Oil and grease extraction and aromatics BG

At the forum of the Bioremediation Discussion group

Question Nicole Merkl:
I do total oil and grease (TOG) extraction with methylene chloride. Does
anybody know which fraction is extracted last? E.g. is it true that the
aromatics get extracted rather late and their content in the final sample
can therefore be influenced by extraction time? Can you recommend any
literature concerning this point?

Answer:
what is the intent to do the extraction - determination of total oil and
grease?
In this case it is not clear, why to worry about the aromatics. They would
normally constitute only a minor part of the whole extracted fraction, that
means in between the limits of error.
If the intent is to gain a fraction for further analysis, then the targeted
compounds are essential for evaluation of the extraction behaviour.
The order of extraction will depend further on the interactions with the
matrix (aromatics sorbed at a clay might desorb later, aromatics
partitioned into oil will not).
The chance of desorbing later is greater for PAH, and the 'unresolved
hydrocarbon fraction in the GC' than for alkylbenzenes and 'normal'
hydrocarbons.

Any comments?

Oil and grease extraction and aromatics BG

At the forum of the Bioremediation Discussion group

Question Nicole Merkl:
I do total oil and grease (TOG) extraction with methylene chloride. Does
anybody know which fraction is extracted last? E.g. is it true that the
aromatics get extracted rather late and their content in the final sample
can therefore be influenced by extraction time? Can you recommend any
literature concerning this point?

Answer:
what is the intent to do the extraction - determination of total oil and
grease?
In this case it is not clear, why to worry about the aromatics. They would
normally constitute only a minor part of the whole extracted fraction, that
means in between the limits of error.
If the intent is to gain a fraction for further analysis, then the targeted
compounds are essential for evaluation of the extraction behaviour.
The order of extraction will depend further on the interactions with the
matrix (aromatics sorbed at a clay might desorb later, aromatics
partitioned into oil will not).
The chance of desorbing later is greater for PAH, and the 'unresolved
hydrocarbon fraction in the GC' than for alkylbenzenes and 'normal'
hydrocarbons.

Any comments?

Water and Wastewater.com Help Forum - Destruction of biocides

Water and Wastewater.com Help Forum - Destruction of biocides

Question from Miguel Blabia
We have a wastewater coming from portable toilets,and with a high content of biocides.Before to send it to a biological treatment plant it must destroy biocides, otherwise,all bacteries in the biological system will killed.
How can we do that destruction?

Answer

Dear Miguel Blabia,

Victor Santa Cruz made the point, destruction mode/efficiency will depend on the biocide in question.
As far as I know formaldehyde based and chlorine based chemicals are used in this field. I would try to use oxidation with cautious addition of hydrogenperoxide or ozonation.
The Alken Murray company states on their websites that
"Alken® Treat-A-Loo provides high-quality, low-priced treatment for mobile and portable toilets"
(http://www.alken-murray.com/PROFILE.HTM).
Eventually, there is a possibility to switch to 'biology-based' solutions for toilet cleaners.

Any input from out there? -
biocids used in toilet cleaners?
destruction in this type of wastewater?