Effect of Dissolved Oxygen Concentration on BOD Decay

• Main Author: AMRIZAL, MUHAMAD FIRDAUS
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi Petronas 2005
• Subjects: TP Chemical technology
• Online Access: http://utpedia.utp.edu.my/7632/1/2005%20-%20Effect%20of%20Dissolved%20Oxygen%20Concentration%20on%20BOD%20Decay.pdf; http://utpedia.utp.edu.my/7632/
• Institution: Universiti Teknologi Petronas

The Biochemical Oxygen Demand (BOD) is a quantity of the dissolved oxygen being utilized bythe aquatic microorganisms in metabolizing the organic matter, oxidize reduced nitrogen, andoxidize reduced minerals suchas ferrous iron. BODis alsoan indirect measure ofthe substrate itself. Forthisproject, the main objective is to identify the relationship between BOD decay and the dissolved oxygen concentration. Dissolved oxygen concentration is oneof the major factors affecting the BOD decay. Basically, the scope of study for this projectis to relate the dissolved oxygen concentration term into the BODdecayrate models, either in the First Order or Second Order Model and then relate the effect ofthe order ofthe models itself to the BOD decay rate. The methods used in this project are to apply the models into a software application to see the graphical presentation oftheBODdecay rate for the model. Thisis done by assuming the First-Order BODdecay rate constant or kj according to other researchers' works and journals and then applied into the models whichfurther integrated into themass transport equation. From themathematical approach and computer modeling works, the main findings of the project is thatwhen the dissolved oxygen concentration is increased, the rate ofBOD decay will increase butthisonly come up until certain value of dissolved oxygen concentration due to the saturation factor ofthe oxygen. This applies to both models that are used in this project. It is also found that the Second-Order Model exhibit a bit faster reaction than the First-Order Model but this difference only applies in the earlier stage of the decaying. Other than that, there are no significant differences between First-Order Model and Second- Order Model. In conclusion, theBOD decay rate increases as the dissolved oxygen concentration increases until the saturation point ofthe oxygen and the Second-Order Model decay rate is slower in theBODremoval comparing to the First-Order Model butthis does not mean that First-Order Model is better than the Second Order Model but only highlighting the importance ofdifferent approaches by researchers in interpreting the BOD decay in order toobtain more accurate interpretation ofthe BOD decay rate in water.