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Yen So Sewage Treatment Plant - Operations and Maintenance Manual
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TABLE OF CONTENT
1 INTRODUCTION 4
2 SYSTEM DESCRIPTION 6
2.1 Design Criteria – 6
2.2 Process Description 6
3 SYSTEM OVERVIEW AND FLOW SCHEMATICS 9
3.1 System Overview and Flow Schematics 9
4 HEALTH AND SAFETY 36
4.1 Mechanical Hazards 36
4.2 Electrical Hazards 37
4.3 Falling Hazards 37
4.4 Chemical Hazards 37
4.5 Gas Hazards 37
4.6 Noise Pollution 38
4.7 Odour Pollution 38
4.8 Infection Hazards 39
4.9 Fire Hazard 40
4.10 Basic Health Measures 40
1.1 GENERAL PLANT SAFETY 40
5 PERSONNEL 42
5.1 O&M Personnel 42
5.2 Personal Responsibiliies 51
6 SEWAGE QUALITY SAMPLING AND TESTING 53
6.1 Process Control & Laboratory Testing 59
6.2 Laboratory Quality Control Program 65
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6.3 Laboratory Safety 67
7 ELECTRICAL AND SCADA SYSTEM 69
7.1 SCADA SYSTEMS 69
7.2 ELECTRICAL SYSTEM 90

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LIST OF APPREVIATION
O&M
Operation & Maintenance
B.O.D
Biological Oxygen Demand
C.O.D
Chemical Oxygen Demand
TSS
Total Suspended Solid

NH4-N
Nitrogen Ammonia
TKN
Total Kjeldahl Nitrogen
TP
Total Phosphorous
WWTP
Waste Water Treatment Plant
NO3-N
Nitrogen- Nitrate
STP
Sewage Treatment Plant
UV
Ultra Violet
KN
Kim Nguu
MIPS
Main Inlet Pumping Station
PTW
Preliminary Treatment Works
SBR
Sequential Batch Reactor
RAS
Returned Activated Sludge
WAS
Waste Activated Sludge
HFMS
Hollow Fiber Membrane Filtrate
FSBR
Filtrate Sequential Batch Reactor

MLD
Milion liter per day
H2S
Hydrogen sulfide
CO2
Carbon dioxide
NH3
Ammonia
JIT
Just-In-Time
P&ID
Process and Instrumentation Diagram
PLC
Programmable Logic Control
SCADA
Supervisory Control And Data Acquisition
I&C
Instrumentation and Control
HR
Human Personel
D.O
Dissolved Oxygen
MLSS
Mixed Liquor Suspended Solid
OUR
Oxygen Uptake Rate
OFG
Oil, Fat and Grease
NO3
Nitrate

NO2
Nitrite
Org-N
Organic Nitrogen
SVI
Sludge Volume Index
EPA
Environmental Protection Agency
ICV
Initial Calibration Verification
CCV
Continuing Calibration Verification
LCS
Laboratory Control System
MB
Method Blank
QCS
Quality Control System
DMR
Discharge Monitoring Report


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1 Introduction

The objective of this operation and maintenance (O&M) manual is to contribute to the objective of implementing
new sanitation facilities for sewage flowing from rivers / canals to Yen So Park of Hanoi. This O&M manual
covers primarily the facility for treatment of the wastewater that is collected from Kim Nguu River, Set River and

future sewer network from Yen So Park Development. The proper use of this manual together with sufficient
resources (manpower and annual operation budget) will help to ensure the following:
 compliance of the effluent quality according to Vietnamese standards
 cost-efficient operation of the facility
 sustainable maintenance of the facility
 proper health and safety for employees
The manual is a guiding tool in the operation of the facilities. It gives explanations about:
 the process design
 the design of the individual parts of the facilities
 procedures for operating the facilities
 procedures for servicing and maintaining the facilities
 procedures for monitoring the performance of the facility
 Personnel requirement.
Further the manual includes suppliers‟ technical documentation, which gives more detailed and precise
explanations about maintenance and safety which are specific to the equipment.
The O&M manual is divided into following volumes:
 Volume 1 provides an introduction and general overview of the system, the personnel requirements, and
safety procedures to be implemented.
 Volume 2A describes Yen So liquid line and STP equipment, operation and its routine preventative
maintenance.
 Volume 2B describes Yen So Solid line and STP equipment, operation and its routine preventative
maintenance.
 Volume 3 contains equipment O&M manuals and data sheets that supplement the information from the
suppliers about equipment maintenance. Inspection records for each piece of equipment are included.
The basic understanding of the system and its design provided in this O&M manual will assist facility personnel
in coping with different conditions as they occur. This O&M manual describes the most probable operating
conditions at the facility; however, conditions not described here can occur. Therefore, it will be necessary to
amend these procedures as different conditions are encountered during the operation of the Yen So STP. O&M
personnel should use industry standards and manufacturer‟s literature to supplement the operating instructions and
procedures described in the following volumes. The manual is bound in such a manner to facilitate this updating.

