Material Flow Analysis as a Tool to improve Waste Management Systems: The Case of Austria

Enhancing circular plastic waste management: Reducing GHG emissions and increasing economic value in Rayong province, Thailand

This study evaluates the greenhouse gas (GHG) emissions and economic value creation of plastic waste (PW) management in Rayong, Thailand, a city on the eastern Gulf Coast with a significant amount of generated and leaked PW. By analyzing current practices, and developing and evaluating improvement scenarios, the study explores strategies for reducing GHG and enhancing economic benefits across the PW management chain. Four primary routes with varying capacities handle approximately 5,445.55 tonnes of PW via source separation recycling (5.18 %), post-sorting recycling (9.30 %), energy recovery (54.86 %), and landfills or opened dump disposal (30.66 %). About 83.21 % of the 16 ± 6.9 % PW in municipal solid waste (MSW) is recyclable, primarily consisting of high-density polyethylene (HDPE), polypropylene (PP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and polyethylene terephthalate (PET). The current management practice generates an economic benefit of approximately 1.68 million USD/yr or 310 USD/t of PW, compared to the proposed scenarios, which enhances recycling efficiency and reduces landfill and energy recovery waste, yielding 2.27-6.48 million USD/yr or 420.64-1200.33 USD/t of PW. The practice emits about 7,028.47 tCO2e annually, while improved source and post-sorting efficiencies reduce GHG emissions by 2.86-3.17 times or -2.83 to -2.42 tCO2e/t of PW or a total of over 13,078.60-15,268.44 tCO2e. Burning PW increases approximately 1.6 times or 11,841.36 tCO2e/yr. Enhancing recycling efficiency, particularly through source separation, is key to promoting more productive and valuable PW separation, increasing economic value and GHG mitigation by approximately 3.87 and 3.17 times, respectively. These findings provide valuable insights for local authorities and policymakers to develop strategic interventions and policies that align with the improved scenario by enhancing source separation and recycling. The results demonstrate that improving the efficiency of separation at the source is critical for transitioning from a linear PW management strategy to a circular economy, significantly reducing landfill waste and mitigating environmental threats.

Characterization of excavated plastic waste from an Indian dumpsite: Investigating extent of degradation and resource recovery potential

In recent years, the concept of landfill mining has gained a lot of traction in India, and tonnes of plastic waste is being excavated. The present shift towards a circular economy necessitates to explore the use of excavated plastic waste as a source of valuable materials and energy. However, the physicochemical characteristics of plastic waste change due to the degradation and weathering process in landfills, making its valorization difficult. The current study investigates the change in physicochemical characteristics of plastic waste with age from an Indian dumpsite to identify the potential valorization options. In addition, a material and energy flow analysis was performed considering incineration treatment of plastic waste. The plastic waste ranged between 3.6 and 21% in the dumpsite and has almost doubled in recent decades, owing to the increase in plastic waste generation in India. Polyethylene (high- and low-density) accounted for approximately 66% of the excavated plastic waste and had a lot of adhered surface impurities. Mechanical pre-treatment using a shredder was effective in the removal of the adhered impurities with a recovery rate of 50-70% for polyethylene and a higher recovery of 70-90% for other types of plastic. Changes in the surface morphology of plastic waste with aging were observed through Scanning Electron Microscopy. The Fourier Transform Infrared Spectroscopy results confirmed low degradation levels for aged plastic waste, which is also confirmed through the high level of oxygen detected. The material and energy flow analysis revealed that incinerating one tonne of excavated plastic waste could produce approximately 1410 kWh of electricity.

Assessing the city-level material stocks in landfills and the landfill mining potential of China

Landfill mining has become an emerging issue in urban metabolism research and environmental remediation practices. Comprehensive understanding of the quantity and distribution of material stocks in landfills, as well as identifying hotspots of landfill mining potential, is of crucial importance. However, high-resolution datasets and systematic analytical tools remain insufficient. This study established a time-series landfill material stock inventory at prefecture level in China. An evaluation system for mining potential of landfills at prefecture level was then constructed using an integrated expert scoring and entropy weight method, based on ten indicators across five dimensions, including environmental impact, energy recovery, resource cycling, economic cost, and social aspect. The results show that over the past twenty years, the material stock in landfills was 2321.07 Tg (106 tons) in China, among which, soil-like materials, ash & stone and plastic & rubber were the three largest fractions, accounting for 61.06 wt%, 18.96 wt%, and 12.69 wt% of the total stock. Regional differences in landfill mining potential were found to be significant, with South China presenting the largest mining potential, while Southwest China showed the lowest. Cities with better economic development in China show the possibility to have greater landfill mining potential. This study established a methodology for the assessment of landfill mining potential for China or other countries, and provided scientific evidences for formulating regional-specific policies on landfill mining in China.

