Economic analysis of a shared municipal solid waste management facility in a metropolitan region

Waste Management 102 (2020) 823–837

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Economic analysis of a shared municipal solid waste management facility in a metropolitan region Diogo Appel Colvero a,b,⇑, José Ramalho c, Ana Paula Duarte Gomes a, Manuel Arlindo Amador de Matos a, Luís António da Cruz Tarelho a a b c

Department of Environment and Planning and Centre for Environmental and Marine Studies, University of Aveiro, Portugal Researcher of the Brazilian National Council for Scientific and Technological Development (CNPq), File No. 207172/2014-5, Brazil Department of Mechanical Engineering, University of Aveiro, Portugal

a r t i c l e

i n f o

Article history: Received 7 December 2018 Revised 30 October 2019 Accepted 21 November 2019

Keywords: Economic analysis Municipal solid waste (MSW) Shared management Tariff Brazil

a b s t r a c t Municipal solid waste (MSW) management in dense urban areas is a challenge for municipalities, especially in developing countries, which commonly have deficient waste management. For example, the metropolitan region of Goiás State, Brazil, has 19 municipalities that dispose of about 72.5% of total MSW in unlicensed MSW final disposal facilities. Therefore, this study analysed the investment and operating costs, and revenues of a municipal solid waste management facility, projected for 20 years, shared among these 19 municipalities. The economic viability analysis, has shown that, regardless of the management facility type, MSW collection and transport are the most expensive cost components, accounting for about 60% of MSW management operating costs. For an Internal Rate of Return of 0%, anaerobic digestion is 11% more expensive (in total) than using community composting. For 2040 (last year), the monthly MSW management tariffs will vary between 3.5 and 10.8 R$
inhabitant1
month1, depending on the municipality. So, as the unit price of biowaste treatments lowers with waste quantities, for the municipalities with large biowaste quantities, anaerobic digestion becomes recommended for its economic attractiveness. This study can serve as a model for other municipalities in Brazil and elsewhere, helping public decision makers to establish a strategy for MSW management. Ó 2019 Elsevier Ltd. All rights reserved.

1. Introduction Currently, municipal solid waste (MSW) management follows different paths in developed and developing countries. In the first case, the MSW management model is focused on the hierarchy of waste management, which consists of prevention, reuse, preparation for reuse, recovery and disposal (EU, 2018). Otherwise, for developing countries, the MSW management model is generally insufficient, with an incomplete waste collection coverage, low source-separation and recovery rates of such waste, which ends up commingled and sent to landfills or dumps (Figueiredo, 2012; World Bank, 2012). Therefore, the world needs to pay attention to the increased production of MSW. If not treated properly, MSW can produce serious environmental damage (Lavee and Nardiya, 2013) and the loss of resources. This is especially true in developing countries with large populations, dense urban areas, fast growth of per capita ⇑ Corresponding author at: Campus Universitário de Santiago, 3810-193 Aveiro, Portugal. E-mail address: [email protected] (D.A. Colvero). https://doi.org/10.1016/j.wasman.2019.11.033 0956-053X/Ó 2019 Elsevier Ltd. All rights reserved.

MSW generation and deficient waste management (Abramovay et al., 2013; Bernstad Saraiva et al., 2017). Brazil is an example of a developing country that presents deficient MSW management. According to ABRELPE (2017), 78.3 million tonnes of MSW were produced in 2016. Of these, approximately 91% were collected, while the remaining 9% were uncollected and dumped in vacant lots, rivers, on city streets, or burned in the open (Alfaia et al., 2017). In Goiás State, Brazil, MSW management is defective, because the practices based on prevention and circular economy are still nascent (Colvero et al., 2017b). Consequently, MSW is commingled and disposed of in dumps or unlicensed landfills (Abreu et al., 2016; Figueiredo, 2012). This breaches Law No. 12,305/2010 (National Solid Waste Policy – PNRS), that stipulates that all Brazilian municipalities should terminate any unsuitable MSW final disposal facilities by August 2014 (Brasil, 2010). In 19 municipalities located in the metropolitan region of Goiás (near capital Goiânia), 97.2% of all collected MSW is sent for final disposal. Of those, 72.5% goes to dumps or unlicensed landfills and only 24.7% are sent to landfills licensed by the Environmental, Water Resources, Infrastructure, Cities and Metropolitan Affairs

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Nomenclature Acronym AD CC CF HC IRR LHV MARR MRF MSW MSWMF

Meaning anaerobic digestion community composting cash flow home composting internal rate of return lower heating value minimum acceptable rate of return materials recovery facility municipal solid waste municipal solid waste management facility

Office of Goiás – SECIMA/GO (Colvero et al., 2017b). The other 2.0% are recycled and 0.8% are uncollected (Supplementary Material – SM Table 1). Similarly, in the rest of Brazil, MSW management is almost exclusively done in landfills (Alfaia et al., 2017). Likewise, almost no actions are currently aimed at reducing waste production in Brazil, such as initiatives to encourage changes in people’s consumption patterns, or information about life cycle impacts and resource costs (Brasil, 2010; EC, 2008; Godecke, Naime, & Figueiredo, 2012). However, this situation can change in the densely populated metropolitan regions of Goiás, by focusing on MSW recovery facilities and only landfilling what definitely cannot be diverted. Aracil et al. (2018), carried out an economic and environmental analysis of incineration technologies with electricity production, replacing landfills. The results have shown that incineration reduces greenhouse gases (GHG) when compared to landfills, also allowing economic revenue from electricity sales. Khan et al. (2016), performed an economic analysis of MSW management facilities and concluded that, as the MSW amounts to be treated increases, the combination of composting facilities and incineration brings greater economic benefits, when compared to MSW management with landfills only. Lohri et al. (2014), point out the importance of a detailed economic analysis to ensure the economic viability of a municipal solid waste management facility (MSWMF). According to Simões and Marques (2012a), a cost analysis is a way to assess the performance of waste services and encourage efficiency and innovation. These concerns must be judiciously evaluated in all its components, especially collection and transport, which significantly burden the MSWMF. The current tools based on geographic information are fundamental in locating MSWMF facilities, in order to minimize waste transport distances, as pointed out by Khan et al. (2016). So, the objective of this study is to analyse the investment and operating costs, and revenues of a MSWMF shared between 19 municipalities. Therefore, each management model cost can be identified, allowing its weaknesses to be handled. The proposed management model should be economically sustainable, integrating different solutions adjusted to the characteristics of the territory and its geographical, demographic and land use asymmetries. Moreover, there are many studies in the literature that provide technical and economic evaluation of alternative MSW management processes within regions or countries (Leme et al., 2014; Maier and Oliveira, 2014; Pin et al., 2018; Santos et al., 2019). However, few studies perform this type of evaluation in a holistic way, discretizing all operations and processes associated with the management of MSW from the conception of the model until the end of the project life, like this study does. While this is a large innovation, this paper also presents an economic viability analysis of a MSWMF with two different alternatives: the first, in which the facility is built by the State, and the second in, which a partnership

