The actual state of wastewater generated from vermicelli production at phu do traditional vermicelli village, nam tu liem district, hanoi city

MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT
VIETNAM NATIONAL UNIVERSITY OF FORESTRY

STUDENT THESIS PROPOSAL
Title

“ The actual state of wastewater generated from
vermicelli production at Phu Do traditional
vermicelli village, Nam Tu Liem district,
Hanoi city ”
Major: Natural Resources Management
Code: D850101
Faculty: Forest Resources and Environmental Management

Student: Nguyen Cam Van

Student ID: 1253090038

Class: K57 Natural Resources Management

Course: 2012 – 2016

Advanced Education Program
Developed in collaboration with Colorado State University, USA

Supervisor: Msc. Nguyen Thi Bich Hao

Ha Noi, November/2016


ACKNOWLEDGE

Successful completion of any type of project requires helps from a number of persons.
I have also taken helps from different people for the preparation of this report. Now,
there is a little effort to show my deep gratitude to that helpful person.
I convey my sincere gratitude to my Academic Supervisor Msc. Nguyen Thi Bich
Hao, Msc of Environmental Engineering of Department of Environmental
Management, Vietnam National University of Forestry. Without her kind direction and
proper guidance this study would have been a little success. In every phase of the
project her supervision and guidance shaped this report to be completed perfectly.
I would also like to express my excessive thanks to Msc. Nguyen Thanh Thao, Deputy
Head of Department of Environmental Toxins Analysis, the Institute of Environmental
Technology for her excellent support and proper guidance in helping me did all
analysis wastewater samples in the laboratory and completing my internship report.
Finally, I want to express my deep gratefulness to villagers in Phu Do village and the
local authority of Phu Do Ward. With their enthusiasm help during wastewater
sampling and interviews processes, I had the opportunity to improve my knowledge
and experience about vermicelli production in Phu Do village. From that, all of these
data and information help me to complete this report.
Hanoi, September 26th, 2016
Student

Nguyen Cam Van


ABSTRACT
This study evaluates the situation of wastewater generated from vermicelli production
of Phu Do traditional vermicelli village, Nam Tu Liem District, Hanoi city. The paper
document study all steps of vermicelli production process; from that considering some
steps which discharged wastewater directly into the environment without any
treatment at different households. All of these indicators such as pH, DO, TSS, BOD5,
COD, N_NH4+, PO43- that were analyzed from wastewater samples at Phu Do village

pointed out that the current state of wastewater in Phu Do village is seriously alarming.
The main reason is the consciousness of local people in the work of wastewater
treatment is still low. Moreover, the only wastewater treatment system of village has
been broken for many years and there are no signs of being repaired so far. If this
situation is prolonged, it would adversely affect the health and living standard of Phu
Do villagers as well as the bad impacts of water/ wastewater pollution to the
surrounding areas.


CONTENTS
1. INTRODUCTION ................................................................................................. 1
2. STUDY GOALS AND SPECIFIC OBJECTIVES ............................................... 3
2.1. Goals ................................................................................................................. 3
2.2. Specific Objectives ............................................................................................ 3
3. STUDY METHODS............................................................................................... 5
3.1. Study area .......................................................................................................... 5
3.2. Interview method ............................................................................................... 6
3.2.1. Questionnaire design ................................................................................... 6
3.2.2. Questionnaire testing ................................................................................... 7
3.2.3. Survey technique ......................................................................................... 7
3.2.4. Survey time ................................................................................................. 7
3.3. Research methods in the field ............................................................................ 7
3.3.1. Investigating the study area ......................................................................... 7
3.3.2. Sampling method ......................................................................................... 8
3.4. Analyzing method in laboratory ....................................................................... 14
3.4.1. Temperature .............................................................................................. 15
3.4.2. pH ............................................................................................................. 16
3.4.3. DO (Dissolved Oxygen) ............................................................................ 16
3.4.4. TSS (Total Suspended Solid) ..................................................................... 17
3.4.5. BOD5 (Biochemical Oxygen Demand) ...................................................... 18

