The good news is that there are many ways to reduce the BOD, COD and TDS levels. The bad news is that there are many ways to reduce these levels
Most of the time, chemical treatment is usually the least expensive, most reliable and requires the least maintenance.
To help me understand a little more about your specific situation, can you describe more about the feedwater that is to be treated? For example, wastewater from a ethylene plant, or runoff water, concentration of hydrocarbons, type of hydrocarbons, has the water been pre-treated with something, etc.
Thanks for your help.