NPV net present value O&M operation and maintenance PLANARES Plano Nacional de Resíduos Sólidos - National Plan for Solid Waste PNRS Política Nacional de Resíduos Sólidos - National Solid Waste Policy SM supplementary material TS transfer station

between the State and the private sector is foreseen. Furthermore, the research is intended to assist the decision makers of these municipalities and Goiás State in developing a strategic plan to meet the recommended landfill diversion targets for Brazil. 2. Materials and methods The proposed MSWMF covers 19 municipalities, located in Goiás State, Midwest Brazil, that are highly heterogeneous in population density and MSW production. In 2015, they accounted for 35% of the total population of Goiás and produced 43.5% of the MSW in the state (Colvero et al., 2017b; IBGE, 2016). The population density of these municipalities is 330 inhabitants∙km2 (IBGE, 2016). 2.1. Management model and host municipality of the proposed shared MSWMF The proposed MSWMF will be based on BNDES (2014), due to the area’s population and MSW production (SM Tables 1 and 2). This model aims to meet the PNRS, which stipulates that MSWMF must establish streams that obey the waste management hierarchy (Brasil, 2010). Alas, virtually no actions are aimed at reducing waste production in Brazil at the moment, such as initiatives to encourage changes in people’s consumption patterns, or information about life cycle impacts and resource costs (Brasil, 2010; EC, 2008; Godecke, Naime, & Figueiredo, 2012). This absence causes inadequate MSW management, therefore the disposal of mixed waste in landfills (licensed or unlicensed) or dumps (Abreu, Gandolfo, & Vilar, 2016; Figueiredo, 2012). So, to change the current MSW management scenario, it is mandatory to abandon obsolete waste disposal facilities, and look for alternatives focused on circular economy, i.e., to keep the resources in the economy for as long as possible (Malinauskaite et al., 2017; Merli et al., 2018). Three alternatives for biowaste treatment in the municipalities were defined, regarding the minimum MSW handling capacity by technology (Tsilemou and Panagiotakopoulos, 2006):  HC (home composting): for 13 of the 19 municipalities, which will handle less than 2,000 t
year1 of biowaste, between 2021 and 2040 (SM Table 3). The generated biowaste is sustainably treated in households, avoiding collection and transport costs, and generating a compost that can be used in orchards and gardens (Vázquez and Soto, 2017);  CC (community composting) or AD (anaerobic digestion): for the six municipalities, that will treat more than 2000 t
year1 of biowaste (SM Table 3), between 2021 and 2040. The choice between CC or AD was supported by an economic analysis. Source-separated biowaste is sent to a local windrow compost-

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scenario, the planned diversion targets for 2023 and 2031 will not be attained, but there will be a higher (linear) diversion rate than in the pessimistic scenario, constituting a plausible hypothesis.  Optimistic scenario: the desired landfill diversions are attained in 2023 and 2031. In this scenario, the proposed MSWMF for the 19 municipalities will operate as expected.

ing facility. Rothenberger et al. (2006) favour decentralised composting facilities in developing countries, because they are less technology-dependent and increase job opportunities for the local community. As established by Matos et al. (2012), the recovery-based MSW treatments (materials recovery facility – MRF, composting and AD) will be decentralised at municipal level. Only the final disposal facilities (incineration and landfill), which will receive commingled MSW and refuse from MSW treatments, would be centralised (i.e. shared between all municipalities). All operations integrating the MSW technological roadmap chosen for each municipality are presented in SM Table 3. Regarding local MSWMF (MRF, composting or AD), the municipalities themselves will define the most suitable areas for to construct these infrastructures. This study only defined possible locations for the construction of shared facilities, involving centralised operations (transfer station – TS, incineration and landfilling). This was done to ensure the principle of proximity and self-sufficiency of the 2008/98/ EC Directive (EC, 2008), which seeks to minimise MSW transportation costs. Consequently, both incineration and landfill should be as close as possible to waste-generating centres. To determine the host municipality for the incineration facility of the proposed MSWMF (Pereira et al., 2013; Russo, 2003), mass point geometry was applied, as explained in SM Item 3. Regarding the landfill, the most suitable construction area was found through the methodology of Colvero et al. (2018) and Gorsevski et al. (2012). 2.2. Landfill diversion targets and the proposed scenarios The municipalities of Goiás must propose an MSWMF to meet the landfill diversion targets of recyclables and biowaste from landfills, as established in the National Plan for Solid Waste – PLANARES (MMA, 2012a) – Table 1. Based on those diversion targets, three future scenarios have been defined, according to the Brazilian Ministry of the Environment. These scenarios should be designed for a 20–year horizon (MMA, 2012b): between 2020 (year of the initial MSWMF construction investments) and 2040 (end-of-life of the proposed MSWMF). The diversion targets should be achieved between 2021 (beginning of MSWMF operation) and 2031 (year of the last PLANARES target). From 2031 to 2040, it is expected that the entire facility will stabilise and maintain the diversion percentages of 2031. The amount of MSW to divert from the landfill, between 2021 and 2040, was obtained from the estimated MSW production of the 19 municipalities evaluated by Colvero et al. (2017b). The three future scenarios are as follows:

