Organic waste valorization in remote islands: Analysis of economic and environmental benefits of onsite treatment options.

Solid waste management (SWM) represents an important issue for small islands. This research evaluates the municipal SWM system of the Pelagian archipelago, in Italy. The research aims to evaluate environmental and econoemic benefits of onsite treatment plants for the valorization of the organic fraction of municipal solid waste. The sizing of the anaerobic digestion (AD) and composting plant was developed, and the characteristics of the plant were used to conduct a cost analysis and an environmental life cycle assessment. The current waste management system (S0) has been compared with the new strategy proposed (S1). Results showed that S1 leads to save more than 250,000 € y-1 due to the avoidance of organic waste final disposal and shipping, determining a payback time of about 7 years. Environmental benefits include a lowering of CO2-eq emission of more than 1100 tonnes per year and a reduction of all the six environmental impacts analysed. The outcomes represent a novel contribution to the scientific literature since the research provides the first comparison of quantitative data about environmental and cost benefits of onsite AD plants in small islands. The research underlines that onsite waste treatment systems are viable options to improve SWM systems in isolated regions.

Zooming on light packaging waste differences by scanning electron microscopy.

In the present paper, different types of pure and commercial plastic waste from different EU countries (UK, France, Italy, and Romania) were investigated for microstructure surface morphology and chemical properties by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). The goal of the current investigation was to determine the chemical composition of selected packaging materials and compare these measurements with data obtained through a carbon-hydrogen-nitrogen-sulfur-oxygen (CHNS-O) elemental analyzer, which is conventionally used to characterize waste materials. The capabilities of the experimental approach are discussed in connection with their application to the study of waste sample materials and in comparison with alternative experimental methods such as elemental analysis. The CHNS-O comparison is made between the present data obtained with SEM-EDXS instrument and EA 3000 elemental analyzer used in previews studies conducted by the authors. Results show a difference of composition among packaging from different countries that can affect the treatment adopted for its valorization and the strategies of circular economy.

Municipal solid waste management during the SARS-COV-2 outbreak and lockdown ease: Lessons from Italy.

The literature on municipal solid waste in relation to COVID-19 is scarce. Based on the experience of Italy, the present article contributes to the strategies aimed at preventing a second virus outbreak. In fact, the mismanagement of municipal solid waste could undermine the strategies during the ease of the lockdown. During the SARS-COV-2 outbreak in Italy, there was a general decrease in the selective collection rate (-15% in one municipality with a well-developed door-to-door collection system). Delays in the publication of guidelines on waste management impacted on the safety of the operators collecting potentially infected waste. Contrarily to expectations, single-use masks and gloves do not have significant impact on waste management, accounting for <1% of the residual municipal solid waste collected annually. However, the dispersion of abandoned masks and gloves outside indoor environments is creating environmental problems. Recommendations on waste management and the protection of waste operators are discussed. Finally, guidelines on the most appropriate waste treatment are presented and analyzed. The results presented in this article show that the MSW management sector has found useful solutions to tackle COVID-19; however, these solutions are not being shared sufficiently. The case study analyzed in the present work could help define strategies for preventing or controlling similar future epidemics or pandemic episodes.

Application of healthcare waste indicators for assessing infectious waste management in Bolivia.

In the developing world, healthcare waste management is a human health and environmental burden that should be solved for improving sustainability. Solutions should be introduced in the short term, concerning management, planning, financial assistance and expertise. The paper introduces an indicator set for assessing healthcare waste management in developing cities, implemented in La Paz (Bolivia) as a case study. The objective is to suggest an integrated management tool as a first assessment technique to identify the prevailing problems with a healthcare waste management system. Results suggest that, in La Paz, the application of such indicators is useful for evaluating which priorities should be addressed for improving the healthcare waste management system. The tool was applied for introducing a study necessary for the application of new management plans, especially concerning healthcare waste treatment. The method can be replicated in other contexts worldwide, with a focus on the developing world, for comparing cities, management solutions and improvements carried out along the years. The approach is of interest for boosting sustainability and human health, improving the awareness of the actors and policy-makers involved in waste management.

