To establish the COD:BOD ratio for your wastewater, simply have both COD and BOD run on several wastewater samples.
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 |
How do you convert COD to BOD?
Typically, the average BOD result is divided by the average COD result to find a “conversion factor” between the two parameters. One would then multiply their COD results by this factor to estimate BOD.
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 |
Is COD equal to BOD?
COD is closely related to BOD or Biochemical Oxygen Demand, the difference being that BOD is a test of the level of organic matter that can be biologically oxidised while COD is a test of the amount of organic matter that can be chemically oxidised.
Is BOD and COD value same?
Only one relation of COD to BOD is COD > BOD always. Some average sewage BOD/COD ratio may be 0.6 and for Industrial waste it varies and depends on type of effluent. The only relation between COD & BOD is – COD > BOD.
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.
Why is BOD calculated?
The BOD test measures the strength of the wastewater by measuring the amount of oxygen used by the bacteria as they stabilize the organic matter under controlled conditions of time and temperature.
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 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.
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.
Why is COD always higher than BOD?
As such, COD will always be higher than BOD. Because the test for COD takes only a few hours (as opposed to the test for BOD, which takes 5 days), it can be used as an operational adjustment parameter in close to real time.
Why is BOD done 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.
Can COD be lower than BOD?
Simply BOD indicates the biodegradable organic matter (OM) while COD represents both biodegradable and non-biodegradable OM in water. If all OM is your sample is biodegradable, so BOD will approximately equal COD. Therefore, COD should be higher than or equal BOD but never be lower than BOD.
What if COD is high in water?
When the COD levels are higher, there is a greater demand for oxygen. This means that there is likely more oxidizable organic material in water with high COD levels. This also means that there are reduced Dissolved Oxygen (DO) concentrations in wastewater with high COD levels.
What is BOD value 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.
What is BOD and How Is It measured?
The BOD test is a bioassay technique involving the measurement of oxygen consumed by the bacteria while stabilizing the organic matter in the waste as they would normally do in nature but under normal laboratory conditions. By convention, the test is conducted for a period of 5 days at 20°C (68°F).
What is the unit of BOD?
BOD’s are generally expressed as milligrams of dissolved oxygen per liter, which is equivalent to parts per million, PPM. BOD levels can vary considerably. Pristine water sources may show a BOD of less than 2 mg/L of water.
How does BOD measure water quality?
Biochemical oxygen demand (BOD) represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (oxygen is present) conditions at a specified temperature. When you look at water in a lake the one thing you don’t see is oxygen.
Which is better BOD or COD?
BOD measures the amount of oxygen required by the aerobic organisms to decompose organic matter and COD measures the oxygen required to decompose organic and inorganic constituents present in the wastewater by chemical reaction. Hence, the value of COD is greater than BOD.
What is the value of COD?
The COD value indicates the amount of oxygen which is needed for the oxidation of all organic substances in water in mg/l or g/m3. The COD (Chemical Oxygen Demand) is closely related to the laboratory standard method named Dichromate-Method.
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