Waste management evolution in the last five decades in developing countries - A review

This review provides the history and current paradigms of waste management (WM) practices in developing nations during the last five decades. It explores the evolution of the challenges, complexities, and trends during this period. This paper, for the first time, presents an estimation of the amount of municipal solid waste (MSW) generated in developing nations in the last five decades based on the material flow analysis approach. Overall, the amount of MSW in developing countries has increased from about 0.64 billion Mt in 1970 to 2 billion Mt in 2019. This review demonstrates the importance of finding new WM approaches in developing nations in the context of formulating policies, strategies, and highlights the major trends that re-define WM in developing countries. It also aims to present the holistic changes in technology, economic and environmental feasibility aspects to attain an integrated sustainable WM system in developing countries. Specific focus on open-burning, open-dumping, informal recycling, food waste, plastic pollution, and waste collection with reference to Sustainable Development Goals are explained. Drivers for the way forward including circular economy are investigated.

Advancing plastic pollution hotspotting at the subnational level: Brazil as a case study in the Global South

Identifying sources is crucial for proposing effective actions to combat marine litter pollution. Here, we used an innovative approach to identify hotspots of mismanaged plastic waste (MPW) within Brazil and subsequent leakage to the ocean, based on population density, socio-economic conditions, municipal solid waste management and environmental parameters. We estimated plastic waste generation and MPW for each of the 5570 Brazilian municipalities, which totaled 3.44 million metric tons per year. Then, we estimated the probability of litter mobilization and transport (P) and the relative risk of leakage to the ocean (MPW × P). The Guanabara Bay and La Plata River comprised the main oceanic entry hotspots of litter produced in Brazil. The use of national databases allowed us to increase spatial and temporal granularity, offering a detailed baseline for the application of prevention and mitigation actions. However, overcoming data limitations is still a challenge in Brazil as in other Global South countries.

A first comprehensive estimate of electronic waste in Canada

Detailed analysis of electronic waste (e-waste) generation and composition is of utmost importance for the proper management of growing e-waste stream worldwide, containing both hazardous and valuable materials. Considering the absence of such comprehensive and up-to-date studies in Canada, this work presents the first estimate of put-on-market electrical and electronic equipment (EEE), the in-use stocks of EEE and e-waste generation in Canada from 1971 to 2030 for 51 product categories comprising 198 product types. Using a dynamic material flow analysis (MFA), the put-on-market EEE is estimated based on trade data retrieved from national and international import and export statistics, and the in-use stocks of EEE and the resulting e-waste are calculated using the Weibull distribution function. The results show that the total mass of EEE within the 60-year period is estimated to be 42.3 million tonnes, with an annual average growth rate of approximately 0.5%. By 2030, the total accumulated in-use stock of EEE is estimated to exceed 13 million tonnes. The estimated e-waste over the 60-year timespan is 29.1 million tonnes. The total annual e-waste generation in Canada is calculated to be 252 kilo tonnes (kt) and 954 kt in the years 2000 and 2020 respectively, which is estimated to reach 1.2 million tonnes by 2030. The e-waste generation per capita increased from 8.3 kg in 2000 to 25.3 kg in 2020 and is estimated to reach 31.5 kg by 2030. This quantification provides valuable insights to policymakers for setting up targets for waste reduction and identifying the resource circularity potential for efficient management of e-waste.

Re-assessing global municipal solid waste generation

This study contributes to estimate the total waste generated at global level. A few studies have provided an efficient and comprehensive global estimate. However, data reporting is globally inconsistent due to varying interpretation of terminology, lacking standardised categories and varying methodologies used to observe and measure waste amounts. This study employs regression analysis and material flow analysis approaches to ensure a cross-comparability of waste generation data. The result implies that total global waste arisings are around 20 billion tonnes in 2017. This corresponds to 2.63 tonnes of total waste per capita (cap) per year. The total global waste generated is expected to grow to 46 billion tonnes by 2050 under a business-as-usual scenario. Municipal solid waste (MSW) is a much smaller amount, ranging from 2.3 to 3.1 billion tonnes (average of 2.7 billion tonnes) in 2019. This figure reflects an increase of between 30% and 50% in MSW generated during the last 15 years (2004-2019). MSW generated is expected to grow to 2.89-4.54 billion tonnes by 2050, depending on which assumptions are used. This represents a 26%-45% increase compared to 2019. The overall assessment in this study reveals that almost one-third of the total MSW generated is not collected, and most of what is collected is not treated accordingly to current ideas of sound management. Moreover, almost 42% of MSW goes to open dumping or uncontrolled burning. The finding provides valuable insight for policymakers to design and assess circular economy policy instruments towards achieving sustainable development goals.

