What types of foam are produced during the activated sludge process of integrated domestic wastewater treatment equipment? The following is a detailed introduction to the four forms of foam.

(1) Initiation of Foaming: During the initial startup of the activated sludge process, surface active substances present in the wastewater can easily lead to surface foaming. The foam appears white and is lightweight, with poor stability. As the activated sludge matures, these surface active substances are biodegraded, and the foaming phenomenon will gradually dissipate.

(2) Denitrification Foam. During the low-load operation of an activated sludge treatment system, denitrification occurs in the sedimentation tank or areas with insufficient aeration, producing nitrogen gas. The release of nitrogen gas reduces the sludge density to some extent and causes part of the sludge to float, leading to foam formation. The suspended foam produced in this manner is typically not very stable.

Surface Active Agent Foam. The extensive use of biodegradable detergents or the large influx of colloidal organic matter and various types of substances can easily cause foaming on the surface of the treatment pond. If such incoming water occasionally occurs, the foaming process only causes a short-term impact. However, if it persists, prolonged operation may lead to the development of biological foam.

(Biofoam) Due to the abnormal growth of certain microorganisms in the activated sludge, bubbles during the aeration process can combine with the microbial body through selective flotation, forming foam. This phenomenon can be described by a system compressed into three components: Microorganisms + Bubbles + Flocs = Biofoam. Biofoam has a high viscosity, is brown with strong stability, and the suspended particles can reach 50 g/L. The relative density of the foam layer is approximately 0.7, and it is generally difficult to blow it away.