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ENVIRONMENTAL ENGINEERING LAB(BKC3771)
2011/2012 Semester I
Title of Experiment: Determination of Chemical Oxygen Demand (COD) In Water and Wastewater
Date of Experiment : 20 OCTOBER 2011
Instructors Name : SAID NURDIN
NORFADHILAH BINTI HAMZAH
Group of Member :Name ID
1. WAN MUHAMMAD SYAHMI BIN WAN MUHAMMAD KA08119
2. AHMAD FIRDAUS BIN MOHD KA08050
3. HAITHAM MOHAMMED ALI AL-ABEE KC09064
4. NOR RASHIDAH BINTI AHMED KA08129
5. RENU A/P SEKARAN KC09041
Group No. : 04
Group : K01
Marks :
Part A 55
Part B 45
TOTAL 100
Tear here
FACULTY OFCHEMICAL AND NATURAL RESOURCES ENGINEERING
UNIVERSITI MALAYSIA PAHANG
Please keep for student reference.
Received by;
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Submitted by;
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Subject Code :
Title of Experiment: Date Submitted :
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REPORT EVALUATION FOR PART A
Instruction:Please assess each item using the given scales. Fractional marks will be given for each category.
Item AssessedUnacceptable
(1)
Acceptable
(2)
Good
(3)
Very Good
(4)
Excellent
(5)Score
Organization and
Format
Not follow FKKSA
laboratory report
format. Not well
organized. Contents
show lack of
knowledge.
Partially follow
FKKSA laboratory
report format.
Contents show
enough of knowledge
but still a few concept
and ideas are loosely
connected.
Follow FKKSA
laboratory report
format of writing; all
needed sections
present. Well
organized. Contents
show enough
knowledge of
subject.
Follow FKKSA
laboratory format of
writing; all needed
sections present.
Well organized and
easily followed.
Contents show full
knowledge of
subject.
Follow FKKSA
laboratory report
format of writing; all
needed sections
present. Tables and
figures are correctly
drawn and numbered.
Excellent organized
and easily followed.
Contents show full
excellent knowledge
of subject.
Keywords: Front page, Content, Page No., Total page >8, Arrangement
Abstract Several major Abstract misses one Abstract contains Abstract contains all Abstract contains
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(2)
Good
(3)
Very Good
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(5)Score
aspects of
laboratory report
are missing.
Incomplete
description of
experiment.
Student displays a
lack of
understanding
about how to write
an abstract.
or more major aspects
of laboratory report.
most major aspects
of laboratory report.
Abstract may be too
technical and only
understood by
specialist in the
discipline.
major aspects of
laboratory report i.e.
main purpose of the
experiment, its
importance,
methodology/
approach, most
significant results or
findings, main
conclusions and/or
recommendation.
references to all major
aspects of laboratory
report i.e. main
purpose of the
experiment, its
importance,
methodology/
approach, most
significant results or
findings, main
conclusions and/or
recommendation.
General audience
easily understands
abstract.
Keywords: Introduction, Objective, Method, Result, Conclusion, Suggestion, 1 page
Introduction Very little
background
Some introductory
information, but still
Introduction is
nearly complete,
Introduction is
complete and well
Introduction is
complete and well
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information or
information is
incorrect OR, does
not give any
information about
what to expect in
the laboratory
report
missing some major
points. OR, gives
little information
missing some minor
points.
written but theory
may not be backed
up to concise lead-in
to the laboratory
experiment.
written; provides all
necessary background
principles and theory
for the experiment.
Present a concise
lead-in to the
laboratory
experiment.
Keywords: Related Theory, Principles, Process Background
Literature
Review
Poor understanding
of topic
experiment,
inadequate
information or very
little information
Acceptable
understanding of
topic, adequate
information evident,
sources cited.
Insufficient literature
Good understanding
of topic, adequate
information evident,
sources cited.
Sufficient literature
review.
Good understanding
of topic, adequate
information evident,
sources cited.
Sufficient and
relevant literature
Complete
understanding of
topic, topic
extensively well-
informed and variety
of sources are cited.
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Item AssessedUnacceptable
(1)
Acceptable
(2)
Good
(3)
Very Good
(4)
Excellent
(5)Score
regarding
experiment topic.
