Dear researcher

My suggestion is use skimmers, your are able to study persian so go to this link and have a look at this paper about skimmers.

https://www.researchgate.net/publication/309413631_brrsy_alwdgy_ab_dryaha_bh_lkh_hay_nfty_w_tdwyn_rwshhay_astandard_mnasb_hdhf_an_mtalh_mrwry

Good luck.

Conference Paper بررسی آلودگی آب دریاها به لکه های نفتی و تدوین روشهای استاند...

Hi, in some cases the use of sodium hypochlorite (or other oxidizing agent) as pre-treatment could be used for the degradation of oily substances (depending on the type of oil). However, if the pH of the effluent is lower than 7, the use of hypochlorite would result to the formation of chlorine gas. The other issue would be the dosage, because an excess amount of an oxidizing chemical could have an negative impact on polymeric membrane.

Hi, you remark that with an active carbon filter you reduce only from 7.5 mg/l to 4 mg/l, which is strange to me because the active carbon is good system to reduce oils to low concentrations.

That's why I'm telling you to try to improve the result with activated carbon by changing the treatment conditions like: carbon type, pore size, activation conditions, contact time, circulation speed, carbon powder versus carbon in grain, carbon saturation percentage, contact temperature, contact pH, etc.

Assuming you have not tried it already.

I agree in investigating the efficiency of the activated carbon filter. Perhaps the contact time is just too low. Try adding several filters in series or experimentally decrease the flow in the existing filter.

Thank you all for your response. It was really helpful.

You can also use regenerable media. Osbor has shown good results. http://prosep.com/products-services/water/osorb-media/

Is this emulsified oil or non-emulsified oil? Food based or mineral?  Is this  dissolved(?) oil generated from the ECF? Not sure what you mean by dissolved oil (non-emulsified?)? Have you tried pre-treatment upstream to reduce the oil before ECF? 

It is non-emulsified oil I think and I should say that ECF removes oil very well but in the end 7.5 mg/l remains (the oil before ECF was much higher than this because of using soap in some steps of production)

Pre-treatment or process changes at the source is  the best way to reduce oil contaminant required to treat downstream. Also how you define the oil can influence the selection of the oil removal treatment system. Is it dissolved oil, emulsified or non-emulsified oil, food based or petroleum based? Depending on what type of oil  you have, select or pilot test the treatment processes. You could even try microwaving see if it works!

Some links below:

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Excerpt from link at  https://ecolink.com/info/oil-dissolving-solvents/

Because oil is a strongly non-polar compound, solvents that dissolve it are highly non-polar, and may feature an organic formulation that is high in volatile organic compounds (VOCs). Examples of oil dissolvers that are used for commercial and industrial oil removal applications include:

Acetone — Commonly used as a cleaner and in cosmetics that remove skin oil

Hexane — Frequently used as a solvent for dissolving various types of cooking oil

Carbon tetrachloride — Often used as a general cleaner in numerous industries

Diethyl ether — Infrequently used to dissolve oils due to its low flash point

Benzene — Commonly used in the quarry industry to extract oil from shale

If you are familiar with the safety profiles of oil dissolving solvents, you may recognize that these solvents have dangerous properties that make them unsafe for human use and toxic to the environment. Although typically cheap to purchase and highly effective for many types of oil removal operations, the long-term cost of using the solvents can be quite expensive indeed.

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See this article using organoclays at:

https://www.wqpmag.com/how-remove-emulsified-oil-wastewater-organoclays

http://wilsonemi.com/wp-content/uploads/2016/07/Removing-Emulsified-Oils-from-Wastewater.pdf

