Biochemical Oxygen Demand (BOD): Eliminating the Difficulty of BOD Analysis
Video Summary
Review of Biochemical Oxygen Demand (BOD) by Standard Method 5210B including method steps as well highlight products to make your setup of a BOD batch quick and easy.
BOD Analysis Method Steps
- Obtain high-quality dilution water
- Obtain acceptable seed source
- Add Glucose Glutamic Acid check standard
- Choose your bottle type: glass or plastic
- Check each sample for the proper pH range
- Obtain the initial developed oxygen rating
- Place the cap onto each bottle for a proper water seal
- Place the overcap onto the bottle
- The bottle is now ready for incubation
- Incubate samples for 5-days at 20° Celsius
- Remove samples from incubator, after the 5 days
- Determine the final dissolved oxygen content
BOD Analaysis Video Transcript
- Obtain high-quality dilution water
Obtaining high-quality dilution water is important when doing a BOD batch, becase it will come into contact with every sample involved in your batch. Deionized water requires the addition of several trace nutrients to ensure a proper environment for the incubation of bacterial populations.
Preparing Your Dilution Water
- Add 1mL of each of the nutrients to dilution water per 1-Liter of your dilution water
- Stir and aerate the water
- After proper aeration, the water is ready for use in your sample
- Obtain an acceptable seed source
Influents are often toxic and highly variable. Effluents are chlorinated to remove microbial populations. To overcome these problems use a freeze-dried seed such as Polyseed
Preparing Your Seed Solution
- Place the contents of one capsule into 500mL of your dilution water
- More or less water can be used to adjust the strength of the seed as needed
- Stir or aerate the seed for 1 hour
- After 1 hour, allow it to settle and decant the liquid from the top
- Your seed solution is now ready for addtion to your sample bottles
- The Glucose-Glutamic Acid (GGA) Check Standard
The glucose-glutamic acid check standard is the primary measure for precision and accuracy of a BOD batch. For ease of use, prepared vials with the appropriate amount of glucose and glutamic acid are recommended.
Adding GGA
- Uncap the vial
- Pour the contents directly into your BOD bottle
- Decide which bottle you would like to use for your BOD batch
Choose between traditional glass bottles or plastic bottles. These plastic bottles are specially designed and approved by the EPA for use in the determination of biochemical oxygen demand and dissolved oxygen. The bottles are manufactured with a special coating on the inside to prevent the migration of oxygen through the plastic and also prevents the leaching of oxidizable materials into your samples during incubation. Plastic bottles fit your standard stoppers and overcaps.
- Check each sample for the proper pH range and for the presence of chlorine
If the sample is outside of the acceptable pH range, it needs to be adjusted with dilute solutions, a sulfiric acid, or sodium hydroxide. If chlorine is present, it needs to neutralized with sodium sulfite. Each sample needs to have several dilutions prepared to ensure an appropriate BOD value. Samples of unknown strength or that are highly variable may need more than 3 bottles in order to ensure an appropriate depletion.
Resolving pH range or chlorine
- Add the appropriate amount of sample to each of your bottles
- Top off with dilution water
- Obtain the initial developed oxygen rating
- Place the cap onto each bottle to acheive a proper water seal
- Place the overcap onto the bottle
- The bottle is now ready for incubation
- Incubate samples for 5-days at 20 degrees Celsius
- Remove samples from incubator, after the 5 days
- Determine the final dissolved oxygen content
In order for a sample to be acceptable, it must have a minimum of 2mg of oxygen per Liter depletion and a residul of least 1 mg of oxygen per Liter remaining. This is known as the 2:1 rule
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