In organic agriculture, black table olive debittering is known to use high level of salt to achieve this goal. But the wastewater produced needs be treated before its disposal in the nature. Is there any approved method to deal with this dark salty wastewater?
There are a couple of different ways depending on the volume of water and salt concentration. If you have time, and the volume is reasonable, the first step would be to use a knock out tank to settle out a large portion of the salts. The supernatant can be pulled from the top. If the salt concentration is low enough, the water can be biologically treated to reduce some salt and any organic matter.
By adding calcium nitrate to release the salt from the exchangeable sites then leach the salt
In our lab, we use electrodialysis to achieve desalination. But before that, you need to remove organic matters in the waste water to reduce ion-exchange membrane fouling during the process of electrodialysis.
Thank you all for your answers and contributions. Dear Dr Teresa, can we make the salt precipitate then after collect the supernatant and treat the organic matter in the water? Dear Pr Choukr-Allah, calcium nitrate can do the previous task to collect the supernatant, this suggest that we will have a solide state of the salt in the bottom of the reservoir (660 cubic meter with 520 cubic meter of the wastewater). Dear Dr Liu, you mean reverse osmosis by electrodialysis or this another mean, organic matter could be treated by oxygenation and/or biological inoculation, but the last one is difficult with regard to the high salinity. Dear Dr Stefanakis, do you have any related paper to the Constructed Wetland systems? it would be great if you share this information.
Thank you all
Khalid
Khalid-
Yes it is possible to precipitate the salt (knock out tank for simple settling, chemical additive such as add/base to precipitate as a metal hyxodroxide, or another physical-chemical method), followed by treatment of the organic material. As mentioned by Alexandros above, wetlands are also very effective at addressing salts.
Teresa, thank you very much. So the treated water could be used again in agricutlure?
A few years ago we tested methanisation on olive oil wastewater. It worked but it was necessary to first dilute it 10 times. So, it was not realy a good deal as we polluted more water.
We didn't continue this experiment but, could it be interesting if we dilute it with another wastewater? It is a way to follow.
In fact, by using electrodialysis, I mean an ion-exchange membrane based desalination but not reverse osmosis. To remove organic matter before electrodialysis, a hybrid process of coagulation followed by sedimentation and ultrafiltration was adopted in our lab. This process shows its effectiveness in treating oliy wastewater containing high salinity. But, I don't know whether this process would be proper to your circumstance.
one of the economic solutions is not to mix washing water with conservation(high salt) waters then you have a small volume that can be sun- evaporated; washing waters(containing small amounts of sugars and polyphenols) are easily treated with conventional aerobic process
regards
Thank you all for your contributions and ideas. Finally, I think that we're going to choose the reverse osmosis method to treat this salty water. But before that , we have agreed to reduce the BOD by bubbling the water prior to reverse osmosis.
Thank you again
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