A high-resolution dynamic probabilistic material flow analysis of seven plastic polymers; A case study of Norway

Plastic pollution has long been identified as one of the biggest challenges of the 21st century. To tackle this problem, governments are setting stringent recycling targets to keep plastics in a closed loop. Yet, knowledge of the stocks and flows of plastic has not been well integrated into policies. This study presents a dynamic probabilistic economy-wide material flow analysis (MFA) of seven plastic polymers (HDPE, LDPE, PP, PS, PVC, EPS, and PET) in Norway from 2000 to 2050. A total of 40 individual product categories aggregated into nine industrial sectors were examined. An estimated 620 ± 23 kt or 114 kg/capita of these seven plastic polymers was put on the Norwegian market in 2020. Packaging products contributed to the largest share of plastic put on the market (∼40%). The accumulated in-use stock in 2020 was about 3400 ± 56 kt with ∼60% remaining in buildings and construction sector. In 2020, about 460 ± 22 kt of plastic waste was generated in Norway, with half originating from packaging. Although ∼50% of all plastic waste is collected separately from the waste stream, only around 25% is sorted for recycling. Overall, ∼50% of plastic waste is incinerated, ∼15% exported, and ∼10% landfilled. Under a business-as-usual scenario, the plastic put on the market, in-use stock, and waste generation will increase by 65%, 140%, and 90%, respectively by 2050. The outcomes of this work can be used as a guideline for other countries to establish the stocks and flows of plastic polymers from various industrial sectors which is needed for the implementation of necessary regulatory actions and circular strategies. The systematic classification of products suitable for recycling or be made of recyclate will facilitate the safe and sustainable recycling of plastic waste into new products, cap production, lower consumption, and prevent waste generation.

Porous adsorbent derived from acid activation of food waste biochar: A sustainable approach for novel removal chlorophenol in wastewater

In this study, porous biochar (PBC) was prepared by acid activation of biochar derived from food waste (FWBC) and used as a suitable approach for the removal of 4-chlorophenol (CP) in wastewater. The characterization of PBC and the influent of different experimental conditions are determined. After the acid activation process, the surface area, porosity, and functional groups of PBC were developed. The removal performances of CP (1 mg/L) by PBC and FWBC were archived at 97.8 and 82.1%, respectively. Adsorption kinetics and isotherms of CP were followed by the second-order and Langmuir models, respectively. The maximum capacities of CP uptake onto mono-layer of FWBC and PBC based on the Langmuir model were determined at 79.8 and 108.7 mg/g, respectively. Besides, PBC could remove more than 89% CP from wastewater within 45 min of reaction time and it is suitable to reuse 8 times with over 60% adsorption efficiency of CP. In addition, the adsorption mechanism and environmental impact were discussed in detail. This work could bring a sustainable approach to the treatment of CP in wastewater as well as the management of food waste in Vietnam.

Food waste and soybean curd residue composting by black soldier fly

This study attempted to manage the food waste and soybean curd residue generated in Taiwan's National Ilan University by black soldier fly-aided co-composting. The food waste and soybean curd residue were co-composted with rice husk as a bulking agent in 4:1 ratio and 0.42 mg BSF/g waste. The higher organic matter degradation of 31.9% was found in Container B (black soldier flies aided food waste and rice husk co-composting) with a rate constant of 0.14 d-1. In Container D (black soldier flies aided soybean curd residue and rice husk co-composting), the organic matter degradation of 29.4% was found with a rate constant of 0.29 d-1. The matured compost of 6.02 kg was obtained from 20 kg of food waste, while 5.83 kg of matured compost was generated from 20 kg of soybean curd residue. The physico-chemical parameters of the final matured compost were in the favorable range of Taiwan's compost standards. The germination index was 188.6% and 194.78% in Containers B and D, respectively. The present study will expand the application of BSF at the institutional level which prove to be a feasible solution for rapid, clean, and efficient composting of post-consumer food wastes.