3.4.6. COD (Chemical Oxygen Demand) ............................................................ 18
3.4.7. N-NH4+ (Ammonium compound) .............................................................. 18
3.4.8. PO43- (Phosphate compound) ..................................................................... 19
3.5. Calculation method .......................................................................................... 20
4. RESULTS ............................................................................................................. 21
4.1. Current state of vermicelli production in Phu Do village .................................. 21
4.1.1. Current state of socio-economic and vermicelli production in Phu Do village
............................................................................................................................ 21
4.1.2. Traditional processes of making vermicelli at Phu Do village .................... 22
a) Inputs and outputs of vermicelli production at Phu Do village ..................... 22
b) Technology and processes of making vermicelli at Phu Do village .............. 23
4.2. Properties of wastewater generated from vermicelli production at Phu Do
traditional vermicelli village ................................................................................... 25
4.2.1. The current status of wastewater from vermicelli production process in Phu
Do village ........................................................................................................... 26
a) Main sources and total discharged volume of wastewater from the vermicelli
production process ........................................................................................... 26
b) Impact of Phu Do vermicelli wastewater to society ...................................... 28
4.2.2. Results of analyzing water samples ........................................................... 29
a) Temperature ................................................................................................ 30
b) pH ............................................................................................................... 31
c) TSS (Total Suspended Solid) ........................................................................ 32
d) BOD5 (Biochemical Oxygen Demand) ......................................................... 33


e) COD (Chemical Oxygen Demand) ............................................................... 34
f) N-NH4+ (Ammonium compound)................................................................... 35
g) PO43- (Phosphate compound) ....................................................................... 36

4.2.3. Current environmental management and wastewater treatment activities at
Phu Do vermicelli village .................................................................................... 37
a) Environmental management in Phu Do vermicelli village ............................ 37
b) Wastewater treatment technology in Phu Do vermicelli village ................... 38
4.2.4. Proposing possible solution for the current state of Phu Do vermicelli
village ................................................................................................................. 40
5. DISCUSSION AND CONCLUSION .................................................................. 41
5.1. Discussion and conclusion ............................................................................... 42
5.1.1. Discussion ................................................................................................. 42
5.1.2. Conclusion ................................................................................................ 44
5.2. Limitations and recommendations ................................................................... 45
5.2.1. Limitations ................................................................................................ 45
5.2.2. Recommendations ..................................................................................... 45
REFERENCES ........................................................................................................ 46


LIST OF ACRONYMS
BOD

BTNMT

Biochemical Oxygen Demand
Ministry of Natural Resources and Environment of the
Socialist Republic of Vietnam

COD

Chemical Oxygen Demand

DO

Dissolved Oxygen

EIAs

Environmental Impact Assessments

ISO

International Organization for Standardization

MONRE

Ministry of Natural Resources and Environment

NH4

Ammonium compound

N

Nitrogen

PO4

Phosphate compound

P

Phosphorus

QCVN

The basic regulation of Vietnam Government

TCVN

The standard of Vietnam Government

TSS

Total Suspended Solids

VEPF

Vietnam Environmental Protection Fund


LIST OF TABLES
Table 3.1: Characteristics of the sampling location .................................................... 10
Table 3.2: Data form of the results of analyzing necessary indicator in wastewater
from Phu Do vermicelli village .................................................................................. 20
Table 4.1: Inputs and outputs sources to produce one ton of vermicelli at Phu Do
village ........................................................................................................................ 22
Table 4.2: Characteristics of wastewater generated from vermicelli production of Phu
Do village .................................................................................................................. 29


LIST OF FIGURES
Figure 3.1: The map of Nam Tu Liem District ........................................................... 5

Figure 3.2: The map of Phu Do vermicelli village, Nam Tu Liem District ................. 6
Figure 3.3: Water bottle 1.5L ..................................................................................... 8
Figure 3.4: Water bottle 500ml .................................................................................. 8
Figure 3.5: Diagram of sampling location ..................................................................11
Figure 3.6: Diagram of sampling process ...................................................................13
Figure 3.7: Main types of wastewater based on their sources .....................................14
Figure 3.8: Digital thermometer ................................................................................. 15
Figure 3.9: pH meter instrument ................................................................................ 16
Figure 4.1: The process of vermicelli production in Phu Do village ........................... 25
Figure 4.2: Temperature value of wastewater from Phu Do vermicelli production
village ........................................................................................................................ 30
Figure 4.3: pH value of wastewater from Phu Do vermicelli production village ......... 31
Figure 4.4: TSS value of wastewater from Phu Do vermicelli production village ....... 32
Figure 4.5: BOD5 value of wastewater from Phu Do vermicelli production village ....33
Figure 4.6: COD value of wastewater from Phu Do vermicelli production village .....34
Figure 4.7: Ammonium value of wastewater from Phu Do vermicelli production
village ........................................................................................................................ 35
Figure 4.8: Phosphate value of wastewater from Phu Do vermicelli production village
..................................................................................................................................36
Figure 4.9: Wastewater treatment system of Phu Do vermicelli village in the past .....38
Figure 4.10: The current wastewater treatment system of Phu Do vermicelli village .
..................................................................................................................................39


