EPA calls to eliminate Teflon precursor

The Environmental Protection Agency (EPA) on Jan. 25 announced a global stewardship program that calls for voluntary withdrawal of use of toxic compound perfluorooctanoic acid (PFOA).

" PFOA is the key ingredient used to manufacture Teflon or fluoropolymers, which are used in the manufacture of a wide range of non-stick and stain-resistant surfaces and products."

' DuPont responded quickly to the invitation. In a statement released on Jan 27, the company said it "has committed to virtually eliminate the sources of exposure to PFOA from our manufacturing operations and products by 2015." '

Source US EPA

Floating floc - Discussion at the Waterandwastewater Help Forum

Question

We are using a new parts washer detergent (mainly Sodium hydroxide, tkpp, soda ash), and have started to have floating flocs.
Some white residue got past the sedimentation tanks, sand filters, 1 micron cartridges, and finaly clogged the RO membranes.

After cleaning the membranes we removed a white solution, that when floculent was aded produced white strings.

Any ideas what this could be?
Is there a chemical that can de-emulsify the oil from the detergent?

Answer

as you said, you have an alkaline cleaner without or with low content of surfactant. Probably part of the oil/grease (mineral oil?) is saponified and precipitated as unsoluble soaps by water hardness? Soaps will be also precipitated by cationic flocculants.

By neutralization or shifting the pH to slightly acidic conditions the emulsions should be demulsified.

Reply
It changed everything!

I reduced the PH to 7. The foam disapeared and small oil particles started to float, however flocculation ceased, I played arround with the qty of floc/coag.and could not fix this situaton.

I returned PH to 9 and continued to produce white floating flocs.

Answer
as your contamination is oil removal by flotation or an oil/water separator is much more efficient than sedimentation. Sedimenting flocs can only be achieved by heavy ballasting, maybe using bentonites or a high dosage of precipitated iron salts.

The situation with demulsification and flocculation is the following.

The emulsion droplets are stabilized by negativ surface charges at high pH. Adding cationic polyelectrolytes or iron/aluminum ions flocculation or coagulation is achieved.
At neutral pH emulsion droplets are destabilized and coalescence, but will not interact with cationic additives. (Question - is the coalescence efficient enough to remove the oil by an oil-water separator or oil skimmer?).
If destabilization is not efficient enough you might either readjust the pH to alkaline and add a low amount of cationic flocculant to enhance separation or adjust the pH to slightly acidic and add an anionic flocculant (low amount). In both cases the oil droplets will float.

New Study Raises Questions About Sustainability Of Metal Resources

Pollution Online SOURCE: The National Science Foundation

'Researchers studying supplies of copper, zinc and other metals have determined that these finite resources, even if recycled, may not meet the needs of the global population forever.'

The problem might only be resolved by improving recycling and develope new technologies with less demand on these resources

Study: Storing Carbon To Combat Global Warming May Cause Other

Durham, N.C. — Growing tree plantations to remove carbon dioxide from the atmosphere to mitigate global warming -- so called "carbon sequestration" -- could trigger environmental changes that outweigh some of the benefits, a multi-institutional team led by Duke University suggested in a new report. Those effects include water and nutrient depletion and increased soil salinity and acidity, said the researchers.

SOURCE: Duke University

Removal of sulfate and phosphate by flocculation

SpringerLink - Article http://www.springerlink.com/content/3323738214278l71/:
Removal of sulphate and phosphate from aqueous solutions using a food grade polysaccharide as flocculant
by Anuradha Mishra and Malvika Bajpai
Department of Chemistry, University Institute of Engineering and Technology, CSJM University, Kanpur, 208 024, India