Agronomic Properties and Heavy
Metals Content in Soil Reclaimed From
Municipal Solid Waste Landfill
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Contents
Contents .......................................................................................................................... i
Abstract .......................................................................................................................... 1
1. Introduction ................................................................................................................ 1
2. Materials and Methods ............................................................................................... 2
2.1 Site study.............................................................................................................. 2
2.2 Sample sampling .................................................................................................. 3
3. Results and Discussion .............................................................................................. 4
3.1 Landfill soil chemical properties ......................................................................... 4
3.2 Heavy Metal Contents in Landfill Soil ................................................................ 5
4. References .................................................................................................................. 7
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Table list
Table 1 Chemical properties of landfill soil compared with background soil and
compost criteria .............................................................................................................. 4
Table 2 Heavy metal (mg/kg) contents in landfill soil compared to regulation limits
for heavy metal content in sludge or compost for agricultural use. ............................... 6
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Figure lists
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รู ปที่ 1 แผนที่จงหวัดขอนแก่น .................................................................................................. 3
รู ปที่ 2 อุปกรณ์การศึกษา ......................................................................................................... 4
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Abstract
Landfill soils reclaimed from municipal solid waste landfill were characterized
for chemical properties and heavy metals. The samples were collected from Khon
Kaen Municipality engineered landfill, Khon Kaen, Thailand, approximately aged 10-
15 years, and screened with a 6.3-mm sieve. Chemical properties analysis was
undertaken by appropriate procedure, and heavy metals were analyzed by inductively
coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled
plasma mass spectrometry (ICP-MS). The landfill soil characteristics measured
include pH, electrical conductivity (EC), cation exchange capacity (CEC), organic
matter (OM), total N, available P, K, Mg and Ca; results obtained were 8.1, 4.2 dS/m,
4.4 cmol/kg, 4.9%, 0.27%, 23.2 mg/kg, 1.24 g/kg, 10.5 g/kg and 0.43 g/kg,
respectively. The heavy metal contents in landfill soil included 2.0 As, 3.25 Cd, 3.3
Co, 38.0 Cr, 166.0 Cu, 1533.0 Fe, 0.72 Hg, 412 Mn, 22.0 Ni, 157.0 Pb, 1.0 Se, 44.0
Sn and 662 Zn mg/kg, respectively. These heavy metal concentrations were within
permissible limits for land application described by Thailand and US EPA. This result
indicated that municipal solid waste landfill had potential for recovery soil, and its use
for soil amendment.
1. Introduction Landfill reclamation is the
process of excavating a landfill using
Landfilling and dumping is the
conventional surface mining
oldest and cheapest way of disposing
technology to recover materials such as
municipal solid waste. Indeed,
metal, glass, plastics and soils5 and has
depending on location, up to 95% of
been used for conservation of landfill
solid waste generated worldwide is
spaces, reduction in landfill area,
currently disposed of in landfills.
elimination of potential sources of
Landfills will continue to be the most
contamination, mitigation of existing
attractive disposal route for solid
contamination sources, energy
waste1 2. Nevertheless, most organic
recovery, recycling of recovered
materials are biodegradable, and
materials, reduction in management
decomposition usually takes place in
system costs, and site redevelopment6-
landfill, where the aerobic and
8. Between 20% and 80% of excavated
anaerobic microbial process will
waste may be extracted for re-use9.
dominate the stabilization of waste,
The cover soil and degraded organic
and hence govern the generation of
waste have been reported to constitute
landfill gas and the composition of
about ~75% of the recovered
leachate1 3. These effects are some of
material10. Potential reuse options for
the major issues that may make
the recovered soil include use as daily
landfills unsustainable. To counter
and intermediate landfill cover material,
these limitations requires landfill
construction fill and as material
design to incorporate significant
support for plant growth or soil
leachate collection systems, heavy use
amendment 10, while other recovered
of liners and long term post-closure
material can be used for energy
monitoring. All these result in
production10-12.
increased cost of establishing and
In Thailand, conventional
managing landfill4 .