2.3. Characterisation and heating value of MSW in Goiás Before calculating the lower heating value (LHV), characterising the MSW in the municipalities of Goiás first is necessary, in order to obtain the amount of energy that the incineration facility will sell annually. According to Colvero et al. (2016), this MSW is typically composed of 55.9% biowaste, 31.9% recyclables and 12.2% other waste. And the estimated average detailed characterisation of MSW in Goiás was obtained from Lima et al. (2018). As MSW diversion targets are different (Table 1) for each year and scenario, the equations presented in SM Item 4 (Matos and Pereira, 2005), were used to calculate the LHV of the MSW submitted to incineration each year, for the three scenarios. 2.4. MSWMF costs and economic viability analysis The investment and operating costs were calculated in Brazilian reais (R$), using exchange rates from the Central Bank of Brazil (BCB, 2017), when necessary. In 10/31/2018, R$ 1 = 0.2373 EUR = US$ 0.2690 (BCB, 2017). This study’s values were presented in Brazilian currency, because they were extrapolated to 2021, and obtained from the mean inflation between 2007 and 2016, as in item 2.4. However, the presented conversion aids readers to obtain the values in a more global currency. While the MSWMF investment costs will be insured by the Government of Goiás (NURSOL/UFG, 2015), the operation and maintenance (O&M) costs will be paid by the residents through tariffs. Oliveira (2010) affirms that MSW management is an individual public service provided to certain users, thus liable to charge. Furthermore, Article 29 of Law no. 11,445/2007 (National Policy of Basic Sanitation - PNSB), states that urban sanitation services and solid waste handling must be financially and economically sustainable. This may be ensured through the collection of tariffs, as defined by the service provision regime (Brasil, 2007). So, to broaden the economic analysis and its usefulness, the total monthly tariff (per household and per capita) for each municipality and year of the project, was also amounted. Given that the tariff is a complex sum of components (costs/revenues), they had to be organized in three categories, then totalized for each municipality:

 Pessimistic scenario: the PLANARES diversion targets (MMA, 2015) planned for 2015 and 2027 are reached in 2023 and 2031, respectively. In this scenario, the objective is to partially achieve the PLANARES targets, as the difficulties inherent to the deployment and operation of a new MSWMF mean the linear diversion rate is lower.  Moderate scenario: the planned PLANARES targets (MMA, 2015) for 2019 are reached in 2023. In 2031, the facility attains the mean between the planned targets of 2017 and 2031. In this

 Individual costs and revenues: each municipality will have its own costs from source-separated and commingled waste collection, MRF and (home or community) composting or AD, as well as revenues from the sale of recyclable materials and electricity from biogas (if AD is implemented);  Costs and revenues shared between all the 19 municipalities: the costs of incineration, landfilling and transport of incineration refuse (to the landfill), and revenues (from the sales of

Table 1 Goiás diversion targets for MSW disposal in landfills. Source: Adapted from MMA (2012a). Goal

Reduction in the percentage of landfilled dry recyclable waste Reduction in the percentage of landfilled biowaste Source: Adapted from MMA (2012a).

Landfill diversion targets 2015(%)

2019(%)

2023(%)

2027(%)

2031(%)

13 15

15 25

18 35

21 45

25 50

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D.A. Colvero et al. / Waste Management 102 (2020) 823–837 Table 2 Waste collection, materials recovery facility, transfer station and home composting investment and operating costs, extrapolated to 2020. Suggested costs (R$
t1)

Facility type

Waste collection – Reichert (2013): Source-separated collection of recyclable waste Source-separated collection of biowaste Commingled waste collection (mixed waste) Materials Recovery Facility – BNDES (2014): Less than 10,000 inhabitants Between 10,000 and 30,000 inhabitants Between 30,000 and 250,000 inhabitants Between 250,000 and 1,000,000 inhabitants More than 1,000,000 inhabitants Transfer station – Pereira et al. (2013) Home composting – EC (2000) Tsilemou and Panagiotakopoulos (2006): Windrow composting (2,000  x  100,000 t
year1) Anaerobic digestion (2,500  x  100,000 t
year1) Incineration (20,000  x  600,000 t
year1) Large landfill (60,000  x  1,500,000 t
year1)

electricity produced via incineration), will be divided proportionally between each municipality, according to the MSW percentage that each municipality sends for incineration;  Other individual/shared costs: the TS costs and MSW transport to incineration will be individual or shared. In the first case, when municipalities carry only their own MSW to incineration (directly or through a TS), these costs will be individual. However, in the second case, for the other municipalities that will share the TS, MSW transport to incineration will also be shared. This division of TS and MSW transport costs will be proportional to the amount of MSW produced by each municipality. The economic viability analysis of the project made use of cash flows (CF) and, consequently, Net Present Value (NPV), Internal Rate of Return (IRR), minimum acceptable rate of return (MARR) and payback period (Barros, 2017). The annual rate of income tax used for the NPV and IRR analysis was 15% (Martins et al., 2016). CF is the net amount of funds obtained by the algebraic sum of inputs (revenue) and outputs (costs) during the time of the project. And the NPV calculates the current value of a series of future revenues, from which the initial investment is subtracted (Sanches et al., 2013). When greater than zero, it indicates that the invested capital will be recovered. IRR is a reference measure that sets an NPV of zero. When IRR is greater than the stipulated MARR, the project will be economically viable, otherwise it should be rejected (Martins et al., 2016). The annual rate of income tax used for the NPV and IRR analysis was 15% (Martins et al., 2016). And finally, the payback period is the time (in years) required to recover the invested capital (Sanches et al., 2013). In this study, all revenues and operating costs for the MSWMF were updated monetarily (Soares et al., 2012), by applying the mean inflation in Brazil from 2007 to 2016, which was 6.217% per year (IBGE, 2017a), and then extrapolating this to 2020 (beginning of the project) using Equation (1) – Lima (2015), Soares et al. (2012).

Initial investment

Operating costs

– – –

269.25 247.47 131.39

47.39 23.69 25.85 16.51 10.05 6.10 238.14

689.30 653.39 710.84 172.32 100.52 28.98 1.02

y y y y

= = = =

4,000 x0.7 35,000 x0.6 5,000 x0.8 3,500 x0.7

y y y y

= = = =

7,000 x-0.6 17,000 x-0.6 700 x-0.3 150 x-0.3

collection, the unit costs from Reichert (2013) were extrapolated for the year 2020 (Table 2). All 19 municipalities will have both commingled and sourceseparated collection of recyclables. However, only the municipalities that have CC or AD have separate biowaste collection, because in the remaining municipalities the biowaste will be home composted. Regarding transport costs, 16 municipalities will send the collected MSW to a TS, and, from there, it will be transported by long-haul vehicles. The used mean cost units in this study are: R $ 0.32 t1
km1 for a 25-t capacity vehicle; and R$ 0.49 t1
km1 for the two municipalities which will carry their MSW directly to incineration in their own vehicles (both values extrapolated for 2020) – Bezerra (2012). Lastly, Goiânia will send 82.9% of its MSW directly to incineration (costing R$ 0.49 t1
km1, at a mean distance of 21.9 km from the urban centre) and 17.1% through the TS (27.1 km away, at a cost of 0.32 t1
km1). According to Vergara et al. (2016), the 53% difference in comparison to long-haul vehicles is because a 10-t vehicle consumes twice the fuel (in L
t1
km1) that a 25-t vehicle does; hence the unit value for the two municipalities that will carry their MSW directly to incineration. Additionally, fuel costs represent almost 50% of the total expenses of a collection vehicle (Marques, 2015),

where: VF: Future value (R$); VP: Present value (R$); i: Annual interest rate; n: Elapsed time (years).