This manual should remain on site and be located in a place that is easily accessible to operating and
maintenance personnel at all times.
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2 System Description
2.1 Design Criteria –
2.1.1 Design Flow and Loads – Yen So Sewage Treatment Plant is designed to treat a maximum of 200,000
m
3
/day with following consideration

Hourly Peak Factor
2.1
Normal Diurnal Peak
1.3
Average dry weather flow
200,000m3/d
2.1.2 Design Wastewater Characteristics
2.1.2.1 STP Wastewater Influent Characteristics–
Water Quality
Parameter
Max Design Value [mg/l]
Min Design Value [mg/l]
Start-up [mg/l]
BOD
250
100
50
COD

500
200
162
TSS
300
120
71
NH
4
-N
30
15
30
TKN
40
20
32
TP
6
4
4
Alkalinity
170
170
170


2.1.2.2 WWTP Effluent Discharge Standards – The Vietnamese Effluent Standards applied is
QCVN24:2009/BTNMT

Water Quality Parameter
QCVN24:2009/BTNMT
[mg/l]
pH
6-9
BOD5
30
COD
50
TSS
50
NH
4
-N
5
Total Nitrogen
15
Total Phosphorus
4
Total Oil & Grease
10
Mineral Oil & Grease
5

2.2 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
Column A

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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. Inlet System is protected by a log boom (from floating debris) which
diver the debris to a debris removal system mounted on the bank of river. Floating debris is removed and
collected in skip for disposal. The river level is raised by two sets of radial weir gate mounted in the river. 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 can be 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 can be isolated by wall-mounted penstocks.

After grit removal, the flow is piped to the main inlet pumping stations where it passes through 25mm coarse
screens. The Kim Nguu river flow passes through three parallel screens and Set river flow passes through two
screens. The Kim Nguu flow will in future be augmented by a further flow from the Yen So development. Each
screen is channel mounted and complete 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 River 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 can be 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 of 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 will 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 can be isolated by actuated weir penstocks.

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 configuration. 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 are provided and doses upstream of the SBR
basins for adjustment of nutrient and alkalinity levels in the influent.
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About third of treated 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 2 No. hollow fibre membrane filtration (HFMS) units operating in parallel. The remaining
water after UV disinfection shall be discharged directly into the 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 for thickening process. 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 produced from the sludge thickeners will flow to the
Kim Nguu main inlet pump station.

The thickened sludge from the sludge thickeners is stored in the 2 No. thickened sludge storage tanks to allow a
continuous flow to the sludge digesters. A macerator is installed in each of the 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 shall be used to mix the
sludge in the digesters, part of the gas shall be used for the heating of digester sludge and the excess gas shall be
flared off.

The digested sludge gravitates to the 2 No. digested sludge storage tanks. Digested sludge will be fed 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 and transfer to skips for disposal
off site. Centrate from the dewatering units will 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 polymer dosing system is designed to accept powder supply. Powdered dry polymer 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 mixing tank to make up
the polymer solution. Polymer solution is drawn from the storage tank by 4 No. dosing pumps and is dosed into
each thickener feed pump delivery. There are separate polymer dosing systems provided for the thickening and
dewatering plant.

Filtrate from sludge dewatering centrifuges gravitates into the filtrate holding tank before being fed to the Filtrate
Sequential Batch Reactors (FSBRs). A bypass shall be 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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3 System Overview and Flow Schematics
3.1 System Overview and Flow Schematics
Sewage treatment plant using Sequence Batch Reactor (SBR) including:

Process Flow Diagram
3.1.1 Intake Works

The Sewage Treatment Plant (STP) at Yen So Park receives flows from both the Kim Nguu and Set rivers.
Each river intake system is protected by a log boom and debris removal system to prevent any floating debris
entering the inlet works.

