ASSESSMENT OF SEDIMENT CONTAMINANTS FROM
CERAMIC PRODUCTION, A CASE STUDY OF FARSTAVIKEN
Ola Öberg (Royal Institute of Technology, Stockholm, Sweden)
ABSTRACT: A factory producing ceramics has discharged wastewater
into a semi-enclosed water basin situated within the Stockholm
archipelago. The objective of this study was to compare the discharge to
the content of additional material at the bottom of the recipient. A material
balance was made for dry substance, zinc, lead and cadmium.
The discharge was estimated from interpolation of production
figures between start year and 1968 when the discharge stopped. The
additional material in the recipient was estimated as the integrated
difference of yearly sedimentation rate between affected sedimentation
beds and background values.
The factory disposal up to 1968 was estimated to 18 000 tons of
dry substance with a content of Zn and Pb of 40 and 50 tons respectively.
The sediments show an additional content of dry substance of 14 000 tons,
Zn 30 tons, Pb 25 tons and Cd 500 kg. Concentration intervals were for Zn
150 – 2 500 mg/kg for Pb 50 – 2 000 mg/kg and for Cd 2 – 60 mg/kg .
It can be concluded that a material balance gives the order of
magnitude and distribution of disposed material including contaminant
components, even for a historical discharge.
INTRODUCTION
Farstaviken, a semi-enclosed fjord like basin situated within the
Stockholm archipelago, has been a wastewater recipient for a factory
engaged in ceramic production and for surrounding municipal wastewater
discharges. Farstaviken is situated 20 km east of Stockholm.
FIGURE 1. Stockholm Archipelago
1
Farstaviken is connected to a larger basin, Baggensfjärden through a
straight with a depth of 6 meters, which reduces an effective water
exchange of particularly bottom water. The surface area of Farstaviken
inside the straight is 0,59 km2. Salinity of the water is 4-6 ‰ ( Lännergren,
C., Johansson, P. 1997). There is no tidal activity in the area but
meteorologically induced water level fluctuations, which together with the
wind are the main driving forces for exchanging water (Engqvist, A.
1999).
Depth profile
Third
deep area
"Baggen A"
Second
deep area
"Farsta C"
First
deep area
"Farsta AB"
Inner
shallow
area
Outlet for
waste
disposal
Farstaviken
Baggensfjärden
FIGURE 2. The depth profile of Farstaviken and of the closest part of
Baggensfjärden. Factory waste disposal outlet and area cods.
The ceramic production had two main production lines, the first
making chinaware like plates and teacups, the other making sanitary
ceramics like toilet seats. The production of chinaware started 1825 and
stopped in 1990 (Arvidsson, et al. 1997). The production of sanitary
ceramics started on a large scale after the Second World War when the
construction of houses increased. This production is still going on. The
origins of the wastewater discharged into Farstaviken was mainly from
washing moulds and factory floors. The installation and use of water
closets in the municipality began about 1950 and the discharges were
disposed untreated to Farstaviken. All discharges stopped in 1968 when
both the factory and the municipality built wastewater treatment plants.
The main ingredients of ceramics are different kind of clays, in
sanitary production kaolin, quarts and feldspar. To create a watertight
surface the product are glazed. The glaze cover has often the same mixture
as the product body but with an addition of something that reduces the
melting temperature, a glazing agent. In the production of sanitary
ceramics the glazing agent was zinc oxide, with a zinc content of 80% and
2
in the production of chinaware lead oxide with a lead content of 90%.
Different metal oxides were used to create colours for decoration. Earlier
studies of the sediments in the basin show elevated concentrations of lead,
zinc and cadmium. The highest concentrations were found close to the
discharge outlet in the inner shallow part of the bay (VIAK. 1984). Windgenerated waves and currents erode these sediments and they may be
displaced to the accumulation areas in the basin.
