Resources, Conservation and Recycling - EURELCO...previous studies in landfill mining (Quaghebeur et al., 2013), in this place study also, plastic, paper/cardboard, wood, and textile

Page 1

Resources, Conservation and Recycling 102 (2015) 67–79

Contents lists available at ScienceDirect

Resources, Conservation and Recycling

jo ur nal home p age: www.elsev ier .com/ locate / resconrec

Environmental and economic assessment of ‘open waste dump’mining in Sri Lanka

Danthurebandara Maheshia,b,∗, Van Passel Stevenb,c, Van Acker Karela

a Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, 3001 Leuven, Belgiumb Center for Environmental Sciences, Hasselt University, Martelarenlaan 42, 3500 Hasselt, Belgiumc University of Antwerp, Prinsstraat 13, 2000 Antwerp, Belgium

a r t i c l e i n f o

Article history:Received 21 March 2015Received in revised form 10 June 2015Accepted 6 July 2015Available online 24 July 2015

Keywords:Open waste dump miningEnhanced Landfill MiningLife cycle assessmentLife cycle costing

a b s t r a c t

Open waste dumps in Sri Lanka generate adverse environmental and socio-economic impacts due toinadequate maintenance. In this study, a concept of ‘open waste dump mining’ is suggested in orderto minimise the environmental and socio-economic impacts, together with resource recovery. A modelbased on life cycle assessment and life cycle costing has been used to assess the environmental andeconomic feasibility of the suggested open waste dump mining concept. Two scenarios have been definedfor a hypothetical case, dependent on the destination of the refuse derived fuel fraction. Scenario 1comprises direct selling of refuse derived fuel as an alternative fuel to replace coal usage in the cementindustry, while Scenario 2 consists of thermal treatment of refuse derived fuel with the objective ofproducing electricity. The study shows that both scenarios are beneficial from an environmental pointof view, but not from an economic view point. However, economic profits can be obtained by adjustingwaste transport distances and the price of electricity. The environmental analysis further reveals that thehigher global warming potential of open waste dumps can be eliminated to a large extent by applyingsuggested mining and waste valorisation scenarios.

© 2015 Elsevier B.V. All rights reserved.

1. Introduction

Increasing population levels, a growing economy, rapid urban-ization and changes in consumption patterns have greatlyaccelerated the solid waste generation rate in developing countries(Troschinetz and Mihelcic 2009; Guerrero et al., 2013; Marshalland Farahbakhsh, 2013). In 1999, the average MSW generation percapita in Sri Lanka was 0.89 kg/cap/day, and it has been predictedto reach 1.0 kg/cap/day by 2025 (WorldBank 1999; Vidanaarachchiet al., 2006; Menikpura et al., 2012). In Sri Lanka, MSW containsa fraction rich in organic matter, moderate plastic and paper con-tent, and low metal and glass fractions (Vidanaarachchi et al., 2006;Menikpura et al., 2007; Gunawardana et al., 2009).

Like in many other Asian countries, solid waste collection anddisposal has been an issue in Sri Lanka for the past decades, whereburning and dumping garbage into collection yards are the mostcommon modes of disposal. After collection and transportation,approximately 85% of the total MSW generated is disposed of in

∗ Corresponding author at: Department of Materials Engineering, KU Leuven,Kasteelpark Arenberg 44, box 2450, 3001 Leuven, Belgium.

E-mail address: [email protected] (D. Maheshi).

‘open dumps’, without any pre-treatment, cover or compaction(Visvanathan et al., 2003; Visvanathan et al., 2004). An open dumpsite is (i) a land disposal site at which solid wastes are disposedof without considering environmental protection, (ii) susceptibleto open burning, and (iii) exposed to the elements, disease vectorsand scavengers. These dumps are located in environmentally sen-sitive areas such as wetlands, marshes, beaches and areas adjacentto water bodies or close to residential houses or public institutions(Joseph et al., 2004; Gunawardana et al., 2009).

As the waste separation is not well developed in Sri Lanka,the dump sites contain heterogeneous waste piles. The continuousdumping of waste in open areas eventually resulted in a numberof garbage mountains in several municipalities in the country. The‘Bloemendhal’ dump site, located in Colombo, Sri Lanka’s commer-cial capital city, is an example: it occupies an area of 6.5 hectares,goes to an average height of 30 m and contains about 1.5–2.5 milliontonnes of garbage (Sathees et al., 2014). For many years Bloemend-hal has been an eyesore for nearby residents, including the poorestpeople of around 350 shanty dwellings (Sathees et al., 2014). Thedaily average waste collection in Colombo city is about 650 tonnes(APO 2007), and such waste is directly dumped into the Bloemend-hal site. In addition to this landmarked dump site, many other smalldump sites exist in the same municipal area. However, the quanti-

http://dx.doi.org/10.1016/j.resconrec.2015.07.0040921-3449/© 2015 Elsevier B.V. All rights reserved.

Page 2

68 D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79

ties of waste dumped in these yards are not yet known. ‘Gohagoda’is another well-known dump site located three kilometres awayfrom Kandy, one of the culturally valued cities of Sri Lanka. Upto 1960 Gohagoda was used as an isolated area to dump hospi-tal waste, then as a sewage dump site, and finally as the place fordumping all the waste generated by the Kandy municipal council.At present, 100 tonnes of MSW collected in the city are dumped atthis site per day (Menikpura et al., 2008).

Open waste dump sites cause a number of environmental andsocio-economic impacts due to lack of engineering design and inad-equate maintenance (Visvanathan et al., 2003; Joseph et al., 2004).The absence of gas collection and utilization systems in open wastedumps results in a severe contribution to global warming poten-tial, as CO2 and CH4 act as greenhouse gases (Joseph et al., 2002;Crowley, 2003). The International Solid Waste Association explainsthat the absence of ground water protection and drainage controlsaccelerates the ground and surface water pollution as the leachatefrom the waste dumps which contains dissolved methane, fattyacids, sulphate, nitrate, nitrite, phosphates, calcium, sodium, chlo-ride, magnesium, potassium, and trace metals migrates to the watertable and surface water (ISWA, 2007). This situation is very seriousas it yields a severe pollution in the aquifers and serious eutrophi-cation conditions in surface waters (Han et al., 2014).

Data on environmental, health, and social impact assessmentsof open waste dump sites in Sri Lanka are very limited and notpublicly available. However, a few studies are available that wereperformed for two landmarked dump sites: the Bloemendhal dumpsite, in Colombo, and the Gohagoda dump site, in Kandy. The studyconducted by Sathees et al. (2014) revealed that the soil of theBloemendhal dump site is sandy, and therefore the percolation ishigh through the deep layers; hence, the contamination of groundwater can be expected. The leachate and soil within 150 and 400 mradius from the centre of the waste pile contain high amountsof nitrate, phosphate, organic matter, heavy metals, and coliformbacteria. These values always exceed the standard levels set bythe Sri Lanka Standards Institute. The data on this site’s gaseousemission has not been reported yet. The characterisation study ofleachate and groundwater of the Gohagoda dump site, performedby Dharmarathne and Gunatilake (2013), showed that the levels ofpH, sulphate, nitrate, nitrites, and heavy metals (Pb, Zn, Ni, Cr, Co,Fe, Mn, Cu) are above the standards required by the World HealthOrganization for drinking water. This dump site exists at a distanceof about 50 m from the Gohagoda water intake plant. Furthermore,Menikpura et al. (2008) proved that the predicted leachate emis-sion rate from this dump site is 30,304 m3/year and that it is highlypolluted, with 15,000–20,000 mg/l of biological oxygen demand(BOD) value. The same study discovered that the predicted amountof greenhouse gas emission of this site is 2.61 Gg/year.