No external
literature review.
review or may contain
unrelated materials.
review. Literature review
contains information
relevant and directly
related to experiment
topic.
Keywords: Experiment Topic Information
Experiment
Objective
No objective or
objective missing
the important
points.
Objective is partially
defined.
Objective is relevant
but not elaborated.
Objective is clear,
relevant and
elaborated but
missing some point
on relevant
explanation.
Objective is precise,
clear, relevant and
well elaborated with
relevant explanation.
Keywords: Objective Elaboration
Methodology Missing several
important
Materials and
methodology nearly
Materials and
methodology are
Materials and
methodology are
Materials and
methodology are
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(1)
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(2)
Good
(3)
Very Good
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(5)Score
explanations of
materials and/or
methodology. Not
sequential. Most
steps are missing or
are confusing.
Some procedural
components
generally described
but are not
replicable.
complete but still
missing some
important
experimental details.
Others may have
difficulties following
procedures; some
steps are
understandable; but
most are confusing
and lack detail. Can
replicate experiment
if reader makes some
inferences.
explained with
sufficient detail;
some lack detail or
are confusing.
Mostly easy to
follow. Description
of procedure makes
it likely that the
work can be reliably
replicated.
complete. Mostly
easy to follow.
Description of
procedure can be
replicated.
complete and
adequately detailed.
Logical and easily
followed. Description
of procedure is
complete, ensuring
that it can be
replicated.
Keywords: Experiment Procedure, List of Equipment
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Good
(3)
Very Good
(4)
Excellent
(5)Score
Conclusions and
recommendations
No conclusions or
conclusion missing
the important
points. No
recommendation
given to improve
the experiment.
Conclusions
regarding major
points are drawn, but
many are misstated,
indicating a lack of
understanding.
Conclusion is too
general. Several
recommendations
have been given but
they are too general
and not contributing
to the experiments
improvement.
All the important
conclusions are
drawn could be
better stated.
Conclusion is
related to general
interest. Several
recommendations
have been stated and
they are partially
contributed to the
experiments
improvement.
All the important
conclusions have
been made.
Conclusion is
precisely stated.
Conclusion and
recommendation
relates the study to
general interest and
other studies that
have been
conducted.
All the important
conclusions have been
clearly made.
Conclusion is
precisely stated and
relates the study to
general interest, other
studies that have been
conducted.
Recommendations
given are significantly
contribute to the
experiments
improvement.
Keywords: Experiment Summary, Recommendation
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Item AssessedUnacceptable
(1)
Acceptable
(2)
Good
(3)
Very Good
(4)
Excellent
(5)Score
References Some citations in
text are not
available in list of
reference.
A few citations in text
are not available in
list of reference.
All citations in text
are available in list
of reference but list
of reference is less
than 3.
All citations in text
are available in list
of reference and list
of reference is more
than 3.
All citations in text
are available in list of
reference. List of
reference is more than
3 and variety source.
Keywords: Book Reference, Journal Reference, Website Reference
Appendices Appendices notavailable in
laboratory report.
Only a fewappendices available
in laboratory report.
Appendicesavailable in
laboratory report but
poorly constructed
Appendicesavailable in
laboratory report in
structured manners
Appendices availablein laboratory report in
structured manners,
clearly and precise
Keywords: List of Formulas, Tables, Figures, Calculation
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Item AssessedUnacceptable
(1)
Acceptable
(2)
Good
(3)
Very Good
(4)
Excellent
(5)Score
Grammar and
Spelling
Numerous spelling
and/or grammar
errors. Transitions
confusing and
unclear.
Still many spelling
and/or grammar
errors. Few or weak
transitions, often
wanders and jumps
around.
Occasional
grammar/spelling
errors. May have a
few unclear
transitions.
Occasional
grammar/spelling
mistakes. Spell
checked and proofed
throughout. Good
sentence and
paragraph structure
and transitions.
Minimal to no
spelling mistakes.
Spell checked and
proofed throughout.
Good sentence and
paragraph structure
and transitions.
