Tài liệu Pilot surface water treatment plant Hoa An, Vietnam pdf

Funded by the Federal Ministry of Research and Education, Germany Project ID 02WD0621 Part Project 2: Improvement of the Rural Water Supply Pilot Surface Water Treatment Plant Hoa An,

Funded by the Federal Ministry of Research and Education, Germany

(Project ID 02WD0621)

Part Project 2:

Improvement of the Rural Water Supply

Pilot Surface Water Treatment Plant

Hoa An, Vietnam

Manual & Documentation

(Version from the 27.09.2007)

The Pilot Surface Water Treatment Plant Hoa An was developed within the

Project – Part Project 2: Improvement of the Rural Water Supply

Contents

1 Introduction 1

1.1 Idea of the pilot surface water treatment plant 1

1.2 Purpose of the manual 1

1.3 Contact 1

2 Treatment Concept 3

2.1 Treatment Capacity 4

2.2 Water Catchment 4

2.3 Flocculation 4

2.4 Sedimentation 5

2.5 Rapid Sand Filtration 5

2.6 Slow Sand Filtration 6

2.7 Disinfection UV-Lamp 6

2.8 Disinfection with Chlorine 6

3 Dimensioning 7

3.1 Sedimentation Tanks 7

3.1.1 Sedimenation Area 7

3.1.2 Flow Rate 7

3.1.3 Flow Velocity 7

3.1.4 Retention time 8

3.2 Tube Reactors 8

3.2.1 Equations for the dimensioning of the Tube Reactors 8

3.2.2 Dimensioning of the Micro Flocculation Reactor R-1a and R-2a: 9

3.2.3 Dimensioning of the Macro Flocculation Reactor R-1b and R-2b 10

3.3 Rapid-Sand-Filter 11

3.3.1 Diameter of the filter 11

3.3.2 Filter Height 11

4 Electrical Set-up 12

4.1 Operating Mode 12

5 How to get the treatment plant started 14

6 How to shut down the treatment plant 18

7 Troubleshooting 18

8 Maintenance 18

9 Literature 22

10 Appendix 23

Symbols, Abbreviations, Dimensions

Figures

Fig 1: Process Overview 3

Fig 2: Process Flow Chart 1/3 24

Fig 3: Process Flow Chart 2/3 .25

Fig 4: Process Flow Chart 3/3 26

Fig 5: Plan View 27

Fig 6: Sedimentation Tanks 28

Fig 7: Electrical Installation 29

Tables Tab 1: Electrical components 12

Tab 2: Parts List 30

1 Introduction

1.1 Idea of the pilot surface water treatment plant

At Hoa An research station - belonging to Can Tho University - a student dormitory and other research facilities are under construction The existing ground water supply will not meet the prospective fresh water demands of about 300 people in the nearest future

In the framework of the SANSED-Project a pilot surface water treatment plant (PSWTP) Is being constructed in Hoa An The PSWTP should be used for scientific purposes but it should also be able to supply the research station with water

For the design of the pilot surface water treatment plant the following conditions had to be reached:

• treatment steps are easy to understand

• treatment plant can be rebuilt with parts available in Vietnam

• low costs and low maintenance but efficient

• robust

Besides standard treatment components (e.g sedimentation tanks, disinfection) tube tors where the flocculation takes place and a slow sand filter are applied The tube reactors provide a reliable formation of settleable flakes even under sub-optimal operating conditions and do not need maintenance

reac-1.2 Purpose of the manual

In this manual treatment steps are explained, the dimensioning of significant components is shown and recommendations for maintenance are given as well as a description how to start

up and how to shut down the plant

This manual also contains a documentation of the treatment plant including technical lines, part lists and pictures taken during the installation process Manuals of additional equipment (e.g dosage pumps, UV-Lamp, etc.) are also enclosed

out-1.3 Contact

For information, questions and problems please contact:

Dipl.-Ing Thomas Nuber

Ruhr-University Bochum, Germany

Environmental Engineering & Ecology

Le Anh Tuan, M.Eng

Can Tho University

College of Technology

Department of Environmental and Water Resources Engineering

Campus II, 3/2 Street,

Can Tho City, Vietnam

email: latuan@ctu.edu.vn

Rapid Sand Filtration

Slow Sand Filtration

UV-Disinfection

Chlorination

To distribution network NaOCl

To Sludge Discharge

Legend

Q max [m³/h] = 3,0 1,5

To Rinsing Water Storage

Al 3+

From Rinsing Water Storage

Project: Treatment Plant Hoa Anh, Vietnam

Editor: Frank Benstöm Date: 30.07.2007

Title: Process Flow 1/3

Fig 1: Process Overview

For detailed process information see Fig 2 to Fig 4 in the appendix A list of all components

of the PSWTP is given with their labelling and technical specifications in Tab 2 of the

catchment itself consists of a fence surrounding the submersible pump preventing bigger particles (e.g leaves) of blocking the system (Photo 1)