Dump site rehabilitation would help moderate the environmen-tal and health impacts described in the above paragraphs (APO,2007). Dumpsite closure through applying a cover layer (such assoil) on top of the dump site and transforming dump sites intosanitary landfills are possible rehabilitation options (APO, 2007).However the latter option is unrealistic in many cases as the basicrequirements of a sanitary landfill (landfill gas and leachate collec-tion facility and protection layers) are missing in the dump sitesand this leads to complete excavations, waste removals and sub-sequent construction of a new landfill sector. On the other hand,landfill mining has been used as an option of exhuming existingor closed dump sites and landfills and sorting the exhumed mate-rials for recycling, processing, or other deposition (Joseph et al.,2002). The objectives of traditional landfill mining could be oneor more of the following: redevelopment of landfill sites; conser-vation of landfill space; reduction in landfill area; elimination ofpotential contamination source; energy recovery from recoveredwastes; and reuse of recovered materials (van der Zee et al., 2004;

Ayalon et al., 2006; Jones, 2008; Prechthai et al., 2008; Raga andCossu, 2014 Prechthai et al., 2008; Raga and Cossu, 2014). Severalstudies address the environmental and economic potential of land-fill mining in material recycling, energy recovery, land reclamationand pollution prevention (Zhou et al., 2014; Frändegård et al., 2015;Winterstetter et al., 2015; Zhou et al., 2015). More details on landfillmining projects in the Asian region can be found in APO (APO, 2007).The novel concept of Enhanced Landfill Mining (ELFM) can also beapplied to open waste dumps as ELFM includes the combined val-orisation of the historic waste streams as both materials and energy(or in other words Waste-to Materials (WtM) and Waste-to Energy(WtE)) and finally regaining the land (Jones et al., 2013). Severalstudies highlighted the usability of ELFM in re-introducing buriedresources in to the material cycle (Jones et al., 2013; Quaghebeuret al., 2013). Besides, Danthurebandara et al. (2015a) and Van Passelet al. (2013) described the feasibility of ELFM from an environmen-tal and economic point of view. Hence, to remove the landmarkedopen waste dumps from urban areas in a sustainable way, the appli-cation of the concept of ELFM as ‘open waste dump mining’ appearsto be possible with the objectives of minimising the environmentalburden, recovery of buried resources and regaining the land. How-ever, the actual situations of landfills/open dumps vary from siteto site, It is obligatory to assess the environmental and economicfeasibility of open waste dump mining prior to bring the concepttowards its operational stage.

The purpose of this paper is to assess the feasibility of open wastedump mining in Sri Lanka by considering the insights of the novelELFM concept. The study includes life cycle assessment (LCA) andlife cycle costing (LCC) to identify the environmental and economicdrivers of open waste dump mining. Moreover, open waste dumpmining scenarios are compared with the existing situation to iden-tify the actual benefits of the concept. The study also encompassesa trade-off analysis to illustrate the association between environ-mental and economic performances.

2. Materials and methods

As the real open dump mining cases do not yet exist in Sri Lanka,a hypothetical case was introduced. The background of the hypo-thetical case and process flow for open waste dump mining aredescribed in detail in Section 2.1. LCA and LCC methodologies arepresented in Section 2.2.

2.1. Hypothetical case

Considering the characteristics and situation of Sri Lanka’s majorlandmarked dump sites: Bloemendhal and Gohagoda, a hypothet-ical case has been drawn. The basic outline for the hypotheticalcase is an open waste dump site which contains approximately1,000,000 tonnes of waste and occupies an urban land of 5 hectares(50,000 m2) within Colombo’s city limits. It is assumed that thewaste dump was open for the past 30 years, with a daily wastedumping of 100 tonnes/day. There is currently no waste inflow.Similar to typical waste dumps in Sri Lanka, no gas or leachatecollection systems are installed in the considered dump site.

The dump site mining scenario is organized as illustrated inFig. 1, which is moderately similar to the process flow of ELFMdescribed in Danthurebandara et al. (2015a) Waste excavation isperformed by excavators, bulldozers, cranes, and other suitableequipment. The oversized waste (chairs, tyres, wooden pieces, etc.)identified during the excavation, are disassembled and sorted outmanually, and added to the relevant end-product category. Afterexcavation, the waste is directed to a proper separation process.Pre-separation takes place at the dump site right after the excava-tion to separate the hazardous waste and ‘fines’. ‘Fines’ denotes the

Page 3

D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79 69

Fig. 1. Open waste dump mining scenario.

material fraction below a certain particle size (<100 mm), which hasto be removed prior to or during the material separation processes(Spooren et al., 2013).

Advanced separation can be done on site or off-site. As theconsidered dump sites are situated in highly populated areas, per-forming advanced processes on site seems difficult. Therefore, inthis study, it was assumed that the necessary processes after pre-separation are carried out in separate premises outside the citylimits. Thus, the pre-separated waste is transported to the requiredpremises. It has to be decided which type of advanced separationtechnology is going to be used according to the moisture contentof the pre-separated waste, composition, and the quantity of thewaste. In this study, air separation, dense media separation, mag-netic separation, and eddy current separation were presumed to bein the advanced separation process. According to the conclusionsof previous studies in landfill mining (Quaghebeur et al., 2013), inthis study also, plastic, paper/cardboard, wood, and textile frac-tions were considered as one refuse derived fuel (RDF) fractiondue to their high level of contamination. The major outputs ofthe advanced separation process include fines, RDF, ferrous met-als, non-ferrous metals, stones/aggregates, and glass. Fines and RDFare considered as intermediate products and they can be trans-formed into valuable materials or energy. In this context, fines areconverted into building materials after performing necessary treat-ments for heavy metal removal while RDF fraction is used as analternative fuel in the cement industry or is incinerated to gener-ate energy. After excavating and processing the entire dump site,the land can be reclaimed either as land for nature reserve, housing,agriculture, or industry. The products of above processes substitutethe virgin material and/or energy production somewhere else or inother words the environmental impact of virgin material/energyproduction is avoided by the use of recovered materials derivedfrom open waste dump mining.

Considering the destination of produced RDF, two major scenar-ios have been developed for the analysis.

• Scenario 1 includes the processes of excavation, transportation,separation, fines treatment, and land reclamation. In this sce-nario, RDF is considered as an end-product of open dump miningand it is sold to the cement industry to be used as an alternativefuel.

• In Scenario 2, RDF is treated as an intermediate product andis subjected to incineration in order to produce energy. Sce-nario 2 comprises the processes of excavation, transportation,separation, fines treatment, thermal treatment of RDF, and landreclamation.

Apart from the scenarios mentioned above, a ‘Do-nothing’ sce-nario is used as reference scenario. The Do-nothing scenario orreference situation supposes that no mining activities are under-taken; the dump site remains as it is, without any maintenance orenvironmental protection activity. No collection or treatment takesplace for the gases and leachate.

2.2. LCA and LCC methodology

The goal of this LCA study was to evaluate the environmentalimpacts of the open waste dump mining for resources and landrecovery. The methodology is in accordance with the InternationalStandards for LCA (ISO14040, 2006; ISO14044, 2006). SimaPro 7was used as the LCA software tool for setting up the LCA model. TheLCA model comprises individual building blocks for each activitydescribed in Fig. 1 with all possible inputs and outputs and alsothe relevant substitution of the virgin material/energy production(avoided impact) due to the products (see Fig. 2). Relevant processeswere combined to estimate the overall impact of open waste dumpmining.

It was assumed that with the exception of the pre-separationequipment, all other processing plants are situated in a specificground, which is 150 km away from the studied dump site. The

Page 4

70 D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79

Fig. 2. Structure of a building block of LCA model.

Table 1Average composition of dump site mined waste in Sri Lanka (Menikpura et al., 2008).

