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Yen So Sewage Treatment Plant - Operations and Maintenance Manual
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TABLE OF CONTENTS
I) INTRODUCTION
II) DESCRIPTION
III) OVERALL PROCESS DESCRIPTION
IV) GENERAL CONTROL SYSTEM AND OPERATION
V) MAINTENANCE OF SEWAGE TREATMENT PLANT
VI) PLANT LAYOUT & PIPING
VII) HAYDRAUILC PROFILE
VIII) PLANT LEVEL
IX) DETAILED DESIGN DATA AND UNIT EFFICIANCY
1. LIQUID STREAM
1.1 RIVER INTAKE WORKS
1.1.1 General Description:
1.1.2 Intake Works Equipment
1.1.3 Intake Works Instruments
1.1.4 P&I Diagram
1.1.5 Process Description
1.1.6 CONTROL PHILOSOPHY
1.1.7 Equipment description, Operation, and Maintenance
1.1.7.1 Debris Removal System Trash rake
1.1.7.2 BELT CONVEYOR
1.1.7.3 Stop Logs
1.1.7.4 Radial Gates
1.1.7.5 Logboom
1.2 INTAKE STRUCTURE
1.2.1 General Description
1.2.2 Intake Chamber Equipment
1.2.3 Intake Chamber Instrumentation

1.2.4 Intake Structure P&I Diagram
1.2.5 Process Description
1.2.6 Kim Nguu Intake Structure Process description
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1.2.7 CONTROL PHILOSOPHY
1.2.8 Intake Structure Equipments Description, Operation, and Maintenance
1.2.8.1 Penstocks
1.2.8.2 Mechanical Screen Description, Operation & Maintenance
1.2.8.3 SPIRAL PRESS CONVEYOR
1.2.9 Intake Structure Check List
1.3 KIM NGUU GRIT CHAMBER
1.3.1 General Description
1.3.2 KN Grit Chamber Equipment
1.3.3 P&I Diagram
1.3.4 Process Description
1.3.5 Control Philosophy
1.3.6 Equipment Description, Operation, and Maintenance
1.3.6.1 Grit Pumps
1.3.6.2 KN Grit Classifiers
1.3.6.3 KN Grit Chamber Penstocks
1.4 SET RIVER GRIT CHAMBERS
1.4.1 Set River Grit Chamber General Description
1.4.2 Set River Grit Chamber Equipment
1.4.3 Set River Grit Chamber P&I Diagram
1.4.4 PROCESS DESCRIPTION
1.4.5 CONTROL PHILOSOPHY
1.4.6 Equipment Description, Operation, and Maintenance
1.4.6.1 Grit Pumps

1.4.6.2 Grit Classifier
1.4.6.3 Penstocks
1.4.6.4 Multistage Pumps
1.4.7 Grit Chamber Checklist
1.5 KIM NGUU COARSE SCREEN
1.5.1 Kim Nguu Coarse Screen General Description
1.5.2 Kim Nguu Coarse Screen Equipment
1.5.3 Kim Nguu Coarse Screen Instruments
1.5.4 Kim Nguu Coarse Screen P&ID Diagram
1.5.5 Process Descrrription
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1.5.6 Control Philosophy
1.5.7 Equipment Description, Operation, and Maintenance
1.5.7.1 Mechanical Coarse Screen
1.5.7.2 Penstocks
1.5.7.3 Conveyor
1.6 KIM NGUU EMERGENCY BYPASS SCREENS
1.6.1 Bypass Screen P&ID Diagram
1.6.2 PROCESS DESCRIPTION
1.6.3 CONTROL PHILOSOPHY
1.7 SET RIVER COARSE SCREENS
1.7.1 Set River Coarse Screen General Description
1.7.2 Set River Coarse Screen Equipment
1.7.3 Set River Coarse Screen Instruments
1.7.4 Set River P&I Diagram
1.7.5 Process Description
1.7.6 Control Philosophy
1.7.7 Equipment Description, Operation, and Maintenance

