Nocardia foam on aeration basin is directly related to FOG in the influent.
Last week I saw an article on a municipality discovering that a biodegradable detergent was effective in reducing grease buildup in a problem lift station. according to the article, this "natural" solution was ecologically friendly solution to the grease problem.
Well solvents and detergents can mobilize grease & fatty acids - cleaning the lift station. But to call this a "good" solution to the problem is a mistake. Surfactants do not degrade or transform grease but instead create oil-water emulsions that move downstream to the wastewater treatment plant. If there is not too much grease, the emulsion and associated grease will be biologically degraded by the wastewater plant bacteria. (I know too much is qualitative and not a hard number, but the exact amount of grease differs for every system). But often using surfactants just pushes the problem to another part of the system and better solutions can be implemented.
If you use surfactant lift station treatment here are the things that can happen:
Well solvents and detergents can mobilize grease & fatty acids - cleaning the lift station. But to call this a "good" solution to the problem is a mistake. Surfactants do not degrade or transform grease but instead create oil-water emulsions that move downstream to the wastewater treatment plant. If there is not too much grease, the emulsion and associated grease will be biologically degraded by the wastewater plant bacteria. (I know too much is qualitative and not a hard number, but the exact amount of grease differs for every system). But often using surfactants just pushes the problem to another part of the system and better solutions can be implemented.
If you use surfactant lift station treatment here are the things that can happen:
- Emulsion breaks in the collection system and redeposits
- Additional FOG enters the treatment system promoting Nocardia growth
- FOG can create non-filamentous bulking conditions by increasing water trapped in MLSS - makes biosolid disposal more difficult.
- Can increase organic loading to biological unit (decrease primary treatment efficiency) - which results in more difficulty in keeping the biological system operating in target zone.
- Utilize programs to keep grease out of the sewers - public education
- Encourage the use of grease traps with routine inspection/cleaning for restaurants & commercial buildings
- Use biological pretreatment - grease degrading microbes (like those in the wastewater plant) can initiate biological treatment in the gravity mains and lift-stations
- Mixers/aeration in the lift station can help by promoting grease biological degradation (best used with above biological treatment program)
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