SlideShare a Scribd company logo
1 of 6
Download to read offline
1
WATER ANALYSIS: BIOLOGICAL
OXYGEN DEMAND
Introduction
Water is a vital natural resource which is essential for
multiplicity of purposes which include drinking, agriculture,
power generation, transportation and waste disposal. Thus it is
important to analyse water physically, chemically and
biologically.
Biological Oxygen Demand or Biochemical Oxygen Demand
or BOD is an important biological parameter for water
analysis. BOD represents the quantity of oxygen required by
bacteria and other microorganisms during the biochemical
degradation and transformation of organic matter present in
water under aerobic conditions.
In simple words, it is the degree of microbial mediated
oxygen consumption in water.
Oxygen Demanding Waste
Pollution due to organic matter such as sewage, industrial
effluents, wastes from food processing plants, paper mills and
tanneries, run off from agricultural lands, etc. undergo
degradation by bacterial activity in the presence of Dissolved
Oxygen (DO). The net result being deoxygenation process and
quick depletion of DO.
In the process of BOD, carbonaceous matter is degraded by
bacterial oxidation. But when nitrogenous material is present,
nitrifying bacteria exert an additional O2 demand.
2
During carbonaceous stage, NH3 is produced by breakdown of
organic nitrogenous materials. Further this is oxidized to
nitrite and finally to nitrate by nitrifying bacteria.
2 NH4
+
+ 3 O2 → 2 NO2
-
+ 2 H2O + 4 H+
2 NO-
+ O2 → 2 NO3
-
Estimation of BOD
BOD in water sample is determined by measuring the O2
concentration in the water sample before and after incubation
in the dark at 20° C for 5 days using Winkler’s method.
The method used for estimation of BOD consists of 2 steps:-
1. Preliminary dilution and aeration of sample – This step is
necessary so that all the O2 present in water is not
consumed during incubation, which may lead to error in
result.
To prepare dilution water, aerate the BOD free distilled
water in a glass container for 30 minutes. Then add 1
mL of phosphate buffer solution, 1 mL of magnesium
sulphate (MgSO4) solution, 1 mL of calcium chloride
(CaCl2) solution and 1 mL of ferric chloride (FeCl3)
solution to 1 L of this aerated water.
Now the pH is adjusted to 7 using sulphuric acid
(H2SO4) or sodium hydroxide (NaOH) solution as per
the requirement.
Now dilute the sample by adding this dilution water
according to the expected content of BOD in the
sample.
3
Expected BOD
content (ppm)
Volume of
sample (mL/L)
Dilution Factor
0 – 6 1000 1
4 – 12 500 2
10 – 30 200 5
20 – 60 100 10
40 – 120 50 20
100 – 300 20 50
200 – 600 10 100
400 – 1200 5 200
1000 – 3000 2 500
2000 – 6000 1 1000
> 6000 0.5 2000
2. Determination of BOD – Fill this diluted sample in two
BOD bottles carefully without allowing any air bubble
and add 1 mL of allylthiourea.
i) Now determine the DO in one bottle by modified
Winkler’s method :
The basic principle involved in this method is to
oxidize KI to I2 with the dissolved oxygen present in
the water sample after adding MnSO4, NaOH and KI.
The basic manganeic oxide formed from NaOH and
MnSO4 act as an oxygen carrier to enable the DO in
the molecular form to take part in the reaction. The
DO present in the sample oxidizes Mn2+
to its higher
valency state. This precipitates as a brown hydrated
oxide after addition of NaOH and KI.
MnSO4 + NaOH → Mn (OH)2 + Na2SO4
2 Mn (OH)2 + O2 → 2MnO(OH)2
(Basic manganeic oxide)
4
On acidification, the Mn revert back to the divalent
state and equivalent amount of I2 is liberated from KI
present.
MnO(OH)2 + H2SO4 → MnSO4 + 2H2O + O
2 KI + H2SO4 + O → K2SO4 + H2O + I2
This liberated I2 is titrated against standard sodium
thiosulphate (Na2S2O3) solution iodometrically using
starch as indicator.
I2 + 2Na2S2O3 → Na2S4O6 + 2NaI
Method: Open the BOD bottle and put 1 mL of MnSO4
solution and 1 mL of alkaline iodide azide solution (in
place of alkaline KI solution in order to remove
interferences). A brown precipitate of basic manganeic
oxide is formed due to O2 present in the water. Now
place the stopper and shake the bottle thoroughly. Now
add 2 mL of H2SO4 and shake. The precipitate will
dissolve. Transfer the contents to conical flask and
titrate against standard Na2S2O3 solution using starch
as indicator. The blue colour is discharged at the end
point. This is D0.
DO (mg L ) =
N × V × 8
Volume of water sample taken
× 1000
N is the normality of standard Na2S2O3 used,
V is the volume of standard Na2S2O3 used,
8 is the equivalent weight of oxygen.
ii) The other BOD bottle is kept in BOD incubator at 20°
C for 5 days. The DO content of this water is then
estimated immediately after taking out the bottle using
modified Winkler’s method. This is D5.
5
DO (mg L ) =
N × V × 8
Volume of water sample taken
× 1000
N is the normality of standard Na2S2O3 used,
V is the volume of standard Na2S2O3 used,
8 is the equivalent weight of oxygen.
Calculations:
The BOD of sample is determined by the formula
BOD5 (mg L-1
) = (D0 – D5) × Dilution factor
Importance of BOD
 The demand of oxygen by microbes in water is directly
proportional to the amount of organic matter which has to
be broken down. Thus, BOD is a direct measure of O2
requirements and an indirect measure of biodegradable
organic matter.
 BOD is used as an index of organic pollution in water and
so an important parameter for analysis of water quality.
 Drinking water usually has BOD < 1 mg L-1
and water is
considered fairly pure with the BOD of 3 mg L-1
. But when
BOD value reaches 5 mg L-1
, the water is of doubtful
purity.
 BOD test is generally performed to determine:-
a) Degree of pollution in lakes and streams at any given
time.
b) Pollution load of waste water on the environment.
c) Efficiency of waste treatment plant.
6
References:-
1. Environmental Chemistry; De, A.K.
2. Textbook of Engineering Chemistry; Dara, S.S.
3. Standard Method of Chemical Analysis Vol I & II, Hulcher
4. Environmental Chemistry; Kaur, H.
THANKS

