Study of evolution of PCDD/F in sewage sludge-amended soils for land restoration purposes

Article abstract of DOI:10.1016/S0045-6535(99)00366-5

The evolution of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in sewage sludge-amended soils used in the restoration of degraded lands, like quarries, has been studied. Two experiments were performed: one in the lab, under controlled conditions, and another in a quarry. Two different doses of sewage sludge were applied in both experiments (with two types of application in the quarry experiment) and the evolution of the amended soils were compared with that of the respective control soils (without addition of sewage sludge). The samples were analyzed with a previously validated method by HRGC-HRMS after the extraction and the necessary clean-up steps. The results reveal that polluted sewage sludge increases PCDD/F concentration in soils and that these compounds are persistent in the matrix after long periods of time. (C) 2000 Elsevier Science Ltd. The evolution of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in sewage sludge-amended soils used in the restoration of degraded lands, like quarries, has been studied. Two experiments were performed: one in the lab, under controlled conditions, and another in a quarry. Two different doses of sewage sludge were applied in both experiments (with two types of application in the quarry experiment) and the evolution of the amended soils were compared with that of the respective control soils (without addition of sewage sludge). The samples were analyzed with a previously validated method by HRGC-HRMS after the extraction and the necessary clean-up steps. The results reveal that polluted sewage sludge increases PCDD/F concentration in soils and that these compounds are persistent in the matrix after long periods of time. Laboratory and field experiments were conducted in Spain to examine the evolution of PCDDs and PCDFs in sewage-sludge-amended soils. The PCDD/F concentrations were measured in the original sewage sludge and in soil samples over time. Results from the laboratory showed that the PCDD/F concentration in amended soils was related directly to the sewage-sludge dose applied. After 1 yr, however, no evolution of PCDD/Fs was observed in any sample. In the field, high dispersion was observed, which did not allow establishment of a concentration trend over time. (from Eighteenth Symp on Halogenated Environ Organic Pollutants-Dioxin '98, Stockholm, Sweden (Aug 17-21, 98)).

Full text of DOI:10.1016/S0045-6535(99)00366-5

Chemosphere 40 (2000) 1173±1178
Study of evolution of PCDD/F in sewage sludge-amended soils
for land restoration purposes
a,b
L. Molina , J. Dõaz-Ferrero , M. Coll , R. Martõ , F. Broto-Puig ,
a,b
a
b
ꢀ
L. Comellas , M.C. Rodrõguez-Larena
ꢀ a
b
a,
*
ꢀ
a
Environmental Laboratory, Institut Quꢀõmic de Sarriaꢁ, Ramon Llull University, Via Augusta 390, 08017, Barcelona, Spain
b
ꢀ
ꢁ
Section of Chromatography, Institut Quõmic de Sarria, Ramon Llull University, Via Augusta 390, 08017, Barcelona, Spain
Abstract
The evolution of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in sewage
sludge-amended soils used in the restoration of degraded lands, like quarries, has been studied. Two experiments were
performed: one in the lab, under controlled conditions, and another in a quarry. Two di€erent doses of sewage sludge
were applied in both experiments (with two types of application in the quarry experiment) and the evolution of the
amended soils were compared with that of the respective control soils (without addition of sewage sludge). The samples
were analyzed with a previously validated method by HRGC±HRMS after the extraction and the necessary clean-up
steps. The results reveal that polluted sewage sludge increases PCDD/F concentration in soils and that these compounds
are persistent in the matrix after long periods of time. Ó 2000 Elsevier Science Ltd. All rights reserved.
Keywords: Sewage sludge; Polychlorinated dibenzo-p-dioxins; Polychlorinated dibenzofurans; HRGC±HRMS; Land restoration
1. Introduction
the high amounts of sludge used compared to those for
agricultural purposes. Our research group has per-
formed several studies about the fate of hydrocarbons,
polychlorinated biphenyls (PCB) and polycyclic aro-
matic hydrocarbons (PAH) in sewage sludge-amended
soils (Mangas et al., 1998). This work faces on the
evolution of polychlorinated dibenzo-p-dioxins (PCDD)
and polychlorinated dibenzofurans (PCDF) in the
amended soils. These compounds are persistent organic
pollutants of great concern due to their toxicological
e€ects (endocrine disruption like thyroid dysfunction,
developmental de®cits, carcinogenicity, etc.) and their
great stability, which allows bioaccumulation and bio-
magni®cation. Several authors have studied the presence
and origin of PCDD/F in sewage sludge (Gihr et al.,
1991; Hortsmann et al., 1993; McLachlan et al., 1996;
Jones and Sewart, 1997; Tiernan et al., 1996; EPA,
1994). In this paper, we study the evolution of PCDD/F
in sewage sludge-amended soils in two experiments, one
in the laboratory, under controlled conditions, and one
in a quarry near Girona (Spain).
The increasing amounts of sewage sludge produced
by waste water treatment plants (WWTP) in Catalunya
and the restrictions in the ®nal fate of them (e.g., the
banning of sewage sludge discharges into the sea since
1998) have increased the search of new possibilities to
use these kind of material. On the other hand, the ex-
tractive activities, like quarries, which produce big ex-
tensions of land without vegetation, constitute an
environmental problem that should be solved. The ap-
plication of sewage sludge-amended soils in order to
increase the fertility of these lands can be a solution for
this problem and also an interesting application for
sewage sludge (Alcaniz et al., 1996). However, sewage
sludge could contain pollutants whose evolution in the
amended soils should be monitored, mainly considering
* Corresponding author. Tel.: +349-3-203-8900; fax: +349-3-
205-6266.
Â
E-mail address: crlar@iqs.url.es (M.C. Rodrõguez-Larena).
0045-6535/00/$ - see front matter Ó 2000 Elsevier Science Ltd. All rights reserved.
PII: S 0 0 4 5 - 6 5 3 5 ( 9 9 ) 0 0 3 6 6 - 5

