Automatic and Unattended Monitoring of Heavy Metals in Waters

with Long-term Stability of the Measurements and with no Toxic material needed

Øyvind Mikkelsen and Knut SchrøderSensAqua AS, Norway

andNorwegian University of Science and

Technology (NTNU)Department of Chemistry

Trondheim, Norwaywww.sensaqua.com

Helsingborg

September 2015

Weather data- are collected by automatic weather stations and the

results are transferred automatically to a central unit, frequently also available immediately to the public via Internet.

But pollution data- are normally collected manually by field visits and the

samples are then brought to laboratories for analysis.

Several resources are spent annually for sample collection and laboratory analyses of heavy metals

OUR METHODS OPEN FOR DOING MUCH OF THIS AUTOMATICALLY

like what has been done for years in meteorology

Advantages• Possibilities to act immediately if the results exceed

given threshold values

• A great number of data will be available for processing

• Low costs, then several sources can be monitored

• If it is wanted, the data can be immediately available for the general public on the Internet

For quality assurance, conventional sampling and analyses in a laboratory are performed from time to time for comparison.

Analyses can in general be performed in three different ways:

• Samples are brought to laboratories to be analyzed with advanced instruments. A huge number of methods are available

• Direct field single analyses. Paper strips methods are very convenient in addition to the use of simple instruments like pH-meters, photometers etc.

• Continuous and on-line remote monitoring in the field.(dealt with in the present presentation)

An improved and more complete environmental monitoring program can be established by combining manually sampling - doing analyses in the laboratories and continuous monitoring in the field - using automatic equipment.

Then it will be possible immediately to detect pollution, immediate action is possible - and the methods can mutually verify each other.

Norway; 139 rivers, 20 incineration plants, 2500 water purification plants.

Europe ……

USA; 5000 already existing stations where heavy metal monitoring may be implemented, 14400 mines, 4000 industrial plants, 54000 water purification plants

Kina; 111 already existing stations where heavy metal monitoring may be implemented, 3000 industrial plants

Japan;135 rivers, 55 lakes, 1,400 incineration plants, 3,000 sewerage treatment plants, 1,500 water purification plants.

India; 72 already existing stations where heavy metal monitoring may be implemented

Korea; about 350 stations where heavy metal monitoring may be implemented

Any needs for monitoring,what is there already…?

- water purification plants and rivers in metropolis - implementation in existing stations monitoring other

environmental parameters - mining and metallurgical industry

- construction work - incineration plants and waste industry- petroleum industry, offshore installations, and shipping- aquaculture- laboratories

Any needs for monitoring, where…?

• Monitoring of environmental parameters are in general carried out with field sampling followed by analyses in a laboratory.

• There are very limited possibilities to perform remote and automatic monitoring of waters and effluents, except from simple parameters, like pH and conductivity, which is a great drawback.

How to monitor..?

What can unattended be measured in waters?

• pH• Temperature• COD, TOC and other major components• Conductivity• Turbidity and colour• Flow rate and water level• Some bacteria etc.

But heavy metals are not on this list, and it is a great interest to be able to offer integrated

systems also including heavy metals

Why are the heavy metals not on that list?

But before this is answered:What kind of chemical methods

are used for such monitoring?

The main problem in remote monitoring is when the concentrations are at trace levels - and too sophisticated instrumentation is required.

This explains why heavy metals are not on the given list.

The very great difference between having a method which works fine in a lab.

Doing the same unattended and remotely in the field has to be emphasized.

Too much published work is done in the laboratory only and then assumed to be adaptable to be used the field.

Different methods for remote monitoring….

• Long-time stability of the measuring system i.e. sufficiently long periods between required manual maintenance

• Acceptable sensitivity

• No use of toxic materials in the measuring system like liquid mercury and mercury salts

• Not too expensive installation costs, this to allow installation of several units, and also considering that the remote installations might be stolen or destroyed

• Presence of electricity (solar cells and batteries can be used if frost is not present)

• Availability of Internet or another telecommunication system

Requirements for remote monitoring

In voltammetry we get information about the analyte by measure the current developing on the surface of an electrode as a consequence of a redox reaction.

Here, the electrodes are essential - they sense the compounds to be measured.

Voltammetry

• Sufficient high overvoltage to allow the measurements without interferences from hydrogen gas formation

• Sufficient long term stability without need of maintenance

• Sufficient sensitivity to allow monitoring of the pollutants

• That non-toxic material is used (very important for off-laboratory methods)

• Not too expensive material needed

Totally there are five requirements for making such automatic voltammetric analyses useful:

The essential is to obtain long time stability, combined with sufficient overvoltage during the measurements to avoid the formation of hydrogen gas on the electrodes.

This because the corresponding flow of current destroys the measuring signal.

How to solve that…..?

Alloy electrodes!

