the floc containing nocardia bacteria that tends to stabilize foams the term hydrophilic used to describe nocardia is misleading because its the air entrapment that forces nocardia to float in the case of the nocardia bacteria get trapped because of the submerged aeration basins outlets in the hydrophilic nature of cationic polymer polymers are used extensively in water and wastewater treatment to enhance the overall coagulation process the mechanism that is used is the ability of the long chained charged polymers to destabilize colloids by forming a bridge between one colloid and another in their interaction with nocardia floc however it however its their ability to lower the surface tension developed between nocardia and air bubbles that plays the main role in the controlling foaming generally defoaming materials can be effective if they lower the surface tension more than the nocardia floc it will then displace the floc and cause the foam to collapse once this happens nocardia loses its buoyancy allowing it to pass through the aeration basins it is therefore hypothesized that polymer has that effect according to the present invention the cationic polymer dose of 0 5 ppm is the most effective nocardia foaming control agent the polymer should be injected at the mixed liquor channel though it is most likely that it is the polymer recycled through retention activation sludge ras that controls nocardia foaming 34 the polymer 39 s effectiveness is most likely due to its interaction with nocardia floc and its hydrophilic nature a way of exploring the effectiveness of polymer as a nocardia foaming control agent made to the industry is described in the following with reference to fig4 1 polymer addition should be considered as a foaming control option 2 before the installation of any.