Assessment of the possible reuse of MSW coming from landfill mining of old open dumpsites

Assessment of the possible reuse of MSW coming from landfill mining of old open dumpsites

Waste Management 34 (2014) 702–710 Contents lists available at ScienceDirect Waste Management journal homepage: www.elsevier.com/locate/wasman Asse...

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Waste Management 34 (2014) 702–710

Contents lists available at ScienceDirect

Waste Management journal homepage: www.elsevier.com/locate/wasman

Assessment of the possible reuse of MSW coming from landfill mining of old open dumpsites S. Masi, D. Caniani ⇑, E. Grieco, D.S. Lioi, I.M. Mancini School of Engineering, University of Basilicata, viale dell’Ateneo Lucano, 10, 85100 Potenza, Basilicata, Italy

a r t i c l e

i n f o

Article history: Received 23 July 2013 Accepted 19 December 2013 Available online 10 January 2014 Keywords: Bioassays Heavy metals Landfill mining Municipal solid waste

a b s t r a c t The present study addresses the theme of recycling potential of old open dumpsites by using landfill mining. Attention is focused on the possible reuse of the residual finer fraction (<4 mm), which constitutes more than 60% of the total mined material, sampled in the old open dumpsite of Lavello (Southern Italy). We propose a protocol of analysis of the landfill material that links chemical analyses and environmental bioassays. This protocol is used to evaluate the compatibility of the residual matrix for the disposal in temporary storages and the formation of ‘‘bio-soils’’ to be used in geo-environmental applications, such as the construction of barrier layers of landfills, or in environmental remediation activities. Attention is mainly focused on the presence of heavy metals and on the possible interaction with test organisms. Chemical analyses of the residual matrix and leaching tests showed that the concentration of heavy metals is always below the legislation limits. Biological acute tests (with Lepidum sativum, Vicia faba and Lactuca sativa) do not emphasize adverse effects to the growth of the plant species, except the bioassay with V. faba, which showed a dose–response effect. The new developed chronic bioassay test with Spartium junceum showed a good adaptation to stress conditions induced by the presence of the mined landfill material. In conclusion, the conducted experimental activities demonstrated the suitability of the material to be used for different purposes. Ó 2013 Elsevier Ltd. All rights reserved.

1. Introduction Landfills have long been considered as a way to store waste at minimum cost. Today it is well known that this kind of waste disposal shows a series of problems related to possible contaminations caused by the degradation of organic waste, which generates methane emissions that contribute to global warming (Sormunen et al., 2008). Old dumpsites, without any sort of protection for reducing emissions, are a source of local pollution due to the leaching of hazardous substances (Krook et al., 2012). In Italy, there are more than 10,000 old open dumpsites, built and developed before current regulations were in place (before 1980), without modern environmental technologies for limiting emissions. These sites, although no longer used, still represent an important source of environmental risk, mainly for the presence of micro-pollutants, such as heavy metals. These sites can cause pollution of groundwater and surface water due to leaching and runoff. Moreover, in many parts of the world, landfilling is still the most important waste disposal method. In Italy, although more advanced systems for waste recycling and treatment have been developed, in 2011 landfilling still was the most common form of manage⇑ Corresponding author. Tel.: +39 0971205209. E-mail addresses: [email protected], [email protected] (D. Caniani). 0956-053X/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.wasman.2013.12.013

ment, affecting 42.1% of municipal solid waste management (ISPRA, 2013). The problem of environmental rehabilitation of a waste disposal site has always been one of the most delicate issues to deal with, in order to complete the phase of restitution of the site to the environment. In literature, recovery methods adopted for remediation have mainly been developed for the treatment of soils of limited size and affected by high contamination. These methodologies, with high costs, if applied to large areas with low concentrations of contaminants are useless. For the remediation of old open dumpsites, it is necessary to set up a recovery plan tailored and developed on the basis of a careful campaign of investigation. At the European level, the excavation and treatment of polluted land are now recognized as important measures to protect air, land and water resources (Hogland et al., 2004). An interesting remediation technology for the mentioned closed open dumpsites is landfill mining. Landfill mining was first introduced in Israel in 1953 as a way to obtain fertilizers for orchards. The interest in this strategy increased in the 1990s, when other studies were carried on and published (Krook et al., 2012). Landfill mining includes the extraction and processing of material buried in closed landfills, often unlined. Many of these old landfills still might be a ‘‘mine’’ of materials. The objectives of this type of treatment are: preservation of volume in landfills, removal of a potential source of pollution,