Vermicomposting process for treating animal slurry in Latin American rural areas.

The management of animal slurry is a big issue in low-income rural areas worldwide. Bolivia suffers this issue related to collection, treatment and final disposal since the main solution applied is the open dumping. The aim of this study is to introduce a feasible treatment of animal slurry in the rural area of Carmen Pampa, where about 670 kg of dung are produced per day and disposed of in open areas. The objective is the improvement of the environmental sustainability and human health, providing an alternative solution for encouraging the circular economy. The study is focused on the vermicomposting process, a sustainable solution for low-income regions. The analysis was conducted in function of the earthworm breeds used locally ( Eisenia fetida and Lumbricus terrestris) and the application of activated bacteria (AB) for improving the process. The mass loss, the treatment time, and the growing rate of the earthworms were analyzed. The results suggest that the different breed of the worms allows gaining up to 19 days, while the use of the AB allows saving about 30 days. Moreover, the vermicomposting process reduced the mass of the slurry of about 65% for the swine's dung and the bovine's dung, and 90% of the hens' dung. Finally, experimental evidence shows that the growing rate of the E. fetida is higher than the L. terrestris (F[1,8] = 78, p < 0.05), with an average of about 193%. The data obtained could be of interest for other stakeholders who live in similar environmental, climatic, and economic conditions for improving sustainability.

Introduction of the circular economy within developing regions: A comparative analysis of advantages and opportunities for waste valorization.

The introduction of effective solid waste management strategies in developing countries should be considered for improving sustainability at global level. Many barriers should be overcome, concerning the introduction of environmental policies, effective investments, social inclusion and public awareness, which are significant issues in low-middle income countries. The Circular Economy could represent the answer for improving current solid waste management activities worldwide, since denote the principle of waste valorization and recycling for boosting developing economies. This paper is focused on this theme, analyzing main opportunities for improving the current state of solid waste management in developing big cities. The solid waste management of two countries are reviewed: Romania is the emerging country where Circular Economy is becoming a future objective due to economic aids and strength regulations which the European Union (EU) established for the nations forming parts the alliance; as a comparison, Bolivia is reported for evaluating main differences founded for developing recycling systems in a no-EU country. These two case studies could be of interest for highlighting main pros and cons of the participation into a wide organization like the EU for introducing in short terms Circular Economy principles. Moreover, a theoretical Circular Economy model for developing big cities in low-middle income countries is described within the study for effectively comparing which chances can spread for these countries as regard municipal solid waste exploitation. Despite the economic level, Romania and Bolivia are both facing with many solid waste management issues although in different magnitude. For the Romanian case study, it is visible how it cannot achieve the European goals for 2020 due the need of change in public recycling behavior. Bolivia, instead, represents the case where international aids and new investments are required, considering the informal sector into the formal management system as a real opportunity for improving local recycling rate. In conclusion, the comparison suggests how external supports led to implement the principles of the Circular Economy within a developing region. The model of Circular Economy proposed is recommended for developing big cities in order to advance a new form of safe employment, encouraging the activities that are still in action (i.e. informal sector) and boosting the principles of sustainable development.

The municipal solid waste management of La Paz (Bolivia): Challenges and opportunities for a sustainable development.

Municipal solid waste management (MSWM) is considered an important public health, economic and environmental concern, especially in developing countries. This paper introduces the situation of MSWM in La Paz (Bolivia) in 2016, and is based on the Wasteaware indicators and waste flow analysis, useful tools for classifying and comparing waste treatment and management plans among other countries. Taking into account the lack of technology in waste treatment and the presence of a developed informal sector, the paper analyses the main strengths and weak points for implementing a sustainable MSWM. The research conducted revealed that the MSWM of La Paz is not efficient with regard to collection, recycling (8%), financial sustainability, and equity of the service. At the same time, local Government and stakeholders are interested in implementing new MSWM methods for improving the current sanitary state of the city and many efforts were made over the last ten years. In general terms, La Paz could be considered as a good study area for developing plans for waste valorization, becoming an example for a low-middle income developing big city of Latin America. The study provided a few considerations about the affordability of the methodology applied and critically analyzed the case study proposed.