Waste fraction Percentage (%) Wastefraction

Percentage (%)

Biodegradable 59.69 Paper 0.92Polyethylene 24.66 Glass 1.28Coconut comb and husk 4.74 Metal 0.02Textile 3.66 Stones 1.35Wood 1.29 Construction

demolitions0.10

Rubber and leather 1.20 Undefined 1.09

quality of the products of open waste dump mining considered inthis study are as follows:

• The metals recovered from separation processes have the qualitywhich enables substituting the corresponding scrap metals.

• Stones and the other construction materials (sand, aggregates,and soil) recovered from separation and fines treatment pro-cesses have the quality of gravel that can be used in constructionactivities.

• When the RDF is used as an alternative fuel in the cement indus-try, one tonne of RDF replaces the production of 0.6 tonnes of coal.Furthermore, it avoids transportation of the same amount of coalfrom Indonesia to Sri Lanka. The calculation is based on the aver-age calorific values of RDF and coal (20 MJ/kg vs. 33 MJ/kg) (Fisher,2003).

• When the RDF is incinerated in order to produce energy, the pro-duced electricity replaces the base load of electricity productionin Sri Lanka, which includes 70% conventional thermal energy,23% hydro energy, and 6% renewable energy (SLSEA, 2012). Theproduced heat is assumed to be used in the process itself.

• Recovered land is converted into land for a nature reserve.

The input data of this study comprises the data obtainedfrom published sources, calculated data, and estimated data (SeeTables 1–3). The data published mainly in the ecoinvent database(version 2.2) was used for the background processes with appropri-

Table 2Adjusted waste composition of dump site mined waste and separation efficienciesof the separation process.

Waste fraction Percentage (%) Recovery efficiency (%)

RDF 72.12 80Fines 24.09 80Ferrous metals 0.01 80Non-ferrous metals 0.01 80Glass 1.28 80Stones 1.35 80Construction demolitions 0.05 80Undefined 1.09

ate modification according to the Sri Lankan standards. In this studywe used a reference flow instead of a functional unit as explainedin the ILCD handbook (European Commission, 2010). Using a ref-erence flow instead of a functional unit is very common in LCAsof waste treatment (Consonni et al., 2005; Frändegård et al., 2013;Laurent et al., 2014). Hence, the reference flow was defined as acertain mass of landfilled waste. Based on this reference flow, theenvironmental impact was calculated for valorisation of (i) 1 tonneof waste and (ii) total waste present in the open waste dump. In thesecond case, the environmental impact of ELFM was compared withthat of the Do-nothing scenario. The environmental performance ofthe Do-nothing scenario was calculated as follows.

The evolution of gas and leachate that can be produced bythe hypothetical dump site has been analysed in order to identifythe current situation. The gas production curve for the considereddump site was obtained from the LandGEM model (version 3.02)and is presented in Fig. 3. LandGEM is an automated estimationtool with a Microsoft Excel interface that can be used to estimateemission rates for total landfill gas, methane, carbon dioxide, non-methane organic compounds, and individual air pollutants fromMSW landfills (USEPA, 2005). The gas production curve revealsthat this dump site is, in 2015, at the peak of gas production; thegas production will then decrease over time and become consid-erably low after 100 years. In order to decide whether or not thevalorisation of waste present in the dump site is environmentallybeneficial against the existing situation (Do-nothing scenario), theresidual impact of the dump site should be determined. In this studythe residual impact starts from year 2015 (Fig. 3), as the wastevalorisation activities are assumed to have started in 2015. Therespective residual environmental impact was calculated for 100years starting from 2015. CO2 emission in the Do-nothing scenariowas considered as CO2 neutral because of its biogenic origin. Theleachate emission and composition data present in Sathees et al.(2014) were used to determine the emission to water and soil.

For the environmental impact assessment of this study, theReCiPe endpoint method (Hierarchist version, H/A) was selected,as it addresses several impact categories such as (i) climate changeon human health; (ii) climate change on ecosystems; (iii) ozonedepletion; (iv) terrestrial acidification; (v) freshwater eutrophica-tion; (vi) human toxicity; (vii) photochemical oxidant formation;(viii) particulate matter formation; (ix) terrestrial ecotoxicity; (x)freshwater ecotoxicity; (xi) ionising radiation; (xii) agriculturalland occupation; (xiii) urban land occupation; (xiv) natural landtransformation; (xv) metal depletion; and (xvi) fossil fuel depletion(Goedkoop et al., 2013).

The goal of the LCC study was to evaluate the economic driversof open waste dump mining. A cash flow model was set up forthe period of 5 years including all costs and revenues associatedwith the different processes. The waste processing is completedwithin 5 years and the depreciation rate is assumed to be 5%. As

Page 5

D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79 71

Table 3Energy, materials and emission data of incineration.

Parameter Value Source

Calorific value of RDF (MJ/kg RDF) 20 Menikpura et al. (2008)Start-up energy (kWh/t RDF) 78 Indaver (2012)Net electrical efficiency (%) 22 BREF (2006, 2010) and UCL (2014)Bottom ash generation (t/t RDF) 0.228 (to be landfilled) Indaver (2012)Air pollution control (APC) residues (t/t RDF) 0.043 (to be landfilled) Indaver (2012)Auxiliary materials Indaver (2012)Activated carbon (kg/t RDF) 0.5Urea (kg/t RDF) 3.5Limestone (kg/t RDF) 6.7Quicklime (kg/t RDF) 4.4Emission Indaver (2012)Carbon dioxide (kg/t RDF)biogenicfossil

839839

Carbon monoxide (kg/t RDF) 0.09Particulates (kg/t RDF) 0.014Nitrogen oxides (kg/t RDF) 1.49Sulphur dioxide (kg/t RDF) 0.019Hydrogen chloride (kg/t RDF) 0.003Dioxins (kg/t RDF) 8 × 10−8

Mercury (kg/t RDF) 1.6 × 10−6

Heavy metals (kg/t RDF) 0.052

0

2000

4000

6000

8000

10000

12000

14000

1984 1994 2004 2014 2024 2034 2044 2054 2064 2074 2084 2094 2104 2114 2124

Gas p

rodu

c�on

(ton

nes/

year

)

Time

Total land fill gas Methane Car bon dioxi de

RESIDUAL IMPACT

Fig. 3. Gas production curve of studied dump site as delivered by LandGEM model (version 3.02).

a result, all processing plants remain with a residual value after5 years. These remaining processing plants are considered to beused in future waste separation and processing under developingnational solid waste management strategy or in other open wastedump mining cases. Hence, the cash flow was facilitated with aresidual value for the processing plants. Net present value (NPV)was used as the major economic indicator in order to determinethe major economic drivers of open waste dump mining. The NPVis calculated by subtracting the investment cost from the sum ofthe discounted cash flow and can be considered as the expectedprofit of the investment (Brealey et al., 2010). It takes the timevalue of money and all the relevant cash flow elements over a pre-defined period into account. Equation 1 shows the mathematicalrepresentation of NPV.

NPV =T∑

t=1

CFt

(1 + x)t−1

Where, CFt is the cash flow in year t, T is the time horizon and x isthe discount rate.

The Monte Carlo simulation approach was used to examine thesensitivity of different parameters on NPV, as explained by VanPassel et al. (2013).

Table 1 shows the composition of dumpsite mined waste pre-sented by Menikpura et al., (2008) which was used in this studywith necessary modifications. To elaborate our study in detail, themetal fraction is further divided into ferrous and non-ferrous met-als with equal percentages. Biodegradables, polyethylene, coconutcomb and husk, textile, wood, rubber and leather, and paper frac-tions are combined into one RDF fraction. The previous landfillmining and open dump mining case studies in Asia and Europerevealed that a considerable amount of fines can be present inthe mined waste due to degraded garden and food waste (Josephet al., 2004; Quaghebeur et al., 2013). Therefore, we assumedthat 25% of the RDF fraction are degraded into fine particles. Fur-

Page 6

72 D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79

Table 4Data used in the economic analysis.