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mitigation of the site contamination, energy recovery, reuse of recoverable materials in landfills, reduction of management cost and redevelopment of the site (Hogland et al., 2004). Recently, the concept of Enhanced Landfill Mining (ELFM) has been receiving a lot of attention. ELFM includes the combined and integrated valorisation of waste streams as both materials and energy, while respecting ecological and social criteria (Quaghebeur et al., 2013). In addition, the volume of the old landfill site, once reclaimed, can be renovated and adapted to the standard rules and reused to store new waste (Prechthai et al., 2008b). The approach for the implementation and evaluation of landfill mining is still immature and does not use standardized rules and principles, although research has been conducted in this field (Krook et al., 2012). Four main type of uncertainties related to landfill mining projects can be listed: waste composition, processing technologies, markets for materials, environmental and health risks (Frändegård et al., 2013). One of the most critical aspects is the destination of the residual matrix coming from landfill mining (with recovery of materials) and remediation activities on landfills and open dumps. This residual matrix represents one of the main products of the storage of waste in landfills and consists mainly of degraded organic matter, soil cover and residues of medium and large size. This material could be reused for final or daily covering of landfills, as shown by Jain et al. (2005). However, it is important to underline that landfills (as we know them) are, ideally, transformed into temporary storage places. The temporary storage is an environmentally and structurally safe storage place that permits in situ recovery of materials and energy from waste streams and allows easy future access to resources whenever needed. The temporary storage is a new concept that enables optimisation of waste recycling and will make waste disposal in landfills and incineration of valuable waste materials (potential resources) unnecessary. Moreover, it can facilitate the retrieval of materials from old and abandoned landfills, thus also creating a connection to the past and realising a delayed recycling. The temporary storage will allow creating a connection among past, present and future, and a new step towards the circular economy (Krook et al., 2013; Quaghebeur et al., 2013; Bosmans et al., 2013; Jones et al., 2013). The complexity of studying the suitability in environmental applications of the residual material originating from landfill mining operations on old landfills is mainly due to its heterogeneity (Masi et al., 2011). In literature, different studies have shown residual material recovery originating from landfill mining activities (Hogland et al., 2004; Prechthai et al., 2008b), but only in recent years papers concerning the study of the possibility of mining very old dumpsites were published (Quaghebeur et al., 2013, Kaartinen et al., 2013, Jain et al., 2013). A good characterization of the site is needed to identify the problems related to the process of reclamation (Raga and Cossu, 2013). Moreover, a qualitative and quantitative analysis of waste is essential, in order to determine the potential of waste recycling in reclamation operations (Prechthai et al., 2008a). Multiple studies showed that the chemical approach does not provide satisfactory tools to define the environmental risk associated to a mixture of pollutants (Pasini et al., 2000). Information about phytotoxicity is necessary for the evaluation of the environmental pollution risk (Wang et al., 2001; Caniani et al., 2013). The presence of toxicological agents can be detected by analysing the changes caused on a test organism. These tests are reliable, convenient, fast and simple (Valerio et al., 2007). Laboratory tests can be divided into acute and chronic (or sublethal) tests. An acute test uses increasing doses (on a logarithmic scale) for short periods, from 15 min to 96 h. Chronic tests have a duration variable from days to months and are conducted typically using low concentrations for long periods. The use of plants offers an advantage if compared to other organisms, because they may be more sensitive to

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environmental stress (Valerio et al., 2007). Furthermore, the use of ecotoxicological assays allows us to evaluate, on one side, the bio-available fraction of the pollutants, and, on the other hand, any synergy and/or antagonism phenomena of different substances (Pasini et al., 2000). In this research paper, an innovative analytical protocol is designed to test the suitability of organic residues from landfill mining activities of very old closed dumpsites. There are several hypothesis of usage of the obtained material, such as: storage in temporary storages, formation of ‘‘bio-soils’’ to be used in geoenvironmental applications, as daily and final covering in controlled landfills in substitution of the soil layer, or in environmental remediation activities. We carried out chemical and physical analyses. Moreover, we applied acute and chronic bioassays, to evaluate the toxicity of some heavy metals on vegetable species by varying the growth substrate. The analysis protocol proposed in this study is able to describe the influence of the analyzed organic matrix on soil receptors, vegetation material and groundwater resources. Vegetation tests were used to evaluate the toxicity of some heavy metals on vegetable species by varying the growth substrate. However, giving the lack in literature of chronic tests on plant species typically used in geo-environmental restoration applications, an innovative chronic test with Spartium Junctium was developed and carried out. The developed analytical protocol is able to verify: the main physical and chemical characteristics of the material to be tested, the possible percolation of pollutants in groundwater, the dry matter production of the aboveground biomass, in order to meet the specific needs for reuse of the material in the fields it is meant for, and the possible use of the material under study in environmental remediation activities. 2. Materials and methods 2.1. Site description and sampling The material used in this research originates from the old closed dumpsite of Lavello (Basilicata Region-Southern Italy), which was developed before current regulations were in place. The samples were collected in the period between June and July 2009. The landfill site was object of solid waste dumping from the 1950s to the early years of the 1980s. The dumpsite does not possess any form of containment of pollutants (unlined landfill). The sampling programme was defined on the basis of a visual observation of the site and the acquired knowledge on historical information. From the studied landfill, which covers an area of about 1 ha, 7 samples were taken, following the scheme showed in Fig. 1, at a depth from the

Fig. 1. Study area and samples collection points (total area of the dumpsite is approximately 10,000 m2).