Characterisation of volatile organic compounds (VOCs) released by the composting of different waste matrices.

The complaints arising from the problem of odorants released by composting plants may impede the construction of new composting facilities, preclude the proper activity of existing facilities or even lead to their closure, with negative implications for waste management and local economy. Improving the knowledge on VOC emissions from composting processes is of particular importance since different VOCs imply different odour impacts. To this purpose, three different organic matrices were studied in this work: dewatered sewage sludge (M1), digested organic fraction of municipal solid waste (M2) and untreated food waste (M3). The three matrices were aerobically biodegraded in a bench-scale bioreactor simulating composting conditions. A homemade device sampled the process air from each treatment at defined time intervals. The samples were analysed for VOC detection. The information on the concentrations of the detected VOCs was combined with the VOC-specific odour thresholds to estimate the relative weight of each biodegraded matrix in terms of odour impact. When the odour formation was at its maximum, the waste gas from the composting of M3 showed a total odour concentration about 60 and 15,000 times higher than those resulting from the composting of M1 and M2, respectively. Ethyl isovalerate showed the highest contribution to the total odour concentration (>99%). Terpenes (α-pinene, ß-pinene, p-cymene and limonene) were abundantly present in M2 and M3, while sulphides (dimethyl sulphide and dimethyl disulphide) were the dominant components of M1.

Potential SRF generation from a closed landfill in northern Italy.

The aim of this work is to assess the possibility of producing solid recovered fuel (SRF) and "combustible SRF" from a landfill located in the north of Italy, where the waste is placed in cylindrical wrapped bales. Since the use of landfills for the disposal of municipal solid waste has many technical limitations and is subject to strict regulations and given that landfill post-closure care is very expensive, an interesting solution is to recover the bales that are stored in the landfill. The contents of the bales can then be used for energy recovery after specific treatments. Currently the landfill is closed and the local municipal council together with an environmental agency are considering constructing a mechanical biological treatment (MBT) plant for SRF production. The municipal solid waste that is stored in the landfill, the bio-dried material produced by the hypothetically treated waste in a plant for bio-drying, and the SRF obtained after the post-extraction of inert materials, metals and glass from the bio-dried material were characterized according to the quality and classification criteria of regulations in Italy. The analysis highlighted the need to treat the excavated waste in a bio-drying plant and later to remove the inert waste, metals and glass. Thus in compliance with Italian law, the material has a high enough LHV to be considered as "combustible SRF", (i.e. an SRF with enhanced characteristics).

Air pollution control through biotrickling filters: a review considering operational aspects and expected performance.

The biological removal of pollutants, especially through biotrickling filters (BTFs), has recently become attractive for the low investment and operational costs and the low secondary pollution. This paper is intended to investigate the state of the art on BTF applications. After an overview on the biodegradation process and the typical parameters involved, this paper presents the analysis of a group of 16 literature studies chosen as the references for this sector. The reference studies differ from one another by the pollutants treated (volatile organic compounds [VOC], hydrogen sulphide, nitrogen oxides and trimethylamine), the geometry and size of the BTFs, and the procedures of the tests. The reference studies are analyzed and discussed in terms of the operational conditions and the results obtained, especially with respect to the removal efficiencies (REs) and the elimination capacities (ECs) of the pollutants considered. Empty bed residence time (EBRT), pollutant loading rate, temperature, pH, oxygen availability, trickling liquid flow rate, inoculum selection and biomass control strategies revealed to be the most important operational factors influencing the removal performance of a BTF.

