How to reduce COD in a wastewater treatment plant ?

Hi, I am working in ESBR wastewater treatment plant. We are struggling with a issue of Low MLSS, MLVSS in aeration tank and high COD after secondry clarifier.

  • MLSS-700 PPM, MLVSS- 300 PPM
  • Inlet COD 700-800 PPM and after secondry clarifier it is upto 400 ppm.

So, please suggest how to increase our MLSS/MLVSS and reduce COD in our plant.