Pulse Technology Centre BV

Transcription

EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
EKO/GRID TM System for Cleaner Environment
MESOCOSM EKO/GRID STUDY AT EUTROPHICATED MATJÄRVI LAKE IN FINLAND
1. Background
Since 2008 the EKO/GRID technology has been tested and used in soil and ground water remediation
projects in Finland and Sweden. Those projects prove that the system can be used ‘in situ’ to remove
organic pollutants, such as aliphatic hydrocarbons, BTEX compounds and PAH compounds.
EKO/GRID is a patented technology based on utilising electricity, or more precisely electrokinetic and
electrochemical reactions in the electric field created between electrodes placed typically 5m apart
in the ground. Remediation is strongly based on enhanced natural oxidation process, and the letter
combination EKO in fact means ElectroKinetic Oxidation.
The Matjärvi trial was started in order to study the effect of the EKO/GRID in remediation of
eutrophicated waters. The main working hypothesis was to validate, if the EKO/GRID reactions could
reduce the amount of nutrients (phosphorous and nitrogen) in water thus reducing the growth of
blue-green algae.
This study was sponsored by Vesijärvisäätiö, Pyhäniemen Kartano and Uponor, and the people from
the neighbourhood of the test site helped greatly with the installation works.
2. Installation
Two plastic tubes, each 3m long and 1m in diameter, were pushed deep in the lake bottom through
the bottom sediment and clay. So we could ensure that water inside the tubes could not be in
contact with the exterior lake water.
Water depth inside the tubes was approximately 1.3m after the installation. The EKO/GRID tube was
fitted with steel electrodes (5m long) connected to the control unit, and the other one was left
without, in order to provide us a reference – a non-active test tube (later called as the Control Tube).
The system was commissioned on 12th July 2012. The output voltage was set to 16V and the unit
gave out approximately 450-400mA. Due to the pulsing voltage patterns the output current is not
stable.
Eko Harden Technologies Oy
Kimmeltie 3, FI- 02110, Espoo, Finland
www.ekohardentechnologies.fi
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
3. Visual Observations
On the installation and commissioning day
12th July 2012 water inside the test tubes was
very cloudy due to the mechanical mixing with
the sediment and clay.
The lake water did show noticeable marks of
blue-green algae bloom, which however
cannot be seen in this photo on the right.
On 15.8.2012 – 37 days after commissioning the water inside the control tube and in the lake was all
green, because of heavily blooming algae. Inside the EKO/GRID tube water was dark in colour had
some algae on the edges, but did not hold any visible signs of blue-green algae!
On 4.9.2012 – 57 days after commissioning the difference was even much stronger. Water in the
EKO/GRID tube was very clear and a large number of small creatures were living in there.
On 23.10.2012 – 87 days after commissioning the test was stopped before the winter to come.
Colder water (6oC) reduced the chlorophyll content and made the water clearer also outside the
EKO/GRID test tube.
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
4. Laboratory analyses and other measurements
The client took water samples in the beginning of the study 12th July and three times during the
treatment – 15th August, 19th September and 24th October 2012. All water samples for the laboratory
analyses were taken at 0.9m depth.
The water samples were taken to analyse following variables:
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Total Phosphorous content (µg/l)
Dissolved Phosphorous content (µg/l)
Total Nitrogen content (µg/l)
Dissolved Nitrogen content (µg/l)
Oxygen content (mg/l)
Temperature (oC)
pH
Chlorophyll-a (µ/l)
Turbidity (NTU)
Colour of the Water (mg Pt/l)
Conductivity (mS/m)
Alkalinity (mmol/l)
Chemical Oxygen Demand –CODMn (mg/l)
Iron Content (mg/l)
Dissolved Iron Content (mg/l)
Manganese Content (mg/l)
On the same occasion, when the water samples were taken, the analysing team measured
temperature and oxygen concentration with a hand held instrument from the surface to the bottom
of the tubes.
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
4.1 Effect of EKO/GRID on the Phosphorous and Nitrogen contents
Main target of the study was to prevent the algae growth by reducing P and N content in the
treatment (EKO/GRID) tube. This really happened; the graphs below show clearly the results.
Case Matjärvi
Phosphorous Content
100
90
80
70
60
50
40
30
20
10
0
20.6.2012
10.7.2012
30.7.2012
19.8.2012
8.9.2012
28.9.2012
18.10.2012
Total P Lake, µg/l
Total P Control Tube, µg/l