The pressure of raw water is increased by pump P-1a(I) situated inside the treatment plant The flow rate of raw water is measured by the flow rate meter I-1 and can be adjusted using valve V-1a to the desired flow rate Water samples of the raw water can be taken at sampling valve V-1b

The PAC stock solution is added to the water stream with dosing pump P-1b The typical

“pulsated-dosage-characteristic” of the dosing pump is smoothened with pulsation damper

D-1 This secures a continuously dosage for optimal mixture with the water stream and to maximize accuracy of measuring the flow rate with flow rate meter I-2 (Photo 2)

In injection nozzle N-1 the PAC stock solution and the water stream are rapidly mixed by changing the tube diameter This leads to an instantaneous change in velocity and therefore turbulences are formed within the tube Water samples can be taken at sample valve V-2b After that the water stream is split into 2 sub-streams Every single stream passes one tube reactor (R-1a and R-2a) with small diameter for micro-flocculation

Water samples can be taken after the micro-flocculation at sample valve V-3b and V-4b

After forming micro-flakes the water flows through another tube reactor (R-1b and R-2b) for macro-flocculation to accumulate the micro flakes to settleable macro flakes Both are wound around sedimentation tanks E-1 and E-2 to save space (Photo 3) The water in the tube re-actors can be released to the sludge stream opening valve V-4a in case of maintenance

Water samples can be taken at valve V-6b

The sludge can temporarily be released by valves V-5a and V-6a

Valve V-7a can be used to empty storage tank E-3 in case of maintenance

2.5 Rapid Sand Filtration

The treatment goal of the rapid sand filtration is to remove residue small non-settleable cles

parti-The water is pumped from the storage tank E-3 through two serially connected rapid-sand filters F-1a and F-2a via pump P-2a (Photo 5 and 6) The flow can be adjusted using valve V-6a

The filters can be backwashed with rinsing pump P-4 which takes water from rinsing water storage tank E-4 (Photo 9) The backwash flow can be measured using flow rate meter I-3 Valves V-9a to V-16a are needed to switch from operating process to backwash process Valve V-7b is used to take water samples

2.6 Slow Sand Filtration

The treatment goal of the slow sand filter consists of aeration, reduction of dissolved organic substances and reduction of germs

The slow sand filter will be designed and built under construction supervision of ITH (Thilo Herrmann) and Le Anh Tuan

2.7 Disinfection UV-Lamp

The treatment goal is the disinfection of the treated water

The water is pumped through the ultraviolet disinfection lamp (UV) by pump P-3a (Photo 7 and 8) After that a sub-stream of the water is used to (re-)fill the rinsing water tank E-4 con-trolled automatically by float valve V-1d (Photo 9) This sub-stream can be adjusted using valve V-18a The flow rate can be adjusted using valve V-17a

Water samples can be taken before and after UV-treatment (V-8b and V-10b)

2.8 Disinfection with Chlorine

The treatment goal is the persistent disinfection of the treated water Either disinfection with the UV lamp or with chlorine or both can be applied

Sodium hypochlorite solution is added to the treated water by dosing pump P-2b Pulsation damper D-2 is needed to smoothen the signal for a continuously injection to gain a homoge-nous mixture (Photo 8)

Water samples can be taken at valve V-11b

After the chlorination step the treated water (re-)fills the water supply tank of the student dormitory throw an underground pipe

The total capacity of the treatment plant is Q=3 m³/h There are two sedimentation tanks with

a maximum flow rate

Q = 1,5 m³/h

each

3.1.3 Flow Velocity

For the sedimentation step the flow velocity of the water within the sedimentation tank has to

be lower than the velocity of particles which should be settled According to (HAHN UND

can be assumed

The flow velocity can be calculated with the following equation:

h m m

h m

²00

,

2

/5

m v

v ref >! →2,38 / >0,75 / => Condition fulfilled

m m

In the following sections the dimensioning of the tube reactors will be described

3.2.1 Equations for the dimensioning of the Tube Reactors

According to [GROHMANN,A.(1981)]the velocity gradient G of a tube reactor can be scribed as:

11 27

3.2.2 Dimensioning of the Micro Flocculation Reactor R-1a and R-2a:

According to GROHMANN(1981) the velocity gradient G and the retention time tr for the cro flocculation can be set to:

3 7 27

11 4 27

301017,44

For the installation l 25= mis chosen

To avoid sedimentation within the tube reactor the velocity has to be higher than 0,1m / s, [see GROHMANN(1981)]

The flow velocity can be calculated according to the following equation

s m s

m d

Q

²025,0

1017,4

3.2.3 Dimensioning of the Macro Flocculation Reactor R-1b and R-2b

According to GROHMANN(1981) the velocity gradient and the retention time for the macro flocculation can be set to:

3 7 27

11 4 27

1001017,44

For the installation a length l 15= m is chosen

To avoid sedimentation within the tube reactor the velocity has to be higher than 0 , 1 m / s

