Selective Collection Research Articles

MSW Management in Two Italian Mountainous Areas

Abstract Two case studies are reported in the present work. They regard municipal solid waste (MSW) management trends in the last decades in two Italian provinces selected to analyse some issues of waste management in mountainous areas. The first case study refers to a selective collection (SC) rate expected to reach 80 % soon. This scenario assumes SC mainly in kerbside mode. The scenario is based on specific local conditions: the absence of a thermo-chemical plant in the territory (but with a part of the residual MSW burnt in a neighbour province), the presence of local plant of anaerobic, and a sanitary landfill for pre-treated residual MSW. The adopted tariff helped increasing the SC rate: indeed, since 2013, a tariff calculated at user level, depending on the behaviour of each user, has been adopted. This is called punctual tariff. The second case study concerns an area where SC reached about 75 %. The punctual tariff has been recently introduced. In this scenario, an incineration plant and a Solid Recovered Fuel (SRF) plant allow implementing an industrial symbiosis solution in conjunction with a cement factory. The work demonstrates that SC can be the core of a correct MSW management and that kerbside collection is fully compatible with mountainous area. However, other issues remain to be optimized yet: the low density of mountain areas makes difficult to implement enhanced solutions of SC (e.g. for diapers) and increases costs for light packaging collection; moreover, the presence of tourist fluxes can significantly affect SC efficiency.

Formal and informal waste selective collection in developing megacities: Analysis of residents' involvement in Bolivia.

The implementation of waste selective collection (SC) schemes in low-income countries is a challenge although it is one important way for improving environmental sustainability. The inclusion of the population is necessary for gaining effective results, and social surveys are support methods for understanding citizens' involvement and behaviour. The aim of the research is to assess the support of the citizens concerning the formal and informal recycling in a low-middle income country. The study presents a questionnaire survey conducted in 2018 in La Paz, Bolivia, where 774 citizens were interviewed for evaluating their support to the formal and informal SC systems. Two questionnaires were submitted to two different users' categories: users of the formal recyclable waste gathering points; and citizens of the neighbourhoods. Evidence of the survey shows that about 8% of the population supports the formal SC while about 48% are used to selecting their waste at home. About 79.2% of them bring the waste to the informal recycling shops or provide it to waste pickers, throwing the waste into or nearby the mixed containers in order to facilitate their collection. This research demonstrates how social inclusion is important for planning recycling systems within a developing big city, starting from the SC. Results suggest that the informal sector can be an effective means for improving the recycling behaviour of the citizens. The study can be of interest to stakeholders involved in introducing recycling policies in developing cities where the SC rate is still low, and informal waste collection exists.

Exergoeconomic analysis of a Mechanical Biological Treatment plant in an Integrated Solid Waste Management system including uncertainties

Municipal Solid Waste disposal is still a crucial issue, which is influenced by heterogeneous factors (political, social, economic and technological). The Mechanical Biological Treatment (MBT) plant is an important element of an Integrated Solid Waste Management system. These plants are aimed at separating the light and dry fraction of the Unsorted Waste from the wet one, producing the Refused Derived Fuel and recovering the metal parts. In the present work, an Exergoeconomic analysis is performed on two MBT plant structures in order to assess the unit exergy-based cost of products and allocate the irreversibility associated to each equipment. A linear variation of degree of Selective Collection (SC) of single materials (±30% respect to the base case) shows that the major influence on production costs is associated to the SC of plastic. A Monte Carlo simulation is then carried out by sampling from distributions of external (waste composition) and internal (energy consumption) uncertain variables. The resulted mean values (μ) and standard deviations (RStD) can be useful at the time of designing a new plant. The influence of the internal variable is definitely lower than the external one, with values of RStD more than 90% lower.

Selective collection of recyclable waste in Universities of low-middle income countries: Lessons learned in Bolivia

The implementation of solid waste selective collection (SC) systems is quite difficult in low-middle income countries. Lack of awareness, infrastructure, administrative support and knowledge about recycling are the main barriers for its operation, reducing the possibility of successes. This paper introduces the methodological approach for assessing a recyclable waste SC project in a Bolivian public University. The waste fractions generated before (2016) and after (2019) the action were assessed, as well as the opinion and knowledge of the students, providing reliable indicators of the improvements and benefits obtained. Results of the waste characterization analysis reported that, after one month of implementation of the system, about 15 kg of plastic and 37.1 kg of paper and cardboard were collected, about 8 wt% and 42.9 wt% of the recyclable waste produced. At the same time, the questionnaire survey allows demonstrating that the SC behavior of the students improved considerably from 2018 to 2019, (t[608] = −7.654, p < 0.05***), as well as the satisfaction about the waste collection service provided (t[608] = −6.6224, p < 0.05***) and about the diffusion of information with awareness campaigns (t[608] = −8.708, p < 0.05***). The project and the phases followed for its implementation can be of reference for other local and international stakeholders, for replicating the study in other Universities and public areas. The novelty of the study is the introduction of a step by step methodology for assessing the SC of recyclable waste for supporting the recycling policies of developing cities in low-middle income countries and for boosting sustainable development according to the principle of the circular economy.