1.7.7.1 Mechanical Coarse Screen
1.7.7.2 Penstocks
1.7.7.3 Conveyor
1.8 SET EMERGENCY BYPASS SCREEN
1.8.1 Set River P&I Diagram
1.8.2 PROCESS DESCRIPTION
1.8.3 Control Philosophy
1.9 KIM NGUU RIVER MAIN INLET PUMPING STATION
1.9.1 Kim Nguu Main Inlet Pumping Station General Description
1.9.2 KN Main Inlet Pump Station Equipment
1.9.3 KN Main Inlet Pump Station Instrument
1.9.4 KN Main Inlet Pump Station P&ID Diagram
1.9.5 KN Main Inlet Pump Station Process Description
1.9.6 KN Main Inlet Pump Station Control Philosophy
1.9.7 KN Main Inlet Pump Station Equipment Description, Operation, & Maintenance
1.9.7.1 ABS Submersible Sewage Pumps
1.9.7.2 Penstocks
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1.10 SET RIVER MAIN INLET PUMPING STATION
1.10.1 Set River Main Inlet Pumping Station General Description
1.10.2 Set River Main Inlet Pump Station Equipment
1.10.3 Set River Main Inlet Pump Station Instrument
1.10.4 Set River Main Inlet Pump Station P&I Diagram
1.10.5 Set River Main Inlet Pump Station Process Description
1.10.6 Set River Main Inlet Pump Station Control Philosophy
1.10.7 Set River Main Inlet Pump Station Equipment Description, Operation, & Maintenance
1.10.7.1 ABS Submersible Sewage Pumps
1.10.7.2 Penstocks

1.10.8 Main Inlet Pump Station Check List
1.11 PRELIMINARY TREATMENT WORKS FINE SCREEN
1.11.1 Preliminary Treatment Works General Description
1.11.2 Equipment
1.11.3 Fine Screen Instruments
1.11.4 Fine Screen P&I Diagram
1.11.5 Fine Screen Process Description
1.11.6 Fine Screen Control Philosophy
1.11.7 Fine Screen Equipment Description, Operation, and Maintenance
1.11.7.1 Bromet Fine Screen
1.11.7.2 Penstocks
1.11.7.3 Conveyor
1.11.8 Fine Screen Checklist
1.12 EMERGENCY BYPASS SCREEN
1.12.1 P&I Diagram
1.12.2 Process Description
1.12.3 CONTROL PHILOSOPHY
1.13 PRELIMINARY TREATMENT WORKS GRIT GREASE REMOVAL SYSTEM
1.13.1 Grit Grease removal General Description
1.13.2 Grit Grease removal Equipment
1.13.3 Grit Grease removal Instrument
1.13.4 Grit Grease removal P&I Diagram
1.13.5 Grit Grease removal Process Description
1.13.6 Grit Grease removal Control Philosophy
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1.13.7 Grit Grease removal Equipment Description, Operation, and Maintenance
1.13.7.1 Travelling Bridge Scraper
1.13.8 Grit Grease Channel Checklist

1.14 GRIT REMOVAL PUMPS
1.14.1 General Description
1.14.2 Grit Removal Pumps Equipment
1.14.3 Grit Removal Pumps Instrument
1.14.4 Grit Removal Pumps P&I Diagram
1.14.5 Grit Removal Pumps Process Description
1.14.6 Grit Removal Pumps Control Philosophy
1.14.7 Grit Removal Pumps Equipment Description, Operation, and Maintenance
1.14.8 Grit Pumps and Classifiers Checklist
1.15 PRELIMINARY TREATMENT WORKS GRIT CLASSIFIER
1.15.1 Grit Classifier General Description
1.15.2 Grit Classifier Equipment
1.15.3 Grit Classifier Instrument
1.15.4 Grit Classifier P&I Diagram
1.15.5 Grit Classifier Process Description
1.15.6 Grit Classifier Control Philosophy
1.15.7 Grit Classifier Equipment
1.15.7.1 Grit Classifiers
1.16 GRIT/ GREASE REMOVAL TANK AIR BLOWERS
1.16.1 General Description
1.16.2 Air Blowers Equipment
1.16.3 Air Blowers Instruments
1.16.4 Air Blowers P&I Diagram
1.16.5 Air Blowers Process Description
1.16.6 Air Blowers Control Philosophy
1.16.7 Air Blowers Equipment Description, Operation, and Maintenance
1.16.8 Grit Grease Air Blowers Checklist
1.17 SEQUENTIAL BATCH REACTOR
1.17.1 General Description
1.17.2 Equipment Inventory of a SBR Basin