More Related Content

What's hot

Biochemical oxygen demand (BOD) AND Chemical Oxygen Demand PDF
Biochemical oxygen demand (BOD) AND Chemical Oxygen Demand PDFBiochemical oxygen demand (BOD) AND Chemical Oxygen Demand PDF
Biochemical oxygen demand (BOD) AND Chemical Oxygen Demand PDFchetansingh999
 
Dissolved oxygen and its method of determination
Dissolved oxygen and its method of determinationDissolved oxygen and its method of determination
Dissolved oxygen and its method of determinationRohit Shrikhande
 
Biological Oxygen Demand
Biological Oxygen DemandBiological Oxygen Demand
Biological Oxygen Demandsharonmak
 
Chemical oxygen demand
Chemical oxygen demandChemical oxygen demand
Chemical oxygen demandUsman Khawaja
 
sorption and desorption phenomenon in soil
sorption and desorption phenomenon in soil sorption and desorption phenomenon in soil
sorption and desorption phenomenon in soil PujaPriyadarsiniNaik
 
Biochemical oxygen demand(bod)
Biochemical oxygen demand(bod)Biochemical oxygen demand(bod)
Biochemical oxygen demand(bod)Masud Alam Ansari
 
WATER ANALYSIS /Water quality testing p.k.k
WATER ANALYSIS /Water quality testing p.k.kWATER ANALYSIS /Water quality testing p.k.k
WATER ANALYSIS /Water quality testing p.k.kPUSHPA KHOLA
 
Do measurement
Do measurementDo measurement
Do measurementVj NiroSh
 
BOD Analysis as per APHA Manual
BOD Analysis as per APHA ManualBOD Analysis as per APHA Manual
BOD Analysis as per APHA ManualGayathri Mohan
 
Ammonical nitrogen- a threat to environment & its solution
Ammonical nitrogen- a threat to environment  & its solutionAmmonical nitrogen- a threat to environment  & its solution
Ammonical nitrogen- a threat to environment & its solutionTipanna Mariyappa
 
Determination of calcium in milk
Determination of calcium in milkDetermination of calcium in milk
Determination of calcium in milkamal shaukat
 
Bod cod do waste water treartment
Bod cod do waste water treartmentBod cod do waste water treartment
Bod cod do waste water treartmentDivya Goel
 

What's hot (20)

Biochemical oxygen demand (BOD) AND Chemical Oxygen Demand PDF
Biochemical oxygen demand (BOD) AND Chemical Oxygen Demand PDFBiochemical oxygen demand (BOD) AND Chemical Oxygen Demand PDF
Biochemical oxygen demand (BOD) AND Chemical Oxygen Demand PDF
 