Keywords: Language
Timeliness Laboratory report
handed in more
than one week late
Up to one week late Up to three days
late
Handed in one day
late
Laboratory report
handed in on time
Keywords: Punctuality
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Item AssessedUnacceptable
(1)
Acceptable
(2)
Good
(3)
Very Good
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(5)Score
Total Assessment Marks (55%)
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ABSTRACT
The wastewater is created when the water is spent or used with dissolved or suspended
solids as well as the water that discharged from communities, homes, industrial, homes,
commercial establishments, and farms. There are a lot of contaminants in the wastewater such
as heavy metal, dissolved solid as well as organic matter. The goal of this experiment is to
determine amount of chemical oxygen demand (COD) of organic pollutants in the water and
wastewater. There are 5 types of solution is used in this experiment which are river, distilled
water that act as a blank, industrial and diluted industrial, domestic and lastly diluted domestic
solution. The diluted solution is form when 2.5mL of domestic and industrial solution were
add with distilled water into 250mL volumetric flask respectively. 2mL of each solution is put
into a vial and hold it 45-degree angle. After that,it was rinsed with distilled water and wipe
with clean paper tower before put into COD reactor. All the samples were put into COD
reactor for 2 hours at temperature of 1500C. After 2 hours, samples were cooling down to
1200C and put out to cool in room temperature. Lastly, after all the samples were cooled, it
was put into spectrophotometer to detect the amount of COD of each samples. Based on the
result, the COD for river water, industrial wastewater and domestic wastewater were (20, 12,
and 35) mg/L. The domestic wastewater contained the most COD level while the industrial
wastewater contained the lowest. As a conclusion, the result that get from the experiment
were complied with the Environment Quality Act 1974 Standard A or B, Sewage & Industrial
Effluent as the result were below both of the standard (A & B).
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TABLE OF CONTENTS
CHAPTER TITLE PAGE
ABSTRACT i
1 INTRODUCTION 1
2 LITERATURE REVIEW
2.1 Literature review 2
2.2 Overview 2
2.3 Method to use 3
2.4 Errors 4
3 METHODOLOGY
3.1 Materials and methodology 6
3.2 The experiment procedure 7
4 RESULT & DISCUSSION
4.1 Result 8
4.2 Discussion 8
5 CONCLUSION & RECOMMENDATION
5.1 Conclusion 12
5.2 Recommendation 12
REFERENCES 13
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CHAPTER 1
INTRODUCTION
Chemical Oxygen Demand (COD) is defined as the quantity of a specified oxidant
that reacts with a sample under controlled conditions. It is used as a measure of oxygen
requirement of a sample that is susceptible to oxidation by strong chemical oxidant. The
quantity of oxidant consumed is expressed in terms of its oxygen equivalence. COD is
expressed in mg/L 02. The chemical oxygen demand test procedure is based on the
chemicaldecomposition oforganic andinorganic contaminants, dissolved or suspended in
water. Theresult of a chemical oxygen demandtest indicates the amount of water-dissolved
consumed by the contaminants. . The dichromate reflux method is preferred over procedures
using other oxidants (e.g. potassium permanganate) because of its superior oxidizing ability,
applicability to a wide variety of samples and ease of manipulation. Because COD measures
the oxygen demand of organic compounds in a sample of water, it is important that no outside
organic material be accidentally added to the sample to be measured. To control for this, a so-
called blank sample is required in the determination of COD.
The mg/L COD results are defined as the mg of O2 consumed per liter of sample
under conditions of this procedure. In this procedure, the sample is heated for two hours with
a strong oxidizing agent, potassium dichromate. Oxidizable organic compounds react,reducing the dichromate ion (Cr2O72-) to green chromic ion (Cr3+). When the 3-150 mg/L
colorimetric or titrimetric method is used, the amount of Cr6+ remaining is determined. When
the 20-1,500 mg/L or 200-15,000 mg/L colorimetric method is used, the amount of Cr3+
produced is determined. The COD reagent also contains silver and mercury ions. Silver is a
catalyst, and mercury is used to complex chloride interferences.