2.4.2. Costs and revenues of recovery facilities for recyclables MRF require machines and operators to segregate the recyclable materials from the remaining waste, to be sold to the recycling industries (BNDES, 2012; Grimberg and Blauth, 1998). To calculate the investment and O&M costs of each one of the 19 MRF, the methodology defined by BNDES (2014), as shown in Table 2, was used. For municipalities that process less than 15 t
day1 of recyclables, fully manual sorting facilities were considered, i.e., separation tables without conveyor belts. If they exceed 15 t
day1 of recyclable materials, the municipality will have mechanically–assisted MRF (BNDES, 2014), having different unit investment and operating costs. All separated materials will be sold and this revenue for the facility will be calculated individually for each municipality. The mean unit sale price of recyclable components (BNDES, 2014), in Goiás, is presented in SM Table 4.

2.4.1. MSW collection and transport costs Because kerbside collection is already consolidated in Goiás, an MSWMF with this kind of operation was considered. To calculate the O&M costs of commingled and source-separated MSW

2.4.3. Transfer station costs The TS, where waste is transferred from collection vehicles to higher capacity vehicles, is located as close as possible to the waste generation centre, to optimise the transport of waste to a

n

V F ¼ V P
ð1 þ iÞ

ð1Þ

D.A. Colvero et al. / Waste Management 102 (2020) 823–837

treatment facility (Bezerra, 2012). According to Pereira et al. (2013), the total investment and operating costs of a TS are 35.1 R$
t1 (Table 2). 2.4.4. Costs and revenues of biological treatments The composting output is a stabilised compost, or soil conditioner. Conversely, AD outputs biogas, and an unstabilised digestate (Carvalho, 2013; Cerda et al., 2018). Biogas is composed of methane (CH4, between 45% and 70%) and carbon dioxide (CO2, between 35 and 60%), and can be used for electricity production (Gueri et al., 2018; Woon and Lo, 2016). To calculate the costs of the two composting types and AD, different methodologies were used:  HC: the mean investment and operating costs were obtained from EC (2000) and are shown in Table 2. The calculations are based on a 300–litre composter with a 10–year lifetime (Carvalho et al., 2011; EC, 2000). To calculate the necessary number of homes with composters to comply with the biowaste diversion targets, the mean number of inhabitants per domicile for each municipality was used (SM Table 5). For Melo et al. (2016), HC has an efficiency of 61%, which is the percentage diverted from final disposal. To guarantee the PLANARES diversion targets for biowaste, 20% more composters were added beyond those strictly necessary.  CC and AD: investment and operating costs of windrow CC and AD are presented in Table 2. While CC contemplates phases of intensive composting and maturation, AD uses dry thermophilic digestion to treat source-separated biowaste (Tsilemou and Panagiotakopoulos, 2006). It was considered that only 80% of waste destined for the CC and AD, through separate collection, will be diverted from MSW disposal facilities, i.e., there will be a 20% rejection rate due to contaminants. In addition to costs, AD also generates revenue from the sale of electricity. According to Fernández-González et al. (2017), the electricity generated each year is calculated through the biogas recovered in the process (Equation (2)). According to ANEEL (2018), electricity from biogas will be marketed at 319.48 R$ (MW
h)-1 (extrapolated to 2020).

EI ¼

0:28
B
ðCH4 Þp
LHV CH4
gb 1; 000

ð2Þ

where: Ei – produced electricity (in MW
h); 0.28 – conversion from MJ to kW
h (1 MJ = 0.28 kW
h); B – yearly treated biowaste in AD (t
year1); (CH4)P – methane generation ratio from the MSW organic fraction (Nm3
t1). As in Fernández-González et al. (2017), a figure of 115 Nm3
t1 was applied; LHVCH4 – methane lower heating value (37.2 MJ
Nm3), as in Gómez et al. (2010) and Lombardi and Carnevale (2016); Ƞb – biogas-to-electricity conversion efficiency. A value of 0.29 was used for internal combustion engines, to account for the electricity consumption of the facility (Fernández-González et al., 2017). 2.4.5. Incineration costs and revenues Incineration is a waste recovery process that produces heat and/ or electricity from the heating power of the materials (Silva et al., 2012). It generates two types of solid emissions: ash and slag, from

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which ferrous and non-ferrous alloys can be extracted for recycling (LIPOR, 2017). A grate combustion incineration plant with energy recovery was selected for the proposed MSWMF (Tsilemou and Panagiotakopoulos, 2006). The investment and operating costs of incineration are presented in Table 2. As in Fernández-González et al. (2017), the amount of electricity generated annually via incineration was calculated using Equation (3).

EI ¼

0:28
W
LHV RF
gi 1; 000

ð3Þ

where: EI – electricity produced (in MW
h); 0.28 – conversion from MJ to kW
h (1 MJ = 0.28 kW
h); W – annual amount of waste treated in the incineration facility (t
year1); LHVRF – lower heating value of the waste that arrives at the incineration facility (MJ
t1); Ƞi – incineration plant efficiency. This study adopted an efficiency of 22%, as per data obtained by Brogaard and Christensen (2016). This figure already accounts for the power consumed by the facility (Fernández-González et al., 2017). The sales of electricity produced by incineration will be recorded as revenue, at a unit price of 267.92 R$
(MW
h)-1 (ABRELPE, 2013), converted from USD to R$ and extrapolated for 2020. This is consistent with FEAM (2012) and Rossi (2014), which define the sale price of electricity generated through incineration as 259.2 R$ (MW
h)-1 and 283.0 R$ (MW
h)-1 , respectively (extrapolated figures for 2020). 2.4.6. Landfill costs In Goiás, there are currently 3 types of MSW final disposal:  Landfill licensed, that uses engineering principles to confine the MSW to the smallest area possible, with the lowest permissible volume (ABNT, 1992).  Unlicensed landfill, in which the MSW is deposited in a ditch with/without waterproofing or leachate treatment (Oliveira and Gonçalves, 2015).  Dump, in which the MSW is dumped on the ground without any technical criteria (Rosa et al., 2017). According to Colvero et al. (2017a), 15 of these 19 municipalities currently send their MSW to unlicensed landfills or dumps and only four municipalities have licensed landfills (SECIMA/GO, 2015). Still, those licensed landfills are located in restricted areas for construction and operation of MSW final disposal facilities, as shown in SM Table 1 (Colvero et al., 2017a). Because of this, the investment and operating costs of the proposed licensed landfill (Table 2), situated in an unrestricted area for MSW final disposal facilities, were calculated. 3. Results and discussion 3.1. Location of the incineration, landfill, and transfer stations The centre of mass indicated the municipality of Goiânia (State capital, and city with the largest population). Yet, the neighbouring municipality of Aparecida de Goiânia was proposed as the host municipality for incineration, because not only it has the second largest population of the State and is adjacent to Goiânia (Anjos, 2009; IBGE, 2016; SEGPLAN and SEPIN, 2011), but also has the largest industrial district of Goiás (FIEG, 2015). So, the incineration

