2 replies to this topic

[peaston]

HI there, just a quick question regarding the retentate from reverse osmosis processes...

would discharging the retentate into the ocean have any effects?

obviously, retentate is just highly concentrated seawater, would this have an effect on aquatic life or the salinity of the sea? - was thinking that maybe in the long run, but i wasn't sure whether these small batches would have a huge significant impact on the ocean initially.

Many thanks in advance

Andrew

[ankur2061]

Andrew,

It depends on the local regulations for discharge into the sea for ionic content of Sodium, Calcium and Magnesium. The retentate could also contain very small levels of toxic metal residue such as Aresenic, Cadmium, Mercury, and, Cobalt which are only acceptable in ppb (parts per billion level). Toxic metal residue can immediately destroy marine life including coral reefs.

You need to strictly check and monitor the retentate discharge in view of the above mentioned issues.

Regards,
Ankur.

[kkala]

A topic on all kinds of pollution created by a big sea water reverse osmosis plant can be seen in http://www.ide-tech....lant-ashkelon-0. See "damage to marine environment" and "interaction with the sea" for the environmental impact requested. Only good dispersion of retentate into sea water is understood to be tried in the referred plant.
Of course local legislation has to be taken into account. High temperature could also be an issue. An environmental study for a local Power plant, using sea water cooling, had to accept Δt = 5 oC between sea water in and out. If retentate were hot, disposal into sea would require a specific permit (that may or may not be given).
In case that reverse osmosis has to purify water contaminated with harmful agents ( http:// en.wikipedia.org/wiki/Reverse_osmosis ) any compounds are possible in retentate. Speaking of plants producing potable water, toxic metals in retentate are not expected. Retentate seems to contain sea water compounds at double concentration (max). It could contain toxic metals, if sea water intake were taken from e.g. a harbor; but this is not proper for the potable water production. Nevertheless information on cases of toxic substances in retentate (of plants producing potable water) would be welcomed.