What is the appearance of biomass on a properly functioning RBC?

The appearance of biomass on a properly functioning Rotating Biological Contactor (RBC) is characterized by a grey to brown coloration, typically measured at a thickness of about 0.05 to 0.1 inches. This specific color indicates the presence of healthy microbial communities that are efficiently digesting organic material in the wastewater, while the thickness is an optimal range that allows for effective treatment without the biomass becoming too dense or sloughing off.

A grey to brown color generally reflects the diversity and maturity of the microbial biofilm, while a thickness of 0.05 to 0.1 inch ensures sufficient area for the attached microorganisms to thrive without excessively inhibiting water flow through the RBC system. This thickness is also manageable during the operational period, preventing issues that could arise from excessive biomass that could lead to reduced treatment efficiency or operational problems.