1.17.3 Instrumentation Inventory of a SBR Basin
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1.17.4 SBR P&I Diagram
1.17.5 SBR Process Description
1.17.6 SBR CONTROL PHILOSOPHY
1.17.7 SBR Equipments Description, Operation, and Maintenance
1.17.7.1 WAS & RAS Pumps
1.17.7.2 Surface Skimming Decanters
1.17.8 SBR Basins Checklists
1.18 SBR AIR BLOWERS
1.18.1 General Description
1.18.2 Air Blowers Equipments
1.18.3 Air Blowers Instruments
1.18.4 Air Blowers P&I Diagram
1.18.5 Air Blowers Process Description
1.18.6 CONTROL PHILOSOPHY
1.18.7 Air Blowers Equipment Description Operation, and Maintenance
1.18.7.1 Air Blowers
1.18.8 Air Blowers Checklist
1.18.8.1 Air Diffusers
1.19 SBR AIR BLOWERS COOLING SYSTEM
1.19.1 General Description
1.19.2 Cooling System Equipment
1.19.3 Cooling System P&I Diagram
1.19.4 Cooling System Process Description
1.19.5 CONTROL PHILOSOPHY
1.19.6 Cooling System Equipment Description, Operation, and Maintenance
1.19.6.1 Cooling Tower

1.19.6.2 Cooling Pump
1.20 TERTIARY TREATMENT WORKS
1.20.1 General description
1.20.2 Equipment
1.20.3 INSTRUMENT
1.20.4 P & ID
1.20.5 PROCESS DESCRIPTION
1.20.6 CONTROL PHILOSOPHY
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1.20.7 EQUIPMENT DESCRIPTION OPERATION & MAINTENANCE
1.21 MEMBRANE FEED PUMPS
1.21.1 General description
1.21.2 Membrane Feed Pumps P&I Diagram
1.21.3 PROCESS DESCRIPTION
1.21.4 CONTROL PHILOSOPHY
1.22 MEMBRANE PLANT
1.22.1 GENERAL DESCRIPTION
1.22.2 INSTRUMENT
1.22.3 P&I Diagram
1.22.4 EQUIPMENT DESCRIPTION OPERATION & MAINTENANCE
1.23 SERVICE WATER SYSTEM
1.23.1 General Description
1.23.2 General Description
1.23.3 PROCESS DESCRIPTION
1.23.4 CONTROL PHILOSOPHY

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I) INTRODUCTION
Volume II A is intended to provide single source of reference on the system and equipment installed in
the waste water treatment facilities.
This manual is an introduction to operation and maintenance (O&M) of specific system and equipment
and is not meant to supersede the manufacture‘s specification or information. The drawing and references
contains with in this text may or may not be (As-built) records audit from original construction
documents depending on the condition of the reference material used at the time. The intent is to reflect
the actual, or as close as possible, to the installed condition of the system and equipment. Original
manufacturers‘ drawing, systematic, specification, and information have been used to the fullest extent.
This manual is divided into 18 sections, each section contains:
 Brief about the general process, and detailed design data.
 Plan layout.
 Equipments
 Instruments
 P&ID
 Process description.
 Control philosophy.
 Equipment description, and operation
 Equipment maintenance.
 Troubleshooting
 Checklist

This manual should be considered a living document, and as such, it should be on enhanced throughout
the life of the plant. Therefore, operational characteristics, maintenance procedures, and O&M data for
equipment and system should be updated as equipment/system are developed, deleted, modified, and/or
upgraded.
Note:
 This manual provides a brief detail about equipment operation and maintenance, for more
information please refer to individual operation manual in volume III.

 This manual dose not includes the electrical equipment; details of electrical equipments
description operation, and maintenance are available in volume 2B.
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II) DESCRIPTION
The Yen So Sewage Treatment Plant is located in Hoang Mai district, about 6km south of Hanoi,
Vietnam. The influents derive from two 'River' sources, which are currently used as open sewer culverts
that are also subject to storm water flows. The flow is screened, degritted and degreased prior to
sequencing batch reactor activated sludge technology followed by UV and membrane treatments for
proportions of the SBR treated flows. SBR flows are discharged to the Kim Nguu River, while UV
disinfected effluents are discharged to the Yen So lakes. Membrane treated SBR effluent is for works
reuse
Yen So Treatment Plant consist of
1. Liquid Stream
2. Sludge Stream
3. Odour Management
4. Support Structures