The trapped debris is directed towards a diversion channel mounted on the side of the riverbank. The debris
is removed by a mechanical 50mm screen which is cleared by a motor driven rake upon detection of high
differential level. The debris is deposited into a skip via a screenings conveyor. The Kim Nguu debris
removal area is connected to odour control unit 3. The Set debris removal area is connected to odour control
unit 4. The debris removal systems can be isolated by stop logs.

The level in the river is maintained by two sets of 2 No. radial weir gates mounted downstream of the log
boom and a level transmitter. The radial weir gates can be isolated by stop logs.

In the future, 10 MLD sewage from the Yen So Park Development will be introduced to the STP.
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Typical Log boom for Kim Nguu & Set River Typical Radial Gate for Kim Nguu & Set River




Typical Trash Rake for Kim Nguu & Set River

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Yen So STP- Flow to Inlet Works
3.1.2 Inlet Chamber

Incoming flow from the Kim Nguu River and Set River flows into the intake screens. Each screen channel has a
motorised inlet and outlet penstock. The screens are cleared by a motor driven rake upon detection of high
differential level measured by a level transmitter. The screenings are deposited via a screw conveyor compactor
into a skip.

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Inlet Chamber for Kim Nguu


3.1.3 Grit Chambers
The influent from the Kim Nguu and Set River intake screens gravitate through the underground pipe to 2nos.
Of grit chambers. the Kim Nguu grit chambers and Set River grit chamber respectively. Both grit chambers
trap readily settable sand and grit in the hoppers. The trapped sand and grit is removed from the hoppers by
Duty/Standby grit pumps, and processed by Duty/Standby grit classifiers. The classified grit is disposed off-
site and the remaining water will return to the common grit chamber inlet channel.
The Kim Nguu and Set River grit chambers can be isolated by inlet and outlet penstocks.
Flow from the Grit removal chambers gravitate to the inlet of the Main Inlet Pumping Station.

Inlet Penstock
Compactor Conveyor
Outlet Penstock
Penstock
Mechanical Coarse Screen
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Kim Nguu Grit Chamber

3.1.4 Kim Nguu Coarse Screens

Flow from Kim Nguu grit chamber gravitates to Kim Nguu Inlet Chamber Coarse Screens and combined with
sewerage from Yen So Development, where it passes through 25mm coarse screens in order to protect sewage
submersible pumps from debris.
Return liquor from rejected flow from hollow fiber membrane system, drain flow from odor control unit 1,
drain flow from odour control unit 2, emergency overflow from digested sludge tank, emergency overflow
from thickened sludge tanks, emergency overflow from sludge holding tank, flow from thickener filtrate, grit
classifier drainage, drainage from grit grease removal tanks, drainage from odour control unit 3, and flow
from filtrate holding tanks gravitate back to main inlet pumping station through manhole No.30 before the
flow passes to the coarse screens. The return liquor will not be considered during the initial operation.
There are 3 no. automatic coarse screens, and two manual screens. Each screen channel can be isolated by
inlet and outlet penstocks, screening screw conveyor and compactor carry the screenings into skips.
The coarse screens are connected to odour control unit 1.

3.1.5 Set River Coarse Screens

Incoming flow from Set River grit chambers flows to 2 No. 25mm coarse screens. The sewage passes through
the screens for screening of large objects, rags and debris to prevent clogging of the pumps.
Grit Pumps
Grit Classifiers
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Each screen channel can be isolated by an inlet and outlet penstocks. The screenings are deposited via screw
conveyor compactor into skip. The coarse screens are connected to odour control unit 1.




Flow to Main Inlet Pumping Station

3.1.6 Main Inlet Pumping Station
Sewage from Kim Nguu and Set River coarse screens flow to the main inlet pumping station, for pumping to
6mm fine screens in the preliminary treatment works.The pumps in the main inlet pumping station lift the
sewage to a level in the preliminary treatment works that allows it flow to gravitate through the whole plant.
Main inlet pumping station is separated into 2 nos. of pumping stations for Kim Nguu & Set River flows.
Both stations are protected by automatic and manual raked standby 25mm coarse screens. The screenings are
deposited via 2 stages screw conveyor compactor into skips.
Kim Nguu and Set River pumping stations contains six nos. submersible pumps each. For each pumping
station, 4 pumps are duty and two pumps are standby. The sewage flow splits into two halves in the wet wells,
and each well containing 3nos fixed speed submersible pumps. Pumped flows are subject to in-pipe flow
measurements.
Kim Nguu and Set pumping stations are odour controlled.