Parameter Value Source

Time length (years) 5 Case studyDepreciation rate (%) 5 Case studyExcavation cost (D /t) 1.60 Industrial reference (United Tractor and Equipment)Transport cost (D /tkm) 0.13 Rathi (2007)Investment cost of separation (D /t) 5 Industrial reference (BERNS, ENVIROMECH)Operational cost of separation (D /t) 7 Industrial reference (BERNS, ENVIROMECH)Investment cost of incineration (D /t) 60 Ducharme (2010)Operational cost of incineration (D /t) 40 Ducharme (2010)Electricity price (D /MWh) 125 PUCSL (2012)Disposal cost of residues (D /t) 90 Central Environmental AuthorityPrice of metals (D /t) 800 Commercial reference (Ceylon steel, Recycleinme.com)Price of RDF (D /t) 33 Calculateda

Price of glass (D /t) 6 Commercial reference (Recycleinme.com)Price of aggregates (D /t) 10 Commercial reference (Recycleinme.com)Price of land (D /m2) 25 Central Environmental Authority

a This value was calculated considering the calorific value of RDF and average price and calorific value of coal. Price of coal: 55 D /t (Infomine, 2015), calorific value of coal:33 MJ/kg (Fisher, 2003)

thermore, we assumed that 50% of the fraction of constructiondemolitions has a particle size less than 10 mm. Hence 25% of RDFand 50% of construction demolitions were considered as fine frac-tion. The adjusted composition is illustrated in Table 2 with therecovery efficiencies applied for all waste fractions in the sepa-ration process. We assumed similar recovery efficiencies for allwaste fractions and performed a sensitivity analysis for the effi-ciencies of most influencing waste fractions. Unrecovered portionsof each waste fraction are considered as residues to be disposedof in a sanitary landfill. Energy, materials, and emission data ofthe incineration plant of Scenario 2 is presented in Table 3. Asincineration plants are not yet available in Sri Lanka, the data of awell-established, large scale incineration plant in Europe (Indaver)were used. It was assumed 50% of biogenic fraction in order to cal-culate the biogenic and fossil CO2 emission. Energy and materialsdata for excavation, separation, fines treatment and land reclama-tion are according to the data presented in Danthurebandara et al.(2015a). Background processes of Eco invent database were used toobtain data for emission due to diesel and electricity consumptionin above processes and transportation process. Costs and prod-uct selling prices used in the economic analysis are illustrated inTable 4.

3. Results and discussion

3.1. Environmental performance of open waste dump mining

Top and bottom panels of Fig. 4 illustrate the environmentalimpact of valorisation of one tonne of waste present in the dumpsite for Scenarios 1 and 2, respectively. Top panel confirms that theseparation and the transportation processes dominate most impactcategories. The significant benefits of the separation process onseveral impact categories are due to the avoided burdens causedby different end-products produced during separation. The indi-vidual environmental profile of the separation process reveals thatthe major benefit is due to the replacement of coal production andtransportation by using RDF as an alternative fuel in the cementindustry. In this study, one tonne of waste present in the dumpsite is responsible for reducing production and transportation of0.348 tonnes of coal. Although the recovery of metals, aggregates,and glass also yield environmental benefits, its importance is lowerthan the benefits due to RDF.

In Scenario 2, thermal treatment of RDF dominates the envi-ronmental profile, and separation and transportation become thenext important processes. In this scenario, the RDF obtained fromthe separation process is treated in an incinerator in order to pro-duce energy instead of direct-selling to the cement industry. One

tonne of waste present in the landfill contributes to a productionof 710 kWh of electricity. In this way, the influence of the separa-tion process in different impact categories is different in the twoscenarios.

Fig. 4 illustrates the contribution of each process in open dumpmining relative to the different impact categories. As the total envi-ronmental impact in each impact category is set to 100% the figuresdo not conclude to what extent an impact category has a significantcontribution and which scenario performs better. Fig. 5 clarifiesthe overall performance of the scenarios and the mostly influencedimpact categories.

Fig. 5 shows that in both scenarios, impact in fossil depletionis very significant. Next to that, the contributions to particulatematter formation and climate change on human health are alsoimportant. The impact on other categories is insignificant. Thebenefit in fossil depletion is higher when the RDF is used as an alter-native to coal fuel in the cement industry (Scenario 1) than whenit is thermally treated in order to replace the conventional elec-tricity production in the country (Scenario 2). Contrastingly, theenvironmental credits in particulate matter formation are higherin Scenario 2. Scenario 1 is beneficial in the climate change impactcategory, while Scenario 2 is not; the flue-gas emission with highCO2 concentration in the thermal treatment process is a reason forthis difference. However, both scenarios yield a net environmen-tal benefit. Furthermore, Scenario 1 is 30% more beneficial thanScenario 2.

We discussed above the environmental impact of the valorisa-tion of one tonne of waste present in the dump site. To bring theopen dump mining concept to the operational phase, it is neces-sary to know whether it is beneficial compared to the Do-nothingscenario or reference situation.

Top panel of Fig. 6 shows the environmental impact of the Do-nothing scenario for the total amount of waste. In addition, thoseimpacts were compared with Scenarios 1 and 2. The impact of thetwo scenarios were calculated for the total amount of waste presentin the dump site (valorisation of total waste present in the dumpsite).

The net environmental impact of the Do-nothing scenarioturns out to be very detrimental compared to the waste min-ing/valorisation scenarios. In the Do-nothing scenario the burdensare mainly found in the impacts of climate change on human healthand climate change on ecosystems. These burdens are mainly due tothe 66,758 tonnes of total methane emission for 100 years, startingfrom 2015. This scenario is not responsible for any environmentalbenefit, as the produced methane is not used in energy productionand no materials are recuperated whatsoever.

Page 7

D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79 73

Fig. 4. Environmental profiles of Scenario 1 (top) and Scenario 2 (bottom) (reference flow—1 tonne of waste in the dump site).

Another impact assessment was performed by using the methodof IPCC 2007 GWP 100a (PRéConsultants 2008); the results are illus-trated in bottom panel of Fig. 6. The figure reveals that the CO2equivalent emission of the Do-nothing scenario can be completelyeliminated by Scenario 2. Not only elimination, but also a CO2equivalent saving is foreseen for scenario 1. Additionally, Scenario2 reduces the CO2 equivalent burden of the Do-nothing scenario upto 98%. From Figs 5 and 6, it can be concluded that a higher fractionof environmental burden taken place due to open waste dumpscan be eliminated by applying appropriate mining and valorisationscenarios at the early stages of the waste degradation of a dumpsite. Over time, a large fraction of methane is freely emitted to theenvironment and the dump site reaches its maturation/long-termphase (final state of waste stabilisation as explained by Vesilind

et al. (2002) and Kjeldsen et al. (2002)). Performing waste miningand valorisation during the maturation phase still allows for envi-ronmental benefits through materials and energy recuperation, butis not advantageous in mitigating the emission of CO2 equivalent,as shown by the case study analysed by Danthurebandara et al.(2015a).

3.2. Sensitivity analysis in environmental profiles

From the analysis of the above open waste dump mining sce-narios, it was identified that the transportation, separation, andthermal treatment are the most influencing processes to the envi-ronment. Likewise, waste transportation distance, RDF recoveryin the separation process, and electricity production in the ther-

Page 8

74 D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79

-35

-30

-25

-20

-15

-10

-5

0

5Scenario 1 Scenario 2

Envi

ronm

enta

l im

pact

in p

oint

s

Fossil deple�on Par�c ula te ma�er for ma�on

Climate change Human Heal th Net impact

Fig. 5. Most significant impact categories of Scenario 1 and 2 (reference flow—1 tonne of waste in the dump site).

