Nocardioforms nearly always ...

Nocardioforms nearly always have some form of fat or oil as a source for their growth. They produce their own surfactant, which then allows them to grow on the surface of the water producing the orange foam.  This foam will be a mixture of bacteria held together by the Nocardia and the surfactant as well as some protozoa.  In the past, I have combined the use of antifoam with chlorine and as others have said being careful with the dosing of chlorine not to kill or upset the plant.  One way to reduce this is to install a form of oil/fat removal prior to the aeration process.  This will reduce the cause of the foam and foam will start reducing.