1. INTRODUCTION
Production in craft villages is an economic form that is relatively typical in Vietnam.
The policy for renovating the economy has blown fresh vitality to traditional craft
villages. According to the recent data of Vietnam Association of Craft Village, until
2013, Vietnam has nearly 1,450 craft villages which are currently distributed in 58
provinces and cities, especially in the Red River Delta with about 800 villages. Over

the past 10 years, Vietnam’s craft villages have achieved an average growth rate of 8%
per year.
In Hanoi, there is a huge number of craft villages with about 272 villages are
recognized as craft villages and 198 traditional craft villages (Trần Việt, Laodong
Magazine, 2013), with their own traditional art practice such as ceramics, rattan
furniture, sculpture, green rice production, rice vermicelli production, etc. The
Department of Science and Technology provided information that until 2013,
traditional craft villages in Hanoi has attracted more than 739,630 participants
involved in the craft production with 175,889 households, 2,063 join stock companies,
4,562 limited companies, 1,466 private enterprise, 164 co-operative society and 50
groups, associations. However, according to the results of traditional craft village’s
survey which was announced recently by Hanoi Centre for Environmental and Natural
Resources Monitoring and Analysis, water as well as wastewater environment in most
of craft villages in Hanoi are polluted in which, some places have reached the alarming
levels of pollution.
Located in Nam Tu Liem district (Hanoi), Phu Do village is one of the longstanding
traditional villages which has been widely known for making vermicelli. Nevertheless,
due to the lack of proper concern on wastewater treatment, water pollution is
becoming worse and more serious. In 2013, the Institute for Environmental Science
and Technology (Hanoi University of Science and Technology) conducted a survey on
the state of water pollution in Phu Do vermicelli village. The results show that
everyday, this village produces more than 10,000 tons of products; nearly 77 tons of
COD; 53 tons of BOD5 and more than 9.38 tons of suspended solids (SS) are
discharged directly into the environment. In addition, according to a health survey of
1


Ministry of Health in 2013, community health in some villages was significantly
influenced by the production activities. The most popular diseases are gynecology (1338%); digestion (8- 30%); dermatitis (4.5 - 23%); respiration (6-18%); ophthalmic (915%). The rate of occupational diseases in Duong Lieu (Ha Tay) and Vu Hoi (Thai
Binh) is 50%; and in Phu Do village is about 70%. Recognizing the seriousness of this

situation,

I come up with a goal of studying “The actual state of wastewater

generated from vermicelli production at Phu Do traditional vermicelli village, Nam Tu
Liem District, Hanoi city” in order to have the most correct view about the wastewater
pollution situation in Phu Do vermicelli village.

2


2. STUDY GOALS AND SPECIFIC OBJECTIVES
2.1. Goals
The research results contribute to enhance the effectiveness of environmental
management and improve life quality of the local people in Phu Do traditional
vermicelli village, Nam Tu Liem District, Hanoi.
2.2. Specific Objectives
To achieve the previous goals, the thesis concentrates on the following objectives:
(1) Studying current state of vermicelli production in Phu Do village
- Studying current state of socio-economic and vermicelli production in Phu Do village
- Examining the processes of vermicelli production:
+ Input and output sources of vermicelli production;
+ Technology and processes to make vermicelli.
(2) Investigating sources and properties of wastewater generated from vermicelli
production at Phu Do traditional vermicelli village.
- Doing survey on the current status of wastewater from vermicelli production process
in Phu Do village:
+ Main sources of wastewater emitted from the production process;
+ The volumes of wasterwater discharged in one day from Phu Do vermicelli
village;

+ Impact of Phu Do vermicelli wastewater to society
- Taking and analyzing wastewater samples to examine the quality and properties of
wastewater from production at Phu Do vermicelli village.
+ Collecting wastewater samples at different areas in Phu Do vermicelli village.