[GROHMANN(1981)]

The flow velocity can be calculated according to equation

s m s

3.3 Rapid-Sand-Filter

For the rapid-sand-filter the following boundary condtions are given:

Filter velocity: v f =12m/h

3.3.1 Diameter of the filter

The required filter area Amin is calculated according to the equation

A

d 4 min 4 0,25 ² 0,56

min = ⋅ = ⋅ =

π π

The chosen diameter is 0,6 m

3.3.2 Filter Height

According to HANCKE (2000) the minimum filter height is h = 2,0 m A height of h=2,4 m is chosen

4 Electrical Set-up

In the following section the electrical set up is described It ensures the power supply of each component of the PSWTP and is responsible for the semi-automatic control See especially Fig 7 and Tab 1 for the electrical installation and Tab 2 for further explanations of con-nected consumer loads (e g pumps)

Tab 1: Electrical components

Item Labelling Properties

Operation Control

Level Control Switch ESS-1 … ESS-4 230 V; 7 A Maximum Current

Pump P-1a(I), P-1a(II), P-2a, P-3a 230 V; 370 W

cuit breaker is used to prevent the installations from over-current Furthermore a ground fault circuit interrupter connected with a grounding behind the PSWTP is used to reduce the risk

of accidents for the operating staff All switches, control lamps and contactors are assembled

in a control panel (Photo 10)

The treatment plant is operated with level control switches which are installed in significant spots within the process The level control switches are operating contactors which are con-trolling the consumer loads (e.g pumps)

The consumer loads can be switched on/off by the manually operated switches 1 to

ES-17 The operating status is displayed by lamps EL-1 to EL-16

When level control switch ESS-1 is switched on the contactor ER-1 supplies the pumps P-1c (I), P-1a (I) and P-1b with electricity

When level control switch ESS-3 is switched on contactor ER-3 supplies pump P-2a with electricity

When level control switch ESS-4 is switched on contactor ER-4 supplies the pump P-3a and P-2b with electricity

UV-Lamp, rinsing pump P-4a and stirring devices M-1 and M-2 are controlled manually by switches

Switches ES-1 to ES-17, contactors ER-1 to ER-4 and operation control lamps EL-1 to EL-16 are built in a control panel for central control of the PSWTP

The electrical set-up described in the following can be used as an option for further sions of the PSWTP Consumer loads are not connected yet

exten When level control switch ESS-2 is switched on contactor ER-2 supplies pumps P-1c (II), P-1a (II) and P-1b with electricity This circuit works simultaneously to consumer loads P-1c (I), P-1a (I) and P-1b described above and may be used for tapping an-other water resource

5 How to get the treatment plant started

In order to get the treatment plant started the following steps have to be done Please read this chapter first before you are starting the treatment plant

Options for the Operational Mode

- If the treatment plant is running without the purpose to (test modus) the valve V 19 -a has to be closed

- If the student dormitory is to be supplied with the treated water (regular modus) the valve V19-a has to be opened For the operational mode check if the floating switch is

in position

- If the treatment plant was not running for a long time it is recommended to release the remaining water from the sedimentation tanks E-1 and E- 2 and also from the storage tank E-3 by opening the valves V5a, V6a and V7a

- After the remaining water is released close the valves V5a, V6a and V7a

- Open the “Electrical Installation Box”

- Check the voltage stabilizor

- Switch on the main circuit breaker

- Switch on the main switch

- Switch on the ground fault circuit interupter

Step 3: Preparation for operating the treatment steps “water catchment” and

“flocculation & sedimentation”

Check and refill the flocculation solution

- Check if there is enough flocculant solution in the flocculation storage tank L-1

- If there is not enough flocculant solutation please proceed as described in the chapter maintenance

- In order to secure a homogeneous turn on the Rührwerk R-1 with the switch ES-6

- After 15 minutes turn it off

Check the valve positions and floating switches

- Close the valves V-5a, V-6a and V-7a

- If you only want to operate the until the floccualtion sedimentation treatment steps open the valve V-7a Please note that in this case you have to turn of the pumps manually by using the switches ES-1 and ES-2 at the control panel

- Open the Valve V-8a

- Check if the floating switch in the storage tank E-3 is in position

After the preparation work is done you can start the water flow The following three steps should be done at almost the same time

- Turn on the dosage pump P-1b by using the switch ES-3 at the control panel

- Turn on the submersible pump P-1c (I) by using the switch ES-1 at the control panel

- Turn on the booster pump P-1a (I) by using switch ES-2 at the control panel

- Check the flow at the flow meter I-1 If two sedimentation reactors are used the flow must be 3m³/h, if one sedimentation reactor is in use the flow must be 1,5 m³/h You can adjust the flow using the valve V-Ia

- Check the dosage of the flocculant at the flowmeter I-2 It should be between 6 – 7