Assessment of municipal solid waste selective collection scenarios with geographic information systems in Bolivia

The analysis of municipal solid waste (MSW) selective collection (SC) scenarios is compulsory for planning future policies and actions towards circular economy. The use of geographic information system (GIS) is appropriated for obtaining reliable data about SC yields and management costs. However, in low-middle income countries, advanced assessments are difficult to introduce due to the lack of technical knowledge, financial support and the presence of the informal recycling sector. This research aims to assess the main potentialities of the introduction of SC systems in a Bolivian developing city taking into account the informal SC system in place. The study was conducted with QGIS3.8 software in order to evaluate the main advantages of the implementation of formal and informal recycling chains. Results reported that, comparing the implementation of formal SC of MSW with the scenario that considered the inclusion of the informal recycling, the activity of waste pickers allows reducing the expenses of about 10%, increasing the recycling rate of about 3.5%, and reducing the distances traveled with compactor trucks of about 7%. It means that, the annual path traveled by the collection trucks for gathering about 16,000ty−1, is reduced by 2734kmy−1, reducing the waste disposed to landfill of about 543.6ty−1 and the expenses of about €59,000 per year. The presentation of these results to policy-makers can support decision-making boosting the implementation of recycling activities including waste pickers. The study provided a contribution to the scientific literature assessing the main challenges and opportunities for implementing the circular economy in developing regions.

Classification and characterisation of SRF produced from different flows of processed MSW in the Navarra region and its co-combustion performance with olive tree pruning residues

The scope of this work is to study the co-combustion of a solid recovered fuel (SRF) produced from household wastes and packaging wastes recovered from selective collection (SC) in the autonomous community of Navarra, located in the northeast of Spain. The municipal solid waste (MSW) is subjected to a mechanical biological treatment (MBT) in order to stabilize the organic matter and recover the recyclable materials as it is done for packaging wastes. Afterwards, rejects from this treatment plant were preconditioned and compressed by a pelletizing process to produce a secondary fuel according to quality and classification criteria of EN 15359, producing the so-called SRF. A fuel characterisation was carried out according to CEN standards and the SRF was classified as follows: NCV 2; Cl 3; Hg 1. SRF pellets were cofired with residual biomass pellets from olive tree pruning (OTP) in a bubbling fluidised bed combustor, as an option of energy recovery. The mixture of fuels, with a mixing ratio close to 50% by weight, showed a significant calorific value of 18.25MJ/kg at 8% of moisture content. In addition, elemental composition of the mixture based on nitrogen (N), sulphur (S) and chlorine (Cl) (1% N, 0.2% S and 0.4% Cl) was not far from some herbaceous biomasses. The co-combustion showed good results as an energy recovery technology because of the synergies of both fuels, improving notably the combustion conditions and reducing significantly CO concentration, regarding to the combustion of OTP, though other contaminants such as NOx and HCl increased. During eight hours of stable operation, the concentration of dioxins and furans was measured obtaining a value of 7.68ng/Nm3 (toxic equivalence: i-TEQ of 0.33ng/Nm3). Proportions of SRF lower than 50% in the mixtures should be tested in order to cut down the emissions of these pollutants, or an abatement system for organochloride compounds may be required.

RDF/SRF Evolution in the MSW sector: coexistence of BMT and selective collection

Mechanical biological treatments (MBTs) are extensively used for managing municipal solid waste (MSW). There are four different methods: fertilizer or compost-like output production, biogas/energy production, wastederived fuel production and disposal in landfills. One issue is the varying characteristics of the waste fed over the lifetime of the plant. This problem is only partially related to the composition dynamics of the generated MSW. Indeed, the main source of input fluctuation of the plant is a result of the implementation of selective collection (SC) strategies, which modify the composition of residual MSW (RMSW). Often the SC strategies are not developed in harmony with the presence or planning of treatment plants, which can consequently suffer from significant variations. A lack of optimization in MSW management strategies and the implementation of new more stringent regulations applied to the final solid products from MBTs could result in a higher tariff for the users. This paper analyses these two problems in terms of two SC scenarios. The consequent effects on the composition of RMSW and on the performance of bio-drying (one of the MBTs options) are discussed. The effect of different SC strategies of MSW is analysed also in terms of RMSW suitability to be converted into refuse derived fuel/solid recovered fuel with simplified treatments. The role of respirometry is also discussed.

From Waste to Resource: Can Selective Collection Really Help?

