I am working on a membrane bioreactor for wastewater treatment using activated sludge. Sludge in my reactor clings to the membrane. I wish to harvest it for microbial community analysis. I have tried sonication but sludge does not leave the membrane. What are the other possible ways?
I thought of 1M NaOH but it might cause cell lysis and I will lose DNA in the supernatant (After harvesting, I would like to do DNA Extraction for further studies). . .
Dear Sheetal,
There are two approaches to harvest the activated sludge: (1) physical & (2) chemical.
Physical: Physical cleaning techniques are based on turbulence promotion close to the membrane surface and include frequent relaxation and/or backwash steps. During relaxation, filtration and thus permeation is stopped, while the membrane is continued to be scoured with air. During the backwash step, permeate flows in the opposite direction, due to a reversed pressure gradient across the membrane.
Chemical: An addition of coagulants or flocculants which form sludge's aggregates which are easily removed from the membrane.
http://www.citg.tudelft.nl/fileadmin/Faculteit/CiTG/Gezondheidstechniek/doc/Proefschriften/Proefschrift_Pawel_Krzeminski.pdf
Hoping this will be helpful,
Rafik
Hi Rafik,
Thanks for your reply!
I am using membranes for gas exchange only. So I guess I can't use physical approach for harvesting sludge.
I will look for chemical way. In my case, there is strong biofouling of the membranes. I need something to break this biofilm.
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