The municipal wastewater discharges consumed more oxygen than
was mixed in by the wind and an anaerobic condition was permanently
established in the bottom water. The sediment in deep bottoms that has the
strongest anaerobic conditions also contains methane gas. This could
clearly be seen on side-scan sonar images. (Anonymous. 1998a)
Objective. The objective of this study was to compare the discharge from
the factory to the content of additional dry substance, zinc, lead and
cadmium at the bottom of the recipient. The objective was also to
investigate possible resuspension and displacement of disposed material
from the inner shallow part of the bay to deeper accumulation bottoms
after 1968. The study will contribute to the basis for choice of remediation
strategy.
METHOD
The study approach was to analyse how the disposed material is
distributed in the different parts of the basin by use of a material balance.
The factory discharge was estimated from production figures and the
accumulation beds in the basin were investigated in a gradient from the
factory.
Factory Discharge. 1997 the production in the factory was 9 700 tons of
sanitary ceramics. In the same year the wastewater treatment plant of the
factory trapped 960 tons sludge, that is about 10% of the raw material
used. Samples from the treatment plant show 4 700 mg/kg zinc in the dry
waste (Anonymous. 1998b). It is possible to estimate the minimum amount
of material that was discharged into the basin by assuming that the
efficiency of using raw material was not higher during the period in which
the wastewater was discharged directly into the basin. In the 1960´s
glazing agents represented 5 % of the glaze cover, which on an average
represented 10% of the weight of the manufactured product (Öberg. 2001).
This is in agreement with the samples from the treatment plant.
Inner Shallow Area. The area close to the factory was examined by core
sampling from ice-cover during winter. The aim of this investigation was
to compare concentrations found 15 (VIAK. 1984) and 25 (Orrje.1976)
years ago in this area.
3
If the concentrations had changed, this can be due to displacement
of the pollutants. The core
sampling plastic-tubes had
a diameter of 50 mm. They
were pressed down 2
meters below sediment
surface. The upper 30 cm
of the cores was mixed
separately. Five cores were
analysed. A known volume
and weight of about 100
grams of the sediment
where boiled 1 minute
with 100 ml 2M HCL.
After depositing, 40 ml
FIGURE 3. Inner shallow area with
was used for analysing
sampling points from 1976, 1984
with
ICP
equipment
and 1999
(Inductively
Coupled
Plasma). The sediments
were dried and weighed to achieve the dry weight. An estimated amount of
Pb, Zn and Cd was calculated from the average of the five samples.
Similar techniques were used in the 1976 and 1984 studies.
Deep Bottom. The deeper bottom was investigated to find out how far the
pollutant had spread from the source and how the deposition have changed
historically in the accumulation bottoms. Farstaviken and the neighbouring
basin Baggensfjärden were investigated. (Anonymous. 1998a). First the
bottom was mapped with Side-Scan Sonar technique for detecting soft
accumulation bottoms. A map showing the area of the soft bottoms was
drawn and core samples were taken in sediment accumulation areas.
The sampler used was a "Gemeni-sampler" which consists of two
parallel metal tubes that are loaded with plastic tubes. The result is a
double sample of two parallel cores with diameters of 8 cm and length of
80 cm taken at a distance of 25 cm from each other. One of the two cores
was cut in two halves by length and photographed, the yearly
sedimentation showed up as coloured layers in black, grey and olive green.
The cores could be dated at all depth with help of the computer programs
Photoshop and AutoCAD. The other core was analysed at 8 different depth
for wet weight, dry weight and loss of ignition. Zn, Pb Cd by boiling with
HNO3/HCL, 3:1 in one hour and then analysed in an atom absorption
spectrophotometer model VARIAN AA-1275. Three double samples were
taken inside Farstaviken in a gradient from the wastewater outlet. Four
samples were taken in the neighbouring basin to investigate if spreading
had occurred out of Farstaviken. One of the cores in each basin was
analysed in a "CG Gamma counter" at 15 different levels for Cesium-137.