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plant would be located in Polo Empresarial (business cluster), next to a highway (BR–153), which crosses the entire state and is the longest in Brazil. This proposed location suggests that thermal and/or electrical energy can be absorbed by the industrial units located in this business park, taking advantage of synergies and fostering industrial ecology (Lauria, 2012; SEPLAN, 2010). Knowing the location of the incineration facility, the location of the landfill that will receive the ash and slag produced by that process could be determined, using the methodology described in item 2.2. This procedure was problematical because nine of the 19 MSWMF municipalities do not have free areas for the construction of a landfill, mainly due to urban occupation and aerodromes. In total, 80.7% of the total area of the 19 municipalities is restricted, 11.5% is free and 7.8% is subject to approval for landfill construction (SM Table 6). Fig. 1 shows the areas that are restricted, subject to approval and free for the construction of MSW final disposal facilities in the 19 MSWMF municipalities, as well as the existing 14 dumps, three non-licensed landfills and four licensed landfills. Like the rest of Goiás, the majority of these municipalities have unlicensed, irregular MSW final disposal facilities (Pinheiro et al. 2015). According to Chen and Lo (2016), the urban centres situated over 25 km away from incineration will first send the MSW to a TS and then to the incineration plant. Consequently, nine TS are required for 17 municipalities. Only Hidrolândia and Aparecida de Goiânia will send their MSW directly to incineration.

The proposed nine TS, incineration facility and landfill are presented in Fig. 2. The landfill (located in the closest free area to incineration) is located in the district of Hidrolândia, with direct access to the BR–153 paved highway and 29.3 km from the incineration facility. The geographic coordinates of the urban centres of 19 municipalities, TS, incineration facility and landfill are presented in SM Table 7. And the distances (in km) that were used to calculate the transport costs for each municipality are presented in SM Table 8. With those distances, the cost of transporting ash and slag from incineration to the landfill was also calculated (58.6 km round trip). The existing licensed landfills (located in the municipalities of Aparecida de Goiânia, Bonfinópolis, Hidrolândia and Senador Canedo) were not used, because they are located in restricted areas, according to the legal documents presented in SM Table 9. They are either situated less than 3 km away from the urban perimeter, or do not comply with the minimum distances to surface water bodies (Fig. 3), as determined by CEMAm Resolution No. 05/2014 (SEMARH/GO, 2014). There is also non–compliance with the 20-km minimum distance buffer to aerodromes (Brasil, 2012). The restrictions for each landfill are:  Aparecida de Goiânia Landfill: located within the urban perimeter, 190 m away from the nearest home, violating CEMAm Resolution No. 05/2014;

Fig. 1. Map of the areas restricted, subject to approval and free for construction of landfills in the 19 MSWMF municipalities.

D.A. Colvero et al. / Waste Management 102 (2020) 823–837

829

Fig. 2. MSW management facility proposed for municipalities in the metropolitan microregion of Goiânia and neighbouring municipalities of Goiás microregions.

 Bonfinópolis Landfill: located within the urban perimeter restriction zone, 700 m away from urban settlements;  Hidrolândia Landfill: located 1.7 km away from a water body with drinking water catchment, while the minimum legal distance is 2.5 km;  Senador Canedo Landfill: located within the urban perimeter restriction zone and 680 m away from urban settlements. 3.2. MSW diversion targets Since PLANARES only established landfill diversion targets for biowaste and recyclables, specifically for 2015, 2019, 2023, 2027 and 2031, the MSW diversion targets for all the years between 2021 and 2031 were calculated (SM Table 10). After 2031 (and until 2040), the MSWMF will stabilize and the diversion percentages obtained in the year of the last PLANARES target (2031) will remain constant. The equations that represent the linear behaviour of the diversions, for 2021 to 2040, for each scenario, are shown in Table 3 (and represented in SM Figs. 1 and 2).

Using the calculated MSW diversions for each scenario and the MSW production estimates for each municipality, the amount of waste to be diverted annually was calculated. In the most favourable scenario, 1.16 million tonnes more would be diverted, compared with the pessimistic scenario (Table 4). Considering that 25% of the waste sent to incineration would end up in Hidrolândia’s shared landfill, this would mean approximately 290,000 t less of landfilled waste in the optimistic scenario, compared to the pessimistic scenario.

3.3. Characterisation and LHV of the MSW in Goiás municipalities To calculate the LHV of the MSW (for each year of the project), the detailed composition of the MSW in Goiás was estimated in the different facility stages (SM Tables 11, 12, 13 and 14). Considering the amount of waste produced by the 19 municipalities in 2015, and an effective diversion of 2%, the current LHV of the MSW is 9.28 MJ
kg1, which is consistent with 9.60 MJ
kg1 (Poletto Filho

830

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Fig. 3. Map of the Aparecida de Goiânia, Bonfinópolis, Hidrolândia and Senador Canedo landfills, all within restricted areas for the installation of MSW final disposal facilities.

Table 3 Diversion targets for recyclables and biowaste for the pessimistic, moderate and optimistic scenarios, from 2021 to 2040. Scenarios

Pessimistic

Moderate

Optimistic

Recyclable materials (% of diverted waste) 8 < 1:9748x  3989 0:4557x  915:99 : 9:570 8 < 2:2786x  4602:7 0:4557x  915:07 : 10:481 8 < 2:7343x  5523:3 0:3988x  798:47 : 11:393

Biowaste (year) 2021 6 x < 2023 2023 6 x < 2031 2031 6 x < 2040 2021 6 x < 2023 2023 6 x < 2031 2031 6 x < 2040 2021 6 x < 2023 2023 6 x < 2031 2031 6 x < 2040

Table 4 Projection of the quantitative limits of MSW that must be diverted from landfill to incineration, for the years 2021 to 2040 and for the pessimistic, moderate and optimistic scenarios.

