investigating the water supply treatment system of an industrial zone factory residential area

Water Intake Structure, Raw Water Pumping Station .... Water Suction Gates of the Raw Water Pumping Station .... The primary source of domestic water supply in Vietnam is surface water,

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

SCHOOL OF ELECTRICAL & ELECTRONIC ENGINEERING

-Supervisor: PhD Dinh Thi Lan Anh

Ha Noi, 2023

1 | P a g eTable of Contents

I Overview 3

1 Water Usage Demand in Vietnam 3

2 Evaluation of Vietnam's Surface Water Sources 4

2.1.2 Raw water quality 6

2.1.3 Clean Water Quality Requirements after Treatment 9

2.1.4 Technological Process 9

2.2 Water Intake Structure, Raw Water Pumping Station 12

2.2.1 Raw Water Intake Pipes 12

2.2.2 Water Intake Compartment 13

2.2.3 Water Suction Gates of the Raw Water Pumping Station 13

2.2.4 Raw Water Pumping Station 13

2.2.5 Raw Water Pipeline 14

2.3 Water Plan 15

2.3.1 Water Plant Capacity 15

2.3.2 Technological Design Solutions for Water Treatment Plant 15

III Equipment statistics 24

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Subject of study: Nui Coc Lake South Water Plant

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I Overview

1 Water Usage Demand in Vietnam

Water, an essential need for all living beings, plays a crucial role in climate regulation and sustaining life on Earth The human body requires 3 to 10 liters of water daily for various activities, obtained through food and drinking water, facilitating metabolic processes and energy exchange, and subsequently excreted through waste Additionally, water is used for activities like bathing and washing

In Vietnam, the demand for water is increasing due to population growth and improved living standards Urban per capita water supply is estimated at 150 liters/day, while in rural areas, it ranges from 40 to 70 liters/day

The primary source of domestic water supply in Vietnam is surface water, sourced from rivers and lakes, treated before distribution to households Over 60% of water supply stations in urban and industrial areas use surface water, providing around 3 million cubic meters/day This figure is expected to rise in response to urban expansion and development

Vietnam is anticipated to face severe water shortages in the next 50 years due to global climate change, resulting in a decline in water sources Recent studies suggest a decrease in surface water by 4% in 2025, 10% in 2070, and 14% in 2100 compared to current levels The per capita availability of water is projected to be around 2,830 cubic meters/person/year by 2025, considering both internal and external water flows, reaching 7,600 cubic meters/person/year

Water resources in Vietnam are unevenly distributed among regions, with over 60% concentrated in the Red River Delta (Mekong River Basin) However, this region holds only 40% of the total water but supports 80% of the population and over 90% of economic activities

Furthermore, Vietnam's water resources exhibit seasonal variations, with

-during the dry months Economic growth, if not accompanied by effective environmental protection, has contributed to increasing water pollution, particularly in deltas with high organic pollutants and bacterial content According to the assessment of researchers, the high economic growth rate, not accompanied by effective environmental protection, has negatively impacted water resources in our country The increasing pollution of surface water

4 | P a g esources in terms of intensity and scale is evident, with some delta areas

high levels of bacteria The manifestations of degradation and depletion of water sources are becoming pronounced and widespread in our country Given the unsustainable characteristics of our water resources, state management efforts with this precious resource need to be strengthened at all levels now, before it's too late

2 Evaluation of Vietnam's Surface Water Sources

Vietnam has a dense network of rivers, including major rivers such as the Mekong River system, followed by the Red River system, Dong Nai River, Ma River, Ca River, Huong River, Thai Binh River, Thu Bon River, and others, with each river basin covering an area of over 10,000 km² and the total flow of major rivers being around 880 km³ per year

The average annual rainfall is 1960 mm, contributing to a renewable water supply of about 324 km³ per year

The distribution density of rivers is uneven and depends on the topography and climate of each region

In general, rivers in Vietnam have large water reserves with the potential to meet immediate and future water needs However, to ensure sustainable use of surface water, it is crucial to have a reasonable usage strategy and protect surface water sources from the impacts of human activities

Apart from surface water sources like rivers and lakes, springs in mountainous areas also play a crucial role in supplying water to highland communities Spring water exhibits variations in water quantity and quality with the seasons During the rainy season, the water is often turbid with high levels of suspended particles and organic matter However, the characteristics of sediment in spring water differ from river water, being coarse, settling rapidly

Key characteristics of surface water sources in Vietnam can be summarized as follows:

a River water:

The quality of river water in Vietnam varies by season and geographic region Surface runoff erodes the surface, carrying suspended materials such as sand, mud, and silt

River water has high sediment content during the rainy season, with an annual

-5 | P a g ethe flood season Turbidity and sediment levels change seasonally and during flood periods, with the highest turbidity occurring in the flood season Main components of river water:

Hardness: River water is generally soft

- Content of Major Ions: Primarily consists of ions such as Ca2+, Mg2+, K+,

-b Lake water:

Vietnam has numerous natural lakes, such as Ba Be Lake, Nuoc Coc Lake, and several artificial lakes serving agricultural irrigation purposes Notably, some large reservoirs from hydroelectric projects, such as Thac Ba and Hoa Binh, have significant water storage capacity

In general, natural lakes have smaller water reserves, with only a few large lakes capable of supplying water for various purposes Hydroelectric reservoirs

-Lake water has lower sediment content compared to river water as it naturally settles and is relatively stable However, sediment levels fluctuate with the seasons; during the rainy season, sediment levels are higher, while during the dry season, sediment levels decrease The water quality, including turbidity, meets the standards for domestic and culinary water use Water quality fluctuations commonly occur in coastal areas and depend on the topography of the coastal region Water quality tends to be more stable in offshore and mid-lake areas

Lake water often has a high color due to algae, moss, and other aquatic vegetation The organic matter content in lakes is typically high due to the decomposition of surrounding vegetation

Generally, lake water quality is good, and the water treatment process can be simpler than that for river water The amount of chemicals used for coagulation is lower, making the cost of lake water treatment usually cheaper than that of river water

II Technology

2.1 Documentation base for design

Based on project documents and the decision to review the investment project for the construction of the "Development of the urban water supply system in

6 | P a g eThai Nguyen city" by the Provincial People's Committee of Thai Nguyen on July 22, 2014

2.1.1 Design specifications

- Calculated capacity in liters per second (Qs'): 13.8 l/s - Operation time of the station (T): 24 hours/day 2.1.2 Raw water quality

The assessment of raw water quality requires comprehensive data for each season within the year and average observational data over multiple years The consulted research data for Nui Coc Lake includes:

- Environmental monitoring reports for Nui Coc Lake over 5 years (from 2008 to 2012) from the Center for Environmental Monitoring and Technology under the Department of Natural Resources and Environment of Thai Nguyen province

- Water testing results for Nui Coc Lake in 2009 conducted by the Preventive Health Center, Department of Health of Thai Nguyen province

- Water quality analysis results at the project site location conducted by the consulting unit (VIWASE) in 2011

- Measurement and analysis results of surface water in the Cong River at Nui

-Environmental Monitoring and Technology under the Department of Natural Resources and Environment of Thai Nguyen province (Details can be found in Appendix 8B)

Water testing form from the Preventive Health Center, Document No 53/KNHH, dated January 22, 2009

Number Testing criteria Unit Testing method Permissible standard Result

No unusual odor or

7 | P a g e5 Hardness level (German degree) degree TCVN 6224 – 1996 15011,12

Water testing form from the project consulting, dated May 28, 2011

Results of measurement and analysis of water samples at the Nui Coc Dam by the Center for Resource and Environmental Monitoring under the Department of Natural Resources and Environment of Thai Nguyen province, dated July 15, 2016

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QCVN MT:2015/BTN

-standard) Therefore, the surface water of Nui Coc Lake can fully meet the requirements for supplying the water plant However, water quality varies with seasons and over the years

Specifically: the average data from various measurements over the years indicate:

9 | P a g eHowever, there are some monitoring results that significantly deviate from the average values For instance, in the first measurement of 2013, the pH was 5.6, in the first measurement of 2015, the pH = 5.7, and in the second measurement of 2014, TSS = 25.7 mg/l Particularly noteworthy is the third measurement in 2014, where TSS = 107.3 mg/l

The Dissolved Oxygen (DO) index tends to decrease in the last months of the year, reaching its lowest point at 4.3 in the fourth quarter of 2014, then increasing again in the early months of the following year

The Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) indices tend to increase in the later months of the year and decrease in the early months of the following year

2.1.3 Clean Water Quality Requirements after Treatment

The treated water must meet the quality standards for domestic use according to QCVN 01:2009/BYT (compiled by the Preventive Health and Environment Department and issued by the Minister of Health through Circular No 04/2009/TT-BYT on June 17, 2009)

2.1.4 Technological Process

Considering the average quality of monitored parameters over the years, several technological processes can be applied However, due to the fluctuating water quality of the lake throughout the year, to ensure the stable treatment efficiency of the water plant, contingency plans are needed for continuous and uninterrupted operation in response to variations in the source water quality

10 | P a g e2.1.4.1 Technological Process Diagram

2.1.4.2 Description of Processes in Water Treatment Technology

- Water Intake Facility and Raw Water Pumping Station: Responsible for directly collecting water from Nui Coc Lake and transporting it to the plant to meet the raw water demand for the facility

- Static Mixer: Utilizes static mixing equipment instead of traditional mixing tanks to reduce construction volume, lower investment costs for agitator equipment and variable frequency drive control systems However, the reaction between coagulant chemicals and raw water is still ensured Polymer and PAC coagulant chemicals are introduced into the static mixer through chemical injection pipes welded onto the static mixing equipment

