BOD Discussion

Discussion The experiment result we obtained is consistent with the theory given in which the Biochemical Oxygen Demand (BOD) is getting higher if there are a lot of microorganism in the water sample. From the result, we can see that the lower the dilution factor would increase the amount of BOD. In the presence of free oxygen, aerobic bacteria use the organic matter found in wastewater as “food”. The BOD test is an estimate of the “food” available in the sample. The more “food” present in the waste, the more Dissolved Oxygen (DO) will be required. The BOD test is used to measure waste loads to treatment plants, determine plant efficiency (in terms of BOD removal), and control plant processes. It is also used to determine the effects of discharges on receiving waters.

However, there are still some considerations that we must take into account in order to get a good result. Firstly, organic matter in the water sample is continually oxidised by the microorganism. Therefore, the sample should be preserved by cooling process in order to slower the rate of oxidation. Secondly, we should also avoid extreme pH value and provide a neutral pH environment for the microorganisms. This is because the microorganisms could be killed in an extreme pH values environment. Moreover, toxic substances in the water sample must be removed by certain chemical reaction or provide acclimated seed. The presence of algae in the water sample will also affect the BOD result. So, we must store the samples in the incubators in order to prevent sunlight. Finally, good sampling is necessary if laboratory testing is to be accurate. The sample must be representative, collected properly, handled carefully and preserved correctly. No matter how accurate the actual testing is, if the sample is not representative, the results of the test will be misleading and can lead to poor plant performance.