Liquid mercury or deposit of mercury film made from a mercury salt Solid and environmental friendly alloy sensors

How to find suitable electrodes which give sufficient overvoltage?

Alloying a metal with high hydrogen overvoltage with a metal with low hydrogen overvoltage.

A significant increase in the hydrogen overvoltage is observed for the alloyed metal, even for small additions (2–4 %).

Alloy electrodes

The use of solid alloy electrodes cannot be new in voltammetry?

Very astonishing this was never done before we did our first experiments in 1997.

One explanation is possibly that it was believed in polarography/voltammetry that an electrode only worked properly being a one-component metal. Consequently nobody had tried.

Later, and after our patenting, several publications appeared.

The new system has some interesting advantages:

• Easy to implement in online apparatus• Non toxic• Stable over a long time without attendance• It can be used for detecting a range of

different heavy metals

Actual measuring electrodes

We use two different types of electrodes:

Gold based alloys, for monitoring metals in the more positive potential range (like As)

Silver based alloys, for monitoring metals in the more negative potential range (like Zn)

In general we cannot use gold or silver alone because the lacking of overpotential for preventing hydrogen gas formation, and we cannot use the alloying metal alone because of passivation of such electrodes over time.

We use solid and homogeneous electrodes and not film electrodes.

This because film electrodes will require frequent replating, lowering the long-term stability between the need for physical attendance.

• The methods have been patented internationally, and have been verified over a long time.

• Our research started at Norwegian University of Science and Technology (NTNU) about 20 years ago, and the first patent was filed in 1998.

Cadmium

Voltammetric detection of Cadmium

4.4

5.4

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12.4

-1 -0.8 -0.6 -0.4 -0.2 0E (V)

I (m

A)

Electrode system:

Working E DAMCounter E PtReference E Ag/AgCl/KClNH4Ac (0,05M)

Some examples

Zinc detection in waste water, DAM electrode

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-1500 -1000 -500 0

E (mV)

I (m

A)

Sample

Sample+ 200ppb Zn

Zinc

Electrode system:

Working E DAMCounter E PtReference E Ag/AgCl/KClNH4Cl (0,05M)

Some examples

Detection of lead in waste water. DAM electrode in

HCl (0.01M)

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90

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-600 -400 -200 0

E (mV)

I (m

A)

Sample

Sample+ 10PbSample+ 20Pb

Lead

Electrode system:

Working E DAMCounter E PtReference E Ag/AgCl/KClHCl (0,01M)

Some examples

Detection of mercury at gold electrode.

0.75

1.25

1.75

2.25

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0.2 0.4 0.6 0.8 1E (mV)

I (m

A)

Hg 10 ppb

Hg 10 ppb

Hg 20 ppb

Hg 20 ppb

Hg 30 ppb

Hg 30 ppb

Mercury

Electrode system:

Working E Au-BiCounter E GCReference E Ag/AgCl/KCl10mM HNO3 + 10mM HCl

Some examples

No liquid mercury

No mercury salts

No toxic materials

X

The SensAqua ATMS 500 Equipment

The new version is SensAqua ATMS 600v3, but the principles are the same

Inside the ATMS 600 v3

ATMS 6011

v3

The SensAqua ATMS 600 Equipment

The chemical principles for the measurements are unchanged.

Previously 230 V AC was used. The ATMS 600 uses 12 V AC (or adapter). This is advantageous if electricity is not available and solar cells or other sources are used.

Previously we used two cabinets, one for the electrode system and one for most of the electronics and the industrial PC to be used for all data processing. In the ATMS 600 series, however, all the electronics is on a microprocessor card and a PC is not needed except from input and output of data and graphical presentation. Normally a laptop or network is used for such purposes. The ATMS 600 consists of one cabinet only, with less weight and easier to handle

The ATMS 600 has• Higher stability over time by using a microprocessor card instead of the PC-processor• More simple maintenance because the card is the only to be replaced if needed• Increased sensitivity also because Square Wave Voltammetry is included• Less weight with one cabinet only • Higher stability because no computer is needed except from input and output of data and data processing. The PC can be

operated remotely, and can be removed during running.

What is new for the ATMS 600 version 3?The chemical principles used and the sensor system are the same, and the mechanical parts and the outer design are

unchanged

The electronics/microprocessor card is extensively redesigned to achieve improved sensitivity and stability

The software (POS) is now also compatible with Windows 7 (32 or 64 bit)

In addition to the previous automatic updating of the software, automatic updating of the firmware is also included.

After being tested at by NEMKO (www.nemko.com), the version 3 in certified for the CE-marking

The SensAqua ATMS 600 equipment compared with previous versions

Electronics in ATMS 600v3

cell 2 cell 1

R C W R C W

Fuse

USB

26-pin plug to the unit

Xport(net)

Applications

Prior to an installation of an automatic measuring system, this has to be adapted to the actual water to be monitored and some information about that water are required: Expected concentration ranges and threshold values of the actual metals and levels of possible interferences.