Acidity in Water
Acidity in WaterAcidity in Water
Acidity in Water
 
Dissolved oxygen and its method of determination
Dissolved oxygen and its method of determinationDissolved oxygen and its method of determination
Dissolved oxygen and its method of determination
 
Chemical oxygen demand
Chemical oxygen demandChemical oxygen demand
Chemical oxygen demand
 
Dissolved Oxygen [DO]
Dissolved Oxygen [DO]Dissolved Oxygen [DO]
Dissolved Oxygen [DO]
 
Biological Oxygen Demand
Biological Oxygen DemandBiological Oxygen Demand
Biological Oxygen Demand
 
Do,cod,bod
Do,cod,bodDo,cod,bod
Do,cod,bod
 
Exp 4
Exp  4Exp  4
Exp 4
 
Chemical oxygen demand
Chemical oxygen demandChemical oxygen demand
Chemical oxygen demand
 
sorption and desorption phenomenon in soil
sorption and desorption phenomenon in soil sorption and desorption phenomenon in soil
sorption and desorption phenomenon in soil
 
Biochemical oxygen demand(bod)
Biochemical oxygen demand(bod)Biochemical oxygen demand(bod)
Biochemical oxygen demand(bod)
 
WATER ANALYSIS /Water quality testing p.k.k
WATER ANALYSIS /Water quality testing p.k.kWATER ANALYSIS /Water quality testing p.k.k
WATER ANALYSIS /Water quality testing p.k.k
 
Do measurement
Do measurementDo measurement
Do measurement
 
Determination of carbonates and bicarbonates in water sample
Determination of carbonates and bicarbonates in water sampleDetermination of carbonates and bicarbonates in water sample
Determination of carbonates and bicarbonates in water sample
 
Practical on BOD
Practical on BOD Practical on BOD
Practical on BOD
 
BOD Analysis as per APHA Manual
BOD Analysis as per APHA ManualBOD Analysis as per APHA Manual
BOD Analysis as per APHA Manual
 
Bod types
Bod typesBod types
Bod types
 
Ammonical nitrogen- a threat to environment & its solution
Ammonical nitrogen- a threat to environment  & its solutionAmmonical nitrogen- a threat to environment  & its solution
Ammonical nitrogen- a threat to environment & its solution
 
Determination of calcium in milk
Determination of calcium in milkDetermination of calcium in milk
Determination of calcium in milk
 
Bod cod do waste water treartment
Bod cod do waste water treartmentBod cod do waste water treartment
Bod cod do waste water treartment
 

Similar to B.O.D.

Determination of dissolved oxygen.pdf
Determination of dissolved oxygen.pdfDetermination of dissolved oxygen.pdf
Determination of dissolved oxygen.pdfMausumi Adhya
 
DO determination in laboratory.pdf
DO determination in laboratory.pdfDO determination in laboratory.pdf
DO determination in laboratory.pdfmadhugupta761139
 
Biochemical Oxygen Demand and its Industrial Significance
Biochemical Oxygen Demand and its Industrial SignificanceBiochemical Oxygen Demand and its Industrial Significance
Biochemical Oxygen Demand and its Industrial SignificanceAdnan Murad Bhayo
 
Biological Oxygen Demand Process and Explanation.pptx
Biological Oxygen Demand Process and Explanation.pptxBiological Oxygen Demand Process and Explanation.pptx
Biological Oxygen Demand Process and Explanation.pptxLloydBryneCervantesL
 
Determinacion dbo informe
Determinacion dbo informeDeterminacion dbo informe
Determinacion dbo informeTCondeJoel
 
Wastewater Parameter Determination
Wastewater Parameter DeterminationWastewater Parameter Determination
Wastewater Parameter DeterminationMd Shah Paran
 
Determination of dissolved oxygen (do) in a given water sample
Determination of dissolved oxygen (do) in a given water sampleDetermination of dissolved oxygen (do) in a given water sample
Determination of dissolved oxygen (do) in a given water sampleMithil Fal Desai
 
unit-1.-Itroduction-to-wastewater-treatment.pdf
unit-1.-Itroduction-to-wastewater-treatment.pdfunit-1.-Itroduction-to-wastewater-treatment.pdf
unit-1.-Itroduction-to-wastewater-treatment.pdfDODDIGARLAPREM
 
Applications of Redox Titrations - Reon Sylvester
Applications of Redox Titrations - Reon SylvesterApplications of Redox Titrations - Reon Sylvester
Applications of Redox Titrations - Reon SylvesterBebeto G
 
Environmental engg
Environmental enggEnvironmental engg
Environmental enggLove Sharma
 