Table 5Overview of the sensitivity analyses.

Parameter Basic value Best case value Worst case value

Transport distance from dump site to the separation plant (km) 150 50 250RDF recovery efficiency in separation process (%) 80 90 70Calorific value of RDF (MJ/kg) 20 25 15Net electrical efficiency of thermal treatment system (%) 22 30 20

mal treatment process were recognised as the main factors thatdominate the environmental profiles. The amount of producedelectricity depends on the calorific value of RDF and the net elec-trical efficiency of the thermal treatment system. In addition, therecovery efficiency of RDF in the separation process is also a factorto decide net electricity production. Hence, the parameters of trans-port distance, RDF recovery efficiency, calorific value of RDF, and thenet electrical efficiency of the thermal treatment process were sub-jected to a sensitivity analysis. Table 5 provides a summary of thoseparameters on which the sensitivity analyses are performed. Fig. 7illustrates the comparative environmental profile of the scenarioswith the sensitivity analyses.

Transportation of excavated waste from the dump site is nec-essary when there is no sufficient space to construct furtherprocessing plants at the dump site, or when it is essential to pro-cess the waste in a specific processing plant, away from the dumpsite. Reducing the transport distance obviously increases the envi-ronmental benefit of the two suggested scenarios. However, thisincrement is not well pronounced, ranging from five to nine per-cent only (Fig. 7). RDF plays a significant role in both scenarios.When the RDF recovery is higher, the amount of coal replacementis also higher in Scenario 1; this results in a 13% increment of envi-ronmental benefit when the RDF recovery efficiency increases by10%. Similarly, the higher RDF recovery efficiencies positively affectthe electricity production in Scenario 2. As illustrated in Figure 7, a10% increment of RDF recovery efficiency leads to a 15% growth inthe net environmental impact (benefit) of Scenario 2. As explainedearlier, this benefit can further be improved with higher calorificvalues and higher electrical efficiencies. The calorific value of RDFis mainly dependent on the biodegradables and plastic content.When they are not in larger fractions, then lower calorific valuesare expected; similarly, when the dump site is in its maturationphase the calorific value of the waste displays lower values due tothe waste degradation. Considering these facts, in the sensitivity

analysis a 15–25 MJ/kg range was used as the calorific value of RDF(Menikpura et al., 2008). According to Figure 7, the net environmen-tal benefit of Scenario 2 increases by 60% for a 25% enhancementof calorific value of RDF. Although the average electrical efficiencyof a typical incinerator is 22%, higher efficiencies such as 30% arealso reported (Bosmans et al., 2013). Hence, an upper margin of 30%was applied for the sensitivity analysis of net electrical efficiencyof thermal treatment system. It expands the environmental benefitof Scenario 2 by 92%.

Apart from improving the calorific value and electrical effi-ciency, the thermal treatment technology can also be altered forobtaining higher benefits. Bosmans et al. (2013) concluded thatplasma gasification/vitrification is a viable candidate for com-bined energy and material valorisation in the framework of ELFM.Moreover, Danthurebandara et al. (2014) highlight that the envi-ronmental performance of plasma gasification is clearly better thanthat of incineration. This finding can also be applied in open wastedump mining in order to improve the current environmental bene-fits. In this context, we replaced incineration technology in Scenario2 with plasma gasification technology with a 27% of electrical effi-ciency as explained by Danthurebandara et al. (2015a). The otherdata related to input materials and emissions of plasma gasificationprocess are also according to Danthurebandara et al. (2015a). Usingplasma gasification in Scenario 2 improves the overall environ-mental impact (environmental benefits) by 79%. Furthermore, Thistechnology yields large improvements on GWP which leads to asaving of 147,687 tonnes CO2 emission. Plasma gasification processis more efficient than conventional incineration in converting theenergy content of the waste to electricity. Therefore, although bothprocesses give rise to the direct emissions of carbon dioxide fromthe waste conversion plant, plasma gasification process displacesmore conventional electricity generation and is therefore associ-ated with significantly lower lifecycle GWP emissions. In this way,the environmental performance of Scenario 2 is higher than that

Page 9

D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79 75

-40000000

-200 00000

0

20000000

40000000

60000000

80000 000

100000000Do-nothing scenario Scenario 1 Scenario 2

Envi

ronm

enta

l im

pact

in p

oint

s

Fossil deple�on Par�cula te ma�er for ma�on Climate change EcosystemsClimate change Human Health Net impact

-200 000

0

200000

400000

600000

800000

10000 00

12000 00

14000 00

16000 00

18000 00Do-nothing scenario Scenario 1 Scenario 2

tonn

es C

O2

eq

Fig. 6. Environmental impact of Do-nothing scenario and waste valorisation scenarios—Single score data (top) and GWP data (bottom).

-60

-50

-40

-30

-20

-10

0Scenario 1 Scenario 2

Envi

ronm

enta

l im

pact

in p

oint

s

Basic Transport distance- 50km Transport distance- 250kmRDF re covery e fficiecy- 70% RDF re covery e fficiency- 90% CV of RD F- 15 MJ/kgCV of RD F- 25 MJ/kg Net electri cal efficiency- 20% Net electrical efficiency- 30%

Fig. 7. Environmental profile of open waste dump mining scenarios with sensitivity analysis—reference flow: 1 tonne of waste in the dump site (basic scenario comprise150 km transport distance, 80% RDF recovery efficiency, 20 MJ/kg CV of RDF and 22% net electrical efficiency of thermal treatment system).

Page 10

76 D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79

scenario 1

scenario 2

(15,00)

(10,00)

(5,00)

-

5,00

10,00

(40,00) (30,00) (20,00) (10,00) - 10,00

NPV

(€) *

106

enviro nme ntal impac t (po ints) * 106

Fig. 8. Economic performance against the environmental performance.

of Scenario 1 when the plasma gasification process is used in RDFvalorisation. This performance can be further improved by usingplasmastone, the residues of plasma gasification in production ofhigher value building materials such as inorganic polymer andblended cement (Danthurebandara et al., 2014; Danthurebandaraet al., 2015b).

3.3. Economic performance of waste valorisation

In Fig. 8, the economic performances of the two scenariosare plotted against the environmental performances. NPVs andenvironmental impacts were calculated for the hypothetical caseexplained in Section 2.1. In fact, the positive values of NPV implyeconomic profits, while the negative values of environmentalimpact indicate environmental benefits. Hence, Fig. 8 shows thatnone of the scenarios are beneficial in both aspects. Although bothscenarios produce environmental benefits, the NPVs are negativewithin the data used in Table 4. Scenario 2 shows better economicresults compared to Scenario 1.

The contributions of the most influencing parameters to the NPVobtained from Mote Carlo simulations are illustrated in Table 6. Anincrease in the NPV with an increase of a parameter is specifiedby a positive value, and the opposite situation is designated by anegative value.