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ground level between 0.5 and 1 m. All 7 samples were composite together in a unique sample (approximately 1840 kg) that was subjected to three operations of quartering, through which a laboratory sample of 230 kg was obtained. 2.2. Merceological analysis and screening The sampled material was subjected to a screening operation at 10 mm and 4 mm. The different merceological categories identified in the oversieve and recognized in the sample were manually separated. It was possible to recognize the following fractions: metals and ferrous materials, plastic and cellulosic materials, glass, stone material and burnt material, which is probably the result of the old and widespread practise of burning waste in dumpsites. 2.3. Preliminary laboratory analyses: determination of heavy metals, total organic carbon and leaching tests The sampled material was subjected to sieving into rotating screens at 10 mm and 4 mm. Chemical analyses were performed on eight waste samples, four from the undersieve at 4 mm and four from the undersieve at 10 mm. We performed two types of analyses: chemical analyses and leaching tests. Heavy metals identified by chemical analyses are the following: Al, As, Cd, Cr, Cu, Mn, Ni, Pb, Zn. The chemical analyses evaluate the concentration of heavy metals in the study matrix and the leaching potentiality. One of the objectives of this research is to test the possible reuse of the material under study not only in geo-environmental applications, as barrier layers in landfills, but even for the formation of ‘‘bio-soils’’ to be used in environmental remediation activities in open field. For this reason, the material under study underwent a leaching test with acetic acid, as described in method 1311 (USEPA, 2006), which is more stringent than other similar tests. The aim of the leaching test is to evaluate the behavior of an organic and inorganic matrix in the release of pollutants in an acid environment, such as a landfill environment. It assesses whether the liquid phase obtained shows noticeable traces of pollutants. The samples were extracted with acetic acid (pH 2.88), 20 times the weight of the sample. The samples were agitated at 30 rpm for 18 h, passed through a 0.45 lm membrane filter and analyzed for heavy metals concentration. The analytical measures of metals are based on the standard methods for water and wastewater analysis (APHA et al., 1998) and were carried out by an inductively coupled plasma spectrometer (ICP), Variant 710. The total organic carbon (TOC) analyses were carried out using a ‘‘ Sulfur / Carbon Analyzer SC-144 DR (LECO)’’, on samples of material that were previously sieved to 2 mm and dried in an oven at 105 °C. The method adopted is the UNI-EN-13137. The measure is obtained by high temperature combustion: the organic carbon is oxidized to CO2, which is detected by an infrared analyzer. It is important to carry out acidification and aeration of the sample before the TOC analysis, in order to avoid errors due to the presence of inorganic carbon. Some organic compounds, however, cannot be completely oxidized. For this reason, the value of C, that is obtained with this analysis, is lower than that is actually present in the sample. 2.4. Biological assays Chemical analyses of the material under study, even if indispensable, are not comprehensive for the aim of this research. It is very important to assess the presence of some substances or properties that cannot be detected with chemical analyses such as: synthetic organic matter (which cannot be foreseen even if the origin of biomass is known), mobility of the different chemical forms of metals under different environmental conditions, additive and

synergistic effects due to the contemporaneous presence of several contaminants, bio-availability and transfer rate of organic and inorganic contaminants to vegetable tissues. Biochemical characteristics of materials can be evaluated through acute and chronic tests, carried out on vegetable species used as indicators. All the biological assays were carried out on MSW samples, taken from the undersieve at 4 mm.

2.4.1. Acute tests: germination test with Lepidum sativum and root elongation test with V. faba The germination test in L. Sativum and the root elongation test in V. faba are phytotoxicity tests reported in the manual ‘‘Methods of microbiological analysis of compost’’ (Italian Environmental Protection Agency, 2003). The germination test evaluates the phytotoxicity of the soil through the assessment of the possible effect of phytotoxic products on the germination of seeds. This bioassay takes into account the germination and root growth of the seeds of L. sativum (after a period of incubation of 24 h at 27 °C), which is a plant particularly sensitive to the presence of phytotoxic factors. The MSW sample, brought to a humidity of 85%, is left in contact with distilled water for 2 h. On the obtained aqueous extract, opportunely diluted, we tested the germination of 5 replicates with 10 seeds of L. sativum placed in Petri dish containing tissue paper. A total number of 15 repetitions were carried out (5 repetitions for each protocol). The standardized testing protocol is the following: one protocol with distilled water and two protocols with aqueous extract at a concentration of 50% and 75%. After incubation, we counted the seeds germinated and their root length and determined the Germination Index Ig, according to the following equation:

Ig ð%Þ ¼

Gc  Lc  100 Gt  Lt

ð1Þ

where Gc is the average Number of seeds germinated in the sample; Gt the average number of seeds germinated in the control (distilled water); Lc the average root length in the sample; Lt is the average root length in the control (distilled water). The purpose of the root elongation test in V. faba is the assessment of the presence of phytotoxins that can cause the reduction of the length of the primary root in seedlings of V. faba, compared to the control. The seedlings were treated for 96 h with three different doses of the material under study and with a control (Table 1). The test was conducted in a climatic chamber at 20 ± 1 °C, on a sandy soil with sand content >90% and very low content of organic colloids and clay. Two trays, indicated with the letters A and B, each containing 25 seeds, were prepared for each assay. After a period of 96 h, we proceeded to the measurement of the primary root of the germinated seeds. The average length of roots (considering both replicates) for each dose was compared with those of the control tests. The Germination Index was calculated with Eq. (1).