Distillery Wastewater Decontamination by the Fenton Advanced Oxidation Method
Distillery Wastewater Decontamination by the Fenton Advanced Oxidation MethodDistillery Wastewater Decontamination by the Fenton Advanced Oxidation Method
Distillery Wastewater Decontamination by the Fenton Advanced Oxidation MethodIJRES Journal
 
Routine analysis of wastewaters quality parameters
Routine analysis of wastewaters quality parametersRoutine analysis of wastewaters quality parameters
Routine analysis of wastewaters quality parametersArvind Kumar
 
ESTIMATION OF DO, BOD AND COD IN CANAL WATER SAMPLE
ESTIMATION OF DO, BOD AND COD IN CANAL WATER SAMPLEESTIMATION OF DO, BOD AND COD IN CANAL WATER SAMPLE
ESTIMATION OF DO, BOD AND COD IN CANAL WATER SAMPLESadia Rahat
 

Similar to B.O.D. (20)

BOD&COD.pdf
BOD&COD.pdfBOD&COD.pdf
BOD&COD.pdf
 
Determination of dissolved oxygen.pdf
Determination of dissolved oxygen.pdfDetermination of dissolved oxygen.pdf
Determination of dissolved oxygen.pdf
 
DO determination in laboratory.pdf
DO determination in laboratory.pdfDO determination in laboratory.pdf
DO determination in laboratory.pdf
 
Biochemical Oxygen Demand and its Industrial Significance
Biochemical Oxygen Demand and its Industrial SignificanceBiochemical Oxygen Demand and its Industrial Significance
Biochemical Oxygen Demand and its Industrial Significance
 
Redox bod ppt
Redox bod pptRedox bod ppt
Redox bod ppt
 
Analysis of fertilizer
Analysis of fertilizerAnalysis of fertilizer
Analysis of fertilizer
 
Biological Oxygen Demand Process and Explanation.pptx
Biological Oxygen Demand Process and Explanation.pptxBiological Oxygen Demand Process and Explanation.pptx
Biological Oxygen Demand Process and Explanation.pptx
 
Determinacion dbo informe
Determinacion dbo informeDeterminacion dbo informe
Determinacion dbo informe
 
Wastewater Parameter Determination
Wastewater Parameter DeterminationWastewater Parameter Determination
Wastewater Parameter Determination
 
Determination of dissolved oxygen (do) in a given water sample
Determination of dissolved oxygen (do) in a given water sampleDetermination of dissolved oxygen (do) in a given water sample
Determination of dissolved oxygen (do) in a given water sample
 
L 16 and 17 bod
L 16 and 17 bodL 16 and 17 bod
L 16 and 17 bod
 
Analisis air
Analisis airAnalisis air
Analisis air
 
Bod
BodBod
Bod
 
unit-1.-Itroduction-to-wastewater-treatment.pdf
unit-1.-Itroduction-to-wastewater-treatment.pdfunit-1.-Itroduction-to-wastewater-treatment.pdf
unit-1.-Itroduction-to-wastewater-treatment.pdf
 
Applications of Redox Titrations - Reon Sylvester
Applications of Redox Titrations - Reon SylvesterApplications of Redox Titrations - Reon Sylvester
Applications of Redox Titrations - Reon Sylvester
 
Environmental engg
Environmental enggEnvironmental engg
Environmental engg
 
Distillery Wastewater Decontamination by the Fenton Advanced Oxidation Method
Distillery Wastewater Decontamination by the Fenton Advanced Oxidation MethodDistillery Wastewater Decontamination by the Fenton Advanced Oxidation Method
Distillery Wastewater Decontamination by the Fenton Advanced Oxidation Method
 
Routine analysis of wastewaters quality parameters
Routine analysis of wastewaters quality parametersRoutine analysis of wastewaters quality parameters
Routine analysis of wastewaters quality parameters
 
ESTIMATION OF DO, BOD AND COD IN CANAL WATER SAMPLE
ESTIMATION OF DO, BOD AND COD IN CANAL WATER SAMPLEESTIMATION OF DO, BOD AND COD IN CANAL WATER SAMPLE
ESTIMATION OF DO, BOD AND COD IN CANAL WATER SAMPLE
 
JWARP_2015032516160270
JWARP_2015032516160270JWARP_2015032516160270
JWARP_2015032516160270
 

More from chemnidhi

Forms of corrosion
Forms of corrosionForms of corrosion
Forms of corrosionchemnidhi
 
C13 NMR spectroscopy
C13 NMR spectroscopyC13 NMR spectroscopy
C13 NMR spectroscopychemnidhi
 
