Washout point occurs when the dilution rate \(D\) exceeds the specific growth rate of the microorganism \(\mu\). At this point, the cells are washed out of the bioreactor faster than they can reproduce, and the culture eventually dies out.

The *washout condition* can be mathematically represented as:

$$ D > \mu$$

Where:

- \(D\) is the dilution rate (L/h or m3/h)

- \(\mu\) is the specific growth rate (h-1 or 1/h)

*The washout point is an important consideration in bioprocess design and operation, as it determines the maximum dilution rate that can be used without losing the culture.*