Life Cycle Assessment and Material Flow Analysis: Two Under-Utilized Tools for Informing E-Waste Management

The unprecedented technological development and economic growth over the past two decades has resulted in streams of rapidly growing electronic waste (e-waste) around the world. As the potential source of secondary raw materials including precious and critical materials, e-waste has recently gained significant attention across the board, ranging from governments and industry, to academia and civil society organizations. This paper aims to provide a comprehensive review of the last decade of e-waste literature followed by an in-depth analysis of the application of material flow analysis (MFA) and life cycle assessment (LCA), i.e., two less commonly used strategic tools to guide the relevant stakeholders in efficient management of e-waste. Through a keyword search on two main online search databases, Scopus and Web of Science, 1835 peer-reviewed publications were selected and subjected to a bibliographic network analysis to identify and visualize major research themes across the selected literature. The selected 1835 studies were classified into ten different categories based on research area, such as environmental and human health impacts, recycling and recovery technologies, associated social aspects, etc. With this selected literature in mind, the review process revealed the two least explored research areas over the past decade: MFA and LCA with 33 and 31 studies, respectively. A further in-depth analysis was conducted for these two areas regarding their application to various systems with numerous scopes and different stages of e-waste life cycle. The study provides a detailed discussion regarding their applicability, and highlights challenges and opportunities for further research.

Biochar produced from wood waste for soil remediation in Sweden: Carbon sequestration and other environmental impacts

The use of biochar to stabilize soil contaminants is emerging as a technique for remediation of contaminated soils. In this study, an environmental assessment of systems where biochar produced from wood waste with energy recovery is used for remediation of soils contaminated with polycyclic aromatic hydrocarbons (PAH) and metal(loid)s was performed. Two soil remediation options with biochar (on- and off-site) are considered and compared to landfilling. The assessment combined material and energy flow analysis (MEFA), life cycle assessment (LCA), and substance flow analysis (SFA). The MEFA indicated that on-site remediation can save fuel and backfill material compared to off-site remediation and landfilling. However, the net energy production by pyrolysis of wood waste for biochar production is 38% lower than incineration. The LCA showed that both on-site and off-site remediation with biochar performed better than landfilling in 10 of the 12 environmental impact categories, with on-site remediation performing best. Remediation with biochar provided substantial reductions in climate change impact in the studied context, owing to biochar carbon sequestration being up to 4.5 times larger than direct greenhouse gas emissions from the systems. The two biochar systems showed increased impacts only in ionizing radiation and fossils because of increased electricity consumption for biochar production. They also resulted in increased biomass demand to maintain energy production. The SFA indicated that leaching of PAH from the remediated soil was lower than from landfilled soil. For metal(loid)s, no straightforward conclusion could be made, as biochar had different effects on their leaching and for some elements the results were sensitive to water infiltration assumptions. Hence, the reuse of biocharremediated soils requires further evaluation, with site-specific information. Overall, in Sweden's current context, the biochar remediation technique is an environmentally promising alternative to landfilling worth investigating further.

Post-consumer plastic packaging waste flow analysis for Brazil: The challenges moving towards a circular economy

Plastic packaging has been used increasingly worldwide in a broad range of application. Plastic packaging has a short lifetime, which generates a large amount of waste. However, robust information on plastic packaging waste flow is generally not available, especially for developing countries such as Brazil. We analyzed and quantified Brazilian post-consumer plastic packaging waste (PPW) flows using material flow analysis (MFA) for the year 2017. The system modeled covered from the manufacturing stage of plastic packaging up to its waste management stage. We used a range of data sources, whose quality we assessed using uncertainty characterization. The results showed that Brazil generated 12 Mt of PPW in 2017, and the management of 63% of that was not monitored. The majority of monitored PPW was disposed of into landfills, but 0.8 Mt of PPW was improperly disposed. Informal collection was 24% greater than formally managed selective collection. Only 4.5% of the PPW generated in Brazil was recycled. The results identified the major national challenges in relation to PPW management as being that information systems needed to be improved, informal waste collectors needed to be socially and productively included in the management systems, and recovery systems needed to be developed towards a circular economy.