Comparison between conventional biofilters and biotrickling filters applied to waste bio-drying in terms of atmospheric dispersion and air quality.

Biofiltration has been widely applied to remove odours and volatile organic compounds (VOCs) from industrial off-gas and mechanical-biological waste treatments. However, conventional open biofilters cannot guarantee an efficient dispersion of air pollutants emitted into the atmosphere. The aim of this paper is to compare conventional open biofilters with biotrickling filters (BTFs) in terms of VOC dispersion in the atmosphere and air quality in the vicinity of a hypothetical municipal solid waste bio-drying plant. Simulations of dispersion were carried out regarding two VOCs of interest due to their impact in terms of odours and cancer risk: dimethyl disulphide and benzene, respectively. The use of BTFs, instead of conventional biofilters, led to significant improvements in the odour impact and the cancer risk: when adopting BTFs instead of an open biofilter, the area with an odour concentration > 1 OU m(-3) and a cancer risk > 10(-6) was reduced by 91.6% and 95.2%, respectively. When replacing the biofilter with BTFs, the annual mean concentrations of odorants and benzene decreased by more than 90% in the vicinity of the plant. These improvements are achieved above all because of the higher release height of BTFs and the higher velocity of the outgoing air flow.

State of the art and advances in the impact assessment of dioxins and dioxin-like compounds.

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are toxic and persistent organic pollutants that are able to enter the food chain, accumulate in the fat tissues of animals, and consequently pose a serious risk for human health. Consolidated tools for exposure assessment have been implemented during the last decades and widely used, both in the environmental monitoring and in modeling activities. Although the emissive trend and the concentrations in the environment have gradually decreased during the last 20 years, some situations are still underrated and not adequately controlled by the environmental legislation. On the other hand, a complete monitoring of all the pathways of exposure to PCDD/Fs and PCBs is technically and economically unfeasible. Therefore, this paper aims at providing an overview of the traditional approaches used to assess the impacts of PCDD/Fs and PCBs and presenting the novelties introduced during the last years. After an initial characterization of their toxicity and their effects on health, this paper focuses on activities and situations that can result in critical releases of PCDD/Fs and PCBs into the atmosphere and that can represent a hidden threat for the population. In the final part, this study presents the current methodologies for exposure assessment, summarizes the food chain models in a unified way, and puts the light on new methods that can help environmental scientists, risk assessors, and decision makers to estimate the risk related to exposure to PCDD/Fs in different contexts.

Treatment and disposal of tyres: Two EU approaches. A review.

The treatment and disposal of tyres from vehicles has long been of considerable environmental importance. The main problem lies in the mixed composition of the tyres. Studies have been undertaken to modify the structure of the tyres, especially with reference to the percentage of granulated rubber incorporated, in order to improve their performance, and also to reduce their environmental impact during normal functioning (noise, particulates, etc.) and facilitate recycling and final disposal. The aim of the present study is to review and compare how used tyres are treated and disposed of in two different EU countries. The first is Italy, which has been part of the European Union since its inception, and has important industrial traditions. The second is Romania, an emerging country which recently became part of the EU, and whose economic and industrial development has had a major boost in recent years, with a strong growth in waste production, together with consumption in urban areas. The occasion was useful to consider the situation concerning the evolution of the different aspects related to the management of the end-of-life tyres. In particular, the paper considers the properties of tyre waste and their potential reuse, the enhancement of end-of-life tires and the various types of recovery, such as the reconstruction of tyres and the material recovery. The aspects related to the energy recovery and the use of the life cycle analysis, as a tool to support the choices of the best management system, were also taken into consideration, not forgetting that an adequate end-of-life planning is important when developing a sustainable product, since it can affect considerably its overall life cycle.

Effluents from MBT plants: plasma techniques for the treatment of VOCs.

