Long-term evolution of the climate change impacts of solid household waste management in Lappeenranta, Finland.

Waste management processes have developed significantly in recent decades and will continue to change alongside the associated environmental impacts. This paper examines the climate change impacts of historical development in waste management, which has not received significant attention in the existing literature, while also exploring possible future developments. The city of Lappeenranta in Finland was selected as a case study, and the climate impacts of household waste (HW) management were calculated for the actual situations in 2009 and 2019 and the foreseen situation in 2029. Separately collected waste fractions of mixed residual waste (MRW), biowaste, cardboard, plastic, metal, and glass were included in the analysis. The results show that the net climate change impact decreased considerably from 945 kgCO2-eq./tHW in 2009 to -141 kgCO2-eq./tHW in 2019 mainly by directing the MRW to energy recovery instead of landfill. The emissions responsible for climate change could be further reduced in 2029 by directing biowaste to digestion instead of composting and by directing more fractions to recycling; e.g., plastic, the impact of which is affected by the demand for recycled plastic. For the year 2029, the net climate change impact was -181 kgCO2-eq./tHW when heat produced from MRW displaced natural gas and was as high as 142 kgCO2-eq./tHW if the heat substituted biomass heat. The findings reveal that as energy production mixes and materials become less fossil carbon intensive, they have a significant impact on the net climate impacts of waste management.

Consequential life-cycle assessment of treatment options for repulping reject from liquid packaging board waste treatment.

Liquid packaging board is one of the highly demanded packaging mediums for liquid food and beverages, generating substantial waste each year. Even though the fibre part of the liquid packaging board is recycled through a repulping process, the plastic and aluminium are usually used for energy recovery and as alternative raw materials in cement factories. This practice reduces the life span and economic value of plastic and aluminium, which does not fit within a circular economy. The plastic and aluminium from liquid packaging board waste can be recycled mechanically and chemically. This study used the consequential life-cycle assessment method to compare the environmental impact of the recovery options of rejected materials from liquid packaging board waste treatment. Four scenarios were established: (1) energy recovery by waste incineration, (2) composite pallet production by mechanical recycling, (3) plastic pallet production by mechanical recycling, and (4) plastic pallet production by chemical recycling. The study showed that when the consumed energy was supplied from renewable sources, plastic pallet production by mechanical recycling process had the lowest environmental impact, and energy recovery by waste incineration had the highest impact. A sensitivity analysis revealed that composite pallet production by mechanical recycling process showed the best impact if the energy was sourced from the average production mix, and plastic pallet production by chemical recycling had the lowest impact when mechanically recycled plastic substituted for 0%, 30%, and 50% of virgin plastic. These results should be of interest to liquid packaging board manufacturers and other related stakeholders.

A comparative cradle-to-gate life cycle assessment of geopolymer concrete produced from industrial side streams in comparison with traditional concrete.

Traditional concrete production is a major contributor to global warming. Industrially produced geopolymer concrete is a viable substitute to limit the negative impacts of concrete production. Thus, this study developed novel geopolymer concrete mix designs using industrial side streams, such as bark boiler ash, construction and demolition waste (CDW), fibre waste, and mine tailings. A cradle-to-gate life cycle assessment (LCA) methodology was conducted to evaluate the potential impacts of these different geopolymer concrete (GPC) mix designs in comparison with traditional concrete. The results showed that industrial-based geopolymer concrete with lower amounts of sodium silicate and metakaolin exhibited better environmental performance. Specifically, a 10 % reduction in metakaolin content reduces the global warming impact by 16 % compared with traditional concrete. The processing and curing of industrial waste for concrete formulations has an environmental impact of less than 1 %. From a sustainability perspective, the environmental performance of geopolymer concrete produced from industrial side streams can be further improved by increasing the concentration of recycled waste in the concrete mixes. In addition, the effective use of industrial side streams can improve the waste management, sustainability, and strength of concrete.

Indicators for resource recovery monitoring within the circular economy model implementation in the wastewater sector.

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.

Environmental performance of dewatered sewage sludge digestate utilization based on life cycle assessment.

Due to the global trend of urbanization, the amount of sewage water is increasing in cities. This calls for efficient treatment of the resulting sewage sludge. To date, in the 27 European Union member countries (EU-27), the prevailing treatment method is application on arable land. Anaerobic digestion is one of the treatment methods being increasingly used nowadays. However, the resulting digestate requires further utilization. Therefore, in this study, the environmental performance of composting, combustion, and pyrolysis options for dewatered sewage sludge digestate is evaluated based on a life cycle assessment. The results show that digestate combustion and composting performed better than pyrolysis for most of the selected impact categories. However, pyrolysis of sewage sludge is still under development, and there are, to some degree, uncertainties in the data related to this technology; thus, more information for the performance assessment of pyrolysis is still required.

Life Cycle Assessment of a Thermal Recycling Process as an Alternative to Existing CFRP and GFRP Composite Wastes Management Options.

There are forecasts for the exponential increase in the generation of carbon fibre-reinforced polymer (CFRP) and glass fibre-reinforced polymer (GFRP) composite wastes containing valuable carbon and glass fibres. The recent adoption of these composites in wind turbines and aeroplanes has increased the amount of end-of-life waste from these applications. By adequately closing the life cycle loop, these enormous volumes of waste can partly satisfy the global demand for their virgin counterparts. Therefore, there is a need to properly dispose these composite wastes, with material recovery being the final target, thanks to the strict EU regulations for promoting recycling and reusing as the highest priorities in waste disposal options. In addition, the hefty taxation has almost brought about an end to landfills. These government regulations towards properly recycling these composite wastes have changed the industries' attitudes toward sustainable disposal approaches, and life cycle assessment (LCA) plays a vital role in this transition phase. This LCA study uses climate change results and fossil fuel consumptions to study the environmental impacts of a thermal recycling route to recycle and remanufacture CFRP and GFRP wastes into recycled rCFRP and rGFRP composites. Additionally, a comprehensive analysis was performed comparing with the traditional waste management options such as landfill, incineration with energy recovery and feedstock for cement kiln. Overall, the LCA results were favourable for CFRP wastes to be recycled using the thermal recycling route with lower environmental impacts. However, this contradicts GFRP wastes in which using them as feedstock in cement kiln production displayed more reduced environmental impacts than those thermally recycled to substitute virgin composite production.

Carbon footprint of different recovery options for the repulping reject from liquid packaging board waste treatment process.

Liquid packaging board (LPB) is an integral part of storing and transporting liquid food. In addition to its significant advantages, LPB has been challenging the existing waste management sector since its introduction into the market. In most European countries, LPB waste is either incinerated or recycled in the recycling facilities where fibre is recycled, and the repulping reject is separated for incineration. Mechanical recycling and chemical recycling processes are other options for repulping reject treatment. This study used life cycle assessment (LCA) to compare the environmental impacts of three treatment processes, incineration, mechanical recycling and chemical recycling; each was considered with the functional unit of 1 tonne of repulping reject. Furthermore, two sub-scenarios based on the substituted heat produced by energy from the treatment processes were considered. In substituting biomass-based heat sources, chemical recycling generated the lowest greenhouse gas (GHG) emissions, about 560 kg CO2 eq. tonne-1 repulping rejects, followed by the mechanical recycling process (approximately 740 kg CO2 eq. tonne-1 repulping reject). The maximum amount of GHG was emitted from the incineration scenario, which was about 1900 kg CO2 eq. tonne-1 repulping rejects. By substituting natural gas-based heat sources, chemical recycling generated about 290 kg CO2 eq. tonne-1 repulping rejects. On the contrary, the mechanical recycling process generated about 430 kg CO2 eq. tonne-1 repulping rejects and incineration process generated 960 kg CO2 eq. tonne-1 repulping rejects. Uncertainty analysis showed that some assumptions significantly impact the results; however, the chemical recycling process had the lowest environmental impact in almost all uncertainty analysis.

Challenges and practices on waste management and disposal during COVID-19 pandemic.

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.

Impact of utilizing solid recovered fuel on the global warming potential of cement production and waste management system: A life cycle assessment approach.

Cement production is responsible for a significant share of global greenhouse gas (GHG) emissions. A potential option to reduce the cement production emissions is to use alternative fuels which can have also an impact on emissions from the waste management sector. This work investigates the change in global warming potential (GWP) of ordinary Portland cement (OPC) production and affected waste management systems when conventional fuels are partially replaced by solid recovered fuel (SRF) made from commercial and industrial waste (C&IW). A life cycle assessment (LCA) was conducted with a functional unit of 1 metric tonne of OPC production and treatment of 194 kg of C&IW. Data from an existing cement plant have been used, where the share of SRF from total fuel energy demand increased from 0% to 53% between 2007 and 2016. Four scenarios were established with varying waste treatment methods and SRF share in the thermal energy mix of cement production. It was found that GHG emissions decreased by 20% from 1036 kg carbon dioxide (CO2), eq. (functional unit)-1 in Scenario 1 to 832 kg CO2, eq. (functional unit)-1 in Scenario 3. Furthermore, it is possible to reach a reduction of 30% to 725 kg CO2, eq. (functional unit)-1 in Scenario by increasing the share of SRF to 80%. In conclusion, significant GHG emissions reduction can be achieved by utilizing SRF in cement production. Especially in the middle-income and low-income countries where waste is dumped to the open landfills, emissions could be reduced without huge investments to waste incineration plants.

Systematic assessment of critical factors for the economic performance of landfill mining in Europe: What drives the economy of landfill mining?

Landfill mining (LFM) is a strategy to mitigate environmental impacts associated with landfills, while simultaneously recovering dormant materials, energy carriers, and land resources. Although several case study assessments on the economy of LFM exist, a broader understanding of the driving factors is still lacking. This study aims at identifying generically important factors for the economy of LFM in Europe and understanding their role in developing economically feasible projects in view of different site, project and system-level conditions. Therefore, a set-based modeling approach is used to establish a large number (531,441) of LFM scenarios, evaluate their economic performance in terms of net present value (NPV), and analyze the relationships between input factors and economic outcome via global sensitivity analysis. The scenario results range from -139 Euro to +127 Euro/Mg of excavated waste, with 80% of the scenarios having negative NPVs. Variations in the costs for waste treatment and disposal and the avoided cost of alternative landfill management (i.e. if the landfill was not mined) have the strongest effect on the scenario NPVs, which illustrates the critical role of system level factors for LFM economy and the potential of policy intervention to incentivize LFM. Consequently, system conditions should guide site selection and project development, which is exemplified in the study for two extreme regional archetypes in terms of income and waste management standard. Future work should further explore the developed model to provide decision support on LFM strategies in consideration of alternative purposes, stakeholders, and objectives.

Technical implications and global warming potential of recovering nitrogen released during continuous thermal drying of sewage sludge.

Thermal drying and consequent incineration of sewage sludge result in an absolute loss of an important macronutrient - nitrogen. To fulfill the growing food demand, humanity relies more on industrial fixation of nitrogen, primarily via the Haber-Bosch process. The present paper examines the nitrogen release during continuous thermal drying of municipal sewage sludge and its consequent recovery for fertilization. Furthermore, the possibility of nitrogen recovery from condensate is assessed. Finally, the study assesses the global warming potential of the proposed nitrogen recovery system and compares it with the baseline system manufacturing fertilizers from industrially fixed nitrogen. The results of the drying experiments showed that 0.73-1.03 g N-NH3 kg-1 total solids of sewage sludge was released to off-gases during its continuous thermal drying under 160 °C, which corresponds to 41-58% of ionized nitrogen content in raw sewage sludge subjected to thermal drying. The global warming potential of the nitrogen recovery was 28% lower compared to that of the commercial fertilizer production of equivalent properties: 4.1 kg CO2-Equiv. kg-1 N versus 5.7 kg CO2-Equiv. kg-1 N. Still, the sensitivity analysis showed that the results might traverse and lead to a higher global warming potential of 6.2 kg CO2-Equiv. during the nitrogen recovery process under certain process parameters.

Applicability of a field portable X-ray fluorescence for analyzing elemental concentration of waste samples.

Determining the chemical properties of waste is crucial to ensure the most effective utilization of waste. The standard laboratory measurements can produce accurate results, but analysis is labor- and time-consuming. The variety of elements that field portable X-ray fluorescence spectrometry (FPXRF) can detect from selected waste materials was studied, including how the results compared with those of inductively coupled plasma mass spectrometry (ICP-MS) measurements. The selected materials were fine fraction reject from solid recovered fuel production, fly ash, biowaste, and compost. Based on the results, FPXRF is reported to be best suited for waste samples, such as ash and compost, because of their physical properties, as follows: not too moist, quite small particle size, and not too heterogeneous. The results obtained from FPXRF showed the lowest relative standard deviation for ash material. The analysis of the limits of agreement between FPXRF and ICP-MS showed that FPXRF was mainly suitable for qualitative assessment. Furthermore, regression analysis showed a linear correlation between FPXRF and ICP-MS results for calcium and zinc in the selected materials. Keeping the limitations in mind, FPXRF could be used for qualitative analysis in waste treatment processes, such as first quality control of waste materials.

Nitrogen behaviour during thermal drying of mechanically dewatered biosludge from pulp and paper industry.

An ongoing call to implement a circular economy is underway in the European Union, and a specific attention has been placed on the forest industry, which seeks additional recycling routes for its side streams, including biosludge. Biosludge is often dried and incinerated, thus wasting the nitrogen contained therein. This paper describes a study in which the release of nitrogen during thermal drying, the impact of the drying temperatures of 130°C, 180°C, and 210°C on the mass of ammonia released, and the potential for recovery of nitrogen from biosludge were examined. The results indicate that 1310-1730 mg kgTS-1 of nitrogen was released, which corresponded to 56-74% of the soluble nitrogen in biosolids or 4.0-5.3% of the total nitrogen. Of this released nitrogen, 83-85% was identified in condensate and absorbing water, thus indicating a high potential for recovering nitrogen from biosludge.

Modeling and comparative assessment of bubbling fluidized bed gasification system for syngas production - a gateway for a cleaner future in Pakistan.

The present study explores the potential of MSW gasification for exergy analysis and has been recently given a premier attention in a region like Pakistan where the urbanization is rapidly growing and resources are few. The plant capacity was set at 50 MW based on reference data available and the total exergetic efficiency was recorded to be 31.5 MW. The largest irreversibility distribution appears in the gasifier followed by methanation unit and CO2 capture. The effect of process temperature, equivalence ratio and MSW moisture content was explored for inspecting the variations in syngas composition, lower heating value, carbon conversion efficiency and cold gas efficiency. Special attention of the paper is paid to the comparative assessment of MSW gasification products in four regions, namely Pakistan, USA, UAE and Thailand. This extended study gave an insight into the spectrum of socioeconomic conditions with varying MSW compositions in order to explain the effect of MSW composition variance on the gasification products.

Potential of phosphorus recovery from sewage sludge and manure ash by thermochemical treatment.

All life forms require phosphorus (P), which has no substitute in food production. The risk of phosphorus loss from soil and limited P rock reserves has led to the development of recycling P from industrial residues. This study investigates the potential of phosphorus recovery from sewage sludge and manure ash by thermochemical treatment (ASH DEC) in Finland. An ASH DEC plant could receive 46-76 kt/a of sewage sludge ash to produce 51-85 kt/a of a P-rich product with a P2O5 content of 13-18%, while 320-750 kt/a of manure ash could be supplied to produce 350-830 kt/a of a P-rich product with a P content of 4-5%. The P2O5 potential in the total P-rich product from the ASH DEC process using sewage sludge and manure ash is estimated to be 25-47 kt/a, which is significantly more than the P fertilizer demand in Finland's agricultural industries. The energy efficiency of integrated incineration and the ASH DEC process is more dependent on the total solid content and the subsequent need for mechanical dewatering and thermal drying than on the energy required by the ASH DEC process. According to the results of this study, the treated sewage sludge and manure ash using the ASH DEC process represent significant potential phosphorus sources for P fertilizer production.

Method for residual household waste composition studies.

The rising awareness of decreasing natural resources has brought forward the idea of a circular economy and resource efficiency in Europe. As a part of this movement, European countries have identified the need to monitor residual waste flows in order to make recycling more efficient. In Finland, studies on the composition of residual household waste have mostly been conducted using different methods, which makes the comparison of the results difficult. The aim of this study was to develop a reliable method for residual household waste composition studies. First, a literature review on European study methods was performed. Also, 19 Finnish waste composition studies were compared in order to identify the shortcomings of the current Finnish residual household waste composition data. Moreover, the information needs of different waste management authorities concerning residual household waste were studied through a survey and personal interviews. Stratification, sampling, the classification of fractions and statistical analysis were identified as the key factors in a residual household waste composition study. The area studied should be divided into non-overlapping strata in order to decrease the heterogeneity of waste and enable comparisons between different waste producers. A minimum of six subsamples, each 100 kg, from each stratum should be sorted. Confidence intervals for each waste category should be determined in order to evaluate the applicability of the results. A new three-level classification system was created based on Finnish stakeholders' information needs and compared to four other European waste composition study classifications.

Technical potential of electricity production from municipal solid waste disposed in the biggest cities in Brazil: landfill gas, biogas and thermal treatment.

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.

Understanding biorefining efficiency--the case of agrifood waste.

The aim of this study was to determine biorefining efficiency according to the choices made in the entire value chain. The importance of the share of biomass volume biorefined or products substituted was investigated. Agrifood-waste-based biorefining represented the case. Anticipatory scenarios were designed for contrasting targets and compared with the current situation in two Finnish regions. Biorefining increases nutrient and energy efficiency in comparison with current use of waste. System boundaries decisively influence the relative efficiency of biorefining designs. For nutrient efficiency, full exploitation of biomass potential and anaerobic digestion increase nutrient efficiency, but the main determinant is efficient substitution for mineral fertilisers. For energy efficiency, combustion and location of biorefining close to heat demand are crucial. Regional differences in agricultural structure, the extent of the food industry and population density have a major impact on biorefining. High degrees of exploitation of feedstock potential and substitution efficiency are the keys.

Potential of energy and nutrient recovery from biodegradable waste by co-treatment in Lithuania.

Biodegradable waste quantities in Lithuania and their potential for the co-treatment in renewable energy and organic fertilizer production were investigated. Two scenarios were formulated to study the differences of the amounts of obtainable energy and fertilizers between different ways of utilization. In the first scenario, only digestion was used, and in the second scenario, materials other than straw were digested, and straw and the solid fraction of sewage sludge digestate were combusted. As a result, the amounts of heat and electricity, as well as the fertilizer amounts in the counties were obtained for both scenarios. Based on this study, the share of renewable energy in Lithuania could be doubled by the co-treatment of different biodegradable materials.

Feasibility of energy recovery from municipal solid waste in an integrated municipal energy supply and waste management system.

A decision-support model for determining the feasibility of a planned energy-from-waste (EfW) investment for an integrated waste management and energy supply system is presented. The aim is to present an easy-to-understand, inexpensive and fast-to-use tool to decision-makers for modelling and evaluating different kinds of processes. Special emphasis is put on forming the model and interpretation of the results of the example case. The simple integrated system management (SISMan) model is presented through a practical example of the use of the model. In the example the viability of the described system is studied by comparing five different cases including different waste-derived fuels (WDF), non-segregated municipal solid waste (MSW) being one of the fuel options. The nominal power output of the EfW plant varied in each case according to the WDF classification. The numeric values for two main variables for each WDF type were determined, the WDF price at the gate of the EfW plant and the waste management fee (WMF) according to the 'polluter pays' -principle. Comparison between the five cases was carried out according to two determinants, the WMF related to each case and the recovery rate related to each case. The numeric values for the constants and variables used in the calculations were chosen as realistically as possible using available data related to the issue. In the example of this paper, the mass-incineration solution ('pure' MSW as a fuel) was found to be the most viable solution for the described system according to the calculations. However, the final decision of the decision-makers might differ from this in the real world due to extra 'fuzzy' information that cannot be reliably included in the calculations. This paper shows that certain key values of modelled systems can be calculated using an easy-to-use tool at the very early stages of a larger design process involving municipal and business partners. The use of this kind of tools could significantly decrease the overall design costs of large systems in the long run by cutting out irrational system options at the very beginning of the planning.