Divide the COD concentration by the BOD concentration for each sample and average the results.
Can I use my COD results to predict my BOD?
| Sample 1: | COD = 2,150 mg/L | BOD = 1,100 mg/L |
|---|---|---|
| Sample 3: | COD = 1,850 mg/L | BOD = 997 mg/L |
| COD ÷ BOD = 1,850 ÷ 997 = 1.86 | ||
| (1.95 + 1.89 + 1.86) ÷ 3 = 1.9 COD:BOD Ratio = 1.9:1 |
What is the formula for calculating BOD?
1.5 Calculate the volume of sulfuric acid or sodium hydroxide required to neutralize the 1000 ml sample.
Biological Oxygen Demand (BOD):
| Recommended sample volume for BOD determination | ||
|---|---|---|
| BOD range (mg/liter) | Sample volume (ml) | Dilution water (ml) |
| 0-10 | 300 | |
| 11-30 | 100 | 200 |
| 31-70 | 50 | 250 |
What is the formula to calculate COD?
There is a formula for calculating COD. Consider the formula for COD calculation: (a – b) X C X 8,000 / the volume of the sample in mL. Let “a” represent the titrant used for your sample expressed in mL. Let “b” represent the titrant used for your blank sample in mL.
How do you measure BOD in water?
BOD measurement requires taking two samples at each site. One is tested immediately for dissolved oxygen, and the second is incubated in the dark at 20 C for 5 days and then tested for the amount of dissolved oxygen remaining.
What is the ratio of BOD and COD?
BOD : COD (Chemical oxygen demand) ratio using the formulated seed comes in the range of 0.7-0.8 whereas that using BODSEED comes in the ratio of 0.5-0.6. The ultimate BOD (UBOD) was also performed by exceeding the 3-day dilution BOD test.
How is COD measured in water sample?
This is usually done by titration, using an indicator solution. COD is expressed in mg/L, which indicates the mass of oxygen consumed per liter of solution. The COD test only requires 2-3 hours, while the Biochemical (or Biological) Oxygen Demand (BOD) test requires 5 days.
How do you determine COD in water samples?
Chemical oxygen demand (COD) is used to determine the quantity of pollution in water after wastewater treatment. The higher value of chemical oxygen demand indicates the higher organic pollution in the water sample. Only chemically digest able matter can be determined by the COD test.
What is COD & BOD in water?
The biochemical oxygen demand (BOD) represents the amount of dissolved oxygen (DO) consumed by biological organisms when they decompose organic matter in water. The chemical oxygen demand (COD) is the amount of oxygen consumed when the water sample is chemically oxidised.
Why is BOD measured for 5 days?
BOD occurs in 2 general stages. While calculating the oxygen demand, the carbonaceous stage is taken into account. This stage is almost completed in 5 days, which means that most of the organic content of the sewage is oxidized under aerobic conditions in 5 days. Hence ,BOD for 5 days is calculated.
How do you calculate BOD load in Kg day?
BOD (or COD) load: Units: kg/day
This is simply done by multiplying the BOD in mg/l by the daily effluent volume in cubic metres (m3) and dividing the product by 1000.
What is BOD level in water?
BOD is a measure of the amount of oxygen required to remove waste organic matter from water in the process of decomposition by aerobic bacteria (those bacteria that live only in an environment containing oxygen).
What is the difference between BOD and COD?
Biochemical oxygen demand (BOD) is the amount of oxygen required by the microorganisms to break down the organic materials, whereas chemical oxygen demand (COD) is the amount of oxygen required to break down the organic material via oxidation.
What is BOD value?
The BOD value is most commonly expressed in milligrams of oxygen consumed per liter of sample during 5 days of incubation at 20 °C and is often used as a surrogate of the degree of organic pollution of water (Sawyer et al., 2003). BOD can be used as a gauge of the effectiveness of wastewater treatment plants.
Why is BOD COD ratio important?
Results of the investigation revealed that BOD: COD ratio is a good indicator for pollution measurement in river. It can be used as an indicator to predict the relationship of BOD and COD in the river. It is also found to be reliable and useful indicator to relate organic matter content in the river water.
What is a good COD level?
Influent COD in normal domestic sewage is therefore generally 600 – 900 mg/l and it is then treated to at least 75 -100 mg/l before discharge to minimise pollution potential.
What is the limit of COD?
The chemical oxygen demand (COD) concentration in a treated effluent, if observed to be persistently greater than 250 mg/l before disposal to any receiving body (public sewer, land for irrigation, inland surface water and marine coastal areas), such industrial units are required to identify chemicals causing the same.
Why Sulphuric acid is used in COD?
Chemical Oxygen Demand (COD) 1% Silver Sulphate in Sulphuric Acid (conc.) provides the primary and secondary digestion catalysts for oxidation of carbon during chemical oxidation.
What is standard of COD and BOD in STP?
According to standards of Central Pollution Control Board, permissible value of BOD is 30 mg/l and COD is 250 mg/l.
What is the range of BOD for good quality of water?
BOD values range widely; generally, pristine waters have a value below 1 mg l−1, moderately polluted waters 2–8 mg l−1, and treated municipal sewage 20 mg l−1. Standards for the discharge of effluent from WWTPs have the range 20–30 mg l−1 and require a minimum flow in receiving waters to ensure sufficient dilution.
What is range of BOD for polluted water?
6 – 9 ppm
Polluted water has a BOD value in the range of 6 – 9 ppm. In polluted water, some organic waste is present. This organic matter is decomposed by bacteria. A BOD value of more than 100 ppm suggests that water is highly polluted.
Why is BOD important in water quality?
The BOD is an important parameter for assessing water quality. It deals with the amount of oxygen consumption (mg O2 L− 1) by aerobic biological organisms to oxidize organic compounds. Sewage with high BOD can cause a decrease in oxygen of receiving waters, which in turn can cause the death of some organism.
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