In Scenario 1, transport costs contribute 54.9% to the NPV. Thenext highest contribution is given by transport distance. In thisstudy we used 150 km of average transport distance, as the wastehas to be transported to a specific ground with enough space,beyond the city limits, for further processing. As the hypotheticaldump site is assumed to be in Colombo, the distance from Colomboto a specific ground where the processing plants can be installedis estimated. In the sensitivity analysis 250 km of maximum dis-tance was used, assuming that the northern part of the countrycan also provide a suitable ground for waste processing due tocomparatively less population than the other areas. Reductions intransport costs obviously yield higher NPVs according to Table 6.The variation of NPV with the different transport costs for threedifferent transport distances is demonstrated in Fig. 9. A decreaseof transport costs by 10% leads to an increment in NPV by 12%, 11%,and 10% for the transport distances of 50 km, 150 km, and 250 km,respectively. This figure leads to the conclusion that avoiding wastetransportation by implementing all processing plants on the dumpsite or nearby is a prerequisite to obtaining the economic benefitsof open waste dump mining for this scenario.

bas ic scenario

-40

-35

-30

-25

-20

-15

-10

-5

-

5

10

-0,05 0 0,05 0,1 0,15 0,2 0,25

NPV

(€) *

106

transport co st (€/t km)

trans port dista nce

50km 150km 250km

Fig. 9. The impact of variations in transport cost and distance on NPV in Scenario 1.

In addition to transport costs and transport distance, the sell-ing price of RDF is another imperative parameter that gives 12.1%positive contribution to the NPV. In this study, the selling price ofRDF was calculated as 33 D /t by considering the ratio of the calorificvalues of RDF and coal (20/33) and the average market price of coal(55 D /t). Depending on the composition of the MSW in Sri Lanka,the minimum and maximum values of calorific value of RDF weredecided as 15 and 25 MJ/kg. Based on these values, the minimumand maximum values for selling prices of RDF were calculated as25 and 42 D /t. It is worthwhile to investigate how the selling priceof RDF can alter with varying transport costs and distance, as Fig. 9confirms that obtaining higher NPVs seems to be less possible bychanging only the parameters related to transport. Fig. 10 shows thevariation of NPV with the different transport costs and distances forthree different selling prices of RDF.

Fig. 10 shows that higher selling prices of RDF obviously lead toa gain in higher NPVs for varying transport distances and transport

bas ic scenario

-30

-25

-20

-15

-10

-5

-

5

-50 - 50 100 150 200 250 300

NPV

(€) *

106

transport distance ( km)

RDF selling price

25 €/t 33 €/t 42 €/t

bas ic scenario

-25

-20

-15

-10

-5

-

5

-0,05 0 0,05 0,1 0,15 0,2 0,25

NPV

(€) *

106

transport co st (€/t km)

RDF selli ng price

25 €/t 33 €/t 42 €/t

Fig. 10. The impact of variations in transport distance (top) and transport cost(bottom) on NPV for different selling prices of RDF in Scenario 1.

Page 11

D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79 77

Table 6Monte Carlo sensitivity analysis.

Parameter Minimum value Maximum value Contribution to variance of NPV (%)

Scenario 1Transport cost (D /tkm) 0.09 0.23 54.9 (−)Transport distance (km) 50 250 31.5 (−)RDF selling price (D /t) 25 42 12.1 (+)RDF recovery efficiency (%) 70 90 1.5 (+)

Scenario 2Calorific value of RDF (MJ/kg) 15 25 31.3 (+)Electrical efficiency of thermal treatment system (%) 20 30 23.1 (+)Electricity price (D /Mwh) 100 150 19.6 (+)Transport distance (km) 50 250 13.6 (−)Transport cost (D /tkm) 0.09 0.23 6.2 (−)RDF recovery efficiency (%) 70 90 2.4 (+)Investment cost of thermal treatment system (D /t RDF) 55 65 2.1 (−)

costs. However, increasing the selling price fully depends on thecalorific value of RDF. Hence, for this study, the selling price can-not exceed the upper margin of 42 D /t. For that selling price, themaximum transport distance and transport costs should be approx-imately 50 km and 0.05 D /t km in order to make the NPV at leastzero instead of having a negative value. Once more, Fig. 10 furtherconfirms the necessity of avoiding transport in this scenario.

For Scenario 2, calorific value of RDF, net electrical efficiencyof thermal treatment system, and price of electricity become thehighest positively contributing parameters to the NPV (Table 6).The range of the price of electricity in the sensitivity analysis wasdecided as follows: according to the announcement of the Pub-lic Utilities Commission of Sri Lanka (PUCSL), the list of rates forelectricity purchased by the Ceylon Electricity Board (CEB) fromNon-Conventional Renewable Energy (NCRE) sources shows thatthe rate for electricity from MSW is 26.10 LKR/kWh (1 D = 165LKR)(PUCSL, 2012). As this technology is not yet well developed inSri Lanka, this price was used in this study as the upper margin(150 D /MWh) of the range of electricity price. For the lowest mar-gin, the price of electricity generated by mini hydro plants thatare well developed in Sri Lanka (17.15 LKR/kWh, 100 D /MWh) hasbeen used. Thus, the average electricity price used in this studyis 125 D /MWh. Fig.11 illustrates the relationship between the netelectrical efficiency, calorific value of RDF, and electricity price. Thetop panel of Fig. 11 shows that for a fixed calorific value (20 MJ/kg),a 10% change in electrical efficiency yields 17% and 38% incrementsin NPV for electricity prices of 100 D /MWh and 125 D /MWh, whileNPV doubles for the electricity price’s upper margin (150 D /MWh).This Figure suggests that Scenario 2 (RDF valorisation via inciner-ation) is economically feasible even with the moderate electricalefficiencies (21–25%) if the electricity purchase price by the CEB ishigh, as suggested above. According to the bottom panel of Fig. 11,for a fixed electrical efficiency (22%), 10%, 18%, and 36% gain inNPV can be foreseen for 100–150 D /MWh of price range whenthe calorific value increases by 10%. The figure reveals that posi-tive NPVs can be obtained even for the calorific values of less than20 MJ/kg when the electricity price is in its upper margin.

Similar to LCA study, plasma gasification was used as an alter-native thermal treatment technology in the LCC study as well withthe similar costs reported in Danthurebandara et al. (2015a) (50 D /tRDF for investment cost and 67 D /t RDF for operational costs). Useof plasma gasification with 27% electrical efficiency in RDF valori-sation shows a positive NPV (7032836 D ). This positive NPV canbe further increased by using plasmastone in production of highervalue building materials (Danthurebandara et al., 2015b).

Apart from the private costs and benefits considered in thisstudy, mining of open dumps obviously generate social costs andbenefits. The related monetary value of such social costs and ben-

bas ic scenario

-30

-20

-10

0

10

20

30

0 5 10 15 20 25 30 35 40N

PV (€

) *10

6

net electrical efficiency (%)

electricity price

100 €/MWh 125 €/MWh 150 €/Mwh

bas ic scenario

-40

-30

-20

-10

0

10

20

30

0 5 10 15 20 25 30 35

NPV

(€) *

106 calorific value of RDF (MJ/kg)

electricity price

100 €/MWh 125 €/MWh 150 €/M wh

Fig. 11. The impact of variations in net electrical efficiency (top) and calorific valueof RDF (bottom) on NPV for different electricity prices in Scenario 2.

efits can be estimated using cost- benefit analysis and contingentvaluation method as used in recent landfill mining research (VanPassel et al., 2013; Marella and Raga 2014; Zhou et al., 2015).

