Harards of oily waste & its management

1. Hazards of Oily Waste & its Remediation
1
Lecture
at
Department of continuing education IIT, Roorkee
27th January, 2010
G.S. Dang
gurbax49@gmail.com

2. 2
Presentation Outline
Oily Wastes / Hazardous Wastes
Sludge Generation/ Environmental Regulations
Sludge Management / Bioremediation
Other disposal ways
Conclusion

3. 3
Oily Wastes
Sources:
 Crude oil spills
 Oily sludge generated in crude oil tanks in oil fields
and in refineries
 Oil contaminated soil / drill cuttings
 Oil sludge generated in petroleum product tanks in
refineries / marketing terminals
 Sludge generated in effluent treatment plants (ETPs)
in refineries / oil installations

4. 4
Oily Sludge- Constituents
 It is a mixture of heavy hydrocarbons like
asphaltenes and waxes together with sand, clays,
water and other solid substances like rust and heavy
metals
 The sludge is an environment hazard & hazardous
waste rules apply on it

5. 5
Hazardous Waste
Definition (As defined in HW Rules 2008)
Any waste which by reason of any of its physical,
chemical, reactive, toxic, flammable, explosive or
corrosive characteristics causes danger or is likely to
cause danger to health or environment whether alone or
when in contact with other wastes or substances is termed
Hazardous
and shall include Wastes listed in Schedule–1 (list of
processes generating waste), Schedule – 2 (concentration
limits of wastes) of HW Rules

6. 6
Sludge Generation in Refineries /
Oil Installations
 Oily Sludge - Generated from cleaning of the crude
oil and heavy product storage tanks and also from
ETP basins
 Chemical Sludge – Generated in ETP during
chemical treatment of effluents. (eliminated with
commissioning of biological treatment plant, BTP)
 Bio Sludge – Generated from clarifier in BTP during
biological treatment of effluents
Sludge is extremely difficult to remove from tanks &
poses very difficult disposal problems

7. 7
Oily Sludge(s) – Composition
Typical high volume hazardous waste generated
by refineries / storage terminals
Tank Bottoms Sludge contains
Crude oil / Product Oil 40 to 80%
Tanks (FO/Diesel) Water 10 to 40%
Solids 5 to 15%
Waste Water Treatment Plant Sludge contains
 ETP Sludge oil 40 to 60%
 Emergency Basin / Lagoons water 50 to 55%
Solids 10 to 15%
Industry average for total refinery solids production is
around 0.32 Ton (oil + solids) per 1000 bbl of crude
processed (API study)

8. Prevailing Environmental Regulations
Hazardous waste (Management & Handling rules – 2008)
requires refineries / oil establishments
 Facility operator to obtain authorization for handling /
storage / transportation of sludge
 Authorization is subject to satisfactory steps taken to
reduce waste generated
 Occupier is responsible for treatment of hazardous waste
& disposal of residual waste
 Storage of raw sludge is temporarily permitted in
secured landfill for a period at the end of which it is to be
treated & disposed off as a part of environmentally
sound management of hazardous waste
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9. 9
Management of Oily Sludge
Approach followed :
 Volume reduction
 Treatment for recovery of oil
 Disposal of residual sludge / solids without affecting
environment

10. Management of Oily Sludge Contd…
Volume reduction / oil recovery
In-situ recovery
 Operation of side entry mixers – dispersing the
sludge particles in the bulk of the crude oil
 Sludge dissolving by hot gas oil (70–80oC) circulation
10
in the tank

11. Management of Oily Sludge Contd…
Ex-situ recovery
 Sludge is removed to melting pit
 Melting of oily sludge by heating to 80-90oC using low
pressure steam, followed by filtering, centrifuging &
settling
 For ETP sludge volume reduction and dewatering is
done through use of thickeners & centrifuges
 With this treatment solid content of sludge is increased
from 1-3% by weight to approximately 20% by weight
11

12. Contd…
 The recovered oil is pumped to slop tanks for
reprocessing with crude oil. Water phase is sent to
effluent treatment plant (ETP)
The residual sludge is disposed off / stored in
specially constructed pits / secured land fill (SLF)
having polymer lining and leachate collection
system
12
Management of Oily Sludge

13. 13
Limitations of Existing Practices
 Recovery of oil is limited. Residual sludge in melting pit
contains oil upto 30 to 35 %wt
 Substantial quantity sludge is to be removed manually
(messy operation)
 Leads to pollution due to VOC emissions
 Manual operation is not only unhealthy / unsafe but leads
to outage of tanks for very long period (8 to 15 months)
 Residual sludge is problem for eco-friendly disposal
 Accumulation / storage of sludge in lined pits (secured
landfill is not solution on long term basis)

14. Sludge Management – Bioremediation
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Method
Residual sludge disposal
 Bioremediation of residual sludge is well reorganized /
adopted by refineries and oil producing companies as
the way to dispose it in environment friendly way