Application of Systems Engineering and Sustainable Development Goals towards Sustainable Management of Fishing Gear Resources in Norway

Commercial fishing is a critical economic sector for Norway, yet deficiency of scientific information, regulatory instruments, inadequate implementation, and lack of management infrastructure are among the significant causes of mismanagement of fishing gear (FG) resources. Mismanagement of FGs results in leakage of plastics through abandoned, lost, or discarded fishing gears (ALDFG), which is the most threatening litter fraction for marine wildlife. In EU-EEA states, the management of ALDFG is prioritized through a dedicated circular economy (CE) action plan. Historically, systems engineering (SE) methods are successfully applied for resource management studies. This study adopts and applies the SPADE method to evaluate sustainable management for the system of FG resources in Norway. SPADE comprises five problem-solving activities covering stakeholders, problem formulation, analysis, decision-making, and continuous evaluation. Each activity is accomplished by data collected through stakeholder interviews and literature analysis to establish an initial structure of problems and associated management strategies across FG’s life cycle phases. The application of SPADE spanned across four years (2017–2020) and resulted in scientific outcomes aimed at the common goal of improving the system of FG resources in Norway within the framework of sustainable development goals and CE. SPADE’s practice to integrate stakeholders at each step and provision for continual systems evaluation proved effective in building a holistic understanding of the complex system.

Material flow analysis and life cycle assessment of food waste bioconversion by black soldier fly larvae (Hermetia illucens L.)

This study provided a systematic analysis on material flow and environmental impacts of a food waste (FW) bioconversion plant using black soldier fly larvae (BSFL), with a daily capacity of 15 tons of FW (wet weight). Food waste feed (FWF) used for BSFL bioconversion consisted of 80% FW (collected from households, restaurants, and canteens) and 20% rice hull powder. Material flow analysis conducted on a dry weight basis showed that 6% of FWF was transformed into BSF pre-pupae, 51% was stored in matured compost, and 43% was emitted to the air. Emissions of high environmental concern such as methane, nitrous oxide and ammonia (NH₃) were sampled and quantified by laboratory analysis. The life cycle assessment revealed that the overall impact was 17.36 kg CO₂-eq/t FW for global warming potential, 5.54 kg SO₂-eq/t FW for acidification, 24.05 mol N-eq/t FW for terrestrial eutrophication, 0.54 kg N-eq NH₃/t FW for marine eutrophication, and 0.18 kg PM_2.5-eq/t FW of particulate matter up to 2.5 μm diameter. Moreover, emissions from post-composting, energy consumptions of drying and chemical fertilizer substitution ratio were detected by contribution analysis as the main contributors to those impacts. Finally, sensitivity analysis indicated that the substitution ratio of mineral fertilizer and protein feed as well as energy consumption were the most influential parameters, therefore control of the post-composting process of residual material should be closely monitored because it was responsible for significant environmental load caused by N-related emissions.

Past, Present, and Future of Virtual Water and Water Footprint

Virtual water and water footprint have received increasing attention. However, no published research has conducted a quantitative and objective review of this field from the perspective of bibliometrics. Therefore, based on the Web of Science Core Collection, this study employs CiteSpace to quantitatively analyze and visualize information about countries, institutions, and authors that have conducted virtual water and water footprint research over the past two decades. As of July 2020, there were 1592 publications on virtual water and water footprint, showing an increasing trend overall. The annual average number of publications was only 7.4 in 1998–2008, while it was 126.5 in 2009–2019. Among them, up to 618 publications in the field of environmental science, accounting for 46%. China was the most productive country with a total of 344 articles, but the Netherlands had the strongest influence with a betweenness centrality of 0.33, indicating its leading position. It is essential to strengthen cooperation between developed (water-rich) and developing (water-poor) countries and to incorporate virtual water into social water cycle research. This study is expected to provide a new perspective for investigating the research frontiers and hot spots of virtual water and water footprint research.

Mass conversion pathway during anaerobic digestion of wheat straw

A material flow analysis (MFA) method was employed to investigate elemental flow direction during the anaerobic digestion (AD) of wheat straw (WS) pretreated with potassium hydroxide. A lab-scale batch AD experiment conducted at 35 ± 1 °C was investigated to realize carbon conversion in biogas, liquid and solid digestates. The results showed that the highest growth rate of carbon conversion in biogas was observed from the fourth day to the twenty-fourth day, which accounted for 70.64%. The cumulative biogas production of WS was 531 mL g-1 VS, along with a high volatile solids degradation rate (55.0%). The MFA results indicated that the flow mass fractions of carbon in biogas, liquid and solid digestates were 49.96%, 5.61% and 44.43%, respectively. The flow mass fraction of nitrogen in liquid and solid digestates was 45.65% and 54.35%, respectively. This study can provide a theoretical basis for elemental flow in each product from biogas projects.