Surface active agents
Surface active agentsSurface active agents
Surface active agentschemnidhi
 
Corrosion Monitoring and Prevention methods
Corrosion Monitoring and Prevention methodsCorrosion Monitoring and Prevention methods
Corrosion Monitoring and Prevention methodschemnidhi
 
Enzymes and r DNA technology
Enzymes and r DNA technologyEnzymes and r DNA technology
Enzymes and r DNA technologychemnidhi
 
Web technology
Web technologyWeb technology
Web technologychemnidhi
 
Refining and bleaching of oil
Refining and bleaching of oilRefining and bleaching of oil
Refining and bleaching of oilchemnidhi
 
Selection and sizing of homogeneous and catalytic reactors
Selection and sizing of homogeneous and catalytic reactorsSelection and sizing of homogeneous and catalytic reactors
Selection and sizing of homogeneous and catalytic reactorschemnidhi
 
Glass transition temperature
Glass transition temperatureGlass transition temperature
Glass transition temperaturechemnidhi
 
Tlc for chlorinated pesticides copy
Tlc for chlorinated pesticides   copyTlc for chlorinated pesticides   copy
Tlc for chlorinated pesticides copychemnidhi
 
Tlc for pesticide analysis copy
Tlc for pesticide analysis copyTlc for pesticide analysis copy
Tlc for pesticide analysis copychemnidhi
 
Biotransformations copy
Biotransformations copyBiotransformations copy
Biotransformations copychemnidhi
 
Biotransformation copy
Biotransformation   copyBiotransformation   copy
Biotransformation copychemnidhi
 
Ion chromatography copy
Ion chromatography copyIon chromatography copy
Ion chromatography copychemnidhi
 
Ion chromatography copy
Ion chromatography   copyIon chromatography   copy
Ion chromatography copychemnidhi
 
Conductometric titrations copy
Conductometric titrations   copyConductometric titrations   copy
Conductometric titrations copychemnidhi
 
Conductometric titrations (1)
Conductometric titrations (1)Conductometric titrations (1)
Conductometric titrations (1)chemnidhi
 

More from chemnidhi (17)

Forms of corrosion
Forms of corrosionForms of corrosion
Forms of corrosion
 
C13 NMR spectroscopy
C13 NMR spectroscopyC13 NMR spectroscopy
C13 NMR spectroscopy
 
Surface active agents
Surface active agentsSurface active agents
Surface active agents
 
Corrosion Monitoring and Prevention methods
Corrosion Monitoring and Prevention methodsCorrosion Monitoring and Prevention methods
Corrosion Monitoring and Prevention methods
 
Enzymes and r DNA technology
Enzymes and r DNA technologyEnzymes and r DNA technology
Enzymes and r DNA technology
 
Web technology
Web technologyWeb technology
Web technology
 
Refining and bleaching of oil
Refining and bleaching of oilRefining and bleaching of oil
Refining and bleaching of oil
 
Selection and sizing of homogeneous and catalytic reactors
Selection and sizing of homogeneous and catalytic reactorsSelection and sizing of homogeneous and catalytic reactors
Selection and sizing of homogeneous and catalytic reactors
 
Glass transition temperature
Glass transition temperatureGlass transition temperature
Glass transition temperature
 
Tlc for chlorinated pesticides copy
Tlc for chlorinated pesticides   copyTlc for chlorinated pesticides   copy
Tlc for chlorinated pesticides copy
 
Tlc for pesticide analysis copy
Tlc for pesticide analysis copyTlc for pesticide analysis copy
Tlc for pesticide analysis copy
 
Biotransformations copy
Biotransformations copyBiotransformations copy
Biotransformations copy
 
Biotransformation copy
Biotransformation   copyBiotransformation   copy
Biotransformation copy
 
Ion chromatography copy
Ion chromatography copyIon chromatography copy
Ion chromatography copy
 
Ion chromatography copy
Ion chromatography   copyIon chromatography   copy
Ion chromatography copy
 
Conductometric titrations copy
Conductometric titrations   copyConductometric titrations   copy
Conductometric titrations copy
 
Conductometric titrations (1)
Conductometric titrations (1)Conductometric titrations (1)
Conductometric titrations (1)
 

Recently uploaded

Jet reorientation in central galaxies of clusters and groups: insights from V...
Jet reorientation in central galaxies of clusters and groups: insights from V...Jet reorientation in central galaxies of clusters and groups: insights from V...
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
 