1174
L. Molina et al. / Chemosphere 40 (2000) 1173±1178
2. Experimental
2.3. Analysis of sewage sludge and sewage sludge-amend-
ed soils
2.1. Experiment design
The samples were freeze-dried, ground and sieved
(2 mm) before extraction. Six grams of dried sludge or
13
2.1.1. Laboratory experiment
soil, spiked with a mixture of
C
12
labeled 2,3,7,8-
Anaerobically established sewage sludge was ob-
tained from DARGISA, an aerobic sewage treatment
plant in Girona (Spain). The sludge was air-dried and
ground to less than 0.4 mm before soil addition. The
sludge was mixed with an alkaline soil (previously
ground and sieved to less than 2 mm) and 12 kg of
mixtures were placed in polyethylene containers (lysi-
meters). The experiment consisted of studying the evo-
lution of PCDD/F in a control soil (0% of sludge) and
two soils with di€erent additions of sewage sludge (7.5%
and 15%). Lysimeters were watered when necessary to
maintain a 20% of moisture in order to assure 50% of
the water holding capacity, appropriate to have best
microbiological activity. Soils were sampled at the be-
ginning of the experiment and after one year. Homog-
enous samples were guaranteed by sampling and mixing
through all the container depths. The samples were
stored in the freezer and in the dark.
PCDD/F (Wellington Laboratories, Ontario, Canada),
were Soxhlet extracted with toluene for 24 h. Two grams
of copper were added to the Soxhlet thimble to remove
sulfur interferences. Afterwards, extracts were trans-
ferred to hexane and cleaned-up with concentrated sul-
phuric acid. This step was followed by a puri®cation in a
multilayer silica column (from bottom to top: glass
wool, silver nitrate±silica, silica, sodium hydroxyde±sil-
ica, silica, sulphuric acid±silica, silica, sodium sulphate)
eluted with hexane and a puri®cation in a Florisil (ac-
tivated at 450ꢀC overnight) column eluted with hexane
and hexane/dichloromethane (95.5) (PCB analysis) and
dichloromethane (PCDD/F analysis). The dichlorome-
thane fraction was concentrated in a Kuderna±Danish
apparatus and under nitrogen stream up to 15 ll and
13
the syringe standards (13C12-1234-TCDD and C12-
123789-HxCDD) were added. Finally, the samples were
analysed by HRGC±HRMS in a CE 8000 gas chroma-
tography coupled to an AutoSpec-Ultima (Micromass,
Manchester, UK) mass spectrometer, operating in EI
ionization (32 eV) at 10,000 resolving power. The sam-
ples were analysed on a DB-5 (60 m  0.25 mm, 0.25
lm) capillary column and on a DB-DIOXIN (60 m Â
0.25 mm, 0.25 lm) capillary column, both from J&W
(Folsom, CA, USA). The latter was used to separate
those 2,3,7,8-congeners that were not resolved on the
DB-5 column. The temperature programme for the DB-
5 column was from 150ꢀC (held for 1 min) at 30ꢀC/min
to 200ꢀC, at 3ꢀC/min to 235ꢀC (held for 10 min) and at
6ꢀC/min to 300ꢀC (held for 15 min). The temperature
programme for the DB-DIOXIN column was from
150ꢀC (held for 1 min) at 20ꢀC/min to 180ꢀC and at 2ꢀC/
min to 270ꢀC (held for 65 min). Monitored masses were
those proposed by EPA 1613 method (EPA, 1994).
2.1.2. Field experiment
This experiment was carried out in a quarry from
RUBAU S.A. in Girona (Spain), near the WWTP of the
city. Five plots were arranged on the quarry: one was
used as control and, in the other four, the soil was mixed
with di€erent amounts of sewage sludge. The doses of
sewage sludge added were the same as in the lab ex-
periment: 7.5% and 15% (7 t/ha and 14 t/ha respective-
ly), but on these experiment two di€erent applications
were studied for each amount: (a) direct application,
where the sludge was directly applied on soil and then it
was plowed to mix it and (b) previous mix, where the
sludge and the soil were mixed previously to the appli-
cation on the quarry. Each plot was 20 m long, 6 m wide
and 40 cm deep. Soils were sampled at the beginning of
the experiment (December 1992) and after four years
(March 1997).
2.4. QA/QC
The whole analytical procedure was validated before
the analysis of samples. The accuracy (expressed as re-
covery), precision (repeatability and reproducibility) and
limit of detection were studied using a sewage sludge
sample from a WWTP (unpublished data).
2.2. Reagents and materials
Hexane and dichloromethane (Pestipur) were ob-
tained from SDS (Peypin, France) and toluene (glass
distilled grade) was supplied by Rathburn (Walkerburn,
Scotland). Sodium sulphate (GR) and silica were from
Merck (Darmstadt, Germany), sulphuric acid (GR)
from Scharlau (Barcelona, Spain), silver nitrate and
sodium hydroxide from Panreac (Barcelona, Spain) and
Florisil from Supelco (Bellefonte, PA, USA).
3. Results and discussion
3.1. Laboratory experiment
The concentrations of PCDD/F in the sewage sludge
used for the lab experiment and in the resulting sewage

