What does it indicate if BOD is high?
Higher BOD indicates more oxygen is required, which is less for oxygen-demanding species to feed on, and signifies lower water quality. Inversely, low BOD means less oxygen is being removed from water, so water is generally purer.
What is COD and BOD of water?
COD or Chemical Oxygen Demand is the total measurement of all chemicals in the water that can be oxidized. BOD- Biochemical Oxygen Demand is supposed to measure the amount of food (or organic carbons) that bacteria can oxidize.
Why is BOD test done for 5 days?
The standard oxidation (or incubation) test period for BOD is 5 days at 20 degrees Celsius (°C) (BOD5). The BOD5 value has been used and reported for many applications, most commonly to indicate the effects of sewage and other organic wastes on dissolved oxygen in surface waters (see TECHNICAL NOTE).
What is the BOD value of pure water?
about 1 ppm
What is COD in wastewater?
The chemical oxygen demand (COD) is a measure of water and wastewater quality. The COD test is often used to monitor water treatment plant efficiency. The COD is the amount of oxygen consumed to chemically oxidize organic water contaminants to inorganic end products.
What is cod limit?
It depends on the water source and receiving body. In General for India, the permissible limit to discharge is COD, less than 250 mg/L and BOD is less than 30 mg/L.
What is the difference between BOD and COD?
The main difference between BOD and COD is that BOD is the amount of oxygen which is consumed by bacteria while decomposing organic matter under aerobic conditions whereas COD is the amount of oxygen required for the chemical oxidation of total organic matter in water.
How do you measure COD in water?
What test methods are typically used to determine COD at water and wastewater laboratories? The most common test method is the colorimetric analysis after oxidizing the COD with acid and using indicator compounds, such as hexavalent dichromate.
How do you increase cod in water?
A common method for Chemical Oxygen Demand analysis is Method 410.4. The method involves using a strong oxidizing chemical, potassium dichromate Cr2O72-, to oxidize the organic matter in solution to carbon dioxide and water under acidic conditions.
What are the interferences during COD test how this can be eliminated?
Total COD is run on undiluted samples. For a soluble COD, the samples are filtered through a 0.45 mm filter before analysis to remove biological interference. 2 mL of the sample is pipetted into a COD digestion reagent vial. Vials with mercuric sulfate can be used to eliminate chloride interference up to 2000 mg/L Cl–.
How cod is calculated?
Chemical oxygen demand, or COD, is a test that measures the amount of organic compounds in water. 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.
How do you calculate COD removal?
I have the influent and effluent COD concentrations (mg l-1), HRT, and OLR for my batch bioreactor system. The COD removal efficiency can be computed using ((Cin-Ceff)/Cin)*100) and expressed in %.
Which indicator is used in cod estimation?
Silver sulfate is used as a catalyst and mercuric sulfate is added to remove chloride interference. The excess dichromate is titrated with standard ferrous ammonium sulfate, using orthophenanthroline ferrous complex as an indicator.
How is dilution factor calculated in cod?
simply calculate the COD and then multiply the result by the dilution factor. The dilution factor is the total volume of the solution divided by the the stock volume.
What is dilution factor in BOD test?
Dilution is needed to prevent the depletion of entire oxygen present in in BOD bottle in less than incubation period of 5 days. For a valid BOD test APHA manual specifies some min DO of 1 mg/L to be present in the bottle after end of 5 days and DO consumed should be at least 2mg/L during incubation.
How do you calculate the dilution factor of a BOD test?
- BOD and COD number in wastewater are more homogenous than faecal sludge waste. Its values tend to vary from one place to another [1].
- Data. BOD5(mg/l)
- Data. BOD/COD Ratio.
- Dilution factors will be determined: (
- Ratio. BOD/COD.
- DO0 (mg/L) △DO O2 Five Days Consumption (mg/L) 7.9.
- 105. 148.
- 137. 127.
How do you calculate dilution ratio?
If a dilution ratio is expressed in this way, you will have to calculate the ounces per gallon. In this example, 256 is our ratio number and by plugging it into our formula, we can determine how many ounces per gallon of product is needed….A Quick Guide to Calculating Dilution Ratios.
| Ounces per Gallon | Dilution Ratios |
|---|---|
| 12 ounces per gallon | 1:10 |
How do you calculate the amount of water needed to dilute a solution?
To make a fixed amount of a dilute solution from a stock solution, you can use the formula: C1V1 = C2V2 where: V1 = Volume of stock solution needed to make the new solution. C1 = Concentration of stock solution.