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http://www.ioscproceedings.org/doi/pdf/10.7901/2169-3358-2003-1-771?code=ampi-site

https://pdfs.semanticscholar.org/569e/d08ec26b6e64c0e13d2d5d33e030ea99705b.pdf

http://ro.uow.edu.au/cgi/viewcontent.cgi?article=4754&context=theses

http://www.nationalacademies.org/hmd/~/media/651D4FE664BE4F38862E2EB3A6C86BC8.ashx

http://www.mntap.umn.edu/greenbusiness/water/6-EmulsifiedOil.htm

https://www.spectrosci.com/product/infracal-2-atr-sp-oil-in-water-analyzer/?fileID=8a808189505a61330150a5b2df8f454c

http://news.mit.edu/2014/separating-finely-mixed-oil-and-water-0701

Some links this time to surfactants used in different applications. Surfactants/dispersants Might or might not help without knowing actual source and process requiring treatment. Maybe adding some may help ecf oil removal.

http://nanoparticles.org/pdf/Salager-E300A.pdf

https://www.researchgate.net/publication/7924070_Treating_chemical_mechanical_polishing_CMP_wastewater_by_electro-coagulation-flotation_process_with_surfactant/figures?lo=1

http://www.afcona.com.my/DispersingTechnology.pdf

https://www.acs.org/content/dam/acsorg/policy/acsonthehill/briefings/oilspillmitigation/congressional-briefing-presentation-on-dispersants-by-lee.pdf

https://etd.ohiolink.edu/rws_etd/document/get/csu1304363574/inline

http://www.cdpr.ca.gov/docs/emon/surfwtr/presentations/gouge_formulation_050510.pdf

https://www.dispersions-pigments.basf.com/portal/load/fid807190/Dispersing%20Agents.pdf

Article Treating chemical mechanical polishing (CMP) wastewater by e...

Is anybody here an activated carbon manufacturer who claims his/her adsorbent reduces 7.5 mg/l dissolved oil in treated wastewater to 0.1 mg/l!?

I would be very thankful to contact him/her.

Here is some links on UV/peroxide treatment processes which you could look at for dissolved oil:

http://www.aops-school.com/wp-content/uploads/2013/07/Summer-School-2015_Sorlini-S.pdf

http://www.calpoly.edu/~ceenve/enve/jsczechowski/enve436/projects/Hydro-Perox/H2O2-UV-Treatment.html

http://webcache.googleusercontent.com/search?q=cache:Hx68KeH0p2sJ:www.ambi-agua.net/seer/index.php/ambi-agua/article/view/216+&cd=12&hl=en&ct=clnk&gl=us

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=18&cad=rja&uact=8&ved=0ahUKEwipk8am5IPVAhVCQCYKHQZVD1o4ChAWCEswBw&url=http%3A%2F%2Fwww.ccsenet.org%2Fjournal%2Findex.php%2Fenrr%2Farticle%2Fdownload%2F57664%2F31914&usg=AFQjCNFv0ZEP-y3a0Sm3ezu7OZBboMAAHQ

http://www.all-llc.com/publicdownloads/ALLConsulting-WaterTreatmentOptionsReport.pdf

https://www.techneau.org/fileadmin/files/Publications/Publications/Deliverables/D2.4.1.1.pdf

http://www.scielo.br/pdf/ambiagua/v7n3/v7n3a03.pdf

https://journal.gnest.org/sites/default/files/Journal%20Papers/31-38_479_DINCER_10-1.pdf

http://iwtj.info/wp-content/uploads/2015/01/V.4-N.1-P.6.pdf

https://cdn.intechopen.com/pdfs-wm/29166.pdf

http://www.tandfonline.com/doi/abs/10.1080/01919510701459311

http://www.tandfonline.com/doi/abs/10.1080/09593332708618638

http://www.waterrf.org/PublicReportLibrary/4040.pdf

https://cdn.intechopen.com/pdfs-wm/52662.pdf

http://www.sciencedirect.com/science/article/pii/S0043135409007040

https://www.ncbi.nlm.nih.gov/pubmed/16548208

https://www.intechopen.com/books/physico-chemical-wastewater-treatment-and-resource-recovery/kinetic-modeling-of-the-uv-h2o2-process-determining-the-effective-hydroxyl-radical-concentration

http://www.tandfonline.com/doi/full/10.1080/09593330.2010.525750

http://www.h2o2.com/industrial/applications.aspx?pid=104