This document provides information about dissolved oxygen (DO) and biochemical oxygen demand (BOD). It discusses several factors that affect the solubility of oxygen in water, including altitude, temperature, and salinity. It also describes methods for measuring DO, such as the Winkler titration method and DO probes. For BOD measurements, the document outlines the bottle test procedure where samples are incubated for 5 days and the oxygen consumed is measured. Factors that can interfere with accurate BOD tests are also mentioned. Chemical oxygen demand (COD) is introduced as a related parameter that measures total oxidizable organic compounds in a sample.

1. Sigid
Hariyadi
DO – BOD – COD
Dept. Manajemen Sumberdaya Perairan - IPB

2. TINGKAT JENUH (SATURASI) OKSIGEN TERLARUT:
Dissolved Oxygen (DO)

3. http://eesc.columbia.edu/courses/ees/slides/climate/gas_comp.gif
http://www.bbc.co.uk/schools/gcsebitesize/science/im
ages/50_composition_of_the_earth.gif

4.  Efek ketinggian (altitude) :
ketinggian bertambah,  tekanan parsial gas menurun,  kelarutan
gas berkurang
ketinggian tingkat berkurangnya kelarutan
 0 - 600 m 4 % per 300 m
 600 - 1500 m 3 % per 300 m
 1500 - 3000 m 2,5 % per 300 m
 Efek temperatur : temperatur meningkat -- kelarutan berkurang
 Efek salinitas : adanya berbagai mineral terlarut -- menurunkan
kelarutan gas.
 tk. kejenuhan gas dalam air laut, 18 - 20 % lebih rendah daripada dalam akuades.
FAKTOR KELARUTAN / TINGKAT SATURASI OKSIGEN:

5. S %o = 0,030 + 1,805 Cl (%o)
S (ppm) = 30 + 1,805 Cl (ppm)
atau
Kandungan chloride (Cl) dihitung
berdasarkan nilai salinitas :
TINGKAT SATURASI O2 DI
PERAIRANLAUT

7. Dissolved Oxygen (DO)
• Oksigen adalah gas terlarut dalam air
• bila sampel terekspose ke udara  DO bisa berkurang
atau bertambah dari seharusnya
• pengambilan sampel utk titrasi  perlu alat khusus
DISTRIBUSI VERTIKAL O2
dipengaruhi oleh:  kondisi kelarutan
 hidrodinamika -- pergerakan air
 input fotosintesis
 penggunaan oleh biota &
proses-proses kimia
Bottle train sampler
Sigid
Hariyadi

8. Prinsip penentuan DO (metode Winkler/Iodometri):
endapan coklat

• bila tidak ada Oksigen:
endapan putih

proporsional dg jumlah O2 yang ada
penambahan asam

indikator
biru
tak berwarna
Sigid
Hariyadi

9. Modifikasi metode Winkler/Iodometri:
 Flokulasi alum : 10% K2SO4Al2(SO4)3 & 35% NaOH
 bila air keruh
Sulfamic acid : NH2SO2OH  bila kadar nitrit tinggi
azide alsterberg : NaN3  bila kadar nitrit & bhn organik tinggi


Pomeroy – Kirscman – Alsterberg : penggunaan NaI (6 N)
dan NaOH (10N) sbg pengganti NaOH + KI
 bila kadar oksigen lewat jenuh (over saturated)

Sigid
Hariyadi

10. Pengukuran dgn DO-meter:
1. Warming up (on & biarkan bbrp menit)
2. Kalibrasi alat pada angka nol (zero adjustment)
3. Kalibrasi alat pada “red line” (red line adjusment)
4. Kalibrasi alat thd kadar O2 udara pada temperatur
dan tekanan udara (atau ketinggian tempat)
 Standardisasi dgn metode Winkler pd sampel yg sama (scr periodik)
Prinsip Pengukuran:
Tekanan O2
dlm air
Sensor/
membran
arus
Jarum penunjuk skala
/ digital
Sigid
Hariyadi