4. Conclusions

This paper discusses the feasibility of open waste dump min-ing in Sri Lanka. The study comprises two scenarios based on thedestination of RDF: Scenario 1 includes the direct selling of RDFas an alternative fuel to replace coal usage in the cement indus-try, while Scenario 2 consists of processing RDF in an incinerationplant in order to produce electricity. The LCA analysis reveals thatboth scenarios yield higher environmental benefits compared tothe Do-nothing scenario. The environmental burden due to wastetransportation is fully compensated by the avoided burden result-ing from the replacement of production and transportation of coalin Scenario 1 and electricity generation in Scenario 2. More than

Page 12

78 D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79

1.6 million tonnes CO2 equivalent of GWP that occurred in the Do-nothing scenario can be eliminated by the discussed scenarios. TheLCA study concludes that starting the waste valorisation duringthe early stage of waste degradation of a dump site is beneficial inGWP’s viewpoint. The sensitivity analysis concludes that the RDFrecovery efficiency, the calorific value of RDF, and the electricalefficiency of the thermal treatment system are the most importantparameters from an environmental point of view. The LCC analy-sis shows that none of the scenarios are beneficial economicallywithin the data used for the analysis; nevertheless, Scenario 2 per-forms better than Scenario 1 in this regard. The analysis furtherhighlights the necessity of avoiding waste transportation in order toobtain economic profits. Moreover, the government may introducehigher subsidies or higher electricity prices in order to encourageentrepreneurs to initiate this type of projects. The study showsthat technological changes such as introducing plasma gasificationinstead of incineration yield higher economic benefits. However,the immaturity of plasma gasification process may create higherlevels of uncertainties and technical, legislative and institutionalbarriers for implementation. Overall, the study concludes openwaste dump mining is beneficial from an environmental point ofview. To realize open waste dump mining in a cost-effective way,above mentioned technological improvements or governmentalsupport will be needed. The environmental benefits can be usedto motivate the development of financial support instruments foropen waste dump mining. The study highlights, the ELFM approachwith energy and materials recovery through efficient technologieswhich results in lower net costs is a promising way to minimise theenvironmental burden of open waste dumps as traditional dumpsite remediation (including excavation, cleaning up the dump sitearea and re-landfilling the excavated waste in a different sanitarylandfill) is an extremely costly operation. Finally, further research isneeded to investigate the possibility of developing the ‘open wastedump mining’ concept as a clean development mechanism (CDM)project.

Acknowledgement

The authors would like to acknowledge the funding of thisstudy by the IWT O&O ELFM project ‘Closing the Circle & EnhancedLandfill Mining as part of the Transition to Sustainable MaterialsManagement’.

References

APO, 2007. Solid waste management- Issues and chalenges in Asia. AsianProductivity Organisation.

Ayalon, O., Becker, N., Shani, E., 2006. Economic aspects of the rehabilitation of theHiriya landfill. Waste Manag. 26 (11), 1313–1323 http://dx.doi.org/10.1016/j.wasman.2005.09.023

Bosmans, A., Vanderreydt Geysen, I.D., Helsen, L., 2013. The crucial role ofWaste-to-Energy technologies in enhanced landfill mining: a technologyreview. J. Clean. Prod. 55 (0), 10–23, http://dx.doi.org/10.1016/j.jclepro.2012.05.032

Brealey, R.A., Myers, S.C., Allen, F., 2010. Principles of corporate finance. McGrawHill, Columbus, OH.

BREF, 2006. Reference document on the Best Available Techniques for WasteIncineration.

BREF, 2010. Reference document on the Best Available Techniques in the Cement,Lime and Magnesium Oxide Manufacturing Industries.

Commission, E., 2010. International Reference Life Cycle Data System (ILCD)Handbook – General guide for Life Cycle Assessment – Detailed guidance.Publications Office of the European Union, Luxembourg.

Consonni, S., Giugliano, M., Grosso, M., 2005. Alternative strategies for energyrecovery from municipal solid waste: Part B: emission and cost estimates.Waste Manag. 25 (2), 137–148 http://dx.doi.org/10.1016/j.wasman.2004.09.006

Crowley, D., Staines, A., Collins, C., Bracken, J., Bruen, M. 2003. Health andEnvironmental Effects of Landfilling and Incineration of Waste – A LiteratureReview.

Danthurebandara, M., Van Passel, S., Vanderreydt, I., Van Acker, K., 2015a.Assessment of environmental and economic feasibility of enhanced landfillmining. Waste Manag. http://dx.doi.org/10.1016/j.wasman.2015.01.041

Danthurebandara, M., Van Passel, S., Machiels, L., Van Acker, K., 2015b. Valorisationof thermal treatment residues in enhanced landfill mining: environmental andeconomic evaluation. J. Clean. Prod. http://dx.doi.org/10.1016/j.jclepro.2015.03.021

Danthurebandara, M., Vanderreydt, I., Van Acker, K., 2014. The environmentalperformance of plasma gasification within the framework of Enhanced landfillMining: A life cycle assessment study. In: Venice 2014: Fifth InternationalSymposium on Energy from Biomass and Waste, San Servolo, Venice,Italy.

Dharmarathne, N., Gunatilake, J., 2013. Leachate characterization and surfaceground water pollution at municipal solid waste landfill of Gohagoda, SriLanka. Int. J. Sci. Res. Publ. 3 (11).

Ducharme, C., 2010. Technical and economic analysis of Plasma-assistedWaste-to-Energy processes. Department of Earth and EnvironmentalEngineering. Earth Engineering Center, Columbia University. MSc.

Fisher, J., 2003. Energy density of coal. The Physics Factbook. Retrieved 19.11.14.,from <http://hypertextbook.com/facts/2003/JuliyaFisher.shtml/>.

Frändegård, P., Krook, J., Svensson, N., Eklund, M., 2013. A novel approach forenvironmental evaluation of landfill mining. J. Clean. Prod. 55 (0), 24–34,http://dx.doi.org/10.1016/j.jclepro.2012.05.045

Frändegård, P., Krook, J., Svensson, N., 2015. Integrating remediation and resourcerecovery: on the conomic conditions of landfill mining. Waste Manag. http://dx.doi.org/10.1016/j.wasman.2015.04.008

Goedkoop, M., Heijungs, R., Huijbregts, M., Schryver, A.D., Struijs J., Zelm, R.v.,2013. ReCiPe 2008 A life cycle impact assessment method which comprisesharmonised category indicators at the midpoint and the endpoint level.Retrieved 02.07.13., from <http://www.lcia-recipe.net//>.

Guerrero, L.A., Maas, G., Hogland, W., 2013. Solid waste management challengesfor cities in developing countries. Waste Manag. 33 (1), 220–232 http://dx.doi.org/10.1016/j.wasman.2012.09.008

Gunawardana, E.G.W., Basnayake, B.F.A., Shimada, S., Iwata, T., 2009. Influence ofbiological pre-treatment of municipal solid waste on landfill behaviour in SriLanka. Waste Manag. Res. 27 (5), 456–462.

Han, D., Tong, X., Currell, M.J., Cao, G., Jin, M., Tong, C., 2014. Evaluation of theimpact of an uncontrolled landfill on surrounding groundwater quality,Zhoukou, China. J. Geochem. Explor. 136 (0), 24–39 http://dx.doi.org/10.1016/j.gexplo.2013.09.008

Indaver, 2012. Environmental impact of grate incinerators at Doel. Retrieved25.05.14., from <http://www.indaver.be/sustainable-approach/emissions/emission-results-grate-incinerators-doel.html/>.

Infomine, 2015. Coal prices and coal price charts. Retrieved 09.02.15., from <http://www.infomine.com/investment/metal-prices/coal//>.

ISO14040, 2006. Environmental Management – Life Cycle Assessment – Principlesand Framework. International Organisation for Standardization, Switzerland.

ISO14044, 2006. Environmetal management – Life Cycle Assessment –Requirements and Guidlines. International Organisation for Standardization,Switzerland.

ISWA, 2007. Closing of Open Dumps. International Solid Waste Association.Jones, P.T., Geysen, D., Tielemans, Y., Van Passel, S., Pontikes, Y., Blanpain, B.,

Quaghebeur, M., Hoekstra, N., 2013. Enhanced landfill mining in view ofmultiple resource recovery: a critical review. J. Clean. Prod. 55 (0), 45–55,http://dx.doi.org/10.1016/j.jclepro.2012.05.021

Joseph, K., Nagendran, R., Palanivelu, K., 2002. Open Dumps to SustainableLandfills. CES. Anna University, Chennai, India.