Table 1 Bioassay with Vicia faba: dosages expressed in grams of the material under study per kilogram of sandy soil. Dose

Dry doses (g of the material under study/kg of dry sandy soil)

Wet doses at 2% humidity (g of the material under study / kg of sandy soil)

0 1 2 3

0 88.3 165.6 441.5

0 90.1 168.9 450.5

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S. Masi et al. / Waste Management 34 (2014) 702–710 Table 2 Bioassay with Spartium junceum: dosages expressed in grams of the material under study per kilogram of inert soil. Dose

Dry dosage g of the material under study/kg of inert soil

Wet dosage g of the material under study/kg of inert soil

1 2 3 4 5 6 7

11.0 22.1 44.2 88.3 165.6 220.8 441.5

11.3 22.5 45.1 90.1 168.9 225.3 450.5

2.4.2. Agronomic suitability bioassays: vegetation test with Lactuca Sativa The applied methodology is described in ‘‘Methods of microbiological analysis of compost’’ (Italian Environmental Protection Agency, 2003). The purpose is to test the agronomic phyto-compatibility and to evaluate the possible agricultural reuse of by-products, such as liquid or solid organic residues. The method is based on the evaluation of the aboveground biomass production for lettuce plants, in the presence of increasing doses of a particular product or biomass waste, applied to a specific growth substrate. The experimental design involved the mixing, at increasing concentrations (9 doses), of the test substance (MSW undersieve at 4 mm) with an artificial substrate, fertilized by a concentrated fertilizer solution. The seedlings of lettuce (L. sativa L.), which were previously germinated in a separate germinator, were then transplanted on the test mixtures. Four replicates were set up for each of the nine assays. Three lettuce seedlings were inserted in each pot. The trial was conducted in a greenhouse (16 h of light, 8 of dark, 25 °C at day, 16 °C at night), using vessels with a capacity of 0.3 l. After a growing period of 14 days, the aboveground part of the plants was taken for the measurement of the fresh weight and, after drying, of the dry weight. 2.4.3. Chronic test: germination and radical elongation tests with Spartium junceum The biological chronic bioassay with S. junceum is a new test that has been developed during this research. This species was selected because it is suitable for carrying out the revegetation activities on closed landfills. In fact, Spanish broom is a species capable of adapting itself to types of soils that are characterized as difficult (for example dry or clayey). Moreover, S. junceum is commonly used in environmental restoration activities. This species has good resistance to water stress and to methane exhalation stress. It is also a species with a surface root system characterized by a maximum depth of the roots equal to 1.5 m.

Table 3 Total organic carbon of the solid waste compared with that of a typical agrarian soil. TOC (%) Agrarian soil Agrarian soil Agrarian soil Mean

Sample 1 Sample 2

TOC (%) Solid waste 0.8% 0.9% 0.8%

Solid waste Solid waste Mean

Sample 1 Sample 2

5.2% 5.3% 5.2%

The purpose of the test is to assess the phytotoxicity of the material under study against the S. junceum. The test allows us to identify the effects that the material under study produces on the development of this species at varying doses, through the analysis of germination, root development and characteristics of the produced aboveground biomass (quantity and color). The material under study was mixed, in seven increasing doses from 11.0 g/kg of S.S. (suspended solids) to 441.5 g/kg of S.S. (Table 2), with inert soil (river natural silica sand, to which about 10% by volume of peat moss was added), for the first scenario, and with agricultural poor soil (which was sieved at 4 mm), for the second scenario. In the first scenario, the peat was added in order to avoid granulometric separation between sand and the studied matrix. The addition of poor soil had the purpose of simulating the behavior of the studied mixture in coatings of landfills or in applications of environmental recovery. The two base substrates are broadly neutral, with a pH of 6.9 for the sand-peat mixture and 7.3 for the agricultural land, while the material under study was slightly sub-acid, with a pH of 6.7. The mixtures were placed in 2.5 l pots in four repetitions for each dose and for each base substrate, for a total of 56 pots (A type). Control samples, consisting of four pots for each of the two base substrates (without the material under study), were also set up. We prepared four additional pots containing a mixture of loam, peat and pumice. These last four pots were prepared in order to have seedlings that were developed on an ideal substrate for the Spanish broom. Thirty seeds of S. junceum were sown in each container. In addition to the pots of 2.5 l, we set up, keeping the same doses and repetitions, two alveolar 5  8 vessels (B type, volume of the single cell = 0,18 l), obtaining, for each of the two base substrates, 5 repetitions for each of the 7 dosages and 5 control samples. We sowed 5 test organisms per cell of the obtained 80 pots. The repetitions were numbered as follows: A1, B1, C1, D1, E1 for the substrate obtained with the poor soil, A2, B2, C2, D2, E2 for the substrate obtained with the mixture of sand and blond peat. Repetitions F and G are related to the containers of type B, i.e. to the larger containers filled one with a mixture of sand and blond peat and the other with poor soil. The containers of type A and B and the alveolar vessels were used to analyze the seed germination. The two alveolar vessels allowed us to measure radical elongation.

Fig. 2. Results of the merceological analyses carried out on samples sieved at 10 mm (left graph) and 4 mm (right graph).

300–400 750–1200 2500–4000

20–40 – 1000–1750

41 39 – 1500 – 420 300 2800

ð2Þ

where Lc is the root length in the control; Li is the root length in the sample.

