The document discusses industrial wastewater treatment at an oil refinery. It provides an overview of the oil refining process and the various units involved. Significant waste is produced, including hazardous materials in wastewater. Refinery wastewater treatment typically involves oil removal through API separation and dissolved air flotation, followed by equalization and biological treatment using activated sludge. Additional steps like nitrification and denitrification may be used to meet strict nitrogen limits. Proper wastewater treatment is important to meet environmental standards and protect public health from potential health hazards of untreated effluent.

1. CYPRUS INTERNATIONAL UNIVERSITY
INDUSTRIAL WASTE WATER TREATMENT (OIL REFINERY)
By
ELEGBELEYE OLADIPO AYODAMOPE

2.  I N T R O D U C T I O N
 P R O C E S S U N I T S F O U N D I N A R E F I N E R Y
 OVERVIEW OF OIL REFINERY WASTE PRODUCTION
 R E F I N E R Y W A T E R
 REFINERY WASTEWATER TREATMENT
 WASTEWATER TREATMENT SCHEME
 Environmental Standards for Petroleum Oil Refineries Effluent
 P U B L I C H E A L T H C O N C E R N S
 Dissolved Air Flotation
 Activated Sludge
 Nitrification With Denitrification
 C O N C L U S I O N

3.  An oil refinery is an industrial process plant
where crude oil is processed and refined into
more useful products such as petroleum
naphtha, gasoline, diesel fuel, asphalt base,
heating oil, kerosene, and liquefied petroleum
gas.
 Oil refineries are typically large, sprawling
industrial complexes with extensive piping
running throughout, carrying streams of fluids
between large chemical processing units.

4. PROCESS UNITS FOUND IN A REFINERY
•De-salter unit washes out salt from the crude oil before it enters the atmospheric
distillation unit.
•Atmospheric distillation unit distills crude oil into fractions.
•Vacuum distillation unit further distills residual bottoms after atmospheric
distillation.
•Naphtha hydro-treater unit uses hydrogen to desulfurize naphtha from atmospheric
distillation. Naphtha is hydro-treat ed before sending to a catalytic reformer unit.
•Catalytic reformer unit is used to convert the naphtha-boiling range molecules into
higher octane reformate (reformer product).The reformate has higher content of
aromatics and cyclic hydrocarbons). An important byproduct of a reformer is
hydrogen released during the catalyst reaction. The hydrogen is used either in the
hydrotreaters or the hydrocracker.
•Distillate hydrotreater desulfurizes distillates (such as diesel) after atmospheric
distillation.
•Fluid Catalytic Cracker (FCC) unit upgrades heavier fractions into lighter, more
valuable products.
•Hydrocracker unit uses hydrogen to upgrade heavier fractions into lighter, more
valuable products.

6. Overview of Oil Refinery Waste Production
The generation of waste is an inevitable consequence of the
operation of refineries and depots. Waste production in
refineries and terminals represents a high operating cost and
as such its minimization should be a priority. Waste
substances generated by oil refineries fall into two categories:
•Non-hazardous waste, e.g. scrap metal, spent catalytic
cracking catalyst or “domestic” waste.
•Hazardous waste, e.g. asbestos, acid tars, sludge with a high
lead content or many oil contaminated materials such as
untreated waste water discharges.

8. Refinery Wastewater Treatment
• In a refinery wastewater treatment system, two steps of oil removal
are typically required to achieve the necessary removal of free oil
from the collected wastewater prior to feeding it to a biological
system.
• This oil removal is achieved by using an APIseparator followed by
a dissolved air flotation (DAF) or induced air flotation (IAF) unit
The wastewater from the secondary oil/water separation unit is
sent to the equalization system that is used to dampen out
variations in flow and concentration in the refinery wastewater.

9. Refinery Wastewater Treatment
cont’d
• The wastewater is then routed to the aeration
tank/clarifier which constitutes the biological
system
The effluent from the clarifier is then sent to
tertiary treatment (if necessary) prior to discharge.