Project Pumping Station for Primary Water Supply

-PAC dosing

Static mixer equipment

Inclined plate settler with sludge blanket

Gravity filter tank

Storage tank Chlorination

Pumping Station for Secondary Water Supply

Water supply meeting QCVN 01;2009/BYT

standards

Network

Sedimentation pit

Drainage

11 | P a g e- Sedimentation Tank: The particulate matter from the reaction basin is retained in the sedimentation tank under the influence of gravity Employing lamellar sedimentation tanks enhances settling efficiency and reduces tank size

- Filtration Tank: Fine particles that do not settle in the sedimentation tank and drift into the filtration tank are captured on the surface of the filter media layer Utilizing a rapid gravity filtration tank, with a layer of clean silica sand as the filter media

- Storage Reservoir: The filtered water is directed to the storage reservoir and disinfected with chlorine at prescribed dosage The reservoir capacity is

-supply to the distribution network

- Clean Water Pump: The disinfected clean water is pumped out to the water supply network Regulating water consumption throughout the day is achieved through a variable frequency drive system The control building, housing the pump station, also accommodates pumps for backwashing, filter cleaning, technical processes, and leakage water

- Phosphorus Dosage: Intended to disrupt the stability of natural floc, concurrently fostering the formation of a new floc with the ability to aggregate

impurities in the water The phosphorus dosing point is located at the mixing basin of the water treatment plant

- Preliminary Chlorination: In cases of organic contamination in the source water, chlorine can be employed for the oxidation of organic substances The preliminary chlorination chlorine supply is obtained from the backup system of the chlorine facility used for water disinfection in the plant The preliminary chlorination point is determined to be within the intake compartment of the raw water pump station

- Water Disinfection Chlorination: Liquid chlorine stored in a 900kg container is used for water disinfection The estimated disinfection dosage is 2mg/l The chlorination point is located downstream of the overflow wall of the clean water storage tank

- Sludge Treatment: During the treatment process, wastewater generated from filter backwashing and sludge settling is collected in the recovery tank Wastewater from the recovery tank is pumped to the sludge thickening tank The settled sludge in the sludge treatment tank is transferred to the sludge

12 | P a g edrying bed, and the collected water is sent back to the receiving tank for further treatment

2.2 Water Intake Structure, Raw Water Pumping Station The construction items include:

- Water intake gates

- Water suction gates of the raw water pumping station - Raw water pumping station

- Operation and management building for the pumping station

Transformer station providing power for the raw water pumping station - Raw water pipeline

- Pipeline from the water plant to the raw water pumping station

The construction is located along the Nui Coc Lake at the base of the Voi Phun mountain within the lake, calculated based on the Nui Coc Lake water levels (according to the Periodic Water Control Results of the Environmental Monitoring and Protection Center)

- Highest water level: +50m (increased by +2m from the current calculated level of 48.0m, according to the project upgrade plan for the Nui Coc irrigation system)

- Average water level: +46.20m - Lowest water level: +34m

- Ground level at the pump station location: +31.20m - Working floor level: +50.50m

2.2.1 Raw Water Intake Pipes

- Utilize 02 DN200 steel pipes, each 57m long, to intake raw water during the dry season (TO1), and 02 DN200 steel pipes, each 30m long, to intake raw water at the +40m elevation (TO2)

- Install debris screens around the intake mouths of the raw water pipes to remove debris, packaging, etc., before the water enters the water intake compartment

- The debris screen for the TO1 raw water pipe consists of 8 B40 screens, V5 steel frame arranged in a circle The TO2 raw water pipe debris screen consists

13 | P a g eof B40 screens, V5 steel frame arranged vertically with dimensions of 3.2m x 3.2m, supported by I100 steel frame

2.2.2 Water Intake Compartment

- 04 raw water pipes bring water into 04 small water intake compartments, each with dimensions of LxWxH = 1.85m x 1.5m x 14.55m

- At each water intake point, install a debris screen to prevent debris, packaging, leaves, etc Two manual opening/closing gates are installed at two water intake points during the dry season (+34m) to stop water intake during the rainy season to prevent high turbidity water intake from the bottom layer 2.2.3 Water Suction Gates of the Raw Water Pumping Station

- Water from the water intake compartments is pumped into the pumping station's suction compartment through a water intake gate with dimensions of LxW = 1.5m x 1.5m, and the gate's water entry level is +34.0m

- The pumping station's suction compartment consists of 02 compartments, each with dimensions of LxWxH = 10.9m x 2.3m x 16.6m A manual gate is arranged between the two compartments

- The pumping station is adjacent to the intake, directly sucking water from the intake to the treatment area Chlorine is dosed in this water suction compartment for preliminary treatment of the raw water:

+ Continuous chlorine pretreatment (at a rate of 0.3g/m3) is carried out to preliminarily treat organic matter, algae, iron, and manganese in the source water to prevent algae and organisms from clogging the pipes

+ Lime treatment on the raw water pipeline is performed when the pH of the water source at Nui Coc Lake is <7.0 to ensure that the treated water has a

-coagulation for floc formation, iron and manganese removal, and the taste of drinking water

2.2.4 Raw Water Pumping Station