Mechanical-biological treatments (MBTs) of urban waste are growing in popularity in many European countries. Recent studies pointed out that their contribution in terms of volatile organic compounds (VOCs) and other air pollutants is not negligible. Compared to classical removal technologies, non-thermal plasmas (NTP) showed better performances and low energy consumption when applied to treat lowly concentrated streams. Therefore, to study the feasibility of the application of NTP to MBTs, a Dielectric Barrier Discharge reactor was applied to treat a mixture of air and methyl ethyl ketone (MEK), to simulate emissions from MBTs. The removal efficiency of MEK was linearly dependent upon time, power and specific input energy. Only 2-4% of MEK was converted to carbon dioxide (CO2), the remaining carbon being involved in the formation of byproducts (methyl nitrate and 2,3-butanedione, especially). For future development of pilot-scale reactors, acting on residence time, power, convective flow and catalysts will help finding a compromise between energy consumption, desired abatement and selectivity to CO2.

Critical analysis of the integration of residual municipal solid waste incineration and selective collection in two Italian tourist areas.

Municipal solid waste management is not only a contemporary problem, but also an issue at world level. In detail, the tourist areas are more difficult to be managed. The dynamics of municipal solid waste production in tourist areas is affected by the addition of a significant amount of population equivalent during a few months. Consequences are seen in terms of the amount of municipal solid waste to be managed, but also on the quality of selective collection. In this article two case studies are analyzed in order to point out some strategies useful for a correct management of this problem, also taking into account the interactions with the sector of waste-to-energy. The case studies concern a tourist area in the north of Italy and another area in the south. Peak production is clearly visible during the year. Selective collection variations demonstrate that the tourists' behavior is not adequate to get the same results as with the resident population.

Treatment of slaughterhouse wastewaters using anaerobic filters.

In this paper, a laboratory-scale experimentation allowed comparing the performances of two upflow anaerobic packed-bed filters filled with different packing materials and operating at mesophilic conditions (30 degreeC) for treating slaughterhouse wastewaters. Methane production was experimentally evaluated considering different volumetric organic loading rates as well as feeding overloading conditions. Although filter performances declined with loading rates higher than 6 kg CODin m-3 d-1 , the chemical oxygen demand (COD) removal efficiency remained always above 60%. The experimental results allowed for determining kinetic parameters for bacterial growth rate and methane production, following Monod and Chen-Hashimoto models, respectively. Results demonstrated that the reactors reached a cellular retention time significantly greater than the hydraulic retention time. The kinetic parameter values (Ks, l/max) revealed the low microorganisms' affinity for the substrate and confirmed the moderate biodegradability of slaughterhouse wastewater. The kinetic analysis also allowed the comparison of the filters performances with another anaerobic system and the assessment of the parameters useful for real-scale plant design. The system design, applied to a medium-sized Argentinean slaughterhouse, demonstrated to (i) be energetically self-sufficient and (ii) contribute to the plant's water heating requirements.

Sewage sludge drying by energy recovery from OFMSW composting: preliminary feasibility evaluation.

In this paper an original energy recovery method from composting is analyzed. The integrated system exploits the heat available from the aerobic biochemical process in order to support the drying of sewage sludge, using a specific solar greenhouse. The aim is to tackle the problem of organic waste treatment, with specific regard to food waste. This is done by optimizing the energy consumption of the aerobic process of composting, using the heat produced to solve a second important waste management problem such as the sewage waste treatment. Energy and mass balances are presented in a preliminary feasibility study. Referring to a composting plant with a capacity of 15,000 t/y of food waste, the estimation of the power from recovered heat for the entire plant resulted about 42 kW. The results demonstrated that the energy recoverable can cover part of the heat necessary for the treatment of sludge generated by the population served by the composting plant (in terms of food waste and green waste collection). The addition of a renewable source such as solar energy could cover the residual energy demand. The approach is presented in detail in order for it to be replicated in other case studies or at full scale applications.

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.