3


+ Analyzing wastewater samples through experiments in laboratory based on
some basic criteria such as: Temperature, pH, DO, TSS, BOD5, COD, N_NH4+, PO43-.
+ Comparing the analysis results for wastewater from Phu Do vermicelli with
the standard criteria for wastewater from food production.
(3) Investigating environmental management and wastewater treatment activities at
Phu Do
- Environmental management in Phu Do vermicelli village
- Wastewater treatment technology in Phu Do vermicelli village
(4) Proposing possible solutions for improving efficiency of wastewater management
at the study area.

4


3. STUDY METHODS
3.1. Study area
Nam Tu Liem is a district located in the west of the center of Hanoi. It was upgraded
to a district based on the splitting from the old Tu Liem Commune. Nam Tu Liem
District has an area of 3,227.36 hectares (32.27 km²) and population of 232,894 people
(Nam Tu Liem web portal, 2013). According to the general planning of Hanoi to 2030
and vision to 2050, Nam Tu Liem district is one of the core district, the administrative
center and commercial services of Hanoi. It is also a district that has many modern

architecture importance of Hanoi capital such as National Convention Center, My
Dinh National Stadium, Vietnam's tallest building- Keangnam Hanoi Landmark
Tower, Hanoi Museum, Thang Long avenue, and Fitness and sport training center for
senior athletes, etc.

Figure 3.1. The map of Nam Tu Liem District
Phu Do traditional vermicelli village belong to Phu Do ward, Nam Tu Liem district,
Hanoi City. The village is far from Hanoi center about 10km to the southwest. The
North is conterminous with My Dinh Commune, the South is conterminous with
5


Thang Long (Lang- Hoa Lac) avenue, the East is conterminous with Me Tri commune
and the West is conterminous with Nhue River. The total natural area of the village is
258.6 hectares, including 164.6 hectares of agricultural land (Data of Phu Do People's
Committee in 2015).

Figure 3.2. The map of Phu Do vermicelli village, Nam Tu Liem District
Phu Do traditional vermicelli village was chose to be a case study because of the
following reasons. Firstly, Nam Tu Liem district (as well as Phu Do village) is located
at the center of Hanoi capital which also possesses a number of traditional villages of
Vietnam. Secondly, this area is known as the main reason leading to water pollution
issues in the village as well as in the surrounding living environment in some recent
years.
3.2. Interview method
3.2.1. Questionnaire design
The questionnaire encompasses questions about the current state of physical and
socioeconomic status, demography and educational background, the number of
households making vermicelli (how many vermicelli productions are made per day,
6

information about the pollution situation inside their village and around their living
environment). The questionnaire form is included in the appendix 01 of the report.
3.2.2. Questionnaire testing
A test of the questionnaire was conducted randomly with 15 households including 10
households making vermicelli and 05 households without making vermicelli. This test
was carried out to ensure that all kinds of errors associated with survey research would
be reduced. It also helped to improve the quality of data significantly. After the pilot
test, both the interviewer(s) and interviewees were asked a series of questions
regarding the survey as well as the process of data collection during the debriefing
session. Such debriefing sessions can help detect the following problems:
- The questionnaire design (ambiguity of words, structure of questions);
- Misinterpretation of questions leading to inability to answer a question;
- Sensitive questions or many other problems associated with the questionnaire
as well as the process of administering the survey.
The debriefing session provides an opportunity to give feedback to the interview to
ensure that data collection procedures can help to answer all objectives of the project.
3.2.3. Survey technique
Face-to-face surveys were conducted in the research. This method allows researchers
to ask more questions, longer questions, more detailed questions, more open-ended
questions, and more complicated or technical questions.
3.2.4. Survey time
The surveys were conducted from 1st August 2016 to 26th August 2016.
3.3. Research methods in the field
3.3.1. Investigating the study area
The thesis conducted investigation and survey at Phu Do vermicelli village, Phu Do
Ward, Nam Tu Liem District, Ha Noi City to:

7

- Directly surveying the research area, figure out vermicelli production process, and
particularly focus on some stages which tend to discharge wastewater and pollutants;
- Investigating the steps of discharging wastewater into the environment;
- Finding out materials and chemicals which are used for each stage of vermicelli
production.
3.3.2. Sampling method
To achieve the best result, it is necessary to carefully prepare required equipment and
tools.
a) Sample containers
The containers which were used to contain selected water/wastewater samples are pure
mineral water bottles with two types of 1.5L and 500mL.