The sediment in the Stockholm archipelago shows a distinct peak at a
4
depth equal to the year 1986 when the Tjernobyl incident occurred. This
peak was used to crosscheck the dating of the cores. To compute the dry
substance deposition, the density, the dry substance and the thickness of
each layer must be known. The density was computed with the following
empirical formula (Håkansson, L., Jansson M. 1983):
ρ = 260/(100 + 1.6*(W+LOI0))
ρ
W
LOI0
In which
(1)
= density (g/cm3)
= water content in %
= loss of ignition in % of wet substance.
The density and the dry substance were interpolated between the
known levels and the calculation of yearly dry substance deposition could
be done with the following formula:
ds-dep = t* ρ * ds * 10 000
(2)
ds-dep = dry substance deposition (g/m2/year)
t
= layer thickness (cm)
ds
= dry substance (g)
In which
Corresponding computations were done for the metals and the
historical profile of yearly load of Zn, Pb and Cd could be constructed.
The accumulation bed in Farstaviken is divided into two deeper
areas "Farsta AB" and "Farsta C", figure 2. The deposition in the two
sampling points "Farsta A" and "Farsta B", figure 4, were averaged to
represent the deposition in area "Farsta AB", figure 2.
E 18o23
Farsta C
N
Farsta B
Farsta A
N 59o18’,5
Straight
Baggen A
1 kilometer
FIGURE 4. The soft accumulation areas of Farstaviken and the
sampling points "Farsta A", "Farsta B", "Farsta C", "Baggen A".
5
Sampling point "Farsta C" represents the second deep area inside
Farstaviken and the sampling point "Baggen A" represents the third deep
area, which is situated in Baggensfjärden. To estimate the additional
amount of sediment due to factory disposal that has reached the deeper
bottoms, all these extra sediments were assumed to have deposited in the
first deep area represented by the averaged "Farsta AB" (Zhang., Öberg.
2000). The annual sedimentation in "Farsta C" was assumed to be close to
natural background value and could for each year be subtracted from the
annual sedimentation in "Farsta AB". To get the total amount of additional
settled sediment, this additional annual sedimentation was applied on the
accumulation area of "Farsta AB". The same calculation was done for Zn
and Pb. In the case of Cd the yearly sedimentation loads show an increased
amount of Cd in "Farsta C" during 1980, so the additional annual load of
Cd was calculated for both the areas "Farsta AB" and "Farsta C". The
subtracted background level used was related to the third deep area
"Baggen A" which does not show an increased load of Cd.
RESULT
Factory Discharge. The production figures of sanitary production was
estimated to 100 tons at 1939 and interpolated to 5 000 tons at 1968, which
gives a total production of 80 000 tons. This would correspond to a
discharge of 8 000 tons, containing 40 tons zinc. The household ceramics
production was estimated to 10 tons at year 1836 and 5 000 tons at 1968
(Öberg. 2001), interpolation gives a total production of 100 000 tons. The
discharge here would be 10 000 tons with a lead content of 50 tons.
Inner Shallow Area. The analysis from the years 1976 (Orrje. 1976),
1984 (VIAK. 1984) and 1999 (Öberg. 2001) are shown in figure 5.
mg/kg
Zn
4 000
mg/kg
4 000
3 000
3 000
2 000
2 000
1 000
1 000
0
1970
1980 1990
Year
2000
Pb
mg/kg
125
Cd
100
75
50
25
0
1970 1980 1990 2000
Year
0
1970 1980 1990 2000
Year
FIGURE 5. Concentrations of Zn, Pb and Cd in the inner shallow part
of Farstaviken 1976 (6 samples of Pb and 3 samples of Cd), 1984 (6
samples of each) and 1999 (6 samples of each)
6
The concentrations are elevated, for Zn 12 times the background value, for
Pb 33 times and for Cd 39 times. The estimated volume of the disposed
material is 15 000 m3 (Öberg. 2001 ) and the dry mass 10 000 tons. The
additional amount of
Zn, Pb and Cd is 20
Zn
Pb
Cd
tons, 9 tons and 360 Year
mg/kg mg/kg mg/kg
kg respectively.