Molecular and Cellular Mechanism of Action of Hormones such as Growth Hormone...
Molecular and Cellular Mechanism of Action of Hormones such as Growth Hormone...Molecular and Cellular Mechanism of Action of Hormones such as Growth Hormone...
Molecular and Cellular Mechanism of Action of Hormones such as Growth Hormone...Ansari Aashif Raza Mohd Imtiyaz
 
TEST BANK for Organic Chemistry 6th Edition.pdf
TEST BANK for Organic Chemistry 6th Edition.pdfTEST BANK for Organic Chemistry 6th Edition.pdf
TEST BANK for Organic Chemistry 6th Edition.pdfmarcuskenyatta275
 
The solar dynamo begins near the surface
The solar dynamo begins near the surfaceThe solar dynamo begins near the surface
The solar dynamo begins near the surfaceSérgio Sacani
 
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
 
Microbial bio Synthesis of nanoparticles.pptx
Microbial bio Synthesis of nanoparticles.pptxMicrobial bio Synthesis of nanoparticles.pptx
Microbial bio Synthesis of nanoparticles.pptxCherry
 
The importance of continents, oceans and plate tectonics for the evolution of...
The importance of continents, oceans and plate tectonics for the evolution of...The importance of continents, oceans and plate tectonics for the evolution of...
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
 
family therapy psychotherapy types .pdf
family therapy psychotherapy types  .pdffamily therapy psychotherapy types  .pdf
family therapy psychotherapy types .pdfhaseebahmeddrama
 
Continuum emission from within the plunging region of black hole discs
Continuum emission from within the plunging region of black hole discsContinuum emission from within the plunging region of black hole discs
Continuum emission from within the plunging region of black hole discsSérgio Sacani
 
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
 
INSIGHT Partner Profile: Tampere University
INSIGHT Partner Profile: Tampere UniversityINSIGHT Partner Profile: Tampere University
INSIGHT Partner Profile: Tampere UniversitySteffi Friedrichs
 
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
 
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 Rp
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpWASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 Rp
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
 
SCHISTOSOMA HEAMATOBIUM life cycle .pdf
SCHISTOSOMA HEAMATOBIUM life cycle  .pdfSCHISTOSOMA HEAMATOBIUM life cycle  .pdf
SCHISTOSOMA HEAMATOBIUM life cycle .pdfDebdattaGhosh6
 
ERTHROPOIESIS: Dr. E. Muralinath & R. Gnana Lahari
ERTHROPOIESIS: Dr. E. Muralinath & R. Gnana LahariERTHROPOIESIS: Dr. E. Muralinath & R. Gnana Lahari
ERTHROPOIESIS: Dr. E. Muralinath & R. Gnana Laharimuralinath2
 
GBSN - Microbiology (Unit 6) Human and Microbial interaction
GBSN - Microbiology (Unit 6) Human and Microbial interactionGBSN - Microbiology (Unit 6) Human and Microbial interaction
GBSN - Microbiology (Unit 6) Human and Microbial interactionAreesha Ahmad
 
A Giant Impact Origin for the First Subduction on Earth
A Giant Impact Origin for the First Subduction on EarthA Giant Impact Origin for the First Subduction on Earth
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
 
GBSN - Microbiology Lab (Compound Microscope)
GBSN - Microbiology Lab (Compound Microscope)GBSN - Microbiology Lab (Compound Microscope)
GBSN - Microbiology Lab (Compound Microscope)Areesha Ahmad
 
In-pond Race way systems for Aquaculture (IPRS).pptx
In-pond Race way systems for Aquaculture (IPRS).pptxIn-pond Race way systems for Aquaculture (IPRS).pptx
In-pond Race way systems for Aquaculture (IPRS).pptxMAGOTI ERNEST
 
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
 

Recently uploaded (20)

Jet reorientation in central galaxies of clusters and groups: insights from V...
Jet reorientation in central galaxies of clusters and groups: insights from V...Jet reorientation in central galaxies of clusters and groups: insights from V...
Jet reorientation in central galaxies of clusters and groups: insights from V...
 
Molecular and Cellular Mechanism of Action of Hormones such as Growth Hormone...
Molecular and Cellular Mechanism of Action of Hormones such as Growth Hormone...Molecular and Cellular Mechanism of Action of Hormones such as Growth Hormone...
Molecular and Cellular Mechanism of Action of Hormones such as Growth Hormone...
 
TEST BANK for Organic Chemistry 6th Edition.pdf
TEST BANK for Organic Chemistry 6th Edition.pdfTEST BANK for Organic Chemistry 6th Edition.pdf
TEST BANK for Organic Chemistry 6th Edition.pdf
 
The solar dynamo begins near the surface
The solar dynamo begins near the surfaceThe solar dynamo begins near the surface
The solar dynamo begins near the surface
 
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...
 