11. Environmental Standards for Petroleum Oil Refineries Effluent
S
/
N
Parameter Limiting value for concentration
(mg/l, except for pH)
Limiting value for quantum (kg/1000
tonne of crude processed, except for
pH)
1 Ph 6.0 – 8.5 -
2 Oil and Grease 5 2
3 BOD3, 27o C 15 6
4 COD 125 50
5 SS 20 8
6 Phenol 0.35 0.14
7 Sulphide 0.5 0.2
8 CN 0.2 0.08
9 Ammonia as N 15 6
1
0
TKN 40 16
1
1
P 3 1.2
1
2
Cr(VI) 0.1 0.04
1
3
TOTAL (Cr) 2.0 0.8
1
4
Pb 0.1 0.04
1
5
Hg 0.01 0.004
1
6
Zn 5.0 2
1
7
Ni 1.0 0.4
1
8
Cu 1.0 0.4
1
9
V 0.2 0.8
2
0
Benzene 0.1 0.04
2
1
Benzo(a)Pyrene 0.2 0.8

12. Water and solid wastes emanating from refineries has
damaging effect on public health and the environment
when pollution parameters are above the set standards.
Localized waste water discharges and habitat degradation
contaminate water supplies, farming lands and fisheries in
poor regions of Ecuador and the Niger River Delta.
Cancer-causing chemicals such as benzene primarily
affect the health of those living in close proximity to
refineries.
Populations living in inner cities often suffer most from
concentrated air pollution -- soot and ozone -- due to the
proximity with truck and bus routes.

13. Dissolved Air Flotation
• The first step in a DAF system is coagulation/ flocculation.
Dispersed particles (oil/solids) are stabilized by negative electric
charges on their surfaces, causing them to repel each other.
• they do not settle, since this prevents these charged particles from
colliding to form larger masses, called flocs.
• Chemical coagulation and flocculation are required to assist in the
removal of colloidal particles from suspension.
• These processes, usually done in sequence, are a combination of
physical and chemical procedures.

14. Dissolved Air Flotation—a Typical DAF
Unit

15. Activated Sludge
• An activated sludge process is the most effective of all the
biological systems available
• It is used in many refineries around the world and offers a
reliable method of biological treatment.
• Activated sludge is a continuous suspension of aerobic
biological growths in a wastewater containing entrapped
suspended colloidal, dissolved organic and inorganic
materials.

16. The PACT® (Powdered Activated Carbon Treatment)
system

17. Nitrification With Denitrification
The biological treatment system could include either a
nitrification(by the use of nitrifying bacteria) or a combined
nitrification/denitrification step in some cases when a refinery
site is required to meet tight ammonia or nitrogen limits.
The level of nitrogen compounds in refinery wastewater can
be controlled by avoiding discharges of spent amines and
proper removal of ammonia in the sour water stripper.
Nitrification is the term used to describe the two-step
biological process in which ammonia (NH4-N) is oxidized to
nitrite (NO2-N) and the nitrite is oxidized to nitrate (NO3-N).

18. Nitrification

19. Nitrification With Denitrification
• In denitrification, the nitrate is reduced to nitric oxide, nitrous oxide
and nitrogen gas.

20.  Oil has many benefits and energy is necessary for
all our activities. But each stage in its life cycle
carries hazards for humans, wildlife and the
environmental systems on which we and other
species depend.
 Understanding the health and environmental
consequences of oil use may help decision makers
assess the true costs of our dependence on this
non-renewable resource hence one major reason
why there is the ultimate need to treat our water
and wastewater discharges emanating from all oil
refineries to meet set international standards.

21. Reference
Gary, James H., Glenn E. Handwerk, and Mark J. Kaiser.
Petroleum refining: technology and economics. CRC press,
2007.
• Leffler, William L. "Petroleum refining for the nontechnical
person." (1985).
• The Environment (Protection) Rule, 1986 are referred to as
principal rules in all subsequent Notifications beginning with
S.O. 32(E), dated 16.2.1987 published in the Gazette No.
66, dated 16.2.1987
.
• EPA Notification [G.S.R 186(E), dt. 18th March, 2008]