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OD-BOD Model for rivers

Explore the dynamics of oxygen in rivers, from production to consumption by organisms and chemical reactions. Understand the impact of temperature on oxygen saturation and eutrophication consequences. Equations and empirical methods for saturation concentration calculation provided.

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OD-BOD Model for rivers

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  1. OD-BOD Model for rivers

  2. Processes involving Oxygen • Production • Consumption by organisms (BOD) • Consumption by Chemical reactions, • Fluxes across the free surface

  3. The OD-BOD evolution equations

  4. O2 Free surface exchange Where is the Henry’s constant (mole/L/atm – Moles per litter per atmosphere) and Pg is the partial pressure of the gas in the atmosphere. Depends on the temperature and on the type of gas. The table below presents values for common temperatures. (from http://thayer.dartmouth.edu/~d30345d/books/EFM/chap15.pdf)

  5. Using the values in this table, the saturation concentration of oxygen in water at 20 degrees is: A O2 molecule has two atoms and their molecular weight is 16g, the saturation concentration in mg/L is: The saturation concentration decreases with temperature. This is an extra reason for eutrophication consequences to be higher in warm water. The other is the more intense biological activity (respiration).

  6. Another empirical equation to compute the saturation concentration ishttps://books.google.pt/books?id=pMyy8ERbZmEC&pg=PA390&lpg=PA390&dq=o2+rivers+aeration+rate&source=bl&ots=N1blM_duQZ&sig=5KarMV3SsahSlcNKwHC-qFWgP9g&hl=pt-PT&sa=X&ved=0ahUKEwjU88GX1t_MAhXEWxQKHQjjBMwQ6AEIITAA#v=onepage&q=o2%20rivers%20aeration%20rate&f=false Examples of correlation to compute K0 :

  7. BOD Equation

  8. Bibliography • Notes provided in the course bibliography;

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