Microbial bio Synthesis of nanoparticles.pptx
Microbial bio Synthesis of nanoparticles.pptxMicrobial bio Synthesis of nanoparticles.pptx
Microbial bio Synthesis of nanoparticles.pptx
 
The importance of continents, oceans and plate tectonics for the evolution of...
The importance of continents, oceans and plate tectonics for the evolution of...The importance of continents, oceans and plate tectonics for the evolution of...
The importance of continents, oceans and plate tectonics for the evolution of...
 
family therapy psychotherapy types .pdf
family therapy psychotherapy types  .pdffamily therapy psychotherapy types  .pdf
family therapy psychotherapy types .pdf
 
Continuum emission from within the plunging region of black hole discs
Continuum emission from within the plunging region of black hole discsContinuum emission from within the plunging region of black hole discs
Continuum emission from within the plunging region of black hole discs
 
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...
 
INSIGHT Partner Profile: Tampere University
INSIGHT Partner Profile: Tampere UniversityINSIGHT Partner Profile: Tampere University
INSIGHT Partner Profile: Tampere University
 
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...
 
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 Rp
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpWASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 Rp
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 Rp
 
SCHISTOSOMA HEAMATOBIUM life cycle .pdf
SCHISTOSOMA HEAMATOBIUM life cycle  .pdfSCHISTOSOMA HEAMATOBIUM life cycle  .pdf
SCHISTOSOMA HEAMATOBIUM life cycle .pdf
 
ERTHROPOIESIS: Dr. E. Muralinath & R. Gnana Lahari
ERTHROPOIESIS: Dr. E. Muralinath & R. Gnana LahariERTHROPOIESIS: Dr. E. Muralinath & R. Gnana Lahari
ERTHROPOIESIS: Dr. E. Muralinath & R. Gnana Lahari
 
GBSN - Microbiology (Unit 6) Human and Microbial interaction
GBSN - Microbiology (Unit 6) Human and Microbial interactionGBSN - Microbiology (Unit 6) Human and Microbial interaction
GBSN - Microbiology (Unit 6) Human and Microbial interaction
 
A Giant Impact Origin for the First Subduction on Earth
A Giant Impact Origin for the First Subduction on EarthA Giant Impact Origin for the First Subduction on Earth
A Giant Impact Origin for the First Subduction on Earth
 
GBSN - Microbiology Lab (Compound Microscope)
GBSN - Microbiology Lab (Compound Microscope)GBSN - Microbiology Lab (Compound Microscope)
GBSN - Microbiology Lab (Compound Microscope)
 
In-pond Race way systems for Aquaculture (IPRS).pptx
In-pond Race way systems for Aquaculture (IPRS).pptxIn-pond Race way systems for Aquaculture (IPRS).pptx
In-pond Race way systems for Aquaculture (IPRS).pptx
 
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243
 

B.O.D.