75 85 – 4300 – 420 840 7500

3.1. Merceological and sieve analyses

68 55 117 538 1241 89 292 1096 71.8 54.0 129.5 871.7 2087.5 205.5 311.9 2092.6 As Cd Cr Cu Mn Ni Pb Zn

73.7 54.5 150.0 2825.0 1983.7 138.2 361.4 2416.6

75.3 54.2 153.9 295.5 4539.1 97.8 261.0 3085.5

70.3 53.7 147.1 275.5 4927.9 110.2 260.2 3520.4

66.5 54.6 161.6 183.5 1566.9 90.0 284.6 906.0

69.9 54.4 106.3 181.0 1207.4 92.4 298.2 116.0

67.5 54.6 100.6 202.7 1199.7 89.4 315.7 788.5

66.3 55.5 100.4 1585.8 988.2 85.0 260.2 2575.2

73 54 145 1067 3385 138 302 2779

41 39 – 1500 – 420 300 2800

The merceological analysis showed, as expected, the presence of a significant quantity of inert materials (glass, stone) and unidentified fine fractions (Fig. 2). The material was then submitted to a 10 mm screen which gave the following results:

Average of the four samples 4 mm Sample 4 4 mm Sample 3 4 mm Sample 2 4 mm Sample 1 4 mm Sample 4 10 mm Sample 3 10 mm

Lc  Li  100 Lc

3. Results and discussion

Sample 1 10 mm

Sample 2 10 mm

After 90 days in the greenhouse, we proceeded to the count of the specimens germinated in each pot and, after the explant from the vessels of 0.18 l, to the measurement of the length of the taproots. We measured the Germination Number and the root elongation and, consequently, we calculated the Germination Index and the Growth Radical Inhibition Index. The Germination Index is calculated with Eq. (1). The Growth Radical Inhibition Index is defined according to the following equation:

In ¼

Average of the four samples 10 mm

High Quality Pollutant Concentration Limits (mg/kg), USEPA

Ceiling Concentration Limits (mg/kg) USEPA

Cumulative Pollutant Loading Rates (kg/ha) USEPA

Concentration limits of heavy metals in sludge for agriculture use (mg/kg) (Annex IB 86/278/CEE)

S. Masi et al. / Waste Management 34 (2014) 702–710

Heavy metal

Table 4 Chemical analyses of the material sieved at 10 mm and 4 mm compared with threshold concentrations for biosolids set by USEPA and with threshold concentrations for sludge for agricultural use set by Directive 86/278/CEE.

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 29.6% oversieve;  70.4% undersieve. This result can be compared with that of Quaghebeur et al. (2013), that found undersieve percentages variable between 40% and 70%, depending on the sampling location in the landfill. The following screening at 4 mm gave 63.6% undersieve and 36.4% oversieve. The results are similar at both levels of screening. Some differences are due to the variability of the examined samples. 3.2. Preliminary laboratory analyses: chemical analyses and leaching tests The results in Table 3 show that the agrarian soil used as substrate has a TOC concentration usual for eluvial agricultural soils, while the analyzed solid waste has higher values. The soil waste material object of study was slightly sub-acid having a pH of 6.7, that is comprised into limits fixed by USEPA for the compost characteristics. The chemical results are showed in Table 4. The obtained results reveal, on average, that the concentrations of heavy metals that could become ‘‘available to the environment’’, contained in the sample with particle size <4 mm, is lower than the concentrations in the undersieve at 10 mm. For the determination of the acceptability limits of concentrations of these pollutants, we referred to the threshold concentrations of contaminants prescribed by the US EPA for land application of sewer sludge (USEPA, 1995) and to the threshold concentrations for sludge for agricultural use set by Directive 86/278/CEE. Concentrations of all heavy metals in waste samples (<4 mm and <10 mm) meet the pollutant Ceiling Concentrations fixed by USEPA and the European Union limits, except for cadmium, which exceed only the European limits (Table 4). In the undersieve at 4 mm only As and Cd exceed the ‘‘High Quality’’ Pollutant Concentration Limits prescribed by the US EPA standards. In the undersieve at 10 mm, As, Cd and Pb exceed the ‘‘High Quality’’ Pollutant Concentration Limits set by the US EPA. We can conclude that, if we assimilate the material to sludge, the obtained concentrations are lower than the ceiling limits prescribed by the US EPA for land application of sewer sludge. The most significant source of the metals detected in the residual matrix could be associated with different materials, such as

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6.00

6.00

5.00 USEPA Limits

4.00 3.00 Sample1( 4mm)

2.00 1.00

Sample2( 4mm)

0.00 As

Cd

Cr

Cu

Mn

Ni

Pb

Zn

Concentration (mg/l)

Concentration (mg/l)

5.00

USEPA Limits

4.00 3.00 Sample3(10mm)

2.00 1.00 0.00

Sample 4(10mm)

As

Cd

Cr

Cu

Mn

Ni

Pb

Zn

Fig. 3. Results of the leaching test carried out on the material sieved at 4 mm (graph on the left) and 10 mm (graph on the right).

very similar results for all the species analyzed. This means that As and Cd present the highest leaching potentials among the other analyzed metals, whereas Mn, Pb and Zn present the lowest.