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Kim Nguu-Set River Coarse Screens
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3.1.7 Preliminary Treatment Works
 Fine 6mm screens + wash-compactors
 Combined aerated grit + grease removal
 Separated grease automatically scraped into skips
 Grit pumped to classifier and loaded to skips

Preliminary Treatment Works General Layout
Preliminary Treatment Works:
Preliminary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can
settle to the bottom while oil, grease and lighter solids float to the surface. The settled and floating materials are
removed and the remaining liquid flows to the SBRs for secondary treatment. Preliminary treatment includes fine
screens, grit/grease removal system including blowers.
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3.1.7.1 Fine Screen:
Sewage from main inlet pumping station is pumped to fine screens inlet chamber, before passing through 6mm
fine screen, prior entering to the 4 numbers of grit/grease removal channels. The purpose of the fine screens is to
remove small objects that escape from coarse screens in order to protect downstream equipments. There are four
fine screens running as three duty and one standby, beside one emergency manual fine screen. All fine screens can
be isolated by penstocks located up-stream and downstream.






Manual Fine Screen
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3.1.7.2 Grit Grease Removal System:

Grit and Grease Removal System is designed to reduce horizontal flow velocity to allow heavy particles to settle
while grease and other floating substances are allowed to rise to the surface to be separated. The removal of grit
and grease elements is important to the durability of downstream equipment, parts, bearings, etc. In addition to
grease and grit removal, the system also contributes to the reduction of BOD and TSS.
There are four Grit Grease removal channels which are equipped with mechanically driven travelling bridge type
of grit scrapers that continually drive the collected sludge towards a hopper in the base of the tank where it is
pumped to grit classifier. Grease and oil from the materials float to the surface where they are removed by
skimmers and chute out to grease skip tanks.
An aeration system is utilized to keep the majority of organic materials in suspension during this process. A
slower spiral flow at the effluent end allows grease to float to the top of the unit for easy removal. The aeration
system consists of blowers, air pipes and diffuser system that cause the grease to coalesce. Grease is trapped

behind the baffle boards and scraped into the grease sump by the grease scraper to chute to skip grease tank.



















Mechanical Fine Screen
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Air Blowers
Grit Scraper
Odour Control
Traveling Bridge
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3.1.8 Sequential Batch Reactor (SBR)

Flow from the grit/ grease removal tanks is split between two SBR modules, each consist of 4 No. treatment
basins.
Each SBR basin contains aeration system (Blowers, air pipes and air diffusers), waste sludge system (WAS
pumps and WAS pipes), sludge recirculation system (RAS pumps and pipes) and surface skimming decanter.
The purpose of SBR basins is to remove BOD, reduce suspended solid and reduce nitrates. A comprehensive
description regarding their system provide in volume 2A.

Flow to Sequential Batch Reactors

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SBR Aeration System

Air Diffusers
Air pipes
Air Blowers
Blower Cooling System
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SBR Aeration and Dosing System
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Sludge Wasting System




Sludge Recirculation System





WAS Pumps
WAS Pipes
RAS Pipes

RAS Pumps
WAS Pipes
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3.1.9 UV Disinfection

67,000m3/ d of the treated flow from the SBR basins gravitates to the 2 No. duty UV units for disinfection. The
remaining effluent from the SBR plant will gravitate to a discharge point in the Kim Nguu River to the east of the
site.

Kim Nguu Discharge




UV Plant


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SBR effluent discharge, and UV discharge

3.1.10 Ultra Filtration Membrane Treatment Plant

After the UV disinfection, approximately 3,000m3/ d of the treated effluent undergoes further tertiary treatment
before being recycled for plant use. 3 No. membrane plant feed pumps transfer the treated effluent to the
membrane plant for tertiary treatment.

Effluent after tertiary treatment gravitates into the service water sump where it is drawn by 3 No. fixed speed
centrifugal pumps and be used as the process water. This process water pumped to odour control units 1, 2 & 3,
dewaterer polymer dosing plant, thickener polymer dosing plant, sludge dewatering units, membrane chemical
cleaning plant, Kim Nguu grit chamber, thickener washwater pumps, site hydrants and hose points.


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Memberane Treatment Plant

3.1.11 Sludge Holding Tanks

Waste activated sludge (WAS) from the SBR basins is transferred to the 2 No. sludge holding tanks. The WAS is
pumped to the sludge holding tanks by WAS pumps. From the sludge holding tanks, the sludge is pumped to the
thickener units by using 6 No. variable speed thickener feed pumps.



RAS Pumps