11. Botol BOD
Sigid
Hariyadi

12. probe DO-meter

13. BOD (Biochemical Oxygen Demand):
(Biological)
( DOi - DO5 ) mg/L
 Inkubasi sampel dlm botol BOD pada 20oC selama 5 hari
 shg O2 terlarut pd hari ke-5 masih ada & terukur
 Perlu pengenceran yg cermat & aerasi
Botol gelap
Inkubasi 20oC
5 hari
DO5
DOi
Sigid
Hariyadi
–
2005/2007

14.  Bahan beracun: Hg, Cr6+, Cl2
 Kurangnya nutrien
 Kurangnya mikroorganisme/bakteri
 pH < 6½ atau pH > 8½
 Senyawa pengganggu:
Sigid
Hariyadi
–
2005/2007

15. Sigid
Hariyadi

16. BOD decomposition rates vary widely
DO
Consumed
(mg/l)
Decaying phytoplanton
biomass
Black water
organic matter
Municipal,
industrial
BOD loads
Time 5 days
BOD5
Sigid
Hariyadi

17. BOD decomposition rates vary widely
Time 50 days
5 days
Black water
organic matter
Municipal,
industrial
BOD loads
DO
Consumed
(mg/l)
Decaying phytoplanton
biomass
Sigid
Hariyadi

18. Sigid
Hariyadi

19. Pre – treatment:
Penambahan
Nutrien
&
Pengenceran
Sigid
Hariyadi

20. BOD (Biochemical Oxygen Demand):
BOD3  inkubasi pada 30 oC selama 3 hari
 Jenis dan jumlah bahan organik terlarut &
tersuspensi (koloid)
 Jenis dan jumlah (komposisi) mikroorganisme
pengurai
 kecukupan oksigen
Nilai
BOD :
 upayakan nilai DO5(end) sekitar 1 mg/L
 sebaiknya selisih DO berkisar 5 – 7
mg/L
 mengubah pH, seluruh
aktivitas ionik
 mengubah aktivitas organik
 mengubah salinitas
lingkungan fisik-
kimia-
biologi air sampel
Pengenceran:
Sigid
Hariyadi
–
2005/2007
(Tropik)

21. From: DHV Consultants BV & DELFT HYDRAULICS, 1999. Training module # WQ - 15
Understanding biochemical oxygen demand test. Hydrology Project Technical Assistance. New Delhi

22. COD (Chemical Oxygen Demand):
 Bhn organik  dioksidasi dg K2Cr2O7 pada kondisi asam & panas
 Kelebihan K2Cr2O7  dititrasi dg FAS (back titration) dg indikator
feroin
potassium dichromate
Ferrous Ammonium Sulfate
 perlu larutan blanko
 senyawa pengganggu: Cl (air laut), NO2
-
sulfamic acid
+ HgSO4 (200 mg/L per 1000 mg/L chloride)
S %o = 0,030 + 1,805 Cl (%o)
S (ppm) = 30 + 1,805 Cl (ppm)
atau
S= 30 %o = 30 000 ppm  Cl = 16603,88 ppm  3,321 g HgSO4 per
liter sampel
Contoh :
Sigid
Hariyadi
–
2005/2008

23. Reflux,
untuk penentuan
COD
Sigid
Hariyadi

24. Wastewater type BOD5 (mg/L) COD (mg/L)
Tomato processing 450 - 1,600 650 - 2,300
Corn processing 1,600 - 4,700 3,400 -10,100
Cherry processing 660 - 1,900 1,200 - 3,800
Poultry plant processing 150 - 2,400 200 - 3,200
Milk plant processing 940 - 4,790 1,240 - 7,800
Becker, 2000. University of Maryland

