Can you measure BOD/COD real time using any sensor?
Realtech.com has a runtime monitoring senser solution for BOD/COD Sensor.
My understanding is that COD is straight-ward to measure in real-time but BOD monitoring cannot be done in real-time.   The sensor listed uses a BOD equivalent monitoring technique.  

The governing environmental regulatory agencies for a specific waste water facility should have public statement of acceptable BOD monitoring methods.