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Question: Determination of sample size for the BOD test
Remember that the amount of oxygen that can be tran…


Determination of sample size for the BOD test
Remember that the amount of oxygen that can be transferred to water
from the atmosphere is not very high (that is, maximum solubility
of 8~12 mg O2/L for water equilibrated…….

x) Determination of sample size for the BOD test Remember that the amount of oxygen that can be transferred to water from the atmosphere is not very high (that is, maximum solubility of 8 12 mg O,/L for water equilibrated with the atmosphere). Most wastewater samples thus have more BOD to exert than the amount of oxygen available in the BOD sample bottle. Because the BOD test depends on the laboratory observing a measurable decrease in dissolved oxygen over time, the water sample is diluted with BOD dilution water. This is so the microorganisms in the BOD sample bottle do not use up all the dissolved oxygen in the system The criteria for the test states there should be 2 mg/L of dissolved oxygen removed over the 5-day incubation period and 21 mg/L of dissolved oxygen should remain in the sample at the end of the incubation. Thus, a laboratory needs to make an estimate of how many mL of sample should be added to the BOD bottle so both of these criteria are met. Too little sample could result in negligible depletion of

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x) Determination of sample size for the BOD test Remember that the amount of oxygen that can be transferred to water from the atmosphere is not very high (that is, maximum solubility of 8 12 mg O,/L for water equilibrated with the atmosphere). Most wastewater samples thus have more BOD to exert than the amount of oxygen available in the BOD sample bottle. Because the BOD test depends on the laboratory observing a measurable decrease in dissolved oxygen over time, the water sample is "diluted" with BOD dilution water. This is so the microorganisms in the BOD sample bottle do not use up all the dissolved oxygen in the system The criteria for the test states there should be 2 mg/L of dissolved oxygen removed over the 5-day incubation period and 21 mg/L of dissolved oxygen should remain in the sample at the end of the incubation. Thus, a laboratory needs to make an estimate of how many mL of sample should be added to the BOD bottle so both of these criteria are met. Too little sample could result in negligible depletion of

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