Joseph, K., Nagendran, R., Palanivelu, K., Thanasekaran, K., Visvanathan, C., 2004.Dumpsite rehabilitation and landfill mining. In: Report Published Under theARRPET Project on Sustainable Landfill Management in Asia. Asian Institute ofTechnology, Bangkok.

Kjeldsen, P., Barlaz, M.A., Rooker, A.P., Baun, A., Ledin, A., Christensen, T.H., 2002.Present and long-term composition of MSW landfill leachate: a review. Crit.Rev. Environ. Sci. Technol. 32 (4), 297–336, http://dx.doi.org/10.1080/10643380290813462

Laurent, A., Clavreul, J., Bernstad, A., Bakas, I., Niero, M., Gentil, E., Christensen, T.H.,Hauschild, M.Z., 2014. Review of LCA studies of solid waste managementsystems—Part II: methodological guidance for a better practice. Waste Manag.34 (3), 589–606 http://dx.doi.org/10.1016/j.wasman.2013.12.004

Marella, G., Raga, R., 2014. Use of the contingent valuation method in theassessment of a landfill mining project. Waste Manag. 34 (7), 1199–1205http://dx.doi.org/10.1016/j.wasman.2014.03.018

Marshall, R.E., Farahbakhsh, K., 2013. Systems approaches to integrated solid wastemanagement in developing countries. Waste Manag. 33 (4), 988–1003 http://dx.doi.org/10.1016/j.wasman.2012.12.023

Menikpura, S.N.M., Basnayake, B.F.A., Boyagod, P.B., Kularathne, I.W., 2007.Application of waste to energy concept based on experimental and modelpredictions of calorific values for enhancing the environment of Kandy city.Trop. Agric. Res. 19, 389–400.

Menikpura, S.N.M., Basnayake, B.F.A., Pathirana, K.P.M.N., Senevirathne, S.A.D.N.,2008. Preediction of present pollution levels in Gohagoda dumpsite andremediation measures: Sri Lanka. In: 5th Asian-Pacific Landfill Symposium(APLAS Sapporo 2008), Sapporo, Hokkaido, Japan.

Menikpura, S.N.M., Gheewala, S.H., Bonnet, S., 2012. Sustainability assessment ofmunicipal solid waste management in Sri Lanka: problems and prospects. J.Mater. Cycles Waste Manag. 14, 181–192.

Page 13

D. Maheshi et al. / Resources, Conservation and Recycling 102 (2015) 67–79 79

Prechthai, T., Padmasri, M., Visvanathan, C., 2008. Quality assessment of minedMSW from an open dumpsite for recycling potential. Resour. Conserv. Recycl.53, 70–78.

PRéConsultants, 2008. SimaPro Database Manual: Methods library PRéConsultants, the Netherlands.

PUCSL, 2012. Non Conventional Renewable Energy Tariff Announcement.Retrieved 21.11.14., from: <http://www.pucsl.gov.lk/english/notices/feed-in-tariffs-2012-2013//>.

Quaghebeur, M., Laenen, B., Geysen, D., Nielsen, P., Pontikes, Y., Van Gerven, T.,Spooren, J., 2013. Characterization of landfilled materials: screening of theenhanced landfill mining potential. J. Clean. Prod. 55, 72–83, http://dx.doi.org/10.1016/j.jclepro.2012.06.012

Raga, R., Cossu, R., 2014. Landfill aeration in the framework of a reclamationproject in Northern Italy. Waste Manag. 34 (3), 683–691 http://dx.doi.org/10.1016/j.wasman.2013.12.011

Rathi, S., 2007. Optimization model for integrated municipal solid wastemanagement in Mumbai, India. Environ. Dev. Econ. 12 (01), 105–121, http://dx.doi.org/10.1017/S1355770X0600341X

Sathees, S., Amarasingha, L.D., Panagoda, G.S., d. Silva, R.C.L., 2014. Potentialenvironmental impacts related with open dumping solid waste atBloemendhal, Colombo, Sri Lanka. J. Pharm. Biol. 4 (2), 81–84.

SLSEA, 2012. Sri Lanka Energy Balance. Retrieved 02.09.14 from <http://www.info.energy.gov.lk//>.

Spooren, J., Quaghebeur, M., Nielsen, P., Machiels, L., Blanpain, B., Pontikes, Y.,2013. Materail recovery and upcycling within the ELFM concept of the Remocase. Second International Academic Symposium on Enhanced Landfill Mining,Houthalen-Helchteren, Belgium.

Troschinetz, A.M., Mihelcic, J.R., 2009. Sustainable recycling of municipal solidwaste in developing countries. Waste Manag. 29 (2), 915–923 http://dx.doi.org/10.1016/j.wasman.2008.04.016

UCL, 2014. Gasification and Engine, Demonstration Integrated plant: a Life CycleAssessment. University College London. Torrington Place, London, WC1E 7JE,UK. UNEP (2009). Guidelines for Social Life Cycle Assessment of Products.Available online: URL, <http://www.unep.fr/shared/publications/pdf/DTIx1164xPA-guidelines sLCA.pdf/> (accessed 01.04.13.).

USEPA, 2005. Landfill Gas Emissions Model (LandGEM) Version 3.02 User’s Guide.U.S. Environmental Protection Agency, Washington, DC 20460, USA.

van der Zee, D.J., Achterkamp, M.C., de Visser, B.J., 2004. Assessing the marketopportunities of landfill mining. Waste Manag. 24 (8), 795–804 http://dx.doi.org/10.1016/j.wasman.2004.05.004

Van Passel, S., Dubois, M., Eyckmans, J., de Gheldere, F., Tom Jones, P., Van Acker, K.,2013. The economics of enhanced landfill mining: private and societalperformance drivers. J. Clean. Prod. 55, 92–102, http://dx.doi.org/10.1016/j.jclepro.2012.03.024

Vesilind, P.A., Worrell, W., Reinhart, R., 2002. Solid Waste Engineering. Brooks/Cole.Vidanaarachchi, C.K., Yuen, S.T.S., Pilapitiya, S., 2006. Municipal solid waste

management in the Southern Province of Sri Lanka: problems, issues andchallenges. Waste Manag. 26, 920–930.

Visvanathan, C., Trankler, J., Basnayake, B.F.A., Chiemchaisri, C., Joseph, K.,Gonming, Z., 2003. Landfill management in Asia- Notions about futureapproaches to appropriate and sustainable solutions. In: Sardinia, NinthInternational Waste Management and Landfill Symposium, Pula, Cagliari,Italy.

Visvanathan, C., Trankler, J., Joseph, K., Chiemchaisri, C., Basnayake, B.F.A.,Gongming, Z., 2004. Municipal solid waste management in Asia. In: AsianRegional Research Program on Environmental Technology (ARRPET). AsianInstitute of Technology.

Winterstetter, A., Laner, D., Rechberger, H., Fellner, J., 2015. Framework for theevaluation of anthropogenic resources: a landfill mining case study—resourceor reserve? Resour. Conserv. Recycl. 96 (0), 19–30 http://dx.doi.org/10.1016/j.resconrec.2015.01.004

WorldBank, 1999. What a waste: Solid waste management in Asia. In: Hoornweg,D., Thomas, L. (Eds.). Urban Development Sector Unit (UDSU): East Asia andpacific Region, Washington DC, USA.

Zhou, C., Fang, W., Xu, W., Cao, A., Wang, R., 2014. Characteristics and the recoverypotential of plastic wastes obtained from landfill mining. J. Clean. Prod. 80,80–86.

Zhou, C., Gong, Z., Hu, J., Cao, A., Liang, H., 2015. A cost-benefit analysis of landfillmining and material recycling in China. Waste Manag. 35, 191–198.