Total P EKO/GRID Tube, µg/l
Dissolved P Lake, µg/l
Dissolved P Control Tube, µg/l
Dissolved P EKO/GRID Tube, µg/l
7.11.2012
Total Phosphorous content started immediately to decrease towards very low values. It is very
interesting to note that the phosphorous compounds formed in the EKO/GRID tube appear to have a
low solubility to the water!
Case Matjärvi
Nitrogen Content
2000
1800
1600
1400
1200
1000
800
600
400
200
0
20.6.2012
10.7.2012
30.7.2012
19.8.2012
8.9.2012
28.9.2012
18.10.2012
7.11.2012
Total N Lake, µg/l
Total N Control Tube, µg/l
Total N EKO/GRID Tube, µg/l
Dissolved N Lake, µg/l
Dissolved N Control Tube, µg/l
Dissolved N EKO/GRID,µg/l
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
The behaviour of nitrogen is very similar to phosphorous.
EKO/GRID has evidently reduced the nitrogen content as well. In September all nitrogen was
in dissolved form, when there were no algae or other vegetation left in the water.
The positive effect of the reduced P and N content is clearly shown with the chlorophyll-a
measurements (following graph), and was clearly visible by eye. Unfortunately the
chlorophyll content at the first treatment day is not known, so we used an estimate 80µm/l.
Case Matjärvi
Chlorophyll-a
160
140
Chlorophyll-a , µg/l
120
100
80
60
40
20
0
20.6.2012
10.7.2012
30.7.2012
19.8.2012
Chlorophyll-a Lake, µg/l
8.9.2012
28.9.2012 18.10.2012 7.11.2012
Chlorophyll-a Control Tube, µg/l
Chlorophyll-a EKO/GRID Tube, µg/l
The target level 20µg/l (ie no algae) could be reached very quickly in the EKO/GRID test tube.
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
4.2 Oxygen content and pH
Case Matjärvi
Oxygen content
12
10
O2, mg/l
8
6
4
2
0
20.6.2012
10.7.2012
30.7.2012
O2 Lake, mg/l
19.8.2012
8.9.2012
28.9.2012
O2 Control Tube, mg/l
18.10.2012
7.11.2012
O2 EKO/GRID Tube, mg/l
Case Matjärvi
pH
10
9,5
9
8,5
pH
8
7,5
7
6,5
6
5,5
5
20.6.2012
10.7.2012
30.7.2012
pH Lake
19.8.2012
8.9.2012
pH Control Tube
28.9.2012
18.10.2012
7.11.2012
pH EKO/GRID Tube
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
Oversaturated oxygen content and very high pH in the lake and control tube are clear marks
of heavily blooming algae during July and August months. Both values are very much lower
ie within the normal range in the EKO/GRID test tube.
Interestingly the oxygen content of the EKO/GRID tube started to increase in September,
probably because there were nothing more to be oxidised inside the tube?
In addition, it’s worth and important mentioning that the pH curve proves that the
EKO/GRID system doesn’t effect on the pH value.
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
4.4 In situ oxygen analyses
Relative Oxygen Content%
60
80
100
120
Oxygen Content mg/l
140
6
0,5
1,0
1,5
9
10 11 12 13 14
0,5
1,0
Control
Lake
EKO/GRID
60
80
100
120
6
140
syvyys (m)
0,0
0,2
0,4
0,6
0,8
1,0
1,2
EKO/GRID
Control
80
100
120
8
9
10
11
12
13
14
Control
Lake
Oxygen Content mg/l
140
6
syvyys (m)
Control
7
EKO/GRID
Lake
0,0
0,2
0,4
0,6
0,8
1,0
1,2
EKO/GRID
Lake
0,0
0,2
0,4
0,6
0,8
1,0
1,2
Relative Oxygen Content %
60
Control
Oxygen Content mg/l
Relative Oxygen Content %
syvyys (m)
8
1,5
EKO/GRID
syvyys (m)
7
0,0
syvyys (m)
syvyys (m)
0,0
Lake
7
8
9
10
11
12
13
14
0,0
0,2
0,4
0,6
0,8
1,0
1,2
EKO/GRID
Control
Lake
Very high oxygen concentrations in the lake and control tube are indications of vigorous algae
blooming. This effect is strongest near the surface.
Oxygen content in the EKO/GRID tube is quite good. Lower values near the bottom may be an
indication of fast oxidation reactions. In the future we should consider installing a sampling tube
within the test area that would allow us to take water samples from the depth of sediment and clay
layers.
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
4.3 Turbidity and the Colour of the water – Content of Humus
Turbidity is the cloudiness of the water, and is caused by suspended solids consisting of particles of
many different sizes. In addition turbidity is partly caused by the growth of phytoplankton. The graph
below shows clearly how EKO/GRID has a great effect in the turbidity figure, especially in relation to
the open water (lake) conditions (blue line).
Humic substances, humus, are the brown substances leached out of the soil by water. The yellow to
brown color is caused by large and complex organic substances which are mainly derived from
decomposing plants and animals. Humus is an important factor for the transport and bioavailability
of inorganic and organic nutrients. It affects the toxicity of heavy metals and organic pollutants in the
environment, since it forms complexes with many toxic substances. Humus is also very important for
