How is BOD calculated in COD?

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

What is 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.

How is wastewater COD measured?

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.

What is 5 days 200c BOD equal to?

5 days 20°C BOD equal to 3 days at 27°C BOD Win over the concepts of Quality and Characteristics of Sewage and get a step ahead with the preparations for Environmental Engineering with Testbook.

What is the permissible limit of BOD in wastewater?

The Significance of BOD in Wastewater Treatment BOD is listed as a conventional pollutant under the U.S. Clean Water Act. Typical maximum values range from 10 mg/L for direct environmental disposal and 300 mg/L for disposal to sewer systems.

What causes high COD in wastewater?

COD increases as the concentration of organic material increases. It also increases if inorganic compounds susceptible to oxidation by the oxidant (typically dichromate) are present. Water with high COD typically contains high levels of decaying plant matter, human waste, or industrial effluent.

Which indicator is used for COD?

Using potassium dichromate . Most commonly, a 0.25 N solution of potassium dichromate is used for COD determination, although for samples with COD below 50 mg/L, a lower concentration of potassium dichromate is preferred.

Why are BOD bottles kept in dark?

Incubation in the dark ensures that no additional oxygen is produced in the samples from photosynthesis. After 5 days, the dissolved oxygen is measured again. The difference between the initial and final oxygen concentrations corrected for BOD of the seed and dilution factor is the BOD.