25. Perairan-peruntukan BOD (mg/L) COD (mg/L)
Air tawar – Kelas I 2 10
Air tawar – Kelas II 3 25
Air tawar – Kelas III 6 50
Air tawar – Kelas IV 12 100
Air laut - Biota 20 -
Air laut - Wisata 10 -
Air laut - Pelabuhan - -
→ rekreasi air
→ budidaya ikan, ternak
→ air baku minum
→ irigasi pertanian
Sigid
Hariyadi
25

26.  COD menggambarkan jumlah bahan organik total, baik
yang mudah urai maupun yang sulit urai
Berdasarkan prinsip analisisnya, maka dapat dikatakan
bahwa:
 BOD menggambarkan bahan organik mudah urai
 Nilai permanganat (TOM-total organic matter) TIDAK
pernah lebih besar daripada nilai COD, karena oksidator
yang digunakan pada analisis COD lebih kuat
 TVS (total volatile solids) juga menggambarkan bahan
organik berdasarkan prinsip analisis pembakaran residu
organik sampel pada suhu tinggi (550oC) dan gravimetri
 Parameter bahan organik lainnya adalah TOC (total
organic carbon)
Sigid
Hariyadi
26

27. BOD
COD
/ rasio antara bahan organik mudah urai dgn
bahan organik total/sulit urai
COD ≥ BOD
COD ≥ TOM
Total Organic Matter
oxidator: KMnO4
TVS Total Volatile Solid
TOC Total Organic Carbon
 bahan organik dibakar
 tidak mengukur Oksigen ekuivalensi
 dapat dihubungkan dgn BOD
COD
BOD
TOM
Sigid
Hariyadi
27

28. Total Carbon (TC) – all the carbon in the sample, including both inorganic and organic carbon
Total Inorganic Carbon (TIC) – often referred to as inorganic carbon (IC), carbonate, bicarbonate, and dissolved carbon dioxide (CO2); a
material derived from non-living sources.
Total Organic Carbon (TOC) – material derived from decaying vegetation, bacterial growth, and metabolic activities of living organisms or
chemicals.
Non-Purgeable Organic Carbon (NPOC) – commonly referred to as TOC; organic carbon remaining in an acidified sample after purging
the sample with gas.
Purgeable (volatile) Organic Carbon (POC) – organic carbon that has been removed from a neutral , or acidified sample by purging with an
inert gas. These are the same compounds referred to as Volatile Organic Compounds (VOC) and usually determined by Purge and Trap Gas
Chromatography.
Dissolved Organic Carbon (DOC) – organic carbon remaining in a sample after filtering the sample, typically using a 0.45 micrometer
filter.
Suspended Organic Carbon – also called particulate organic carbon (PtOC); the carbon in particulate form that is too large to pass through a
filter.
TOC:

29. 1. Acidification
2. Oxidation
3. Detection and Quantification
Analysis of TOC:
Acidification :
The removal and venting of IC and POC gases from the liquid sample by acidification and sparging occurs in the following manner.
Oxidation :
The second stage is the oxidation of the carbon in the remaining sample in the form of carbon dioxide (CO2) and other gases.
Modern TOC analyzers perform this oxidation step by several processes:
1. High Temperature Combustion
2. High temperature catalytic (HTCO) oxidation
3. Photo-oxidation alone
4. Thermo-chemical oxidation
5. Photo-chemical oxidation
6. Electrolytic Oxidation
High temperature combustion:
Prepared samples are combusted at 1,350o C in an oxygen-rich atmosphere. All carbon present converts to carbon dioxide,
flows through scrubber tubes to remove interferences such as chlorine gas, and water vapor, and the carbon dioxide is
measured either by absorption into a strong base then weighed, or using an Infrared Detector.[3] Most modern analyzers use
non-dispersive infrared (NDIR) for detection of the carbon dioxide.
Detection and quantification:
Accurate detection and quantification are the most vital components of the TOC analysis process. Conductivity and non-dispersive
infrared (NDIR) are the two common detection methods used in modern TOC analyzers.
TOC: