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The paper presents the MEFLO ranking method and the Simple Integrated System Management (SISMan) concept for assessing the feasibility of integrated energy and Waste Management System (WMS) alternatives. The MEFLO method is based on dividing the decision-making process into five modules, including mass, energy and financial flows, legislative criteria (e.g., environmental restrictions and target values) and other decision support criteria, such as the local political guidelines. The utilisation of the MEFLO method is presented by comparing five system alternatives, including energy recovery from household waste. The calculations needed in the MEFLO assessment were performed with the SISMan spreadsheet calculation model developed at the Lappeenranta University of Technology. The MEFLO method and the SISMan concept contribute to the design and assessment of different integrated management systems. Any of the appropriate available tools can be used in the model forming and assessment processes, according to the proposed methods.

This study focused on identifying various system boundaries and evaluating methods of estimating energy performance of biogas production. First, the output-input ratio method used for evaluating energy performance from the system boundaries was reviewed. Secondly, ways to assess the efficiency of biogas use and parasitic energy demand were investigated. Thirdly, an approach for comparing biogas production to other energy production methods was evaluated. Data from an existing biogas plant, located in Finland, was used for the evaluation of the methods. The results indicate that calculating and comparing the output-input ratios (Rpr1, Rpr2, Rut, Rpl and Rsy) can be used in evaluating the performance of biogas production system. In addition, the parasitic energy demand calculations (w) and the efficiency of utilizing produced biogas (η) provide detailed information on energy performance of the biogas plant. Furthermore, Rf and energy output in relation to total solid mass of feedstock (FO/TS) are useful in comparing biogas production with other energy recovery technologies. As a conclusion it is essential for the comparability of biogas plants that their energy performance would be calculated in a more consistent manner in the future.

The COVID-19 pandemic has imposed a global emergency and also has raised issues with waste management practices. This study emphasized the challenges of increased waste disposal during the COVID-19 crisis and its response practices. Data obtained from the scientific research papers, publications from the governments and multilateral organizations, and media reports were used to quantify the effect of the pandemic towards waste generation. A huge increase in the amount of used personal protective equipments (facemasks, gloves, and other protective stuffs) and wide distribution of infectious wastes from hospitals, health care facilities, and quarantined households was found. The amount of food and plastic waste also increased during the pandemic. These factors caused waste treatment facilities to be overwhelmed, forcing emergency treatment and disposals (e.g., co-disposal in a municipal solid waste incinerator, cement kilns, industrial furnaces, and deep burial) to ramp up processing capacity. This paper discussed the ways the operation of those facilities must be improved to cope with the challenge of handling medical waste, as well as working around the restrictions imposed due to COVID-19. The study also highlights the need for short, mid, and longer-term responses towards waste management during the pandemic. Furthermore, the practices discussed in this paper may provide an option for alternative approaches and development of sustainable strategies for mitigating similar pandemics in the future.

The speed of the propagation of the ignition front downwards against the air flow in a fixed bed of burning wooden particles has been studied. The ignition speed reaches a steady state soon after ignition at the surface, if the inlet air temperature is the same as the initial temperature of the fixed bed. Modeling of the quasi-steady-state speed of propagation of the ignition front is considered. The effects of the flow rate of air, moisture, particle size, density, and wood species on the velocity of the ignition front and on the maximum temperature in the bed are studied experimentally and interpreted by modeling. A maximum speed of propagation was observed with a specific air rate. Correlations for estimating the velocity of the ignition front and maximum temperature in the bed are presented.

The European Union is currently in the process of transformation toward a circular economy model in which different areas of activity should be integrated for more efficient management of raw materials and waste. The wastewater sector has a great potential in this regard and therefore is an important element of the transformation process to the circular economy model. The targets of the circular economy policy framework such as resource recovery are tightly connected with the wastewater treatment processes and sewage sludge management. With this in view, the present study aims to review existing indicators on resource recovery that can enable efficient monitoring of the sustainable and circular solutions implemented in the wastewater sector. Within the reviewed indicators, most of them were focused on technological aspects of resource recovery processes such as nutrient removal efficiency, sewage sludge processing methods and environmental aspects as the pollutant share in the sewage sludge or its ashes. Moreover, other wide-scope indicators such as the wastewater service coverage or the production of bio-based fertilizers and hydrochar within the wastewater sector were analyzed. The results were used for the development of recommendations for improving the resources recovery monitoring framework in the wastewater sector and a proposal of a circularity indicator for a wastewater treatment plant highlighting new challenges for further researches and wastewater professionals.

Abstract The aim of the study was to quantify the environmental impact of four alternative recycling methods of thermal residues generated within the case study area chosen. Overall, 90 combinations of 13 scenarios were included in the study and a sensitivity analysis was performed. The recycling methods that were assessed included forest fertilization and neutralization, landfill construction, road construction, and road stabilization. Other scenarios focused on the regional optimization, distribution of heavy metals under L/S ratio 10 L kg − 1 , and uncertainty related to the determination of heavy metals at levels that were lower than the analytical limits of quantification. The alternative scenarios were studied using a comparative life cycle assessment method with the system expansion. The results indicated the extent to which each recycling method was superior to landfilling within non-toxic impact categories, with the average reduction in the environmental impact being 10–30% when the residues were utilized for forest fertilization, road construction, and stabilization, and by 3–12% when the residues were utilized for landfill construction. The majority of the impact resulted from avoiding the need to landfill the residues since this could be achieved even at a zero substitution rate in the majority of the cases. In terms of the toxic impact categories, the use of the residues for road construction purposes had a more positive impact on the environment that the alternative uses, resulting in a reduced ecotoxicity potential and carcinogenic human toxicity potentials of 30% and 40% respectively, and an increase in non-carcinogenic human toxicity potential of only 4%. Most of the toxic impact was the result of Ba, V, Sb, Co, Cr, and Zn leaching. In addition, the study concluded that a lack of the leaching data below the limits of quantification was significant for the overall toxic results of the study.

This article presents an analysis of possibilities for electrical energy production by using municipal solid waste disposed in the biggest Brazilian cities. Currently, the municipal solid waste in Brazil is collected and disposed of at landfills, but there are also other technologies, which in addition to dealing with the garbage can also provide benefits in terms of energy provision. The following scenarios were studied in this work: electricity production from landfill gas (reference scenario); incineration of all municipal solid waste; anaerobic digestion of organic waste and incineration of refuse-derived fuel fractions after being separated in separation plants. According to this study, the biggest cities in Brazil generate about 18.9 million tonnes of municipal solid waste per year (2011), of which 51.5% is biogenic matter. The overall domestic consumption of electricity is 480,120 GWh y−1 in Brazil and the municipal solid waste incineration in the 16 largest cities in the country could replace 1.8% of it using incinerators. The city of São Paulo could produce 637 GWh y−1 with landfill gas, 2368 GWh y−1 with incineration of municipal solid waste and 1177 GWh y−1 with incineration of refuse-derived fuel. The latter two scenarios could replace 27% and 13.5% of the residential electrical energy consumption in the city. This shows that thermal treatment might be a viable option of waste-to-energy in Brazil.

Abstract Energy decisions play an essential role in reducing greenhouse gas (GHG) emissions in the transportation sector. Biogas is a renewable energy source and can be used as an energy source for gas-operated cars or for electric cars. This paper compares different ways to use biogas, which is produced on a medium scale anaerobic digestion plants, as an energy source for transportation. The research is conducted from an economic and environmental point of view, and the option to deliver upgraded biogas via a natural gas grid is taken into account. Different processes for the use of biogas for transportation purposes are compared using life cycle assessment (LCA) methods in the Finnish operational environment. It seems that the most economical way is to use biogas in gas-operated cars due to the high price of methane for vehicle fuel use. A new feed-in tariff for electricity produced with biogas will, however, have highly positive economic effects on electricity production from biogas. From the environmental point of view, the highest CO2 reductions are gained when biogas is used in gas-operated cars or in CHP plants for power and heat production. During the transition stage, it might be reasonable to use biogas in gas-operated cars and most importantly in heavy vehicles to reduce GHG and local pollutants rapidly. If biogas production is located near a natural gas grid, the biogas can be delivered effectively via the natural gas grid. The use of biogas in gas-operated cars is an effective way to reduce carbon dioxide significantly in the transportation sector.

For the estimation of greenhouse gas emissions from waste incineration it is essential to know the share of the renewable energy content of the combusted waste. The composition and heating value information is generally available, but the renewable energy share or heating values of different fractions of waste have rarely been determined. In this study, data from Finnish studies concerning the composition and energy content of mixed MSW were collected, new experimental data on the compositions, heating values and renewable share of energy were presented and the results were compared to the estimations concluded from earlier international studies. In the town of Lappeenranta in south-eastern Finland, the share of renewable energy ranged between 25% and 34% in the energy content tests implemented for two sample trucks. The heating values of the waste and fractions of plastic waste were high in the samples compared to the earlier studies in Finland. These high values were caused by good source separation and led to a low share of renewable energy content in the waste. The results showed that in mixed municipal solid waste the renewable share of the energy content can be significantly lower than the general assumptions (50-60%) when the source separation of organic waste, paper and cardboard is carried out successfully. The number of samples was however small for making extensive conclusions on the results concerning the heating values and renewable share of energy and additional research is needed for this purpose.