Waste Management 34 (2014) 702–710

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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

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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 (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


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


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.


 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

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

The present study addresses the theme of recycling potential of old open dumpsites by using landfill mining. Attention is focused on the possible reus...
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