Re: Aquatic Plants Digest V2 #190

> From: Cynthia Powers <cyn at metronet_com>
> Date: Tue, 10 Sep 1996 17:08:58 -0500 (CDT)
> Subject: Sulfate-utilizing plants
> - ---------- Forwarded message ----------
> Date: Tue, 10 Sep 1996 14:36:18 -0400
> To: Aquatic-Plants at actwin_com
> From: jbravo at cimm_cl (jorge bravo)
> hello
> I work in the minig and metalurgical research center, and have some problems 
> whit big levels of sulfate in wastewater.  This water go to sea for the 
> river and the leves of sulfate are about 2.000 ppm.  and need some treatment 
> for this wastewater.
> Do you know some  acuatic-plants which accumulate sulfate in their  tissues??

The ocean is full of sulfate, so if you get the water there, I'd think it 
would be just a matter of diluting it, as long as sulfate is the only 
contaminant of concern.  I assume that the problem is with diluting the 
sulfate out into the freshwater system around these mines.

I don't have specific information on sulfate-accumulating plants.  
Generally plants uptake sulfate for incorporation into the amino acids 
cysteine and methionine, but that is a minor demand.  

Have you thought about chemically precipitating the sulfate with calcium 
hydroxide?  The downside there is that the pH of the treated water is 
going to be outrageously high, which could theoretically be brought down 
with carbon dioxide, I guess.  Calcium sulfate is reasonably inert.  You 
could make wallboard with it, I guess.

What were you planning on doing with the sulfate-laden plants?  How much 
volume of 2,000 mg/L sulfate water are you treating daily?  

The other option is anaerobic reduction of sulfate to H2S, but that is not
going to make you any friends with the neighbors, and I suspect that
depending on what you are mining, this sulfate might have started life as
sulfide ions, right?  So you have already been there, done that, it
doesn't work.