L. Molina et al. / Chemosphere 40 (2000) 1173±1178
1175
Table 1
Results from the laboratory experiment
Concentration of PCDD/F (pg/g d.w.)
PCDD/F
Control soil
0 yr
7.5% Amended soil
0 yr 1 yr
0.67 0.87
15% Amended soil
0 yr 1 yr
0.83 1.47
Sewage
sludge
1 yr
0.38
2,3,7,8-TCDF
0.22
0.29
0.21
0.26
0.25
<0.22
<0.08
2.22
0.17
3.01
<0.11
0.13
<0.08
0.17
<0.29
2.54
13.4
3.18
1.93
2.15
3.25
1.11
1.29
1.56
4.91
0.34
(0.52)a
1.6
4.17
1,2,3,7,8-PeCDF
2,3,4,7,8-PeCDF
1,2,3,4,7,8-HxCDF
1,2,3,6,7,8-HxCDF
2,3,4,6,7,8-HxCDF
1,2,3,7,8,9-HxCDF
1,2,3,4,6,7,8-HpCDF
1,2,3,4,7,8,9-HpCDF
OCDF
0.32
0.31
0.29
0.26
0.19
<0.07
2.80
<0.11
2.03
<0.04
<0.08
<0.11
0.21
0.21
2.67
13.2
2.53
1.84
2.58
3.24
1.29
1.79
2.89
5.29
0.39
(0.49)a
2.0
0.68
0.82
1.05
0.95
1.25
<0.20
9.42
0.72
16.7
<0.11
0.65
0.65
1.89
1.05
37.0
422
0.54
0.68
0.84
0.80
1.09
<0.16
8.33
0.66
13.8
0.1
0.81
1.08
1.40
1.25
1.79
<0.19
12.7
1.06
28.7
0.16
1.07
0.88
3.71
1.78
120
0.92
1.41
1.41
1.63
2.14
<0.20
16.3
1.38
31.2
0.17
1.06
1.02
3.75
1.65
78.1
3.72
4.94
6.29
5.75
8.34
<0.50
53.5
5.65
165
2,3,7,8-TCDD
1,2,3,7,8-PeCDD
1,2,3,4,7,8-HxCDD
1,2,3,6,7,8-HxCDD
1,2,3,7,8,9-HxCDD
1,2,3,4,6,7,8-HpCDD
OCDD
0.8
0.53
0.50
1.51
0.94
38.7
493
5.62
6.38
119
32.6
2813
14700
74.0
72.0
81.3
141
1470
16.9
12.2
17.1
27.3
11.1
59.4
31.4
236
1000
Total TCDF
Total PeCDF
13.7
8.89
12.2
18.2
8.18
15.3
18.9
71.0
2.43
(2.56)a
7.7
9.44
8.17
11.3
17.4
5.88
19.2
11.2
77.2
2.37
(2.39)a
10
23.0
19.4
21.2
34.0
12.7
32.7
32.9
Total HxCDF
Total HpCDF
Total TCDD
164
Total PeCDD
5640
630
Total HxCDD
Total HpCDD
I-TEQ
148
4490
68.1
(68.2)a
48
5.28
(5.30)a
18
4.61
(4.63)a
9.5
R
ꢁPCDD=PCDF†
a Values in parentheses include detection limits.
sludge-amended soils (sampled at the beginning of the
experience and after one year) are shown in Table 1. The
PCDD/F concentration in the sewage sludge used in this
experiment was 68.1 pg I-TEQ/g d.w., a value in the
range usually reported in the literature for this kind of
samples (Jones and Sewart, 1997). Concentrations of
PCDD (specially hepta- and octa-congeners) were
higher than PCDF, which is the trend reported by other
authors for most urban sewage sludges (Sewart et al.,
Moreover, the PCDD/F concentration in amended
soils is directly related to the sewage sludge dose ap-
plied and after one year, no evolution is observed in
any sample. The levels remain constant in all of them
(Fig. 2). These results con®rm those obtained by Sch-
wartz and McLachlan, 1993 in a experiment with
amended soils for agricultural purposes over a 6-week
period.
1995; Eljarrat et al., 1996; Tiernan et al., 1996), with a
1
3.2. Quarry experiment
ratio R
of sewage sludge in the concentration of PCDD/F in the
ˆ 48. This ratio shows the in¯uence
ꢁPCDD=PCDF†
The high content of organic matter in the sewage
sludge, the presence of nitrogen, phosphorus, etc. in-
creased the fertility of those plots that have been ar-
ranged with sewage sludge-amended soils. Therefore,
those plots showed an important revegetation already in
the ®rst year, having been accomplished the land resto-
ration purposes.
amended soils: for control soils R was 2
ꢁPCDD=PCDF†
whereas it ranged from 7.7 to 17.7 for amended soils. In
addition, the pro®le of sewage sludge-amended soils was
more similar to that of the sludge than to that of the
control soil (Fig. 1). These results are similar to those
obtained by Eljarrat et al. (1996) in a study with addi-
tion of sewage sludge in agricultural soils.
The concentrations of PCDD/F obtained in the
samples from this experience, both at the beginning of
the experiment and after four years, are shown in Table 2.
The most important congeners in the homologue pro®les
1
R
has been calculated as the ratio between total
ꢁPCDD=PCDF†
PCDD (in pg/g) and total PCDF (in pg/g).