3.3. Biological assays

Fig. 4. Results of the bioassay on Lepidum sativum: Germination Index (%) calculated for the three protocols and the five repetitions.

Nickel/Cadmium batteries, impurity in several products, including phosphorus-based fertilizers, pesticides and detergents and refined petroleum products. This confirms our hypothesis about the presence of every type of material that was dumped in the landfill during the past. The results of the leaching tests are reported in Fig. 3. Detected heavy metals are the following: As, Cd, Cr, Cu, Mn, Ni, Pb and Zn. The comparison can be carried out only for the species for which the U.S. Legislation indicates limits, specifically As, Cd, Cr, Cu, Ni and Pb. The concentration values of the analyzed metals are lower than the allowable heavy metal US TCLP standard concentrations (USEPA, 2006), for both the samples passing at 4 and 10 mm (Fig. 3). It is interesting to observe that, although the concentrations of As and Cd are the lowest in the material, the leaching test gives

Germination Index

2 1.5 1

3.3.1. Acute tests: test of germination in L. sativum and test of the primary root elongation in V. faba Results of the germination test in L. sativum are reported in Fig. 4. The results of the Germination Index, which comprises the results of germination and root length, were subjected to a statistical treatment of data by applying an analysis of variance. We assessed whether the three concentrations, 0, 50% and 75% (control, protocol 1 and protocol 2), are statistically differentiated at the level of significance a = 0.05. A preliminary verification of the hypotheses of applicability of this method is needed (normally distributed data and homogeneity of variances). The data do not follow a normal distribution and at least one of the two variances is different from the others. For these reasons, it was not possible to carry out an ANOVA test. Therefore, a non-parametric test with k samples, the Kruskal– Wallis test (K-W test), was applied. The result of the K–W test affirms that the major variability of data is due to the diversity of the values in each series rather than to the diversity of the three series of measurements (probability = 0.233 > 0.05). There are not significant statistical differences among the tested samples. The reading of the box plots in Fig. 5 demonstrates that the distribution of the obtained samples does not show a great variance. This means that it is not possible to recognize a dose–response relationship. In order to recognize a dose–response effect, we carried out the bioassay with V. faba. The trends of Germination Index and Radical Elongation show, on average, a decrease with the increasing of the doses added to the reference substrate (Fig. 6). Since the radical elongation data do not follow a normal distribution, we applied the non-parametric K-W test. This analysis detected, from the statistical point of view, a significant difference in the level of growth of the test organism for the different doses, as shown in the boxplot in Fig. 6. This second acute test confirmed that the investigated waste could induce adverse toxic effect for the plant growth.

0.5 0 Control

Protocol 1

Protocol 2

Fig. 5. Box plot of the Germination Index (%) calculated on Lepidum Sativum for the 3 protocols and the five repetitions.

3.3.2. The agronomic suitability bioassay: phytotoxicity test with L. sativa The results of the phytotoxicity test with L. sativa (Table 5) are expressed in terms of a judgment of compatibility with the plant growth, or suitability for agricultural use. The judgment of suitabil-

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Fig. 6. Bioassay with Vicia faba: Germination Index (%) calculated for the four doses (left graph); Box plot of the Radical Elongation (cm) (right graph).

Table 5 Results of the vegetation test with Lactuca sativa. DOSE

Repetition

Epigeal biomass weight (g)

Epigeal biomass dry weight (g)

DOSE

Repetition

Epigeal biomass weight (g)

Epigeal biomass dry weight (g)