Then a suitable working electrode is selected as well as the supporting electrolyte, the potential range and the deposition time to be used.

It is recommended to start up with laboratory tests with the ATMS using pure water with the actual metals added. The application notes in the product manual is useful for that. The next step is to repeat with real solutions. Finally, time has come to move to the field station for automatic monitoring.

Pilot projects in Norway:

Løkken

HVS

TBS

From Raubekken

Continuous analyses of zinc, iron, and copper for a time period of four months (middle of January to middle of May, 2004), in polluted river water (Raubekken) at Løkken Verk, Norway. The point in red are results from ICP-MS analyses.

We can see from here that the speciation (of iron) is a very important factor.

Copper mine pollution

Heimdal incineration plant outside Trondheim

Continuous remote monitoring of zinc, cadmium and lead. Scrubbing wastewater added NH4Cl (to 0.05M). DPASV, 120 s dep. time at -1300mV, scan rate 15 mV s-1, mod. pulse 50 mV.

Incineration plant

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08-aug-03 18-aug-03 28-aug-03 07-sep-03 17-sep-03 27-sep-03 07-okt-03 17-okt-03

Date

Conc

(m

g/L)

Continuous monitoring of mercury in purified scrubbing water at Heimdal incineration plant Trondheim, Norway.

Continuous monitoring vs. lab

An interesting project:Forecasting of earth quakes

Some indications show that there is an increase of the level of heavy metals in the groundwater prior to an outbreak of an earth quake.

Automatic monitoring of heavy metals can then be used for such forecasting.

A collaboration with geologists at University of Stockholm in Sweden is established to work out these new possibilities.

Automatic monitoring of labile copper

with special focus for aquaculture installations with recycling of water

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 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 thesystem via Internet)

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

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

The measuring system

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

Platinum counter electrode

Silver/silver chloride reference electrode for the reference circuit

Analytical cell; test solution + HCl (0.01 M)

The sensor system

Voltammogram (system response) for a scan with and withoutaddition of 5 g/l Cu2+

Single plots with and without addition of copper

Long term measurements of copper

Results from measurements over time

Conclusions from the monitoring of copper

From 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.

Mikkelsen, Øyvind and Schrøder, Knut H.Dental Amalgam in Voltammetry - Some Preliminary Results.Analytical Letters 2000, 33, 15, 3253-3269.

Mikkelsen, Øyvind and Schrøder, Knut H.Alloy electrodes with high hydrogen overvoltage for analytical use in voltammetry. Some preliminary results. The Analyst 2000, 125, 12, 2163-2165.

Mikkelsen, Øyvind, Schrøder, Knut H. and Aarhaug, Thor A.Dental Amalgam, an Alternative Electrode Material for Voltammetric Analyses of Pollutants.Collection of Czechoslovak Chemical Communications 66, 3, 465-472 (2001).

Mikkelsen, Øyvind and Schrøder, Knut H.Voltammetry using a Dental Amalgam Electrode for Heavy Metal Monitoring of Wines and Spirits. Analytica Chimica Acta. 458, 1, 249-256 (2002).

Some documentation

Mikkelsen, Øyvind and Schrøder, Knut H.Amalgam Electrodes for Electroanalysis.Electroanalysis (2003) 15(8), 679-687.

Mikkelsen Øyvind, Skogvold Silje Marie, Schrøder Knut H.,Gjerde Magne Ivar, Aarhaug Thor AndersEvaluation of Solid Electrodes for Use in Voltammetric Monitoring of Heavy Metalsin Samples from Metallurgical Nickel Industry.Analytical and Bioanalytical Chemistry (2003) 377, 322-326.

Mikkelsen, Øyvind and Schrøder, Knut H.Voltammetric Monitoring of Bivalent Iron in Waters and Effluents, using a DentalAmalgam Sensor Electrode. Some Preliminary Results.Electroanalysis (2004) 16(5), 386-390.

Mikkelsen Øyvind, Nordhei Camilla, Skogvold Silje M., Schrøder Knut H.Detection of Zinc and Lead in Wine by Potentiometric Stripping on NovelDental Amalgam Electrodes.Analytical Letters (2004) 14,37, 2925-2936.

Mikkelsen Øyvind, Skogvold Silje M. and Schrøder Knut H.

Continuous Heavy Metal Monitoring System for Application in River and Seawater.

Electroanalysis (2005), 17(5-6), 431-439.

Mikkelsen Øyvind, Skogvold Silje M. Schrøder Knut H.

Electrochemical Properties and Application of Mixed Silver-Bismuth Electrodes

Electroanalysis, (2005) 17(21), 1938-1944.