Total MSW Recyclables diversion Biowaste diversion Waste not diverted

(% of diverted waste) 8 < 3:4937x  7057:4 2021 6 x < 2023 2:6203x  5290:4 2023 6 x < 2031 : 31:444 2031 6 x < 2040 8 < 5:8229x  11762 2021 6 x < 2023 1:9652x  3958:2 2023 6 x < 2031 : 33:191 2031 6 x < 2040 8 < 8:1521x  16467 2021 6 x < 2023 1:3102x  2626 2023 6 x < 2031 : 34:938 2031 6 x < 2040

Pessimistic scenario (t)

Moderate scenario (t)

Optimistic scenario (t)

19,082,405.4 1,098,407.9 3,776,334.5 14,207,663.0

19,082,405.4 1,214,794.2 4,235,405.1 13,633,206.1

19,082,405.4 1,346,636.6 4,692,475.7 13,043,293.1

and Poletto, 2017) and 10 MJ
kg1 (Berton, 2016; Pavan, 2010), for non-diverted MSW in Brazilian municipalities. The effective LHV of MSW sent to incineration from 2021 to 2040, per scenario (Table 5), varies from 9.51 MJ
kg1, for 2021, in the pessimistic scenario (lowest MSW diversions) to

(year)

Table 5 Estimate of the effective lower heating value of MSW sent for incineration in 2021 and 2031–2040 (constant) for the pessimistic, moderate and optimistic scenarios. Year

2021 2031–2040

Lower heating value (MJ
kg1) Pessimistic Scenario

Moderate Scenario

Optimistic Scenario

9.51 10.97

9.64 11.04

9.76 11.11

11.11 MJ
kg1, for 2040, in the optimistic scenario (highest diversions). The lowest LHV for technical feasibility is 8.37 MJ
kg1 (EPE, 2008), ensuring the viability of the proposed MSWMF. Increasing the diversion rate of recyclables, without raising the diversion rate of biowaste, means reducing the LHV of mixed waste. This could compromise the energy recovery of incineration (Merrild et al., 2012), thus showing the relevance of attaining the

D.A. Colvero et al. / Waste Management 102 (2020) 823–837

targets. As, the diversion target will be constant from 2031 to 2040, the LHV will also be the same, over that period. The advantages of incineration include the elimination of pathogens and toxic elements, and the possibility of producing steam and electricity. Furthermore, incineration reduces 80–90% in the waste’s original volume (Russo, 2003; Sharholy et al., 2008). Fernández-González et al. (2017) indicate that approximately 24.6% of the original weight of incinerated waste is converted into fly ash and slag to be sent to landfills. According to APA (2015), on average, 26.7% of the waste from the two existing incineration facilities in Portugal (located in Lisbon and Maia) leaves as ash and slag. In this study, 25% will be used for the ash and slag emissions. Considering the amount of MSW sent to incineration each year, the LHV for each scenario and an efficiency of 22% (Brogaard and Christensen, 2016) were obtained. Moreover, the calculated electricity generation ranges between 0.59 MW
h
t1 (2021, pessimistic scenario) and 0.68 MW
h
t1 (2040, optimistic scenario). In the current scenario, incineration would produce 0.57 MW
h
t1 of MSW, which is comparable to 0.58 MW
h
t1 of MSW (Fernández-González et al., 2017), and 0.45–0.70 MW
h
t1 (EPE, 2008). In the pessimistic scenario (with the lowest MSW diversions) and the optimistic scenario (with the highest MSW diversions), it is estimated that 457,593 MW
h and 434,526 MW
h of electricity will be produced, respectively. For the 19 municipalities, electricity consumption is, on average, 2.063 MW
h
household–1
year1 (IMB, 2017). This is close to the 2.200 MW
h
household–1
year1 for Campo Largo and Curitiba (Brazil), found by Berton (2016). Thus, from the mean consumption of each residence, it is estimated that

831

the produced energy is sufficient to supply 221,809 and 210,628 households in the pessimistic and optimistic scenarios, respectively. This represents 34% of the households of the 19 municipalities, or 95% of the households of 18 municipalities (all except the capital – Goiânia). 3.4. Economic analysis of the proposed MSWMF and collection for MSW management services In order to compare CC with AD, an economic analysis of the three scenarios was performed, with the total costs and revenues of the MSWMF proposed for the 19 municipalities. Fig. 4 shows the mass balance for the optimistic scenario, in 2040. In this year alone, approximately 1076 million tonnes of MSW will be produced, and the target will be to divert 8% of recyclables and 28% of biowaste. The remaining 64% will be sent directly to incineration (53.7%), or accounted for by the refuse from MRF and biological treatments (10.3%). The MSWMF will have nine TS to serve 16 municipalities, plus 17.1% of MSW from Goiânia. The other two municipalities, plus the remaining 82.9% of MSW from Goiânia, will be sent directly to the Aparecida de Goiânia incineration facility. All municipalities will collect recyclables (which will be sent to MRF) and biowaste (for composting or AD). A total of 13 municipalities will have HC, while the remaining six municipalities, will have CC or AD. Incineration will produce electricity that will be sold, and ash and slag to be sent to the Hidrolândia landfill. Regarding total costs, the optimistic MSWMF with AD scenario is the most expensive (Table 6), costing 8951 million R$ over the

Fig. 4. Predicted mass balance for the proposed MSWMF, for 2040, optimistic scenario.

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Table 6 Total investment and operating costs estimated (in R$ million) for the proposed MSWMF, from 2020 to 2040, for the three scenarios - extrapolated to 2020. Pessimistic scenario

Investment Transfer station Materials recovery facility Home composting Community composting Anaerobic digestion Incineration Landfill Total Investment Operation Separated recyclables collection Separated biowaste collection Commingled waste collection Transport Transfer station Materials recovery facility Home composting Community composting Anaerobic digestion Incineration Landfill Total Operation Total Investment and Operation

Moderate scenario

Optimistic scenario

Community composting (Million R$)

Anaerobic digestion (Million R$)

Community composting (Million R$)

Anaerobic digestion (Million R$)

Community composting (Million R$)

Anaerobic digestion (Million R$)

