Is it possible to have greater Electric Conductivity (EC) value for Waste Water than Total Dissolved Solid (TDS)?

Hello.

I am facing a problem with our waste water treatment setup. The TDS found in waste water is 1200 mg/l whereas the EC calculated for the same waste water is around 1600dS/m.

My experience says that EC has relation with TDS, which is EC = 0.67 x TDS.

In our factory we process waste water generated from Personal Care Cosmetics and Soaps .

I know that EC varies with temperature and ionic compounds, but what we are experiencing is confusing. So I need your advice. It is normal to have greater EC value for waste water than TDS ? If not, what could be the possible reasons behind it?

Thanks in advance.

Regards,

Forhad, Chemical Engineer, BUET.