Mikkelsen Øyvind, van den Berg Constant M. G., Schrøder Knut H.

Determination of Labile Iron at Low nmol L-1 Levels in Estuarine and Coastal

Waters by Anodic Stripping Voltammetry.

Electroanalysis, (2006) 18(1), 35-43.

Øyvind Mikkelsen, Kristina Strasunskiene, Silje Marie Skogvold,

Knut Henning Schrøder, Camilla Constance Johnsen,

Marion Rydningen, Patrik Jonsson, Anders Jonsson

Automatic Voltammetric System for Continuous Trace Metal Monitoring in

Various Environmental Samples.

Electroanalysis 2007(19-20):2085-2092.

Øyvind Mikkelsen, Kristina Strasunskiene, Silje M. Skogvold,

Knut H. Schrøder

Solid Alloy Electrodes in Stripping Voltammetry.

Current Analytical Chemistry, (2008), 4(3), 202-205.

Conclusions and intentionsOur method opens for new possibilities for

environmental surveillance

It has low costs and enables one to carry out water monitoring in a great number of water systems

The pollution data can immediately be available to the general public e.g. via Internet

Legal action can be taken immediately if irregularities appear in order to obtain better water quality and less polluted sewage systems

Our intentions here are to introduce the new possibilities.

Contacts

Knut Schrøder, Professor, General Manager

EMAIL: Knut.Schroder@sensaqua.com

Øyvind Mikkelsen, Professor, Chairman of the Board

EMAIL: Oyvind.Mikkelsen@sensaqua.com

SensAqua AS www.sensaqua.comCompany registration details:

http://w2.brreg.no/enhet/sok/detalj.jsp?orgnr=988639346

Norwegian University of Science and Technology (NTNU) www.ntnu.no

Actual groups of customersThe determination of heavy metals related to monitoring of the environment has gained increasing interest. Our new method enables one to carry out such monitoring unattended and automatically on site, consequently the current control of short time effluents can be done. Traditional methods by collecting samples to be brought to well equipped laboratories will render this impossible because only a discrete number of samples can be collected.

Our new method can monitor the levels of more important heavy metals and trace metals (e.g.: nickel, cobalt, zinc, arsenic, iron, cadmium, lead, chromium, copper, silver, mercury, thallium and manganese) in water and effluents in actual concentrations to classify drinking water, effluents and process water from industrial processes:

a) Private and public institutions – surveillance of quality of municipal drinking water and effluents

It is a huge market potential in Europe Asia and the USA, UK and several other countries consider the importance of public access to environmental data, with the new possibilities to present heavy metal levels on-line on Internet.

b) Already established automatic monitoring stationsA great number of automatic measuring stations exist already to

register quality parameters for water (pH, conductivity, turbidity etc.). None of them could monitor heavy metals. Here is a huge market potential. Such stations are established with tenders in extensive international competition. By now to include heavy metals among the parameters will give competition advantages. It is expected that the international regulations for water control will be modified to include the new possibilities.

c) Metal and metallurgical industry – Power plantsControl of effluent water and process solutions are very important

for the actual companies. Sens Aqua AS offers tailored solutions for the actual industry.

d) Terminated industrial areas and minesIn particular when the production or a mining activity is terminated

the problem with the leakage of heavy metals to nearby rivers and water systems can be serious as nobody feels the responsibility and environmental damage often appear. We can see this in the river system several places in Norway, USA, China and many other countries. The marked potential for automatic monitoring in such areas is high.

e) Construction workHere we have activities related to road construction and

buildings. Such activities can change the natural surroundings with run-off of heavy metals. This can be changes of pH when uncompacted material is removed which might increase the level of heavy metals in the ground water or in the run-off water. The same is with cleaning of tunnels and other road constructions. Road authorities have shown interest in using mobile units for monitoring during such constructions. SensAqua AS can offer such units.

f) Oil and shippingHere are new possibilities for environmental monitoring

around oil installations in seawater. Additionally, discharge of heavy metals from cleaning and emptying of oily water sump tank from ships and offshore installations are actual fields of operation.

g) Solid waste and incineration plantsLeakage of heavy metals from deposits of solid waste can be

monitored continuously. Similar is for incineration and destruction plants by controlling the solid as well as the smoke and the effluent water being used to purify the smoke.

h) Sea farmingI sea farming materials containing copper and other metals

are used and monitoring of heavy metals in the water is important to obtain optimum production with a good and safe quality for the consumers.

i) Fundamental research and laboratory useIn fundamental research in biology, geosciences etc. where

continuous monitoring is needed to follow seasonal variations. A market is also for use in laboratories, including educational purposes.

Our home page with more information: www.sensaqua.com

Finally we can conclude that our system fulfills the needed requirements for automatic and unattended monitoring of heavy

metals.

Thank you for your attention!