
4. no requirement for discharging chemicals or treating agents;
5. absence of non-commercial by-products; and
6. reliable, inexpensive treatment of waste water contained in the
wasted lube oil.

30. The PROP technology was developed by Phillips Petroleum
Company. The key elements of the process are the chemical
demetallization (mixing an aqueous solution of diammonium
phosphate with eated base oils) and a hydrogenation process. A
bed of clay is used to adsorb the remaining traces of contaminants
to avoid poisoning of the Ni/Mo catalyst.

31. The Safety Kleen process uses atmospheric flashing for removing
water and solvents, a vacuum fuel stripper, vacuum distillation with
two thin-film evaporators, and a hydrotreater with fixed bed Ni/Mo
catalysts.
When using high severity the hydrotreater can reduce the content of
polynuclear aromatics; it also removes higher boiling chlorinated
paraffins.
In 1998 the Safety Kleen process was used in the largest waste oil re-
refinery in the world (East Chicago, Indiana, USA, plant capacity 250
000 t/a).
The Safety Kleen process is, based on a combination of wiped-film
vacuum distillation and fixed-bed catalytic hydrotreatment.
The process begins by removing the water and light solvents using
an atmospheric flash drum.
The vacuum column/fuel stripper removes most of the fuel and
heavier solvents.
The vacuum distillation unit performs the combined functions of
separating the lubricating oil from the heavy ends and generating
multiple product streams.
Chemically non-pretreated waste oil tends to foul heated surfaces
over time, so thin-film evaporators are used.
The lubricating oil cuts are then hydrotreated over fixed beds of
nickel-molybdenum catalyst. The hydrotreating is performed in

33. The best results with regard to the technical and environmental quality of
the re-refined oil and the elimination of PAH are provided by a combination
of thin film distillation followed by selective solvent extraction. In this
process, the distillate from vacuum thin-film distillation towers equipment
at the re-refinery are finally treated in a lube refinery solvent extraction
plant followed by hydrofinishing. After this extraction process, the PAH
content is lower than that of virgin solvent neutrals.

34.  This innovative re-refining technology has evolved from existing
commercial petroleum refinery technology, and involves treating the
entire waste oil in a heated hydrogen-rich atmosphere, whereby the yield
of recyclable high-quality products is increased by up to 30%, while at
the same time eliminating the coproduction of hazardous distillate
fractions.
 Halogenated and oxygenated compounds are destroyed in such
treatment, and high-quality, re-usable lighter distillate hydrocarbons are
produced, along with purified base oils.
 The waste oil is mixed with hot hydrogen gas, and then injected into a
recirculating heated hydrogen gas stream directly upstream of a
metal/solid separator. The hydrocarbon mixture, along with the aqueous
contamination, leaves the separator with the heated hydrogen gas, and
goes directly to a fixed bed catalytic reactor.
 The flash drum separates the base oil product from the lighter
components prior to condensing the aqueous phase, thus keeping the
base oil product dry.
 Light oil is recovered and fractionated to produce naphtha range
products and diesel fuel. The base oil product is stabilised to remove
light gases before directing the material to a product fractionator, where
light and heavy base oils are produced.

36.  Vaxon (Enpotec fabrication facilities in Denmark) uses three or four
vacuum cyclone evaporators and finishing treatment with chemicals
for re-refining of lubricating oils.
 The key step in the ENTRA technology is the special vacuum
evaporation in a vacuum linear tubular reactor (single tube). After
continuous evaporation by means of rapidly increasing temperature,
vapor condensation is performed by fractional condensation.
Complete dechlorination can be achieved with metallic sodium. Clay
polishing is used as a finishing process.
 The thermal deasphalting (TDA) process has been developed by
Agip Petroli/Viscolube using the technology of PIQSA Ulibarri in
Spain. The process is based on chemical treatment to facilitate
subsequent deasphalting.
 The Viscolube technology, also known as thermal deasphalting
(TDA)7, is an improvement of a deasphalting process which has
been operated for over 15 years by Viscolube Italiana SpA as a
40,000 t/y capacity plant, using propane deasphalting, followed by
vacuum distillation and clay finishing.
 In Resource technology re-refining technology, the used oil is
dewatered, heated, and then flashed in an atmospheric distillation
column to remove remaining emulsified water and fuel fractions. The
dehydrated oil is then heated and transferred to a vacuum flash