15. Bioremediation of Residual Oily Sludge
 Bioremediation is a process that employs
microorganisms capable of degrading toxic
contaminants present in hazardous wastes like oily
sludge etc
 Naturally occurring microorganisms transform
harmful substances containing hydrocarbons to
carbon dioxide and water
 Safe disposal of sludge without affecting the quality
of soil and ground water
15

16. 16
Bioremediation Methodology
 Oily sludge is spread over the soil of the earmarked site
and tilling is carried out
 Bacterial consortium (oil zapper / oilivorous’S’) is applied
along with nutrient at the farmed out site
 The area is tilled every fortnight in 12-16 weeks, all the oil
gets decomposed to carbon dioxide and water
 Soil & sludge samples are analyzed every quarter for
parameters including heavy metal content. No built up of
concentration of heavy metals (Zn, Mn, Cr, Cu, Ni, Pb, Co,
As, Cd, Se) in the soil
 Around 16 weeks of initial application the cycle is
complete and fresh cycle can be started. No adverse
impact on quality of ground water

17. 17
Phytoremediation
Bioremediation has been broadly successful with
petroleum based constituents
Microbial digestion however has met limited success for
widespread residual organic and metal pollutants
To remove trace concentration of heavy metals from soil
and water phytoremediation using certain plants is fast
emerging
Type of phytoremediation techniques include
phytoextraction, phytotransformation, phytostabilization,
phytodegradation and rizofiltration
Phytoremediation is well suited for use at very large field
sites where other methods of remediation are not cost
effective or practicable

18. 18
Advantages of Bioremediation
A way to safe disposal of oily sludge in petroleum
industry (conventional methods expensive and
cumbersome)
Bioremediation produces harmless products like carbon
dioxide, water and cell biomass
Technology well accepted in industry
Commercially used for large quantities of sludge
(>20,000 MT)
Cost effective vis-à-vis available technologies

19. Disadvantages of Bioremediation
A Bioremediation is limited to those compounds that are
biodegradable. Not all compounds are susceptible to
rapid and complete degradation
Bioremediation often takes longer than other treatment
options, such an excavation and removal of soil or
incineration
Regulatory uncertainty remains regarding acceptable
performance criteria for bioremediation. There is no
accepted definition of “clean”, evaluating performance of
bioremediation is difficult, and there are no acceptable
endpoints for bioremediation treatments
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20. Other disposal ways
for
hazardous wastes

21. Incineration
• Incineration is applied to certain wastes that
cannot be recycled, reused or safely deposited in
a landfill.
• Incineration is high temperature, thermal
oxidation process in which hazardous wastes are
converted, in presence of oxygen in the air, into
gases and incombustible solid residue. Gases are
vented into atmosphere through Gas cleaning
system and solid residue go to landfill

22. Incineration
Applicability of incineration of hazardous
waste depends on certain considerations:
• The waste is biologically hazardous
• It is resistant to biodegradation and persistent
• It is volatile and therefore easily dispersed
• It cannot be safely disposed into landfill even after
stabilization
• Volume reduction of waste is necessary

23. Incinerable wastes
Typical wastes that would need to be
incinerated by the operator of TSDF
(waste treatment facility ) may
include
- solvent wastes (spent solvents)
- waste oils, oil emulsions
- oil mixtures / Refinery waste
- Others with calorific value > 2500
Kcal/kg

25. Guidelines for Incineration
Incineration aims - destroying the toxicity of wastes and
get products of combustion that are harmless. The 3 Ts
of combustion are:
• Temperature
• Time
• Turbulence
Availability of oxygen is additional parameter which
forms an integral part of the incineration system.

26. Guidelines for Incineration
When waste is burnt at the higher temperature
destruction would be complete and formulation
of un-burnt waste, formation of organic by-products
etc would be eliminated. The longer the
waste is held at high temperature, the greater will
be the degree of destruction and the less
likelihood of formation Products of Incomplete
Combustion (PICs)

27. Guidelines for Incineration
Temperatures of 900-1100 C for hydrocarbon wastes
and 1100-1200 C for certain waste like PCBs, waste
Oil residues etc. For other halogenated organics case
to case tackling may be needed.
Minimum gas phase residence time of 2 seconds has
to be maintained
Combustion air – 100% excess of stochiometric
requirements
Turbulence is achieved through good incinerator
design

28. 28
Conclusion
Oily wastes generated in refineries / oil installations are
hazardous as per HW rules 2008
Management of oily wastes include recovery of valuable
oil and separating the hazardous constituents
Hazardous constituents need to be handled / disposed
off in a way that the environment pollution is minimum
Bioremediation is one such way to convert the
hazardous constituents into harmless products to a
greater extent
Research is still on to make the bioremediation process
as clean as possible
Bioremediation/ Phytoremediation techniques are
improving as greater knowledge & experience are gained

29. Tel: 0135-2654989
09997168805
E-mail : gurbax49@gmail.com
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C O N T A C T S

30. Melting Pit

31. PVC LINED PIT FOR OILY SLUDGE
STORAGE

32. TILLING OPERATION DURING BIOREMEDIATION

33. SAMPLE BEFORE AND AFTER BIOREMEDITATION
oily sludgey
soil sample after
bioremediation

34. PHYTO EXTRACTION