Figure 3.3. Water bottle 1.5L

Figure 3.4. Water bottle 500mL

Note: the desirable criteria of sample containers are perdurable, easy sealed, easy to
open, can resist certain temperature, reasonable volume and sized, easy to clean and
reusable, easy to find and low price.

8


b) Manual sampling equipment
The simple equipment which is used to collecting wastewater samples are buckets and
large bottle which are tied to a long stick (that has suitable length). Volume of the
bottle should not be less than 100ml. The manual sampling equipment must be made
of inert material and does not affect to the later analysis.

Before taking the samples, the device muse be cleaned with detergent and water, or
follow the manufacturer's instructions, and finally rinse with clean water. When
sampling process is complete, conducting rapidly temperate and pH measurement then
close the bottle cap tightly and preserve by styrofoam cooler with ice.
c) Sampling locations
In 2015, Phu Do Village has about 8,000 people, with 1,270 households (Phu Do
People’s Committee). Therefore, the author chose randomly two households who
making vermicelli and collect the wastewater samples directly at vermicelli production
areas of each household. At the same time, collecting at least three wastewater samples
at the only one common ditch of Phu Do village from upstream, center and
downstream. Total samples are 15 and their characteristics are listed in the table 3.1.

9


Table 3.1. Characteristics of the sampling location

No.

Symbol of
sample

Characteristics of the sampling location

1

S1

Wastewater from washing rice step

2

S2

Wastewater from soaking rice step

3

S3

Wastewater from decanting the sour water (of
incubated flour) step

4

S4

Wastewater from washing the flour step

5

S5

Wastewater from boiling the flour step

6

S6

Wastewater from washing vermicelli fibers step

7

S7

Wastewater from washing rice step

8

S8

Wastewater from soaking rice step

9

S9

Notes

Mr. Đào Xuân
Thưởng
household

Wastewater from decanting the sour water (of
incubated flour) step

Mrs. Nguyễn
Thị Bé

10

S10

Wastewater from washing the flour step

11

S11

Wastewater from boiling the flour

12

S12

Wastewater from washing vermicelli fibers step

13

S13

Wastewater from the upstream

14

S14

Wastewater from the center

The common

ditch of Phu Do
vermicelli

15

S15

Wastewater from the downstream

10

village


* Sampling diagram
Figure 3.5 shows positions of sampling at different steps of vermicelli production
process.

06 wastewater
samples

SAMPLING

06 wastewater
samples

15 wastewater
samples

03 wastewater

samples

Figure 3.5. Diagram of sampling location

d) Time of sampling
- Date of sampling:
+ Wastewater samples from Mr. Đào Xuân Thưởng household were collected
on August 18th, 2016.
+Wastewater samples from Mrs. Nguyễn Thị Bé household were collected on
August 19th, 2016.

11


+Wastewater samples from the common ditch were collected on August 19th,
2016.
- Time of sampling: samples were taken in the morning from 6h30’ to 13h00.
e) Sampling process
The wastewater samples were taken following the single sampling method/ plan based
on the standard TCVN 5996-1995 of Vietnam: Quality of water samples - Sampling
instructions - Guidance on sampling in rivers and streams.
- Necessary tools for sampling and water samples preservation: water bottle 500ml,
long stick (the length is about four to five meter), hemp string (with the length is about
two to three meter), adhesive tape, styrofoam cooler (ice box), ice, correction pen,
pencil/pen, notebook, map (of Nam Tu Liem district which includes Phu Do vermicelli
village), GPS device, camera, …
- When doing the sampling, the author needs to ensure certain requirements:
+ The sample container needs to be clean. It should not be coated by
water/wastewater which will be taking; it may affect the future results of the analysis.
+ Do not disturb the water surface.

+ Samples were taken should have highly representative ability
- Conducting sampling: firstly, grabbing the neck of sampling bottle and the long stick
together, we can use adhesive tape fixed them together for more steady. After that,
dropping the sampling bottle down to the sampling location (the sample should be take
at a depth of 20cm to 30cm compare to the water surface and far from the shore about
1.5m to 2m) until water full the bottle, then pull up, clean the outside and close the
bottle cap. Using correction pen to signs the number order, date and time of sample
and write down necessary information which are need to be analysis of sample into the
notebook. Finishing the taking samples process, the author analysis at the scene
parameters that can be measured quickly (temperature, pH).
12


- Preservation and transportation of samples: putting water samples into styrofoam
cooler with ice and bring it carefully to the laboratory of Vietnam National University
of Forestry and the laboratory of Department of Environmental Toxins Analysis, the
Institute of Environmental Technology based on the standard TCVN 5996-1995 of
Vietnam.

