Date: 20 Oct 1997
From: "Gaudet, Mario MPA/DFA" <mariog@gov.nb.ca>
To: AQUA-L <AQUA-L@killick.ifmt.nf.ca>
QUESTION:
I try to find a system that would remove iron and manganese present in salt water (28ppt, pH 7.7, Temp. 6.5 C) pumped from the ground (for some; "salt water well"). The concentration of iron and manganese is 0,21 mg/l and 7,38 mg/l respectively and the total
suspended solides are 10 mg/l. I have read that some systems do exist for this type of removal but I would like to receive some feedback from people whom have had experience in salt water use. The water will be used for growing macro algae in a flow-through system.
Also, I would like to know if such systems remove other nutrients and at what concentrations.
Mario Gaudet
Department of Fisheries and Aquaculture
Province of New Brunswick, Canada
P.O. Box 1010
Shippagan, NB
E0B 2P0
Tel: (506) 336-3013
Fax: (506) 336-3057
E-mail: mariog@gov.nb.ca
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COMMENTS 1:
Date: 20 Oct 1997
From: SGNEWM@aol.com
To: AQUA-L@killick.ifmt.nf.ca
Ozonation would do the trick.
Steve Newman
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COMMENTS 2:
Date: 21 Oct 1997
From: Jerome HUSSENOT <Jerome.Hussenot@ifremer.fr>
To: AQUA-L@killick.ifmt.nf.ca
In the soil the form of Fe is generally Fe++ (high solubility). When the salt well water is pumped there is a reoxygenation and Fe++ changes to Fe+++ combined with a precipitation because of low solubility.
You can use this principle using successive (i) intense oxygenation and (ii) mechanical filtration or decantation to stop the particulate Fe+++ compounds.
Dr Jerome HUSSENOT
"Aquaculture-Environment" team leader
Ecology and Pond Management
Centre de Recherche en Ecologie Marine et Aquaculture (CNRS-IFREMER)
B.P. 5
17137 L'HOUMEAU, FRANCE
Voice: Int. +33 5 46500611
Fax: Int. +33 5 46500600
E-mail: jhusseno@ifremer.fr
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COMMENTS 3:
Date: 21 Oct 1997
From: howard <dryden@globalnet.co.uk>
To: AQUA-L@killick.ifmt.nf.ca
We have supplied any systems for the removal of iron and manganese
from ground water in both freshwater and marine systems. Firstly, the ground water will usually have a pH of around 7.8 in a marine system, there may also be a high level of carbon dioxide, gas supersaturation with nitrogen, low oxygen levels and high volatile organic compounds. The first stage is to gas-strip the water under slight negative pressure. This process will remove the volatile components including the carbon dioxide and increase the pH back up to 8.1 to 8.3. The gas stripping will reduce the partial pressure of nitrogen below 100%, it will also increase the oxygen levels to 96 to 97% saturation and oxidize the iron and manganese.
The metals now form small precipitates, these could be partially removed by sedimentation, but this is never 100% successful. It is absolutely essential that all of the metal ion particles are removed from the water. If any metal particles are left in suspension they may become trapped in the gills of the fish. Any metal in the gills will cause mechanical irritation, the metals will also act as a focus for free radical production on the gill surface which will oxidize the surrounding tissue. This will lead to bacterial gill disease, fungal infections and even mortalities among small fish. The water must therefore be mechanically filtered using a pressure sand filter. In addition to the sand or AFM (Dryden Aqua Advanced Filtration Media) we use MagpHlow media, this product is composed of magnesium oxide. Any metals remaining in solution will form insoluble salts on the surface of the MagpHlow media. During a back-flush of the sand filter, the MagpHlow media is scrubbed to remove the metals in the back-flush water. The process is now complete after the sand filtration and the water is ready to use.
Further notes: the level of manganese in your water is horrendous, you will probably have to go off-line with the de-gasser and clean out the manganese every 3 to 6 months.
Howard T Dryden
Dryden Aqua
Scotland
Tel 44 018758 22222
Fax 44 018768 22229
E.Mail howard@DrydenAqua.com
Web Site http://www.DrydenAqua.com