1999
1 952
861
36
The
average 1984
1 850 1 143
54
concentrations of Zn, 1975
2 967
27
Pb and Cd are in the Mean
1 901 1 657
39
same
order
of
magnitude during the
Background values
150
50
1,2
25 years that the
samples represent. A
TABLE 1. Mean concentrations from the
decreasing trend can
samples in figure 5 and site-specific
be seen for Pb. This
background concentrations in the inner
can
indicate
that
part of Farstaviken (VIAK 1984)
washing out of Pb has
taken
place.
The
concentration of Zn is about the same in 1999 and in 1984 but Cd shows a
different pattern with the highest value at 1984.
Deep bottom. The sediment map in figure 4 shows that the total area of
sedimentary beds is 0,24 km2 and the area that contain gas in the sediment
is 0,13 km2. The area of "Farsta AB" and "Farsta C" were estimated to be
0,12 km2 each. The concentration of metals in the sediment shows the
following pattern when plotted against the year of deposition.
Concentrations
Zn
Year
Farsta AB
Farsta C
Baggen A
2000
1990
Concentrations
Concentrations
Cd
Pb
Farsta AB
Farsta AB Year
Year
Farsta C
Farsta C 2000
2000
Baggen A
Baggen A
1990
1990
1980
1980
1980
1970
1970
1970
1960
1960
1960
1950
1950
1950
1940
1940
1940
1930
1930
1930
0
1000
2000
mg/kg
0
1000
2000
mg/kg
0
10 20
30 40
mg/kg
FIGURE 6. Concentrations of Zn, Pb and Cd
The concentrations of Zn, Pb and Cd show a declining trend away from the
factory outlet in recent as well as historical time. Zn shows a peak at the
7
level corresponding to the middle of the 1960’s with max concentrations of
2 000 mg/kg, Pb at the early 1950’s with max concentrations of 2200
mg/kg, Cd at the late 1970’s with max concentrations of 35 mg/kg.
The annual sedimentation in the first deep basin of Farstaviken,
"Farsta AB", has a peak at a depth corresponding to the early 1960´s with
at most 5 kg/m2 after which it declines to about 500 g/m2. In "Farsta C" the
yearly sedimentation has declined to 500 g/m2. In Baggen"A", the
sedimentation during the last 10 years is 3-5 times higher than in
Farstaviken. The additional amount of material that has been deposited in
"Farsta AB" compared to "Farsta C" is about 4 000 tons.
Year
2000
Year
2000
Dry substance
1990
1990
1980
1980
1970
1970
1960
1960
Farsta AB
Farsta C
Baggen A
1950
1940
Zn
Farsta AB
Farsta C
Baggen A
1950
1940
1930
1930
0
2
Year
2000
4
2
Year
2000
Pb
Farsta AB
Farsta C
Baggen A
1990
1980
0
6 kg/m
1960
1960
1950
1950
1940
1940
1930
4
6
6
2
g/m
Cd
Farsta AB
Farsta C
Baggen A
1980
1970
2
4
1990
1970
0
2
1930
2
g/m
0
20
40
2
mg/m
FIGURE 7. Annual deposition of dry substance, Zn, Pb, and Cd in
"Farsta AB", "Farsta C" and "Baggen A"
Zinc has two peaks in the 1960´s with the maximum peak at 7
g/m2, after 1970 the yearly load of zinc decreases. The additional amount
of Zn that has been deposited in "Farsta AB" compared to "Farsta C" is
about 10 tons.
8
Lead has its peaks of distribution at a depth corresponding to the
early 1960´s. After 1970 the yearly load of lead is decreases. The
additional amount of Pb that has been deposited in "Farsta AB" compared
to "Farsta C" is about 16 tons.
