Automatic monitoring of labile copper

with special focus for aquaculture installations with recycling of water

ATMS600

Copper and other heavy metals can be monitored by sending samples to a laboratory or by automatic and continuous in situ monitoring.

The advantages by using automatic monitoring are obvious, but no acceptable method has so far been available.

As a result from research in analytical chemistry at Norwegian University of Science and Technology (NTNU) in Trondheim, Norway, new methods

are developed enabling automatically to monitor heavy metals in waters, and this is patented internationally.

The company SensAqua AS in Trondheim and Oppdal takes care of the commercial aspects of this activity.

As given below, we have worked out a method for continuous monitoring of copper of particular interest for aquaculture with reused water. A pilot station has been established at Nofima AS in Sunndalsøra, Norway. This

has worked satisfactory in a testing period of about seven weeks.

Control system and measuring unit

The software program POS for controlroutines and data presentation(including communication with the systemvia Internet)

Dosage pump for addition of electrolyte (1 M HCl being diluted to 0.01 M in the sample)

HCl (1 M) reservoar, Consumption; about 1 liter for about 3months for once an hour continuous use .

The measuring system

Working electrode, gold based alloy designet for monitoring of low concentrations of copper

Platinum counter electrode av platina for the electrolysis circuit

Silver/silver chloride reference elektrode for the reference circuit

Analytical cell; test solution + HCl (0.01 M)

The sensor system

Voltammogram (system responce) for a scan with and without addition of 5 g/l Cu2+

Single plots with and without addition of copper

5/1/2011 0:00 5/9/2011 12:00 5/18/2011 0:00 5/26/2011 12:00 6/4/2011 0:00 6/12/2011 12:00 6/21/2011 0:00 6/29/2011 12:000

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Analyses of Cu (ppb) in the period 6th May to 26th June 2011 Cu (ppb)

Date

[Cu]

g/

l

Shut down timebecause of electricitybreakdown

Running-in period

Addition of Cu(II) corresponding to 5 ppb (solution + standard = 6,6 ppb)

Shut down timebecause of electricitybreakdown

Measuring rate; 1 recording/hour (no maintenance on the system in that periode)Average concentration of copper in that period 1,29 g/l, max/min concentrations 2,3 and 0,5 g/l respectively.

Lang term measurements of copperResults from measurements over time

CONCLUSIONFrom the results during the testing period it is found that the concentration of copper in the water can be monitored continuously with satisfactory results.It was electricity breakdown for some days during the actual period, and the results were then lost, but it was found that the breakdown did not affect the further measurements.We assume that the monitoring can be run continuously at least one month before manual attendance is needed.We also tested by comparing after addition of standard copper solution, with satisfactory results.The method is specially designed for copper, but other metals can also be monitored.