0.87 1.04 13.42 208.96 – 1573.52 108.49 1906.30

0.87 1.04 13.42 – 613.57 1573.52 108.49 23100.91

0.84 1.15 14.34 226.34 – 1522.41 1050.40 1870.48

0.84 1.15 14.34 – 656.96 1522.41 105.40 2301.11

0.80 1.28 15.28 243.16 – 1469.48 102.18 1832.18

0.80 1.28 15.28 – 698.52 1469.48 102.18 2287.54

422.49

422.49

467.26

467.26

517.97

517.97

1146.52 1866.75 358.68 411.75 297.21 0.06 283.49 – 1144.87 98.74 6030.56 7936.86

1146.52 1866.75 358.68 411.75 297.21 0.06 – 688.48 1144.87 98.74 6435.55 8746.46

1285.55 1791.27 344.21 395.10 328.64 0.06 300.42 – 1112.29 95.93 6120.73 7991.21

1285.55 1791.27 344.21 395.10 328.64 0.06 – 729.58 1112.29 95.93 6549.90 8851.00

1424.58 1713.76 329.35 378.01 364.18 0.07 315.05 – 1078.34 93.00 6214.31 8046.48

1424.58 1713.76 329.35 378.01 364.18 0.07 – 765.12 1078.34 93.00 6664.38 8951.91

20 years of the project. This value is 11% more than the optimistic scenario with CC, which will cost 8046 million R$ (extrapolated to 2020). Comparing the MSWMF with the same technologies, the optimistic scenario is costlier than the pessimistic and moderate scenarios. Even though the optimistic scenario has CC, it is 8.7% cheaper than the pessimistic scenario with AD. However, if comparing the environmental impacts of CC and AD, probably the results would be different from the ones of this economic analysis, i.e. AD would be preferable over CC. For instance, the life cycle assessment (LCA) carried out by Lima et al. (2018) shows that windrow composting has superior global warming potential than AD. This indicates that, even if the economic analysis shows that CC is desirable, it is important to complement this information with an LCA. The costs per tonne vary significantly for CC and AD, depending on the MSW amount of each municipality, because of the negative exponential expression (Table 2). Although, for the same municipality, the CC unit costs are always 40% lower than those of AD. In the best case, for Goiânia, the difference between the unit operating cost of CC and AD is less than 40 R$
t1 (2040, optimistic scenario). In this municipality, the population is growing, and generating more waste per capita, which reduces the unit cost. At the other extreme, in Hidrolândia, AD is R$ 580
t1 costlier than CC. Not only does this municipality have a much less MSW than Goiânia, but also the trend of population and per capita generation growth is much lower (Table 7). Is should be noted that the total costs with MSW collection and transport, represent 43.4–49.3% of the all MSWMF costs over the 20-year period of the project (depending on the scenario and whether the MSWMF has CC or AD). If operating costs alone are considered, MSW collection and transport will represent 59– 64.1% of waste management costs, which is consistent with the 60% found by Carvalho et al. (2011). As this would be a non-profit project, IRR was set to 0%, which will cover the costs over the lifetime of the project and ensure future reinvestments. Thus, the aim was to fine-tune the tariff to

obtain a positive NPV, with the lowest possible fee (Barros, 2017). This would mean that, irrespective of the scenario or biowaste treatment technology, payback would occur in 2040, as shown in Fig. 5 (for the optimistic scenario). Revenue in the scenarios with AD will be around 12–15% higher than in the same scenarios with CC (Table 8), due to biogas production. Furthermore, the revenue increase in the optimistic scenario, in relation to the pessimistic scenario, is explained by the revenue increase from the sale of recyclables and the electricity generated from biogas from AD. This revenue will be higher than it would be if this fraction of recyclables and biowaste were sent for incineration to produce electricity. As economic viability is crucial to attract capital and guarantee profitability to investors (Castro, 2017), an economic analysis with a MARR of 8%, (above the average inflation rate in Brazil over the last 10 years) was also accomplished, in a similar fashion to Barros (2017). The calculated payback is around 10 years and 2 months for an 8% MARR (SM Fig. 3). For an IRR of 8%, it is estimated that the NPV varies from 2000–2560 R$
million (scenarios with CC and AD, respectively), over the 20 years of the project (SM Table 15). Besides, this scenario may be a more viable alternative from the financial point of view, since a partnership between Goiás State

Table 7 Estimate of unit operating costs per tonne for community composting and anaerobic digestion, for 2040, for the optimistic scenario.

Aparecida de Goiânia Goiânia Goianira Hidrolândia Senador Canedo Trindade

Community composting (R$
t1)

Anaerobic digestion (R$
t1)

63.4 26.0 171.6 407.7 130.5 166.8

153.9 63.2 416.9 990.1 316.9 405.0

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D.A. Colvero et al. / Waste Management 102 (2020) 823–837

MSWMF with Community composting MSWMF with Anaerobic digestion

2021

2023

2025

2027

2029

2031

2033

2035

2037

2039

Fig. 5. Cumulative value extrapolated over the 20 years of the project, with an Internal Rate of Return (IRR) of 0% - optimistic scenario.

and the private sector would have more financial resources to execute the proposed management model. 3.4.1. Tariffs for the proposed MSWMF As in Fernández-González et al. (2017), the difference between the total costs and revenues resulted in the monthly tariff to be paid by each inhabitant (and also per household), for each year of the project, at an IRR of 0%. And the MSW tariff will be different for each municipality, as they will treat different amounts of MSW. Moreover, the technology cost of treating biowaste, waste transport distances (directly to incineration or via TS in higher capacity trucks), revenues from the sale of electricity and recyclables will vary for each location. Thus, comparing the costs of the different scenarios and analysing the economic viability of MSWMF with CC or AD (for the six most populated municipalities), the tariff was determined. As shown in Fig. 6, each inhabitant will pay between 3.5 and 7.0 R $
month1 in Brazabrantes (with HC) and Hidrolândia (with AD), respectively, in the optimistic scenario, in 2021. As for 2040 (same scenario, Fig. 7), the tariff range will be 3.5–10.8 R$
month1 (same municipalities). This increase is due to the higher MSW amounts in 2040. Furthermore, as SM Figs. 4–7 show, in the pessimistic and moderate scenarios (with lower MSW diversion), the tariffs would be lower than in the optimistic scenario. All amounts to be paid by the population have already been extrapolated to 2020. As the mean monthly nominal per capita income in the Goiás municipalities in 2017 is R$ 1277.00 (R$ 1530.29, extrapolated to 2020) – IBGE (2017b), in the municipality with the highest charge (Hidrolândia, optimistic scenario in 2040), the tariff represents 0.7% of each inhabitant’s monthly income. ERSAR (2016) data showed that, in 2015, the mean monthly MSW tariff in Portugal was 5.94 EUR
domicile–1, equivalent to 34.13 R$
domicile–1
month1 (extrapolated to 2020). Considering