Yen So Liquid Stream Layout





PTW
MIPS
Intake Structure
SBR
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1

2

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1,2& 3 Yen So Sludge Stream Layout

Yen So Odour Control Units Layout
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Yen So Support Structures
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III) OVERALL PROCESS DESCRIPTION
The project is for the design and build of a new Sewage Treatment Plant (STP) at Yen So Park located in
Hanoi, Vietnam. The proposed new treatment works comprise of new river debris removal systems, grit
chambers, 25mm coarse screens, main inlet pumping stations, 6mm fine screens, grit and grease removal
tanks, sequential batch reactor (SBR) basins, UV disinfection units, tertiary filtration plant, filtrate
treatment plant , sludge storage facilities, gravity belt thickeners, sludge digesters, gas holders,
centrifuge dewaterers, odour removal systems, polyelectrolyte dosing systems, carbon dosing system and

alkalinity dosing system.

The Sewage Treatment Plant at Yen So Park receives flows from Kim Nguu River, Set River and the
future sewerage network from the Yen So development. The works is designed to treat a maximum of
200,000 m3/ day with a peak hourly flowrate of 2.1 times this. The flow to treatment passes through river
intake screens mounted in the riverbank; three for Kim Nguu and two for Set. Screenings are collected
and disposed of in skips. Each screen is isolated by wall mounted actuated penstocks. After river
screening, the flow passes to two sets of two number grit chambers. Grit is removed and is classified prior
to disposal to skips for removal. The liquor from the grit classifiers is returned to the common inlet
channel and each grit chamber is isolated by wall-mounted penstocks.

After grit removal, the flow is piped to the main inlet pumping stations where it passes through the
25mm coarse screens. The Kim Nguu river flow passes through three parallel screens and Set river flow
through two. The Kim Nguu flow will in future be augmented by a further flow from the Yen So
development. Each screen is channel mounted and completed with actuated isolation penstocks and
emergency bypass hand raked screens.

After coarse screening, each river stream is pumped via dedicated main inlet pumping stations (MIPS) to
the combined 6mm fine screening stage. Kim Nguu and Set pump stations each comprise of 6 No. fixed
speed submersible pumps operating on 4 No. duty and 2 No. standby configuration.

The combined fine screen process includes 4 parallel channel mounted 6mm screens and an emergency
bypass hand raked screen. Each screen is isolated by actuated penstocks. The screenings are transferred to
a skip for disposal.

Following fine screening, the combined flow passes to a grit/ grease removal stage. There are four grit/
grease removal tanks. Grit is removed from the front hopper of the tank by dedicated grit pumps and
pumped to 2 No. grit classifiers. Grit is disposed via skip and effluent drained to the Kim Nguu main inlet
pump station. Grease is floated by air to the surface of the tank and removed by scraper to an outlet
hopper for removal by skip. The air is introduced to the base on the tank via a common header supplied

by four number air blowers.

After the grit/ grease removal tanks, the flow gravitates to the sequential batch reactor (SBR) basins.
There are eight treatment basins operating in two modules. The SBR basins in each module treat sewage
in batches, with the operation of basins staggered to allow continuous acceptance of sewage and
continuous discharge of effluent. Each SBR basin inlet is isolated by actuated weir penstocks.
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Each SBR undergoes a treatment cycle that consists of the fill, react, settle and decant sequences. During
the fill sequence, the SBR basin is filled with untreated sewage. Once the SBR basin is filled, aeration
commences which is known as the react sequence. After the treatment process is complete, the aeration is
stopped and biomass will be allowed to settle to the bottom of the tanks (settle sequence). When the
biomass has settled, a layer of clear treated water at the top of the SBR basin is removed by two decanters
during the decant sequence.

Each SBR module has 6 No. air blowers, operating in a 4 No. duty and 2 No. standby configurations.
Excess biomass from each of the SBR basins is removed during the settle sequence by 2 No. waste
activated sludge (WAS) pumps and directed to the sludge holding tanks. Return activated sludge (RAS) is
returned to the bioselectors for simultaneous nitrification denitrification and enhanced biological
phosphorus removal by 2 No. RAS pumps. A carbon dosing system and alkalinity dosing system is
provided and doses upstream of the SBR basins for adjustment of influent.