Dose 0

vase A vase B vase C vase D mean st. deviation

0.057 0.021 0.028 0.026 0.033 0.016

0.005 0.002 0.002 0.002 0.003 0.001

Dose 5

vase A vase B vase C vase D mean st. deviation

0.000 0.025 0.021 0.022 0.017 0.012

0.000 0.002 0.002 0.002 0.002 0.001

Dose 1

vase A vase B vase C vase D mean st. deviation

0.033 0.019 0.029 0.008 0.022 0.011

0.002 0.001 0.002 0.004 0.002 0.001

Dose 6

vase A vase B vase C vase D mean st. deviation

0.032 0.035 0.021 0.019 0.027 0.008

0.003 0.003 0.002 0.004 0.003 0.001

Dose 2

vase A vase B vase C vase D mean st. deviation

0.014 0.019 0.021 0.027 0.021 0.005

0.001 0.001 0.003 0.002 0.002 0.001

Dose 7

vase A vase B vase C vase D mean st. deviation

0.023 0.016 0.016 0.021 0.019 0.004

0.002 0.003 0.002 0.002 0.002 0.001

Dose 3

vase A vase B vase C vase D mean st. deviation

0.033 0.024 0.069 0.015 0.035 0.024

0.002 0.002 0.006 0.002 0.003 0.002

Dose 8

vase A vase B vase C vase D mean st. deviation

0.012 0.047 0.017 0.023 0.025 0.016

0.001 0.007 0.002 0.002 0.003 0.003

Dose 4

vase A vase B vase C vase D mean st. deviation

0.033 0.012 0.026 0.018 0.022 0.009

0.003 0.001 0.004 0.002 0.002 0.001

Dose 9

vase A vase B vase C vase D mean st. deviation

0.033 0.036 0.016 0.024 0.027 0.009

0.007 0.004 0.002 0.003 0.004 0.002

ity is based primarily on the results of the statistic comparison regarding the average dry weight of the epigeal biomass. The average production of dry material, which is obtained on the substrate treated with the studied product, is higher than that of the control (dose 0). But, the result of the K–W test affirms that the major variability of data is due to the diversity of the values in each series rather than to the diversity of the ten series of measurements. The distribution of the samples obtained does not show a great variance (Fig. 7). For this reasons, increasing dosage does not influence the growth of L. sativa. The phytotoxicity test with L. sativa showed that the material under study does not show an adverse effect for its agronomic usage. 3.3.3. Chronic test: germination and radical elongation tests with S. Junceum Observing the trend of Germination Index and Radical Elongation Inhibition Index (Figs. 8 and 9), it can be observed that the

dosages did not affect the seedling development. The substrate constituted of poor soil gave the best results, both in terms of germination than in terms of root length. The residue matrix mixed with the substrate made up of sand and peat showed the best germination results with increasing doses of the tested material but lower lengths of the roots. From a statistical point of view, we observed a fluctuation around the value of the controls (100%). In relation to this, it seems that the residual material did not cause adverse effects to the growth of vegetal species. This conclusion is also confirmed by the K–W tests, carried out on the results concerning the Germination Index, which gives a probability of 0.12 for poor soil experiment. In the case of the peat-sand mix, the K-W test gives a probability of 0.05, which suggest a dose–response effect, as shown in Fig. 8. The chronic test carried out with the S. junceum showed that the link between the doses of the stabilized product and the effects produced on the plant species was not clearly predictable.

S. Masi et al. / Waste Management 34 (2014) 702–710

Epigeal dry biomass weight (g)

x 10-3 6 5 4 3 2 1 0 Dose 0 Dose 1 Dose 2 Dose 3 Dose 4 Dose 5 Dose 6 Dose 7 Dose 8 Dose 9

Fig. 7. Bioassay with Lactuca sativa: Box plot of the epigeal biomass dry weights for the ten dosages.

Fig. 8. Results of the Germination Index (%) calculated for the bioassays on Spartium junceum, carried out, for the seven doses, using, as a base substrate, poor soil (black line and dots) and peat-sand mix (grey line and dots).

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that the composition of very old dumpsites is uniform and constituted mainly of a very fine fraction (<4 mm). The analyses show that this very fine fraction has a percentage of the total organic carbon equal to more than six times the TOC in a conventional agrarian soil. The organic finer fraction, which represents a significant part of the extracted material (70%), can be used in different environmental applications. In fact, there is a considerable demand for organic fractions, which are usually characterized by very high supply costs. Chemical analyses of waste fractions showed the presence of heavy metals in concentrations always lower than the USEPA standards for the use of biosolids. The concentrations of heavy metals in the finer fraction (<4 mm) are, on average, 30% lower than the <10 mm fraction. The leaching potential of heavy metals is very low and below the allowable heavy metal concentration in U.S. TCLP standard (USEPA, 2006). The biological phytotoxicity test on L. sativa and the acute tests did not demonstrate particularly adverse effects on the growth of test species, except for the test on V. faba, which showed that the investigated matrix could have an adverse effect on it. The toxic effect that the material causes on V. faba should be deeply investigated in further studies. The S. junceum, especially suitable for revegetation activities, showed a good adaptation to the stress conditions induced by the presence of this residual matrix. This effect was evaluated with a long term experiment. Therefore, the organic residual material of the Lavello old dumpsite is suitable for the analyzed plant species and does not induce negative effects on the environment. In conclusion, in the case of very old dumpsites, landfill mining activities include mainly the reuse of organic finer fractions (size < 4 mm). We can conclude that the investigated material can have multiple usages, such as: disposal in temporary storages, formation of ‘‘bio-soils’’ (obtained by mixing agronomic soil) to be used in environmental remediation activities or in geo-environmental applications, in substitution of the soil layer, or for the cultivation of non-edible crops. Further studies will be concentrated on the possible use of this material as compost, especially for non-edible crops, by performing chemical analyses of percolating water and chemical analysis of absorption on the developed seedlings. In a full scale application, however, the removal of stone, glass, metal and plastic from the compost product is needed. Moreover, it is useful to evaluate the effective mobility of heavy metals from the soil matrix to water matrix, taking into consideration the mitigating effects of this phenomenon produced by plants through mechanisms of phyto-stabilization and phyto-accumulation. Acknowledgements

Fig. 9. Radical Elongation Inhibition Index (%) calculated for the bioassay on Spartium junceum, carried out, for the seven doses, using a base substrate made up of poor soil (black dots) and made up of peat-sand mix (grey dots).