The municipal solid waste (MSW) generation depends on the industrialisation and the sustained growth population in the world. The first data regarding the people waste production referred to the Paleolithic era, thanks to the Absolon discovery in 1945 [1]. During the years the composition of MSW was on continuous changes. For example a century ago the MSW contained mainly coal ash and food scraps, with a small proportion of paper and glass [2]. Instead today after the economic-industrial development in the MSW it can be found a high quantity of organic and packaging materials and only a very low quantity of inorganic ones. The first concept of waste selective collection (kerbside) and open dumps constructed at about 2 km away from the cities, date back to the birth of the first civilization in 2000 B.C. [3]. However in the 1960s, 1970s, and 1980s, the waste Selective Collection (SC) was implemented more and more in order to reduce the waste flow sent to landfills [4] and incinerators whilst municipalities were considered responsible for recycling collection [5]. The waste SC during the years has been one of the most discussed topics in the scientific sector [6]. The first proposed treatment for the selected organic waste was the composting one [7], followed by anaerobic digestion [8], whilst biostabilization [9] and biodrying [10] are involved if food waste SC shows a low quality. In the last years, in European Union, with the introduction of the Waste Framework Directive (2008/98/EC) that established a target of re-use/recycling/valorization of at least 50% of household waste by 2020 this situation is changing putting the attention on MSW as “future resource”. The question raised in the latest years, regards the efficient use of SC in order to transform the MSW in materials that can be re-used by recycling as glass, PET, paper and cardboard, organic fraction and the remaining ones, the “residual MSW” that can be reused as a solid recovered fuel (SRF) in order to substitute fossil combustible [11]. In the MSW sector the following questions, often related with the SRF that will be produced after an extreme SC, represent the main topics on the carpet and the priorities of the international research:• Does the residual MSW will be directly suitable as SRF? This opportunity could decrease the costs for waste management as a complex mechanical-biological treatment could be avoided. • Does extreme SC efficiencies could decrease the amount of residual MSW to levels often not compatible with the construction of an incinerator? In the sector it is clear that the scale effect plays and important role in the feasibility of an incinerator, thus in the future some regions could renounce to the construction of such a plant as a consequence of the evolution of SC; the option of SRF generation could become more and more attractive.• Does SC and streams valorisation give to residual MSW a secondary role? Where selective collection has got the best results in harmony with valorisation strategies, residual MSW can be reduced to about 20% of the generated MSW.• Does SC open to unconventional strategies of material valorisation? Top results in SC generate source-separated streams that never in the past were taken into account; an example is the diapers SC that requires, for a correct valorisation, the construction of a treatment plant suitable for separating the cellulosic and plastic materials used for this product.In this frame it is clear that only a high quality SC can help in changing the role of MSW: from waste to resource.Finally, as an opportunity to increase the know-how of the sector, the open access journals and specifically the OMICS Group activities are contributing to have a complete scientific answer to the above questions.

Selective collection as a pretreatment for indirect solid recovered fuel generation

Effective selective collection (SC) has been increasing in many countries of the European Union. As a consequence the composition of residual municipal solid waste (RMSW) is changing not only because of economic development, but also due to the collection system. The input of RMSW treatment plants is thus not homogeneous. This paper analyses two case studies involving a total of five SC scenarios and their impact on the generation of solid recovered fuel (SRF) with/without bio-drying, post-treatment and packaging take back programs (TBPs). These case studies are based on two types of SC: kerbside and drop-off. The latest regulation on SRF classification is taken into account: energy content, Cl and Hg concentrations are assessed and discussed. The role of the respirometric index (RI) is also analyzed. Results show that when SC is highly efficient RMSW can be classified directly as SRF, but only if the introduction of RI does not set stringent respirometric targets. The role of packaging TBPs is important as the residual waste remaining after the packaging has been processed, can be valorized increasing the lower heating value (LHV) of the residual RMSW and minimizing the streams that should be landfilled. The source separation of food waste has a significant impact on the suitability of bio-drying: when the SC of food waste is very efficient, its percentage in the RMSW may be too low for effective bio-drying.

Integrated municipal solid waste scenario model using advanced pretreatment and waste to energy processes

In this paper an Integrated Municipal Solid Waste scenario model (IMSW-SM) with a potential practical application in the waste management sector is analyzed. The model takes into account quantification and characterization of Municipal Solid Waste (MSW) streams from different sources, selective collection (SC), advanced mechanical sorting, material recovery and advanced thermal treatment. The paper provides a unique chain of advanced waste pretreatment stages of fully commingled waste streams, leading to an original set of suggestions and future contributions to a sustainable IMSWS, taking into account real data and EU principles. The selection of the input data was made on MSW management real case studies from two European regions. Four scenarios were developed varying mainly SC strategies and thermal treatment options. The results offer useful directions for decision makers in order to calibrate modern strategies in different realities.