Effluent from the SBR basins is channelled into UV disinfection units and the remaining treated effluent
from the SBR basins is discharged back into the Kim Nguu River. After UV disinfection, 3,000m3/ d of
the treated effluent undergoes tertiary treatment before being recycled for plant usage. Tertiary treatment
comprises of 2 No. hollow fibre membrane filtration (HFMS) units operating in parallel. The remaining
water after UV disinfection shall be discharged directly into Yen So Lake.

Sludge holding tanks are provided to store the SBR waste sludge. From the sludge holding tanks, the
sludge is transferred to 4 No. gravity belt thickeners that are employed for sludge thickening. Sludge is
fed into a static flocculator tank by means of 6 No. thickener feed progressive cavity pumps (4 duty/ 2
standby). Polymer is dosed into the sludge prior to the thickeners to flocculate fine particles. Filtrate from
the sludge thickeners will flow to the Kim Nguu main inlet pump station.

From the sludge thickeners, the thickened sludge is stored in the 2 No. thickened sludge storage tanks to
allow continuous flow to the sludge digesters. A macerator is installed in each thickened sludge holding
tank outlet to macerate any solids left in the sludge before being fed to the sludge digester. The thickened
sludge is fed to 2 No. anaerobic digesters to reduce the thickened sludge volatile suspended solids
content. The gas generated by the digesters is stored in 2 No. double membrane type gas holders. Part of
the gas use to mix the sludge in the digesters, part of it used to heat the digester sludge and the remaining
gas shall be flared off.

The digested sludge gravitate to the 2 No. digested sludge storage tanks. Digested sludge feed to 4 No.
centrifuge dewaterers to dewater the digested sludge via 6 No. fixed speed progressive cavity dewaterer
feed pumps (4 duty/2 standby). The sludge cake is conveyed to sludge storage area where transferred to
skips for disposal off site. Centrate from the dewatering units flow to the works liquor tank. Polymer is
dosed into the sludge prior to the dewaterers to flocculate fine particles to increase dewatering efficiency.

The polyelectrolyte dosing system is designed to accept powder supply. Powdered dry polyelectrolyte is
stored in big bags and is transferred to a hopper. The hopper discharges into the powder feeder that feeds
the polymer mixing tank. Service water from the service water booster pumps is added to the polymer
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mixing tank to make up the polyelectrolyte solution. Polyelectrolyte solution is drawn from the storage
tank by 4 No. dosing pumps and is dosed into each thickener feed pump delivery. There are separate
polyelectrolyte dosing systems provided for both the thickening and dewatering plant.

Filtrate from sludge dewatering centrifuges gravitates into the filtrate holding tank before being fed to the
FSBRs. A bypass is provided from this holding tank back to manhole MH26B from where filtrate could
be returned directly to the main SBR process in case that the FSBRs are only partially or not operational
during maintenance activities, or in case that the influent sewage and operational conditions do not
require utilisation of the FSBRs.

Potentially odorous air is drawn from the main inlet pumping stations, coarse screens, 6mm screens, grit
and grease removal tanks, grit handling plant, works liquor tank, sludge holding tanks, sludge thickening
units, thickened sludge holding tank, digested sludge storage tank, sludge dewatering units, collection
skip for Kim Nguu and Set River debris removal to 4 No. odour control facilities.



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IV) GENERAL CONTROL SYSTEM AND OPERATION
The treatment works is designed to run with minimum of operator intervention.
The control system is based around a series of Programmable Logic Controllers (PLC's) working in
conjunction with their associated Motor Control Centres (MCC‘s), local control panels (if applicable) and
field instrumentation, and supervised by a Supervisory Control And Data Acquisition system (SCADA).

All data required for continuous monitoring of the plant will be made available to the operator via a
telemetry link.

DEFINITIONS
Unless otherwise stated, the following definitions shall apply throughout this section of manual:
I. Automatic Control Mode
The operation of individual items or groups of equipment in Automated control mode will be by a
works PLC, or specific control equipment in the field, without the need for operator intervention.

