Dear all;
Recently I have seen foam in water treatment plant (WTP) outlet. Also I have observed them simultaneously on the lake surface where the treated water of WTP entering to lake. What are the possible causes of the foam in WTP that is treating the lake water?
I have attached a photo of these foams on the lake surface.
Sincerely.
Dear Javad Bayat,
It seems the wastewater is not treated well before disposing in the lake.
There are many reasons associated with foaming: presence of slowly biodegradable surfactants (eg. household detergents) from industrial or municipal wastewater, excess production of extracellular polymeric substance (EPS) by activated sludge microorganisms under nutrient-limited condition, proliferation of filamentous organisms and gas provided in aeration tank or produced in anoxic zone of aeration tanks, secondary clarifiers and anaerobic digesters.
Filamentous bacteria serve as hydrophilic particles which play important role in stabilizing foaming in WWTP. There are two main groups of filamentous bacteria: the most commonly observed group: Candidatus Microthix parvicella , and members of the Mycolata.
Good luck.
Regards
Pankaj
Dear Pankaj Kumar
Many thanks for your answer, but it is not a wastewater treatment plant. It is water treatment plant which uses just NaClO for disinfection and FeCl3 for removing phosphorus.
Dear Javad Bayat,
If it is from water treatment plant, then here are two possible cause which may brought foaming in the lake:
1) The nutrient value of water is favorable for microorganism responsible for foaming process.
and
2) The soil properties of lake is working itself as trigger to form foam when added some specific nutrient containing water as you mention above ( NaClO for disinfection and FeCl3 for removing phosphorus).
You should remember that foam forming bacteria are thermophilic and their reproduction is usually enhanced in presence of Fe3+ ions (refer to some papers describing this process) and liberate oxidizing air bubbles in water bodies/WWTP tanks.
If this is a water treatment storage basin after treatment, I would be a little concerned about the colour of the water - (if the photo is colour correct). It is a dull green. Filamentous actinomycetes are notorious for causing foaming in activated sludge treatment under faculative conditions. Check the dissolved oxygen. The water should be well aerated.
Dear All;
Many thanks for your helpful information. About two days ago I stopped injection of NaClO, and I found that foams on the lake surface are becoming less. May be it is because of NaClO that kills the phytoplanktons in the water resulting in foam on the lake.
But I do not know if my assumption is correct or not?
Sincerely.
Javad Bayat : If I understand well, the only purpose of water treatment is reduction of phosphorus (FeCl3) and disinfection (NaClO). Is it the secondary or tertiary treatment of wastewater? What is the microbiological quality of treated water stored in the basin? I agree with Dr. Sherman, that color of treated water is dark. Are there any filamentous organisms in treated water there?
Best regards
Vit
Dear Vit Mateju;
It is tertiary treatment of water not wastewater. We have the maximum of 460 MPN of Total Coliform in the outlet. May be the dark color of the photo is caused by lack of light. But we have green color in the lake water due to the Eutrophication of phytoplanktons.
Here is a fact sheet that may have helpful information:
https://www.michigan.gov/documents/pfasresponse/PFAS_Foam_Fact_Sheet_657070_7.pdf
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