Hello Everyone! We recently discovered what we believe are freshwater sponges living at the outfall of our Rotating Biological Contactor (RBC) Tanks. The RBC's at our facility follow Secondary Clarification and are used as a polishing stage prior to Sand Filer Tertiary Treatment with Chlorine Disinfection introduced at the inlet of the Tertiary Treatment. The population of sponges seems rather large, and we are concerned about any negative effects these organisms may have on our effluent, particularly any increase in BOD. Information on the internet seems relatively positive and that the sponges are a good indicator of good water quality. I just wondered if anyone had any thoughts or personal experience in dealing with them. Thank you.