II. Manual Control Mode
The operation of individual items of equipment in MANUAL control mode will be via a works
PLC, specific control equipment or by operator intervention from a suitable interface e.g. a panel
mounted operator interface or Human Machine Interface (HMI) system.
All specific automated sequences associated with the equipment will be inhibited.
III. Hand Control Mode
The operation of individual items of equipment in HAND control mode will be via operator
intervention from a relevant MCC or local control panel. All control of the equipment via any
works PLC or specific control based on field instrumentation will be inhibited.
All specific automated sequences associated with equipment will be inhibited.
When in HAND control mode equipment can be controlled in REMOTE HAND control mode or
LOCAL HAND control mode (where applicable).

a. Remote Hand Control Mode
The operation of individual items of equipment in REMOTE HAND control mode will be via
operator intervention from a relevant MCC or local control panel. All control of the equipment
via any works PLC, or specific control equipment in the field, will be disabled. All specific
automated sequences associated with the equipment will be inhibited.

b. Local Hand Control Mode
The operation of individual items of equipment in LOCAL HAND control mode will be via
operator intervention at or immediately adjacent to the equipment. All control of the equipment
via any works PLC, specific control equipment in the field, relevant MCC or local control panel
will be disabled. All specific automated sequences associated with the equipment will be
inhibited.



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c. Hardwired Control
Unless otherwise stated, hardwired control will provide fall-back control of an area of plant. This
will over-ride control in all modes.

d. Hardwired Interlocks
Unless otherwise stated, hardwired safety interlocks will over-ride control in all modes.

IV. Inhibit
Prevent normal operation by means of software interlock.
Software interlocks normally operate in automatic control mode only. In this mode the PLC
prevents control of the unit according to the automatic control sequence. Hardwired control can
override this condition.

V. Permit
Allow normal operation by removal of software interlock.
In this mode, PLC controls the unit according to the automatic control sequence. Hardwired
control can override this condition.

VI. Disable
Prevent operation by means of hardwired interlock.
The interlock normally prevents operation in all modes. (Specific exceptions will be detailed in
the relevant section.)

VII. Enable
Allow normal operation by removal of hardwired interlock.
Manual reset may be required before Enable signal allows restart of equipment. (Details will be
provided in the relevant section.)

VIII. General

Unless otherwise stated, the following will apply as general principles:
a. Under normal operation, the treatment works will be controlled via the
PLC(s) and can be monitored from the HMI.
b. All analogue flow, level, pressure and quality instruments will give a
continuous display at the control panel. In addition all analogue flow
meters will provide an integrated total.
c. All alarm conditions will be displayed at the HMI or local control panel
where provided.
d. All motor drive hardwired failures e.g. overload trip, pump seal failure
etc., will be alarmed at the relevant MCC. Motor drive failures generated
by software will be alarmed at the HMI.
e. All actuated valve/penstock failures will be alarmed at the HMI.
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f. Selector switches at the works MCCs will allow all motor drives to be
designated as operating in ―AUTO" control mode, " HAND" control
mode or OFF .
If a switch designates "AUTO" control mode then all operation of the
respective motor will be controlled via the PLC.
When the selector is switched into "HAND" control mode then the
respective motor will be controlled from the respective MCC. The motor
speed of variable speed drives can be adjusted by the operator at the
relevant MCC using a potentiometer. All control via the PLC will be
disabled.
If a switch designates OFF then all operation of the respective motor will
be disabled, and the motor isolated from all PLC and MCC control.
g. All motorised valve actuators will have the facility to be designated as
operating in

" AUTO" control mode, " LOCAL" control mode at the actuator or
REMOTE control mode at the HMI.
If "AUTO" control mode is selected then all operation of the respective
actuator will be controlled via the PLC.
If "LOCAL" control mode is selected then the actuator will be
controlled from the actuator. All control via the PLC will be
disabled.
h. A duty to standby change-over will occur upon failure of the duty
equipment if the respective duty and standby mode selector switches at the
MCC are both designated in ―AUTO control mode. If either or both the
duty and standby equipment mode selector switches at the MCC are not
designated in AUTO control mode, then the changeover will be inhibited
and an alarm raised at the PLC
i. Rotating or electric motor driven process equipment will be supplied with
emergency stop push buttons, where applicable, which are operative in all
control modes. All emergency stop push buttons will be the "stay-put" type
requiring to be reset by hand.
j. Hardwired interlocks will override control in all modes. Hardwired trips
will be manually reset by individual push-buttons at the respective MCC.
k. On failure of any control instrument, the PLC will use the last known value
for control purposes and an alarm raised at the PLC, unless stated
otherwise.

