It is assumed that you have activated sludge plant with secondary settling tank, where the scum formation is detected. In well operated wastewater treatment plants with secondary treatment, very little scum is formed in secondary settling tank. However, if there is present some floating material, scum will occur. Skimming of the secondary settling tank is essential. There are various devices for scum removal for both rectangular and circular settling tanks. Typical scum removal equipment includes scraper type, rotating pipe through skimmer and slotted pipes. Scum should not be returned to the plant headworks, because microorganisms responsible for foaming (typically Nocardia) will be recycled, causing foaming to persist because of continuous seeding of the unwanted microorganisms. Scum could be discharged to sludge thickening facilities or directly to digester feed. In general controlling foam in activated sludge plants, includes operational adjustments, additional structures, controlling dissolved oxygen levels, water sprays, steam application, polymer addition, chlorination and a novel and eco-friendly approach that is treatment of filamentous bacteria with the specific phages.

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It is assumed that you have activated sludge plant with secondary settling tank, where the scum formation is detected.

In well operated wastewater treatment plants with secondary treatment, very little scum is formed in secondary settling tank. However, if there is present some floating material, scum will occur. Skimming of the secondary settling tank is essential. There are various devices for scum removal for both rectangular and circular settling tanks. Typical scum removal equipment includes scraper type, rotating pipe through skimmer and slotted pipes.

Scum should not be returned to the plant headworks, because microorganisms responsible for foaming (typically Nocardia) will be recycled, causing foaming to persist because of continuous seeding of the unwanted microorganisms. Scum could be discharged to sludge thickening facilities or directly to digester feed.

In general controlling foam in activated sludge plants, includes operational adjustments, additional structures, controlling dissolved oxygen levels, water sprays, steam application, polymer addition, chlorination and a novel and eco-friendly approach that is treatment of filamentous bacteria with the specific phages.