handling of MSW poses serious
2
environmental and public health because most Thai agricultural soils
concerns, as a large number of the have been used extensively for crop
landfills in Thailand are not well- production for extended periods of
engineered, but use techniques such as time and are usually low in soil organic
open dumping and open burning. Of matter and essential plant nutrients
the estimated 1,000 or more disposal Before stabilized materials
sites nationwide, only 104 have been reclaimed from landfill are applied on
constructed to appropriate standards13. land, they should be characterized for
MSW contains 47% organic waste and chemical properties and heavy metals
40% recyclable waste. The actual related to human health and
amount of municipal solid waste being environmental concerns. Regarding
separated for utilization was 5% in their content of potentially hazardous
199014 and up to 19% of total MSW heavy metals (e.g. Cd, Cr, Ni, Pb, Zn,
generation in 200315; in fact most Cu) still persist. 4 8 17 18If excessive
organic waste and recyclable waste is loads of pollutants are introduced with
disposed of in landfill. The ability to the application of low-quality waste,
stabilize waste within landfill and soil fertility may be adversely affected,
reutilize the volume within landfill ground-water quality threatened, and
cells has become very attractive. the food chain contaminated19-21. The
Particularly, the used of soil reclaimed aim of this work is to describe the
from MSW landfill for use as an chemical characteristics and heavy
alternative source of organic matter metals concentration in landfill soil
and plant nutrients for land application reclaimed from MSW landfill.
2. Materials and Methods
2.1 Site study
Khon Kaen Municipality Landfill is located in Amphoe Muang,
Changwat Khon Kaen, northeast Thailand, about 445 km. from Bangkok. It is situated
between north latitude 16º 16.8´ and east longitude 112º 27.8´, about 155-160 m.
above sea level. The average temperature is 26.7 ºC (22.0-32.6 ºC). The annual
average rainfall is 1,225 mm. Around 36,000 tons/year of MSW were deposited in the
Khon Kaen Municipality Landfill. The composition of MSW consists of food waste
(47%), plastic (16%), paper (15%), glass (6.28%) and yard waste (5.4%) and other
materials22. Landfilling operation was designed as an engineered landfill system with
area method to commence operation in 1987.
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2.2 Sample sampling
Because the material was buried in a landfill, it is heterogeneous. The
landfill material samples were collected from 6 locations. The sampling locations
were identified in consultation with the municipal authorities responsible for
operation of the sites; the wastes at these locations were filled about 10-15 years ago.
Landfill material samples were excavated using a backhoe and removed from the
landfill cell by truck, and then unloaded on a clean area beside the MSW landfill site.
Each landfill material sample, one to two cubic meters, was combined and mixed
using a front-end loader. Six samples, approximately 100 liters each, were randomly
sampled for analysis. Each landfill material sample was screened with a 6.3-mm sieve
with a simple vibrating screen. This screen size was selected because on the basis of
the study by Jain et al.23 and Das et al.4. It was suggested that the fraction less than
6.3 mm is like soil and can be used for soil amendment. Das et al. recommended that
soil less than 3/8 inch (9.6 mm) can be used for soil amendment, but as this screen
size has foreign material contamination of 3.5%, it is dangerous as it may contain
broken glasses.
After screening, the fraction retained on a 6.3-mm sieve was defined as
refuse material, while the material passing through the 6.3-mm sieve was defined as
landfill soil. One liter of each landfill soil sample was collected in a plastic sample
bag and taken to the laboratory for chemical analysis.
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รูปที่ 2 อุปกรณ์การศึกษา
3. Results and Discussion
3.1 Landfill soil chemical properties
The chemical properties of landfill soil were determined; the results are
shown in Table 1. Landfill soil chemical properties show that it is moderately alkaline
with a pH range from 8.0-8.2 (average pH 8.1), has slight salinity to high salinity with
an electrical conductivity (EC) range from 2.7-6.2 (average 4.2 dS/m), low cation
exchange capacity (CEC) with CEC between 4.2-4.7 cmol/kg (average 4.4 cmol/kg),
and high organic matter (OM) with of 4.6-5.1% (mean 4.9%). Landfill soil plant
macronutrient constituents, such as available phosphorus (P), potassium (K), calcium
(Ca) and magnesium (Mg), are at a high to very high level; 21-26 mg P/kg, 1.1-1.4 g
K/kg, 8.8-11.1 g Ca/kg, 349-496 mg Mg/kg, respectively.