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V) MAINTENANCE OF SEWAGE TREATMENT PLANT
Preventative Maintenance
Routine inspection and maintenance is important in preventing breakdown and help to prolong the service
life of the equipment and improve the downtime of the plant. It can also identify malfunctions in the

preliminary stages and reduce the repair to the minimum. Preventative maintenance involves the
servicing, repair or replacement of items subject to normal wear and tear on a scheduled basis.
Owing to the varied time, conditions and circumstances of equipment usage, it is impossible to set the
equipments and periods for regular inspection and maintenance. However, as a guide it is recommended
to perform periodic maintenance according to the schedule reproduced below. Others may be added when
adverse or unusual service conditions exist. These schedules are only for guidance – where if these differ
in any aspect from the Manufacturer‘s recommendations, the latter shall take precedence.
For safety reason, but only properly trained personnel who familiarize themselves with the equipment
must carry out maintenance and repair.
Systematic routine and records should be kept on the equipment which contains at least the following,
among others:
 Complete equipment data
 List of spare parts
 Service records (including dates and results of routine inspections and repairs)
 Lubrication data, including types of lubricants used and the maintenance cycle. Always
use lubricants as recommended by the manufacturer.


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Breakdown Maintenance
Breakdown maintenance is undertaken "on demand" when an equipment can no longer be operated.
The Breakdown Maintenance has two components:

1. Defect or malfunction covered within the defects liability period :
 Defective or Insufficient Design;
 Defective Materials;
 Defective Installation / Workmanship;
 Inadequate Maintenance.

2. Defect or malfunction other than that described above. For example:
 Exposed pipework or fittings damaged in automobile accidents;
 Generator failure as a result of coolant or lubricant not having been checked and topped up;
 Force Majeure.

In addition to the normal contractual obligation to rectify defective work, replace defective materials, and
correct design insufficiencies, a procedure will be implemented to enable the probable cause of a problem
to be investigated and the cost of rectification to be properly allocated.
In the first instance, the contractor will attend to site and assess the extent of damage and necessary
repairs. Items of a minor nature (not requiring major parts replacement) will be repaired under the terms
of the contract and a full report submitted to the Contractor's Operations & Maintenance Manager.
Items of a major nature, and for which stand-by facilities are available, will, after initial investigation by
the Contractor, be subjected to a joint inspection by representatives of the Contractor, the Operating
Agency, the Equipment Supplier and the Installation Sub Contractor, where appropriate.
At this joint inspection, the circumstances surrounding the problem will be fully examined and the
probable cause or causes identified and agreed. The party or parties deemed responsible will themselves
arrange for the necessary repair work to be carried out or will request the Contractor to undertake this
work on their behalf and at their cost.
Should the parties to the joint inspection be unable to agree on the probable cause of the problem, the
Contractor will issue instructions for the repair work to be undertaken on an interim basis. The party or
parties instructed to execute the repair work will forthwith carry out such work and will keep full and
detailed records of the resources used. Within 28 days of repairs being instructed, the Contractor will,
with the full cooperation and agreement of all parties involved, prepare a fully detailed report on the
repair works and submit this to the Employer for his decision.
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* Only qualified personnels are allowed to carry out maintenance works. Please read manufacturer‘s
manual thoroughly prior to any maintenance works.

Items Supplied by the Operating Agency
All capital or consumable items which are not associated with the maintenance of Mechanical and
Electrical and Chemical Equipment supplied under the Contract are to be provided and where appropriate,
fitted or installed by the Operating Agency including, but not limited to:
 Water Treatment / Disinfection Chemicals
 Topping Up of Filtration Media
 Water for Disinfection / Flushing / Testing
 Power (electricity)
 Petrol, Diesel and Lubrication Oil
 Grease
 Gear/Lubrication oil
 Air /Fuel / Oil filters
 Transformer lubricating oil / gases
 Silica gel
 Mechanical seal
 Oil seal, seal and O-ring
 Pump diaphragm, damper and rubber bellow
 Sealed bearings
 Rubber coupling
 Drive belts
 Chlorine Connecting Tubing
 Chlorine leak detector sensor
 On-line Analyzer sensors
 Lead gasket
 Ammonia solution
 Refrigerant for air-conditioning unit
 Laboratory Chemicals / Reagent
 Light Bulbs / Fluorescent Tubes and starters
 Fuses / MCB
 Wear Pads/Shoes for Sludge Scraper