that in the 27 municipalities served by two MSWMF with incineration in Portugal, the mean number of inhabitants per household is 2.62 inhabitant
domicile–1 (PORDATA, 2017), a value of 13.0 R$
inhabitant1
month1 was obtained. This is 20.4% higher than the estimated MSW tariff for Hidrolândia, in 2040, for the optimistic scenario (the most expensive situation). Other MSW management cost data indicate that the monthly tariffs obtained in this study are viable for Brazil. In Buenos Aires (also in South America), the average MSW management tariff is 12.5 R$
inhabitant1
month1. In New York and London, the average MSW management rate is around 18 R$
inhabitant1
month1. Furthermore, in Barcelona, Rome and Paris the average tariff is around 44 R$
inhabitant1
month1 (PWR, 2010). For an IRR of 6.5% and 8%, the monthly tariff per capita will increase, because the revenues from the sale of electricity and recyclables will remain the same, irrespective of the IRR. Thus, to enable a MARR with attractive percentages for potential investors, the tariffs need to be increased. For an 8% IRR (Fig. 8), tariffs would range between 6.0 and 17.4 R$
month1 (optimistic scenario, in 2040), an increase of 55–72% over a 0% IRR situation. However, if decision-makers opt for an MSWMF with CC instead of AD, the monthly tariffs will be lower than those charged by LIPOR and VALORSUL, even in municipalities with the highest fees. Additionally, the landfilling rates can deter or incentivise landfill diversions depending on whether they are low (like in Spain, at R$ 48.8 t1 – Fernández-González et al. (2017)) or high (like in the United Kingdom, at R$ 329 t1 – UK Government (2014)), respectively. Though, in the case of the studied MSWMF, the landfilling rate is even lower, at R$ 27.2 t1, not incentivising waste treatments. As the waste quantities rise, the unit costs become lower, explaining the lower values compared to Fernández-González et al. (2017) that has lower waste generation. An important element to correct and mitigate the shortcomings of a newly created MSW management facility is the implementation of a regulatory body that will act as a ‘‘visible hand” that protects the public interests (Simões and Marques, 2012b). It should also be noted that the partnership between the State and the private sector can have a positive or negative outcome, depending how the performance of the private partner companies are measured. So, the contracts signed with the private sector may, for instance, provide performance indicators linked to payments for the provided services (Simões, 2012).

4. Final considerations This paper presents an economic analysis of a proposed shared MSWMF for 19 municipalities situated in Metropolitan Goiânia and neighbouring microregions. The MSWMF shall have an incineration facility in Aparecida de Goiânia and, because 98.5% of the

Table 8 Estimate of costs and revenues of the proposed MSWMF over 20 years, for the pessimistic, moderate and optimistic scenarios - IRR 0% (extrapolated for 2020). IRR 0%

Revenue: Sales MSW tariff Costs: Operation Investment NPV

Pessimistic scenario

Moderate scenario

Optimistic scenario

Community composting (Million R$)

Anaerobic digestion (Million R$)

Community composting (Million R$)

Anaerobic digestion (Million R$)

Community composting (Million R$)

Anaerobic digestion (Million R$)

4222.82 4045.04

4737.00 4411.83

4184.33 4131.79

4760.86 4491.13

4142.79 4222.17

4781.67 4568.60

6030.56 1906.30 ffi0

6435.55 2310.91 ffi0

6120.73 1870,48 ffi0

6549.90 2301.11 ffi0

6214.31 1832.18 ffi0

6664.38 2287.54 ffi0

MSW incineration in Goiás Metropolitan region can produce 0.59–0.68 MW
h
t1.

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Home composting Community composting Anaerobic digestion

Fig. 6. Monthly tariff per inhabitant, per household, in 2021, for each of the 19 municipalities - IRR optimistic scenario (0%).

Home composting Community composting Anaerobic digestion

Fig. 7. Monthly tariff per inhabitant, per household, in 2040, for each of the 19 municipalities - IRR optimistic scenario (0%).

area in this municipality is restricted for such facilities, the landfill would be in the neighbouring municipality, Hidrolândia. In terms of total project costs, the optimistic scenario with the MSWMF with AD will cost 8,951 million R$ over the 20 years of the project, approximately 13% more than the pessimistic scenario with CC (the cheapest, irrespective of the scenario). The highest cost burdens for MSWMF are MSW collection and transport, which represent 59–64.1% of total expenditures. As a result, the initiative to decentralise facility operation at municipality level, coupled with the identification of the most central area for installation of the incineration plant, will minimise MSW transport costs.

Project revenues in the scenarios with AD are up to 15% higher than in the same scenarios in which the MSWMF has CC. Even without profits, the project is paid for within 20 years, while for an IRR 8%, payback will take little more than 10 years. It should be emphasised that an IRR of 0% translates into lower MSW tariffs. The tariffs for this IRR, in the optimistic scenario, in 2040, will vary between 3.5 and 10.8 R$
month1. For an IRR of 8%, they will vary between 6.0 and 17.4 R$
month1. As tariffs are higher for municipalities with AD, the alternative to attract investors (8% IRR) without burdening the service users is to implement the MSWMF with CC. In this case, the maximum monthly tariff (in 2040, optimistic scenario) would not exceed 12.7

D.A. Colvero et al. / Waste Management 102 (2020) 823–837

835

Home composting Community composting Anaerobic digestion

Fig. 8. Monthly tariff per inhabitant, per household, in 2040, for each municipality - optimistic scenario (8% IRR).

R$
month1 for the municipality with the highest tariffs. This is less than the mean price (13.0 R$
month1) of the two MSWMF with incineration in Portugal. It is important to emphasize that the municipalities involved in the proposed MSWMF should make a detailed evaluation of the MSW’s LHV, since the data used in this study are secondary. Another limitation found in this study refers to the exact location of the MSW treatment technologies in the municipalities, which were not defined in this study. This should be determined by the municipalities that integrate MSWMF. Finally, this study may serve as a model for other municipalities in Brazil and elsewhere that have inefficient MSW management. It may also assist the public decision makers in these municipalities to establish a strategy for MSW management. The public managers of the municipalities of Goiás must seek partnerships with recycling industries and encourage the installation of these industries closer to the MSWMF. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements The authors gratefully acknowledge the Brazilian National Council for Scientific and Technological Development (CNPq) for its financial support, File No. 207172/2014-5. We thank Secretaria de Meio Ambiente, Recursos Hídricos, Infraestrutura, Cidades e Assuntos Metropolitanos – SECIMA/GO. Appendix A. Supplementary material Supplementary data to this article can be found online at https://doi.org/10.1016/j.wasman.2019.11.033.

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