37. Physical and Chemical Tests of Used Lubricating Oil
Standard chemical and physical tests were used to evaluate the nature and the
extent of the contaminants in the used automotive oils. These tests involve the
following measurements:
 Viscosity: viscosity testing can indicate the presence of contamination in used
lubricating oil. The oxidation and polymerization products that were dissolved
and suspended in the oil cause the increase of oil viscosity. While a decrease in
the viscosity of lubricating oil indicates the fuel contamination.
 Pour Point: pour point is the lowest temperature at which the oil will flow. Low
pour point indicates good lubricating oil.
 Flash Point: flash point is the lowest temperature at which the vapors in air will
burn momentarily if ignited by flame or spark. A decrease in flash point
indicates contamination by dilution of lubricating oils with unburned fuel.
Increasing of flash point indicates evaporation of the light components from the
lubricating oil.
 Acidity or Neutralization Number: this is a measure of the amount of alkali
required to neutralize one gram of the oil. An increase in acid number is due to
oxidation of lubricating oil.
 Ash Content: the remaining solid ash, when the oil is completely burned, is a
measure of oil purity.
 Carbon Content: this evaluates the solid residue obtained when the oil is
heated to complete vaporization and it refers to the amount of deposit formed.
 Water Content: this test is done by distillation and indicates the amount of
water emulsified in the oil.
 Fuel Contaminants: this test indicates the amount of fuel diluting in the
lubricating oil during automotive operation

41.  Foreign exchange equivalent to 1,500 crores of rupees is spent
every year towards procurement of lube base stocks.
 After a certain period of useful life, the lubricating oil loses its
properties and cannot be used as such in machinery.
 From the total volume of lubricating oils consumed in India, five
hundred thousand tonnes of used oil can be collected and
recycled to obtain approximately 3.5 lakh tonnes of base oil.
 The statistics reveal that one barrel of lube base stock is
obtained by refining around 30-35 barrels of crude oil.
 On the other hand, re-refining 30-35 barrels of used lube oils will
yield 20-22 barrels of lube base oil.
 This will result in a forex saving of more than 500 crores of
rupees every year.
 Used oil, a valuable resource, is wasted if improperly disposed
off. Used oil can be re-refined and used over and over again after
blending with suitable additives and with no compromise on
quality.
 It will effectively conserve valuable oil reserves and will lessen
the import burden as our country is totally dependent on lube
base oil imports.

42.  Used oil is a pollutant, and, by re-refining, the pollution is
reduced. Hence, it should get the status of eco-friendly
technology and get grants and incentives from the Ministry of
Environment.
 The quality of thoroughly re-refined oil is comparable with
nascent base oils. Hence, it should be Evaluation awarded
import-substitute status.
 While making fresh lubricating oils, blending with 5 - 10% of re-
refined base oils should be done for viscosity correction.
 All such blended oils should be stamped with eco-label/green
label to make the public aware about the concept of re-refining.
 The eco-conscious customers would buy the product with green
label.
 Since re-refining leads to oil conservation, the concept of re-
refining should be strongly supported by the Petroleum
Conservation Research Association.

44.  Kirk-Othmer’s Encyclopedia of Chemical Technology, vol. 15, vol.
21.
 Ullmann's Encyclopedia of Industrial Chemistry, Vols. 23.
 Design Aspects of Used Lubricating Oil Re-Refining by Firas
Awaja and Dumitru Pavel
 MODERN RECOVERY METHODS IN USED OIL RE-REFINING by
H. Bridjanian*, M. Sattarin, Research Institute of Petroleum
Industry , Tehran
 Re-refining of Used Lube Oils, An Intelligent and Eco-friendly
Option by Mithilesh Kumar Jha, Indian Chem. Engr., Section B,
Vol. 47, No. 3, July – September 2005
 Techno-economic evaluation of waste lube oil rerefining
Muhammad Farhat Ali*, Faizur Rahman’, Abdullah J. Hamdan
King Fahd University of Petroleum d Minerals, Saudi Arabia Int. J.
Production Economics 42 (1995) 263-273
 EVALUATION OF OIL REFINING AND RECYCLING
TECHNOLOGIES , US -ASIA ENVIRONMENTAL PARTNERSHIP
 Major Pathways for Used Oil Disposal and Recycling, by Czeslaw
Kajdas, Warsaw University of Technology, Poland