1176
L. Molina et al. / Chemosphere 40 (2000) 1173±1178
Fig. 1. Homologue pro®les of sewage sludge, control soil and sewage sludge-ammended soil.
of the samples of the amended soils were hepta- and
octachlorinated dioxins, in a similar way to lysimeters
not so high. In any case, the concentration of PCDD/F
was higher in the amended soils than in those without
addition of sewage sludge (Fig. 3).
results. The ratio R
ranged between 2.9 and
ꢁPCDD=PCDF†
4.9 although in this experiment the di€erence in this
parameter between control soils and amended ones was
Results of PCDD/F from amended soils in this ex-
periment showed high dispersion, which did not allow to
establish a trend about the di€erent kinds of application
or about the PCDD/F evolution in the plots. The vari-
ability in PCDD/F concentrations is not due to the an-
alytical method because it is clearly higher than the
reproducibility variability. This dispersion, obtained in
spite of sampling carefully, is attributed to the lack of
homogeneity in the plots when high amounts of soils
and sewage sludge are used, big machines are needed to
mix them and the conditions (temperature, humidity,
etc.) during the evolution time can not be as controlled
as in a lab experiment. This theory is con®rmed by the
dispersion also found in other parameters (e.g. organic
matter, Fig. 4). In addition, other authors have reported
similar problems in variability of results due to a lack of
homogeneity in plots amended with sewage sludge
(Wilson et al., 1977).
Fig. 2. Evolution of PCDD/F concentration (pg I-TEQ/g d.w.)
in soils from laboratory experiment.

