Hello!

There are two questions about kinetic equation of chemical oxygen demand. The equation is showed in the following figure.

- What does “ΔZ” mean in the equation?
- I want to know the references for this equation.

Hello!

There are two questions about kinetic equation of chemical oxygen demand. The equation is showed in the following figure.

- What does “ΔZ” mean in the equation?
- I want to know the references for this equation.

Hi yunyingli,

- In the kinetic equation of COD, the “ΔZ” term stands for the thickness of the bottom layer where the exchange of COD from sediment flux and water column take place.
- The Water Quality model in EFDC+ code was derived from the CE-QUAL-ICM water quality model. For the reference of equations, you can have:

*A Three-Dimensional Hydrodynamic-Eutrophication Model (HEM-3D) : Description of water quality and sediment process submodels*by Park et al., 1995 which you can download from the link below

"A Three-Dimensional Hydrodynamic-Eutrophication Model (HEM-3D) : Descr" by Kyeong Park, Albert Y. Kuo et al.- Or the book “
*Hydrodynamics and Water Quality: Modeling Rivers, Lakes, and Estuaries*” by Zhen-Gang Ji https://onlinelibrary.wiley.com/doi/book/10.1002/9781119371946 that you can find a pdf version on internet.

Kien

Thank you for your reply!