http://www.businessdictionary.com/definition/decomposition.htmlhttp://www.businessdictionary.com/definition/organic.htmlhttp://www.businessdictionary.com/definition/inorganic.htmlhttp://www.businessdictionary.com/definition/contaminant.htmlhttp://www.businessdictionary.com/definition/result.htmlhttp://www.businessdictionary.com/definition/test.htmlhttp://www.businessdictionary.com/definition/test.htmlhttp://www.businessdictionary.com/definition/result.htmlhttp://www.businessdictionary.com/definition/contaminant.htmlhttp://www.businessdictionary.com/definition/inorganic.htmlhttp://www.businessdictionary.com/definition/organic.htmlhttp://www.businessdictionary.com/definition/decomposition.html -
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CHAPTER 2
LITERATURE REVIEW
2.1 Literature review
Chemical oxygen demand (COD) is used as a measure of oxygen requirement of a
sample that is susceptible to oxidation by strong chemical oxidant. The dichromate reflux
method is preferred over procedures using other oxidants (e.g. potassium permanganate)
because of its superior oxidizing ability, applicability to a wide variety of samples and ease of
manipulation. Oxidation of most organic compounds is 95-100% of the theoretical value.
2.1 Overview
For many years, the strong oxidizing agent potassium permanganate (KMnO4) was
used for measuring chemical oxygen demand. Measurements were called oxygen consumed
from permanganate, rather than the oxygen demand of organic substances. Potassiumpermanganate's effectiveness at oxidizing organic compounds varied widely, and in many
cases biochemical oxygen demand (BOD) measurements were often much greater than results
from COD measurements. This indicated that potassium permanganate was not able to
effectively oxidize all organic compounds in water, rendering it a relatively poor oxidizing
agent for determining COD.
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Since then, other oxidizing agents such as ceric sulphate, potassium iodate, and potassium
dichromate have been used to determine COD. Of these, potassium dichromate (K2Cr2O7)
has been shown to be the most effective: it is relatively cheap, easy to purify, and is able to
nearly completely oxidize almost all organic compounds. In these methods, a fixed volume
with a known excess amount of the oxidant is added to a sample of the solution being
analyzed. After a refluxing digestion step, the initial concentration of organic substances in
the sample is calculated from a titrimetric or spectrophotometric determination of the oxidant
still remaining in the sample.
2.2 Methods to use
According to J.Stone, Chemical Oxygen Demand (COD) is a quick, inexpensive
means to determine organics in water. COD samples are prepared with a closed-reflux
digestion followed by analysis. Determinations can be made titrimetrically by several
approved methods, or photo metrically (colorimetric ally) with EPA Method 410.4, Hach
Method 8000 and Standard Method 5520D. The COD chemistry reviewed here applies to
colorimetric methods. The first step is digestion. Concentrated sulfuric acid (H2SO4)
provides the primary digestion catalyst. The secondary catalyst, Silver Sulphate (AgSO4),
assists oxidization of straight-chain hydrocarbons such diesel fuel and motor oil. Heat from
the digestion block (150 C) also acts as a catalyst. During digestion the samples organic
carbon (C) material is oxidized with the hexavalent dichromate ion (Cr2O72-) found in
potassium dichromate (K2Cr2O7). The dichromate readily gives up oxygen (O2) to bond
with carbon atoms to create carbon dioxide (CO2). The oxygen transaction from Cr2O72-to
CO2 reduces the hexavalent Cr2O72- ion to the trivalent Cr3+ ion. In essence a COD test
determines the amount of carbon based materials by measuring the amount of oxygen the
sample will react with. This oxygen transaction is the source of the tests name, Chemical
Oxygen Demand.
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2.3 Errors
According to T.Lofuts, COD has two common error sources. First, the oxidation step
does not distinguish between organic and inorganic carbons. Where carbons are available,
oxidation will create Cr3+ ions. Its the organic carbon fraction of the sample thats sought
after, and its the organics that found the correlation basis for Biochemical Oxygen Demand
(BOD) and Total Organic Carbon (TOC). Unfortunately unknown oxidizable inorganic
introduce positive error, and skew any attempt to directly substitute COD results for BOD or
TOC. The more common interfering however is chloride (Cl).
The mass of any object is simply the volume that the object occupies times the density of the
object. For a fluid (a liquid or a gas) the density, volume, and shape of the object can all
change within the domain with time. And mass can move through the domain. On the figure,
we show a flow of gas through a constricted tube. There is no accumulation or destruction of
mass through the tube; the same amount of mass leaves the tube as enters the tube. At any
plane perpendicular to the center line of the tube, the same amount of mass passes through.
We call the amount of mass passing through a plane the mass flow rate.