But the Germination Index trend seems to suggest an increase of the germination with the increase of the dosages. 4. Conclusion Old open dumpsites are a significant problem in terms of occupation of land and environmental impact. The conducted research focused on a quality assessment of residual materials originating from landfill mining operations carried out on the old closed municipal dumpsite of Lavello (Potenza, Italy). This study demonstrated

The experimental activities were performed by a synergy between the Laboratory of Sanitary and Environmental Engineering of the University of Basilicata and the CODRA Mediterranean spa (Operational Center for Defence and Environmental Restoration). This work forms part of a research project supported by grant of the Italian Ministry of Education, University and Research (MIUR) through the Research project of national interest PRIN2012 (D.M. 28 December 2012 n. 957/Ric – Prot. 2012PTZAMC) entitled ‘‘Energy consumption and GreenHouse Gas (GHG) emissions in the wastewater treatment plants: a decision support system for planning and management’’ in which the corresponding author is the Principal Investigator. References APHA, AWWA, WPCF, 1998. Standard methods for the examination of water and wastewater. In: 20th ed. American Public Health Association, Washington, DC, USA.

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Bosmans, A., Vanderreydt, I., Geysen, D., Helsen, L., 2013. The crucial role of Wasteto-Energy technologies in enhanced landfill mining: a technology review. J. Clean. Prod. 55, 10–23. Caniani, D., Masi, S., Mancini, I.M., Trulli, E., 2013. Innovative reuse of drinking water sludge in geo-environmental applications. Waste Manage. 33, 1461– 1468. http://dx.doi.org/10.1016/j.wasman.2013.02.007. Frändegård, P., Krook, J., Svensson, N., Eklund, M., 2013. A novel approach for environmental evaluation of landfill mining. J. Clean. Prod. 55, 24–34. Hogland, W., Marques, M., Nimmermark, S., 2004. Landfill mining and waste characterization: a strategy for remediation of contaminated areas. J. Mater. Cycles Waste Manage. 6, 119–124. Italian Environmental Protection Agency (EPA), 2003. Microbiological Methods of Analysis of Compost. Manuals and Guidelines 20/2003. Italian Institute for Environmental Protection and Research (ISPRA), 2013. Urban waste report – edition 2013, . Jain, P., Kim, H., Townsend, T.G., 2005. Heavy metal content in soil reclaimed from a municipal solid waste landfill. Waste Manage. (Oxford) 25, 25–35. Jain, P., Townsend, T.G., Johnson, P., 2013. Case study of landfill reclamation at a Florida landfill site. Waste Manage. 33, 109–116. Jones, P.T., Geysen, D., Tielemans, Y., Van Passel, S., Pontikes, Y., Blanpain, B., Quaghebeur, M., Hoekstra, N., 2013. Enhanced landfill mining in view of multiple resource recovery: a critical review. J. Clean. Prod. 55, 45–55. Kaartinen, T., Sormunen, K., Rintala, J., 2013. Case study on sampling, processing and characterization of landfilled municipal solid waste in the view of landfill mining. J. Clean. Prod. 55, 56–66. Krook, J., Baas, L., 2013. Getting serious about mining the technosphere: a review of recent landfill mining and urban mining research. J. Clean. Prod. 55, 1–9. Krook, J., Svensson, N., Eklund, M., 2012. Landfill mining: a critical review of two decades of research. Waste Manage. (Oxford) 32, 513–520. Masi, S., Schiavone, C., Mancini, I.M., 2011. Analysis and motion recovery for undifferentiated waste disposed of in landfill. In: Proceedings of Thirteenth

International Waste Management and Landfill Symposium, Sardina 2011 S. Margherita di Pula, Italy. Pasini, M.A., Gazzola, M., Secondi, A., Villa, M., 2000. Monitoring of water surface by means of multi-species ecotoxicological test for waters and sediments. In: Proceedings of the National Conference on Ecotoxicology. Torino, Italy, pp. 78– 83. Prechthai, T., Parkpian, P., Visvanathan, C., 2008a. Assessment of heavy metal contamination and its mobilization from municipal solid waste open dumping site. J. Hazard. Mater. 156, 86–94. Prechthai, T., Padmasri, P., Visvanathan, C., 2008b. Quality assessment of mined MSW from an open dumpsite for recycling potential. Resour. Conserv. Recycl. 53, 70–78. Quaghebeur, M., Laenen, B., Geysen, D., Nielsen, P., Pontikes, Y., Van Gerven, T., Spooren, J., 2013. Characterization of landfilled materials: screening of the enhanced landfill mining potential. J. Clean. Prod. 55, 72–83. Raga, R., Cossu, R., 2013. Bioreactor tests preliminary to landfill in situ aeration: a case study. Waste Manage. (Oxford) 33 (4), 871–880. Sormunen, K., Ettala, M., Rintala, J., 2008. Detailed internal characterisation of two Finnish landfills by waste sampling. Waste Manage. (Oxford) 28, 151–163. US Environmental Protection Agency (USEPA). SW-846 Test Methods for Evaluating Solid Wastes, (20.08.06). US Environmental Protection Agency (USEPA), 1995. Summary of 40 CFR part 503 Standards for the use or Disposal of Sewage Sludge, . Valerio, M.E., García, J.F., Peinado, F.M., 2007. Determination of phytotoxicity of soluble elements in soils, based on a bioassay with lettuce (Lactuca sativa L.). Sci. Total Environ. 378, 63–66. Wang, X., Sun, C., Gao, S., Wang, L., Shuokui, H., 2001. Validation of germination rate and root elongation as indicator to assess phytotoxicity with Cucumis sativum. Chemosphere 44, 1711–1721.