Figure 3.6. Sampling process diagram

13


f) Storage and transportation
Because the selected parameters which cannot be measured directly at the field, the
most common way to preserve wastewater samples are cooled to a temperature of
about between 00C and 40C.
Water samples were kept in styrofoam cooled with ice and carried carefully to the
laboratory of Vietnam National University of Forestry and the laboratory of

Department of Environmental Toxins Analysis (the Institute of Environmental
Technology) based on the standard TCVN 5996-1995 of Vietnam.
3.4. Analyzing method in laboratory
According to the Decree QCVN 24:2009/BTNMT of Vietnam Environment
Administration, sewage water/wastewater is water which was discharged after having
used, or created in a technological process. They have no direct value to the previous
process. They also were changed their original properties. Generally, wastewater is
classified according to their origin.

Figure 3.7. Main types of wastewater based on their sources
(QCVN 24: 2009/BTNMT)
14


According to the classification of wastewater types, wastewater at Phu Do vermicelli
village is considered as the production wastewater, also known as industrial
wastewater. To assess wastewater quality and wastewater pollution levels, we can rely
on some basic norms and limits of each indicator that comply with the Law on
Environmental Protection of Vietnam or International Standards for each type of
wastewater from different purposes. In this research, we choose some key indicators as
follow: temperature, pH, DO, TSS, BOD5, COD, N-NH4+, PO43-.
3.4.1. Temperature
Temperature measurement in wastewater applications provides an important back up
to measurements such as pH, BOD, COD, TSS, etc. In wastewater, the microorganisms present that they eat more and reproduce more when the temperature
increases. It is estimated that every 10°C increase in temperature doubles the microorganism’s reproduction rate up to a limiting maximum, with optimum efficiency
being between 10°C and 40°C. The more micro-organisms that are present the more
DO concentration is required. So when the temperature increases too high, other
species live together in wastewater environment can be affect negatively to their
living.
*How to measure temperature?

Water/wastewater temperature is often measured with a thermometer. There are many
different types of thermometer available today and the two main kinds of them are
analogue thermometer and digital thermometer. In this project, the author use digital
thermometer to measure temperature of wastewater samples.
At first, wastewater sample need to be collected. Then
carefully place the ending of thermometer into the
wastewater sample (just about 2-5cm of the thermometer’s
depth compares with the water surface) and wait at least
two minutes until the number on the screen of
digital thermometer is stable, then note the
15

Figure 3.8. Digital thermometer


temperature. To continue with others, press “restart” button and wait about one minute
before do it with other samples.
Note: Each wastewater sample was measured three times and determined the mean
value obtained final results. Besides, to make sure the error is not too large, the author
have to measure the temperature of the wastewater samples immediately at the scene
sampling, after sampling has finished and measured in the sample container.
3.4.2. pH
pH is a mathematical unit denotes H+ ion concentration in the water and can scale from
0 to 14 values. pH is one of the important parameters and is
used to assess the level of pollution of water resources,
wastewater quality, etc. Therefore, measuring pH to complete
the water quality in line with the technical requirements for
each stage of management is very important,
even more is the quality assurance for the users.

Figure 3.9. pH meter instrument

When pH <7 is acidic environment; pH> 7 is alkaline, this shows the influence of
chemicals when they enter the water environment. Low or high pH values have
harmful effects to aquatic life. The simple way is using pH meter instrument to
measure pH indicator and detail process is included in the appendix 02 of the report.
3.4.3. DO (Dissolved Oxygen)
Dissolved oxygen refers to the level of free, non-compound oxygen present in water or
other liquids. It is an important parameter in assessing water/wastewater quality
because of its influence on the organisms living within a body of water. Dissolved
oxygen is necessary to many forms of life including fish, invertebrates, bacteria and
plants. These organisms use oxygen in respiration, similar to organisms on land.
Microbes such as bacteria and fungi also require dissolved oxygen. These organisms
use DO to decompose organic material at the bottom of a body of water. Microbial
decomposition is an important contributor to nutrient recycling. So if DO
concentration is not large enough, the nutrient cycling can be stop and has negative
impacts to other organisms. Or if DO concentration is too large, the micro16