Table 1 Chemical properties of landfill soil compared with background soil and
compost criteria
Properties Mean± SD Backgrounda Compost Criteriac
pH 8.1 ± 0.1 4.0-5.0 5.5-8.5
EC (dS/m) 4.2 ± 1.3 0.02-0.41b <3
CEC (cmol/kg) 4.4 ± 0.2 <3 -
OM (%) 4.9 ± 0.2 0.5-0.75 -
N (%) 0.27 ± 0.1 ND ≥0.5 %
P (mg/kg) 23.2 ± 1.7 2.5 ≥0.5 %
K (mg/kg) 1243 ± 91 <30 ≥1.0 %
Ca (mg/kg) 10526 ± 884 ND -
Mg (mg/kg) 437 ± 49 ND -
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3.2 Heavy Metal Contents in Landfill Soil
Heavy metal concentration in landfill soil is shown in Table 2. The
concentrations of zinc, copper, lead, manganese, tin and chromium were high relative
to other heavy metals.
In comparing heavy metal contents in landfill soil and background levels
(Thailand soil) (i.e.2.7 mg As/kg, 0.01 mg Cd/kg, 15.3 mg Cr/kg, 6.9 mg Cu/kg, 0.03
mg Hg/kg, 6.2 Ni/kg, 9.0 mg Pb/kg, 14.0 mg Zn/kg)29, the results show that all
element concentrations are higher than for Thailand soil; the exception was arsenic,
which was lower. In particular, cadmium, lead, mercury, chromium and nickel had
much higher concentrations than Thailand soil of 325, 17, 23, 2.5 and 3.5 times,
respectively. The concentrations of zinc and copper, which are plant micronutrients,
are higher than Thailand soil by 47 and 24 times, respectively.
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Table 2 Heavy metal (mg/kg) contents in landfill soil compared to regulation limits for heavy metal content in sludge or compost for
agricultural use.
Regulated limit a
Element Landfill soil
AUS CAN DEN FIN FRA GER ITA NED NOR ESP SWE SWZ THA USA
As 2.0 ± 0.1 - 170 - 50 - - 500 15 - - - - 50 41
Cd 3.25 ± 0.18 1 34 0.8 3 8 1.5 10 1 2 40 1 1 5 39
Co 3.3 ± 0.1 - 340 - - - - - - - - - - - -
Cr 38 ± 6 70 2800 100 - - 100 10 50 100 750 100 100 300 1200
Cu 166 ± 27 100 1700 1000 600 - 100 600 60 650 1750 100 100 500 1500
Fe 1533 ± 800 - - - - - - - - - - - - - -
Hg 0.72 ± 0.06 1 11 0.8 2 8 1 10 0.3 3 25 1 1 2 -
Mn 412 ± 21 - - - - - - - - - - - - - -
Ni 22 ± 3 60 420 30 100 200 50 200 20 50 400 50 30 - 420
Pb 157 ± 8 150 1100 120 150 800 150 500 100 80 1200 100 120 500 300
Se 1 ± 0.2 - 34 - - - - - - - - - - - -
Sn 44 ± 2 - - - - - - - - - - - - - -
Zn 662 ± 27 400 4200 4000 1500 - 400 2500 200 800 4000 300 400 - 2800
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4. References
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Flyhammar P. Estimation of heavy metal transformations in municipal solid waste.
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Das KC, Smith CM, Gattie KD, Hale Boothe DD. Stabilty and quality of municipal
solid waste compost from a landfill aerobic bioreduction process. Advances in
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Morelli J. Landfill reuse strategies. Biocycle 1990; 31 (4):60–61.
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waste material resource: disposed thermoplastics. Proceedings Sardinia 99,
Seventh International Waste Management and Landfill Symposium. Cagliari,
Italy: CISA, Environmental Sanitary Engineering Centre, 1999.