Mass flow is the movement of a quantity of material through a conveyance per
quantity of time. SI units of measure for this parameter are kg/sec. Conversions of kg/sec to a
variety of other mass flow units are possible, such as g/s and mole/s. Other very common
mass flow units used in gas flow measurement are the volumetrically based type such as
sccm, slm, scfm, etc. Volumetrically based mass flow units should not be confused with
volume or actual flow units. Volumetrically based mass flow units define mass in terms of the
quantity of gas that occupies a volume understandard conditions of pressure and temperature.
When a gas flow system is in steady state, mass flow is the same at all locations in the
system and it is independent of the gas pressure and temperature conditions. Therefore, the
measurement of mass flow made by the molbloc/molbox system represents the mass flow at
all other points at the same time in a flow system that is in steady state. This characteristic
represents the strong value of mass flow measurement over volumetric flow measurement in a
gas flow system.
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Flow devices that are fundamentally based on the measurement of mass, or have the internal
capability to measure gas conditions and calculate mass flow from volume, can be directly
compared to the molbloc/molbox system in mass flow units.
In a gas flow system under steady state conditions, volume flow is likely to be
different throughout the system and it is highly dependent upon the gas pressure and
temperature at the point where it is measured. This means that the volume flow will not be the
same at all points within a system due to changes in pressure and temperature that naturally
occur as the gas moves through the restrictions caused by plumbing, valves, regulators, filters,
etc., even though the mass flow rate is the same.
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CHAPTER 3
METHODOLOGY
3.1 Materials and methodology
There are some material and equipment that been use in this experiment which is
a) COD Digestion Reactorb) Spectrophotometer, HACH DR/2400 @ DR/2800c) COD Digestion Reagent Vial LR @ HRd) COD racke) Volumetric pipette, 2 mLf) Paper towel/Tissue
3.2 The experiment procedure
The COD Reactor is turned on and preheated to 150C. The safety shield is placed in front of
the reactor.
The caps from two COD Digestion Reagent Vials are removed. The vial for the appropriaterange is chosen.
One vial is held at a 45-degree angle. A clean volumetric pipette is used to add 2.00 mL of
sample to the vial. This is the prepared sample.
A second vial is held at a 45-degree angle. A clean volumetric pipette is used to add 2.00 mL
de-ionized water to the vial. This is the blank.
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Figure 3.1.1: Flow work of methodology
The vials are held by the cap over a sink. They are inverted gently several times to mix them.
The vials are then placed in the preheated COD Reactor.
The vials are heated for two hours. The reactor is then turned off. About 20 minutes is let for
the vials to cool to 120C or less.
Each vial is inverted several times while still warm. The vials are then placed into a rack and
cooled to room temperature.
Touch Hach Programs. Program 430 COD LR(Low Range) is chosen. Touch Start.
The outside of the vials is cleaned with a damp towel followed by a dry one to remove
fingerprints or other marks. The 16-mm adapter is installed and the blank is placed into the
ada ter.
Touch Zero. The display will show: 0 mg/L COD. When the timer beeps, the sample vial is
placed into the adapter. Touch Read. Results will appear in mg/L COD.
The vials are capped tightly. They are rinsed with de-ionized water and wiped with a clean
paper towel.
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CHAPTER 4
RESULTS & DISCUSSION
4.1 Results
Types of Samples COD (mg/L)
River 20
Industrial 12
Domestic 35
Table 4.1: COD Data for Different Types of Sample Sources
4.2 Discussion
In order to reduce the concentration of the industrial and domestic samples, these
samples were diluted with the distilled water, where 2.5 mL of industrial and domestic
samples were diluted into 250 mL volumetric flask. Table 5.1 shows the chemical oxygen
demand (COD) for particular sample which are river, industrial wastewater, and domestic
wastewater. COD is a standard method for indirect measurement of the amount of pollution
that cannot be oxidized biologically in a sample of water. The COD test is used to determine
the oxygen needs by the sample effluences that go through oxidation to degrade the organic
pollutant. In other word, the higher the value of COD, the water is more polluted.