  • 1. 1 WATER ANALYSIS: BIOLOGICAL OXYGEN DEMAND Introduction Water is a vital natural resource which is essential for multiplicity of purposes which include drinking, agriculture, power generation, transportation and waste disposal. Thus it is important to analyse water physically, chemically and biologically. Biological Oxygen Demand or Biochemical Oxygen Demand or BOD is an important biological parameter for water analysis. BOD represents the quantity of oxygen required by bacteria and other microorganisms during the biochemical degradation and transformation of organic matter present in water under aerobic conditions. In simple words, it is the degree of microbial mediated oxygen consumption in water. Oxygen Demanding Waste Pollution due to organic matter such as sewage, industrial effluents, wastes from food processing plants, paper mills and tanneries, run off from agricultural lands, etc. undergo degradation by bacterial activity in the presence of Dissolved Oxygen (DO). The net result being deoxygenation process and quick depletion of DO. In the process of BOD, carbonaceous matter is degraded by bacterial oxidation. But when nitrogenous material is present, nitrifying bacteria exert an additional O2 demand.
  • 2. 2 During carbonaceous stage, NH3 is produced by breakdown of organic nitrogenous materials. Further this is oxidized to nitrite and finally to nitrate by nitrifying bacteria. 2 NH4 + + 3 O2 → 2 NO2 - + 2 H2O + 4 H+ 2 NO- + O2 → 2 NO3 - Estimation of BOD BOD in water sample is determined by measuring the O2 concentration in the water sample before and after incubation in the dark at 20° C for 5 days using Winkler’s method. The method used for estimation of BOD consists of 2 steps:- 1. Preliminary dilution and aeration of sample – This step is necessary so that all the O2 present in water is not consumed during incubation, which may lead to error in result. To prepare dilution water, aerate the BOD free distilled water in a glass container for 30 minutes. Then add 1 mL of phosphate buffer solution, 1 mL of magnesium sulphate (MgSO4) solution, 1 mL of calcium chloride (CaCl2) solution and 1 mL of ferric chloride (FeCl3) solution to 1 L of this aerated water. Now the pH is adjusted to 7 using sulphuric acid (H2SO4) or sodium hydroxide (NaOH) solution as per the requirement. Now dilute the sample by adding this dilution water according to the expected content of BOD in the sample.
  • 3. 3 Expected BOD content (ppm) Volume of sample (mL/L) Dilution Factor 0 – 6 1000 1 4 – 12 500 2 10 – 30 200 5 20 – 60 100 10 40 – 120 50 20 100 – 300 20 50 200 – 600 10 100 400 – 1200 5 200 1000 – 3000 2 500 2000 – 6000 1 1000 > 6000 0.5 2000 2. Determination of BOD – Fill this diluted sample in two BOD bottles carefully without allowing any air bubble and add 1 mL of allylthiourea. i) Now determine the DO in one bottle by modified Winkler’s method : The basic principle involved in this method is to oxidize KI to I2 with the dissolved oxygen present in the water sample after adding MnSO4, NaOH and KI. The basic manganeic oxide formed from NaOH and MnSO4 act as an oxygen carrier to enable the DO in the molecular form to take part in the reaction. The DO present in the sample oxidizes Mn2+ to its higher valency state. This precipitates as a brown hydrated oxide after addition of NaOH and KI. MnSO4 + NaOH → Mn (OH)2 + Na2SO4 2 Mn (OH)2 + O2 → 2MnO(OH)2 (Basic manganeic oxide)
  • 4. 4 On acidification, the Mn revert back to the divalent state and equivalent amount of I2 is liberated from KI present. MnO(OH)2 + H2SO4 → MnSO4 + 2H2O + O 2 KI + H2SO4 + O → K2SO4 + H2O + I2 This liberated I2 is titrated against standard sodium thiosulphate (Na2S2O3) solution iodometrically using starch as indicator. I2 + 2Na2S2O3 → Na2S4O6 + 2NaI Method: Open the BOD bottle and put 1 mL of MnSO4 solution and 1 mL of alkaline iodide azide solution (in place of alkaline KI solution in order to remove interferences). A brown precipitate of basic manganeic oxide is formed due to O2 present in the water. Now place the stopper and shake the bottle thoroughly. Now add 2 mL of H2SO4 and shake. The precipitate will dissolve. Transfer the contents to conical flask and titrate against standard Na2S2O3 solution using starch as indicator. The blue colour is discharged at the end point. This is D0. DO (mg L ) = N × V × 8 Volume of water sample taken × 1000 N is the normality of standard Na2S2O3 used, V is the volume of standard Na2S2O3 used, 8 is the equivalent weight of oxygen. ii) The other BOD bottle is kept in BOD incubator at 20° C for 5 days. The DO content of this water is then estimated immediately after taking out the bottle using modified Winkler’s method. This is D5.
  • 5. 5 DO (mg L ) = N × V × 8 Volume of water sample taken × 1000 N is the normality of standard Na2S2O3 used, V is the volume of standard Na2S2O3 used, 8 is the equivalent weight of oxygen. Calculations: The BOD of sample is determined by the formula BOD5 (mg L-1 ) = (D0 – D5) × Dilution factor Importance of BOD  The demand of oxygen by microbes in water is directly proportional to the amount of organic matter which has to be broken down. Thus, BOD is a direct measure of O2 requirements and an indirect measure of biodegradable organic matter.  BOD is used as an index of organic pollution in water and so an important parameter for analysis of water quality.  Drinking water usually has BOD < 1 mg L-1 and water is considered fairly pure with the BOD of 3 mg L-1 . But when BOD value reaches 5 mg L-1 , the water is of doubtful purity.  BOD test is generally performed to determine:- a) Degree of pollution in lakes and streams at any given time. b) Pollution load of waste water on the environment. c) Efficiency of waste treatment plant.
  • 6. 6 References:- 1. Environmental Chemistry; De, A.K. 2. Textbook of Engineering Chemistry; Dara, S.S. 3. Standard Method of Chemical Analysis Vol I & II, Hulcher 4. Environmental Chemistry; Kaur, H. THANKS