surface water acidity due to its acid-base properties. Many surface waters are naturally acidic (pH<6)
due to humic acids.
Case Matjärvi
Turbidity
40
35
Turbidity, NTU
30
25
20
15
10
5
0
20.6.2012
10.7.2012
Turbidity Lake
30.7.2012
19.8.2012
8.9.2012
Turbidity Control Tube
28.9.2012
18.10.2012
7.11.2012
Turbidity EKO/GRID Tube
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
Case Matjärvi
Water Colour - Content of Humus
160
140
Colour, mg PT/l
120
100
80
60
40
20
0
20.6.2012
10.7.2012
30.7.2012
Water Colour Lake
19.8.2012
8.9.2012
Water Colour Control Tube
28.9.2012 18.10.2012 7.11.2012
Water Colour EKO/GRID
Case Matjärvi
Chemical Oxygen Demand
30
25
mg/l
20
15
10
5
0
20.6.2012
10.7.2012
30.7.2012
COD Mn järvi, mg/l
19.8.2012
8.9.2012
COD Mn kontrolli, mg/l
28.9.2012
18.10.2012
7.11.2012
COD Mn EKO/GRID, mg/l
Rapid increase of the turbidity and COD values in the lake are probably caused by heavy rains
flushing topsoil into the lake.
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
4.5 Iron and Manganese contents
Case Matjärvi
Iron Content
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
20.6.2012
10.7.2012
30.7.2012
19.8.2012
8.9.2012
28.9.2012
18.10.2012
Fe lake, mg/l
Fe Control Tube, mg/l
Fe EKO/GRID Tube, mg/l
Dissolved Fe Lake, mg/l
Dissolved Fe Control Tube, mg/l
Dissolved Fe EKO/GRID TUbe, mg/l
7.11.2012
High iron content in the EKO/GRID tube is caused by the steel electrodes, which are slowly corroding.
Interestingly iron content in the lake reached same level in October.
Case Matjärvi
Manganese Content
0,08
0,07
Mn, mg/l
0,06
0,05
0,04
0,03
0,02
0,01
0
20.6.2012
10.7.2012
30.7.2012
Mn Lake, mg/l
19.8.2012
8.9.2012
Mn Control Tube, mg/l
28.9.2012
18.10.2012
7.11.2012
Mn EKO/GRID Tube, mg/l
The manganese contents are relatively low.
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
4.5 Conductivity and Alkalinity
Case Matjärvi
Conductivity
12
Conductivity, mS/m
10
8
6
4
2
0
20.6.2012
10.7.2012
Conductivity Lake
30.7.2012
19.8.2012
8.9.2012
Conductivity Control Tube
28.9.2012
18.10.2012
7.11.2012
Conductivity EKO/GRID Tube
Conductivity is considerably lower in the EKO/GRID tube than in the Lake or the Control tube. This
means that the water contains smaller number of ionic (water soluble) or colloidal compounds.
Case Matjärvi
Alkalinity
Alkalinity, mmol/l
2,5
2
1,5
1
0,5
0
20.6.2012
10.7.2012
Alkalinity Lake
30.7.2012
19.8.2012
8.9.2012
Alkalinity Control Tube
28.9.2012 18.10.2012 7.11.2012
Alkalinity EKO/GRID Tube
The alkalinity is lowest in the EKO/GRID tube, which could mean that there are a smaller number of
reactive compounds that could provide a buffer capacity to the water.
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
5. Sediment sampling
Vesijärvisäätiö provided to us these two photos, with some interesting observations. On the left we
can see the sediment sample taken from the Control tube having a 50cm thick soft layer of sediment,
but on the right one taken from the EKO/GRID tube has only 15cm of sediment on top of the clay.
The client concluded that the situation seems to be as shown in the drawing below.
This illustration shows the test conditions EKO/GRID tube on the right side. According to the sampling
the sediment layer in that one is thinner. If this isn’t a coincidence, it is a very interesting observation
that could help us to understand better the functioning of the EKO/GRID.
The drawing also illustrates how the water level inside the test tubes was all the time on a higher
level than on the lake.
EKO/HARDEN
Matjärvi Project
Final Report
4 December 2012
6. Conclusions
Obviously EKO/GRID is a very effective method to inhibit the growth of blue-green algae. The drastic
decrease of the chlorophyll content is a strong evidence of the effect.
From these results available our team concluded that EKO/GRID seems to activate reactions that will
tie phosphorous and nitrogen with iron and manganese into compounds that are not very soluble in
water.
Future studies
It will be very important to study the importance of using steel electrodes. They produce iron ions,
which as said are taking part of the process. However, when used in certain other applications (eg
enhanced settlement of particles) steel may corrode too fast and we have to consider using titanium
instead.
During the winter2012-13 we will carry out testing in controlled laboratory conditions (in climate
rooms) using steel and titanium electrodes. These tests will be done in various conditions and to
study the effect eg to fish and fish-egg.
The EKO/GRID system is very accessible, but for larger projects the up-scaling will require some
engineering and additional testing.
Erkki Lindberg

Pulse Technology Centre BV

Transcription

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