L. Molina et al. / Chemosphere 40 (2000) 1173±1178
1177

1178
L. Molina et al. / Chemosphere 40 (2000) 1173±1178
~
J.M. Alcaniz, for the determinations of organic matter.
The authors thank Junta de Sanejament (Generalitat de
Catalunya) and the CICYT (Spain) for ®nancial support
(AMB-95-0728). J.D.F. gratefully acknowledges the
support of the CIRIT, Generalitat de Catalunya.
References
~
Alcaniz, J.M., Comellas, L., Pujola, M., 1996. Manual de
Restauracio d' Activitats Extractives amb Fangs de Depur-
ꢀ
ꢀ
ꢀ
adora. Recuperacio de Terrenys Marginals 1st Edn. Gen-
eralitat de Catalunya-Dept. Medi Ambient, Barcelona.
Mangas, E., Vaquero, M.T., Comellas, L., Broto-Puig, F.,
1998. Analysis and fate of aliphatic hydrocarbons linear
alkylbenzenes polychlorinated biphenyls and polycyclic
aromatic hydrocarbons in sewage sludge-ammended soils.
Chemosphere 36, 61±72.
Fig. 3. Evolution of PCDD/F concentration (pg-I-TEQ/g d.w.)
in soils from quarry experiment (D.A. ˆ direct application;
P.M. ˆ previous mix).

Gihr, R., Klop€er, W., Rippen, G., Partscht, H., 1991.
Investigations on potential sources of polychlorinated
dibenzo-p-dioxins and dibenzofurans in sewage sludges.
Chemosphere 23, 1653±1659.
Hortsmann, M., McLachlan, M.S., Reissinger, M., 1993.
Investigations of the origin of PCDD/F in municipal sewage
sludge. Chemosphere 27, 113±120.
McLachlan, M.S., Horstmann, M., Hinkel, M., 1996. Poly-
chlorinated dibenzo-p-dioxins and dibenzofurans in sewage
sludge: sources and fate following sludge application to
land. Sci. Tot. Environ. 185, 109±123.
Jones, K.C., Sewart, A.P., 1997. Dioxins and furans in sewage
sludges: a review of their occurrence and sources in sludge
and of their environmental fate behavior and signi®cance in
sludge-amended agricultural systems. Crit. Rev. Environ.
Sci. Technol. 27, 1±85.
Tiernan, T.O., Garrett, J.H., Solch, J.G., VanNess, G.F.,
Wagel, D.J., Rukunda, F., 1996. Polychlorinated dibenzo-p-
dioxins (PCDDs) and polychlorinated dibenzofurans
(PCDF)s in sewage sludges from rural and urban/industrial
wastewater treatment plants (WWTPs). Organohalogen
Compound 32, 98±102.
Fig. 4. Organic matter (% oxidable C) in soils from quarry
experiment (D.A. ˆ direct application; P.M. ˆ previous mix).
4. Conclusions
EPA, 1994. 1613 Method: Tetra-Through Octa Chlorinated
Dioxins and Furans by Isotope Dilution HRGC-HRMS,
Revision B.
The revegetation of degradated lands, like quarries,
with sewage sludge-amended soils is successful. How-
ever, and in spite of the variability of results in the ®eld
experiment, we can conclude that the amendment with
polluted sewage sludge increases PCDD/F concentration
in soils. In addition, these compounds are persistent in
soils after long periods of time (one year) as can be
concluded according to the controlled experiment in
lysimeters.
Sewart, A., Harrad, S.J., McLachlan, M.S., McGrath, S.P.,
Jones, K.C., 1995. PCDD/Fs and non-o-PCBs in digested
UK sewage sludges. Chemosphere 30, 51±67.
Eljarrat, E., Caixach, J., Rivera, J., 1996. E€ects of sewage
sludges contaminated with polychlorinated dibenzo-p-diox-
ins dibenzofurans and biphenyls on agricultural soils.
Environ. Sci. Technol. 31, 2765±2771.
Schwartz, K., McLachlan, M.S., 1993. The fate of PCDD/F in
sewage sludge applied to an agricultural soil. Organohalo-
gen Compound 12, 155±158.
Acknowledgements
Wilson, S.C., Alcock, R.E., Sewart, A.P., Jones, K.C., 1977.
Persistence of organic contaminants in sewage sludge-
amended soil a ®eld experiment. J. Environ. Qual. 26,
1467±1477.
The authors are indebted to CREAF (Universitat
ꢀ
Autonoma de Barcelona, Bellaterra), specially to Dr.