Based on the table, domestic wastewater contained the highest COD level with 35
mg/L while industrial wastewater contained the lowest COD level with only 12 mg/L. TheCOD level for domestic wastewater was the highest because there is no wastewater treatment
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facilities exist for domestic wastewater treatment compared to industrial wastewater
treatment. The difference of COD values found in the different sources of sample is because a
sample of waste water containing organic material is placed in contact with a very strong
inorganic oxidant, a mixture of dichromate and sulphuric acid with silver sulphate as a
catalyst. The temperature is increased to the point of ebullition of the mixture, resulting in an
increase of the oxidation rate. The different of oxygen requirement that is inclined to
oxidation by strong chemical oxidant.
The importance of COD test was to measured the pollution potential of organic matter
in particular wastewater. Besides, it can also be used to determine the decomposable organic
matter results in consumption of dissolved oxygen (DO) in the receiving streams. Based on
Environment Quality Act 1974 Standard A or B, Sewage & Industrial Effluent it state that for
COD standard A and standard B is 50mg/l and 100mg/l which mean that the solution cannot
exceed this limit. The result show that for industrial waste is 12mg/l, river waste is 20mg/l
and domestic 35mg/l. The value of COD for this wastewater is in a standard A which mean it
follow the standard that be state by Environment Quality Act 1974. The wastewater from
river, domestic and industrial do not need further treatment because the level of COD in the
solution is below the standard and the solution is not dangerous to human and environment.
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Table 4.2:Environment Quality Act 1974 Standard A or B, Sewage & Industrial Effluent.
The basis for the COD test is that nearly all organic compounds can be fully oxidized to
carbon dioxide with a strong oxidizing agent under acidic conditions. The amount of oxygen
required oxidizing an organic compound to carbon dioxide, ammonia, and water is given by:
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This expression does not include the oxygen demand caused by the oxidation of ammonia
into nitrate. The process of ammonia being converted into nitrate is referred to as nitrification.
The following is the correct equation for the oxidation of ammonia into nitrate.
It is applied after the oxidation due to nitrification if the oxygen demand from nitrification
must be known. Dichromate does not oxidize ammonia into nitrate, so this nitrification can be
safely ignored in the standard chemical oxygen demand test. Once a sample is taken, the
constituents of the sample should be maintained in the same condition as when collected.
When it is not possible to analyze collected samples immediately, samples should be
preserved properly. Biological activity such as microbial respiration, chemical activity such as
precipitation or pH change, and physical activity such as aeration or high temperature must be
kept to a minimum. There are two ways in which a sample can be preserved for a longer time
before being analyzed by doing COD test. Firstly, preservation of the sample can be
accomplished by adding sulphuric acid to depress the pH to 2 and the holding time with
preservation is 7 days. Secondly, preservation of the sample also can be achieved by cooling
the sample at around 4 C. However, freezing the sample is not usually recommended.
COD can be reduced by using chemical treatment. Two processes, known as flocculation
and coagulation, usually used to reduce the COD in the wastewater. In flocculation, small
particles with non-rigid surfaces are made to agglomerate by mixing the water (and thus
bringing the particles into contact with one another so that the surfaces can become stuck
together). When the agglomeration of the particles gets large enough, the aggregate can settle
in still water by sedimentation. Other suspended particles do not agglomerate well by
flocculation. To remove these particles from the water, coagulation must be used. Coagulation
is the process of gathering particles into a cluster or clot, often achieved by the addition of
special chemicals known as coagulants. The coagulant used is aluminium sulphate (alum,
Al2(SO4)3).
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CHAPTER 5
CONCLUSION & RECOMMENDATION
5.1 Conclusion
As a conclusion, the chemical oxygen demand in the particular river water, industrial
wastewater and domestic wastewater were (20, 12, and 35) mg/L. As the result were to
comply with the standard ruled on Environment Quality Act 1974, the result came back below
the standard ruled on Environment Quality Act 1974. Thus, it can be concluded that the water
and wastewater sample was safe for the environment and do not have to treat further.
5.2 Recommendation
In order to make this experiment more better, some recommendation can take into
action which is do not touch vial with hand because the hand contain a finger print and this
can effect UV light when analyze the sample. Another rrecommendation for this experiment,for every sample from domestic water and industrial water, it need to be dilute into 1:10000 to
make sure the data retrieve is in range. The data is recommended to take to authority to have
further investigation.
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REFERENCE
DOBBS, R.A. & R.T. WILLIAMS. 1963. Elimination of chloride interference in the chemical
oxygen demand test.Anal. Chem. 35:1064.
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