1. ARL Up-gradation of Effluent
Wastewater Treatment
Plant (ETP Phase-II)
A sustainable Environmental Initiative
Muhammad Fahad Khan
Attock Refinery Ltd.

2. Introduction
 Enhance capacity of effluent treatment
system.
 Compliance with the National
Environment Quality Standards
(NEQS), in view of future expansion.
 Addition of secondary treatment system.

3. Brief Description
 API separators for separation of oil from
effluent water.
(C-Separator, D-Separator, B-Separator)
 From separators, oil pumps to oil treatment
tanks & effluent water flows towards large
sump called C-Sump.
 Form C-Sump effluent pumps to existing
effluent treatment plant.
 Effluent from C-Sump first treats in 2 #
parallel 100 gpm SRC (Slant Rib
ETP-I

4. (cont.)
 At downstream of SRC unit we have 100
gpm DAF (Dissolved Air Floatation)
unit, for chemical treatment of effluent.
 Coagulation & Flocculation phenomenon to
remove oil, grease & organic contents present in
effluent.
 Reduce BOD, COD, O&G contents.
 From DAF unit separated O&G contents
pumped to C-Sump & then to oil treatment tanks.
 At the end treated water at DAF outlet,
released from refinery after meeting
ETP-I

5. Block flow diagram of
ETP-I
ETP-I
SRC Unit
C & D-Separator
Slop Oil
Tanks
C-Sump
Waste Water
Oil
Water
Oil
O & G
DAF Unit
Treated Water
Released from
Refinery
Demulsifier
FFO Tanks
OR
Oil for Reprocessing
Water
O & G
Coagulant
Flocculent

6. Alum Polymer
Influent
White Water Vessel
White Water
Clear Water
DAF Sludge

7. Upgraded API
Separators
 Existing API separators (C, D & Vac.)
are upgraded.
 Scrapper system removed the settled solids
& sludge.
 Pumping of sludge to drying beds.
 1st
stage oil skimmer system remove free floating
oil.
 Pumping of removed oil to oil collection tanks.
 Oil coalescers to coalesce the small
droplets of oil in water.
 2nd
stage oil skimmer to remove the
ETP-I

8. Block Flow Diagram of
Upgraded API Separators
ETP-II
Waste Water
Scrapper
System
Oil
Skimmer-I
Sludge
Drying Bed
Oil Tank
Oil
Oil Skimmer
Oil
Coalescer
Effluent Flow to
C-Sump*
Oil
Skimmer-II
Oil
Slop Oil
Tank
Sludge

9. ETP-II Section
Vise
 Capacity
 200 USGPM
 Primary Treatment
 Chemical treatment using DAF.
 Secondary Treatment
 Biological treatment using activated sludge
system and secondary calarifier.
 Sludge Treatment
 Gravity sludge thickener, sludge holding tank
and filter press.
ETP-II

10. Primary Treatment
 Chemical Treatment
 pH adjustment to favor the onward
chemical reactions.
 Coagulants dosage to react with fine
suspended solids to form flocs.
 Flocculants dosage to form large clumps
of loose flocs.
ETP-II

11. ETP-II
(cont.)
 Dissolved Air Floatation System
 Removal of generated flocs & suspended
solids.
 Pressurized water saturated with air
injects to the DAF tank.
 Fine bubbles formed, attach with flocs and
suspended solids, bring them on surface.
 Surface particles removed mechanically
or overflowed
 Removed particles treats as primary
sludge & transferred to filter press.

12. Secondary Treatment
 Biological treatment process.
 Aeration Tank
 Conventional activated sludge system to favor
micro-organism growth.
 Micro-organisms uptake BOD and COD
load present in wastewater for metabolic
growth.
 Supply of air/oxygen for micro-organism
growth.
 Maintaining of MLSS (2800 – 3500 mg/l) by
ETP-II

13. ETP-II
(cont.)
 Secondary Clarifier
 Remove the solids by sedimentation
process.
 Recycle part of sludge to aeration
tank to keep continue the treatment
process.
 Treated effluent meeting national
environment and quality standards,
will released from refinery to
polishing pond.

14. Sludge Treatment
 Sludge collected from secondary clarifier
thickens by filtering the water out of the
sludge.
 Pumping of reduced volume sludge to
sludge holding tank.
 Filter press will use to eliminate the
moisture content of sludge up to 30 % and
to produce cake.
ETP-II

15. Process Flow Diagram
@ C-Sump
ETP-II
Scrapper
System
Oil
Skimmer-I
Sludge
Drying Bed
Oil Tank
Oil
Oil Skimmer
Oil
Coalescer
Effluent o ETP-II
Oil
Skimmer-II
Oil
Slop Oil
Tank
Sludge

16. (cont.)
ETP-II
Effluent
Meeting NEQS
Pre-DAF
Acid/Alkali
Flocculent
Coagulant
DAF UNIT
White
Water
Primary Sludge
~25% COD & BOD Removed
~90% TSS/O&G Removed
Activated
Sludge System
Secondary
Clarifier

17. Comparison
 Automate the removal of sludge & solids to
minimize manual handling.
 Automate removal of free oil to minimize
manual handling.
 Increase the overall efficiency and effectiveness
of the API Separators to achieve 80% removal
of oil.
 Increased capacity for effluent treatment
system to cater the future scenario.
 Improved quality of treated effluent by utilizing
the secondary treatment technology, even this
ETP-II

18. THANKS
Q . . . ?