 Wear & Tear Items
 Paint
 Items necessary for the maintenance of Infrastructure:
 (Structures, Chambers, Buildings, Roads, Drains, Embankments, Fences etc.)
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VI) PLANT LAYOUT & PIPING

Plant Layout
item
Description
No.
Diameter
(mm)
Channel Width
(m)
Channel Depth

Pipe/Channel
length (m
1
SBR effluent channel to the
River
2
-
1.2
0.75
70
2

UV disinfection to the river
2
900
-
-
160
3
UV outlet channel
1
-
4.5
-
-
4
UV inlet channel
1
-
3.8
-
15
5
Culvert from SBR to UV
disinfection
1
-
3.0
2.5
20
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item
Description
No.
Diameter
(mm)
Channel Width
(m)
Channel Depth

Pipe/Channel
length (m
6
SBR effluent channel
1
-
2.0
-
-
7
Grit/Grease outlet/ SBR inlet
channel
1
-
1.7
-
-
8
SBR inlet channel (after
split)

2
-
1.5
-
-
9
Grit/Grease outlet channel
1
-
1.7
-
17




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VII) HYDRAULIC PROFILE

Yen So Park STP is located in Hanoi, Vietnam. It is to be constructed as part of the JICA Hanoi Sewerage
Master Plan. It is proposed the sewage treatment works treats the river water from the Kim Nguu River at
125,000 m³/d and Set River at 65,000m³/d and an additional 10,000m³/d from sewer connections. These
rivers are heavily polluted by the sewage which drains directly from Hanoi City.
Yen So Park STP will consist of a river intake system in the River Set and River Kim Nguu. From each
intake system the flow gravitates to the main inlet pumping station.
The flow is then pumped to preliminary treatment which consists of 3 Duty/1 standby fine screens with an
emergency bypass manual bar screen, and 3 duty/1 standby grit grease removal tanks.
From here the flow enters by gravity a sequencing batch reactor plant, consisting of 2 No.Modules each

consisting of 4 No.SBR basins.
133,000m³/d (67,000m³/d initially) of the treated flow will to gravitate to a UV system consisting of 4
Duty UV units and then discharge to Yen So Lake 1 (Pond), south of the site. The remaining effluent
from the SBR plant will gravitate to a discharge point in the Kim Nguu Canal to the west of the site.
3,000m³/d of the UV treated flow is pumped to a membrane treatment plant for further treatment so it can
then be recycled back into the plant for any water use requirements.

Main Flows

Average DWF
200000 m³/d
2.31 m³/s

Peak Hourly
17500 m³/h
4.86 m³/s

Peak flowrate through inlet works, grit grease tanks
and feed to SBRs
5.03 m³/s

Maximum flow to UV disinfection
133000 m³/d
1.539 m³/s

Peak SBR Decant Flow
5622.33 m3/h per basin
Number of basins decanting simultaneously
2
Peak SBR Decant Flow

3.124 m3/s

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Starting top water levels

Effluent (non UV treated) discharges from the sewage treatment works to the Kim Nguu River to the east
of the site
TWL in Kim Nguu River = 5.7 mAD
Effluent (UV treated) discharges from the sewage treatment works to the pond to the south of the site
TWL in Pond = 4.5 Mad

SBR Effluent Channel to River
Flows up to 133,000 m³/d pass to the UV plant (67,000 m³/d initially) and any excess flow passes directly
to the River.

Straight line losses from SBR effluent channel to the River

Discharge from the SBR plant to the River passes through two culverts due to the high flow rate.

Flood TWL in River
5.70 mAD

LWL in River
3.70 mAD

IL in River
2.00 mAD

Flow from the SBR plant
3.124 m³/s

Initial peak flow to UV plant
67000 m³/d

Peak flow to River
2.348 m³/s

No of culverts
2
Width of culvert
1.2m
Depth of culvert
0.75m
Equivalent diameter
0.923 m

Minimum water depth in River
1.700 m

Flow from the SBR plant
1.17 m³/s

Equivalent diameter
923 mm

Equivalent velocity
1.754 m/s

Total straight length of
70 m