The deposition of cadmium in "Farsta AB" shows two peaks, one
during the late 1950’s and one in the early 1970’s with sedimentation loads
of 25-35 mg/m2. A smaller peak at 1982 is also visible. "Farsta C has a
peak at the beginning of the 1980’s. After 1980 the yearly load of
cadmium decreases. The additional amount of Cd that has been deposited
in "Farsta AB" and in "Farsta C" compared to "Baggen A" is about 125 kg.
TABLE 3. Mass balance for waste material
Dry material Zn
Pb
ton
ton ton
Disposal from factory
18 000
40
50
Inner shallow area
10 000
20
9
Accumulation area
4 000
10
16
Difference
4 000
10
25
Cd
kg
360
125
DISCUSSION
The bigger difference for Pb compared to Zn in Table 3 may have
an explanation in that the sample cores did not get deep enough to reach
background values for Pb, this is indicated in figure 7. Pb is also heavier
than Zn and may therefore more remain on the harder bottom between the
inner shallow area and the deep accumulation area.
As figure 7 shows no vital difference in the yearly load of dry
substance in "Farsta AB" and "Farsta C" can be seen after 1975. This lead
to the conclusion that no significant amount of sediment has been eroded
and transported from the inner shallow area to the inner deep accumulation
area after 1975. The estimated amount of sediment in the inner shallow
area is then approximately the same in 1975 and in 1999, 10 000 tons. The
mean concentration of Pb 1976 and 1999, Table 1, give a difference of 21
tons that may have been resuspended and transported in direction of the
deeper accumulation areas.
Some explanations for the sedimentation pattern in figure 7 can be
that in the production of household ceramics a more refined use of Pb was
introduced in the 1950´s because of working health problems. In 1968
Swedish legislation prohibited pollution of natural water systems and the
factory built a treatment plant for the wastewater. In 1980 the factory
stopped a production line of plastic components, this production used
cadmium as UV-stabilisation for the plastic material.
The peak of Zn deposition in the 1960´s corresponds well with the
increase of production due to the Swedish "million-programme" for
construction of houses launched in Sweden. One million apartments were
supposed to be built. They all needed a toilet seat.
9
The mass balance of the waste disposal in the basin is uncertain
because of a lack of production figures, few bottom samples and material
temporarily deposited on hard bottoms and different analysis procedures.
It gives however an idea of the order of magnitude and distribution of
disposed material including contaminant components, even for a historical
discharge.
REFERENCES
Anonymous. 1998. "Methods of Sedimentologic Investigations in Coast
Areas", Uppsala University, Report from PhD student course, Sweden
Anonymous. 1998. “Environmental Report of the Gustavsbergs Ceramic
Factory", Gustavsbergs Fabriker, report made for the Local Environmental
Authority, Värmdö, Sweden
Arvidsson, E.S., Aspfors, J., Gullmert, L. 1997. The Ceramic Factory of
Gustavsberg, ISBN: 91-971577-3-2. 17-114
Engqvist, A. 1999. Coast and Seas, Swedish Environmental Protection
Agency background Report 4910, ISBN: 91-620-4910-0, 10-13
Håkansson, L., Jansson M. 1983. Principels of Lake Sedimentology.
Springer-Verlag, Berlin, ISBN: 3-540-12645-7. 316
Lännergren, C., Johansson, P. 1997 Investigations in Stockholm
Archipelago 1996. Stockholm Water Company Report. 36, 49-51
Öberg, O. 2001 "Assessment of Sediment Contaminants From Ceramic
Production, a Case Study of Farstaviken". Licentiate thesis, Royal Institute
of Technology, Stockholm, Sweden.
Orrje. 1976. “Investigation of the Inner Part of Farstaviken”. Report made
for the Factory of Gustavsberg.
VIAK. 1984. “Investigation of the Inner Part of Farstaviken”. Report made
for the Swedish National Road Authority.
Zhang, Z., Öberg, O. 2000. A Baroclinic Model with Sediment Deposition
in a Small Basin in the Stockholm Archipelago. 4th International
Conference on Hydro-Science & Engineering , Korea Water Resources
Association, Korea
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