Material Flow Analysis (MFA) and waste characterizations for formal and informal performance indicators in Tandil, Argentina: Decision-making implications

In cities, the achievement of waste-related legal requirements and the main drivers of Integrated Sustainable Waste Management (ISWM) need adequate indicators and adaptable-to-case tools and strategies. In this work, we combine Material Flow Analysis (MFA) and waste characterizations to develop a mass balance table to design, calculate and analyse indicators related to the formal and informal waste sub-circuits of Tandil, a medium-sized city of the Buenos Aires province (Argentina). Results show that global recovery is very low (2.3% ± 0.16) and mainly driven by the Informal Recovery Sector (IRS). Also, the IRS strategy is more effective, recovering 40% ± 8.0 of its targeted materials from non-household sources. Regarding each material recovery performance, results show significant differences. For paper and board, recovery exceeds 20%. For HDPE, Tetra brik and Ferrous Metals are lower than 1%. In the case of PET and Glass, 9.6 and 9.0% of what is generated in households is recovered, respectively. However, the global recovery rate of each material is different: 2.9% ± 0.4 for PET and 5.5% ± 1.4 for Glass. Our research show that strategies in place are insufficient regarding legislation in force. Even a hypothetically 100% effectiveness in them will account only for 20.9% ± 2.1 of global recovery. Addressing organic waste, therefore, is imperative. Considering the current province law provision of final disposal diversion, accounting for the work of the IRS is key because they recover more waste than the official strategy. Regarding open dumps eradication, we estimate that up to 17% of generated waste is incorrectly final disposed through private skips illegally dumped. A tracking system for skips could avoid this situation.

Rice life cycle-based global mercury biotransport and human methylmercury exposure

Protecting the environment and enhancing food security are among the world’s greatest challenges. Fish consumption is widely considered to be the single significant dietary source of methylmercury. Nevertheless, by synthesizing data from the past six decades and using a variety of models, we find that rice could be a significant global dietary source of human methylmercury exposure, especially in South and Southeast Asia. In 2013, globalization caused 9.9% of human methylmercury exposure via the international rice trade and significantly aggravated rice-derived exposure in Africa (62%), Central Asia (98%) and Europe (42%). In 2016, 180 metric tons of mercury were generated in rice plants, 14-fold greater than that exported from oceans via global fisheries. We suggest that future research should consider both the joint ingestion of rice with fish and the food trade in methylmercury exposure assessments, and anthropogenic biovectors such as crops should be considered in the global mercury cycle.

Fish consumption is considered to be the only significant dietary source of MeHg. Here the authors show that rice could also be a significant global dietary source, especially in South and Southeast Asia. International rice trade and joint ingestion of fish and rice could aggravate the MeHg exposure levels in many areas.

Solid waste management practice in a tourism destination - The status and challenges: A case study in Hoi An City, Vietnam

This study aims to present waste characterisation, solid waste management practice and analyse the challenges in the solid waste management system in the tourism destination of Hoi An City, Vietnam. The sampling and questionnaire surveys were conducted for measuring characterisation and management practice of solid waste. A material flow analysis method was used for analysing the waste flow. The results show that the tourism destination generated daily around 15080 kg t of waste, in which the significant proportions come from restaurants (46%), hotels (22%) and households (13%). The feature of the waste composition is high rates of kitchen waste (46.8%), tissue (11.54%) and recyclable materials (12.58%), which result in high moisture (46.79%) and a low heating value (16,866 kJ kg^-1) of waste. Also, solid waste management practices were evasively implemented by stakeholders with low rates and efficiency. Furthermore, a substantial gap of the solid waste management system is the confusion in waste collection activities, which is shown by the overload of waste in street bins and the financial loss for the solid waste management system owing to the non-compliance with collection regulation of stakeholders. Also, the mixing of waste by collection crews after separation at sources, the in-appropriation of collection time and manner are the dark points of the solid waste management system that may be causes of the non-cooperation of stakeholders. These gaps and confusion in the solid waste management system are the significant challenges in the improvement of the solid waste management system in the tourism destination toward sustainability.

Traditional Tibetan Medicine Induced High Methylmercury Exposure Level and Environmental Mercury Burden in Tibet, China

Highly elevated concentrations of total mercury (THg) and methylmercury (MeHg) were found in the municipal sewage in Tibet. Material flow analysis supports the hypothesis that these elevated concentrations are related to regular ingestion of Hg-containing Traditional Tibetan Medicine (TTM). In Tibet in 2015, a total of 3600 kg of THg was released from human body into the terrestrial environment as a result of TTM ingestion, amounting to 45% of the total THg release into the terrestrial environment in Tibet, hence substantially enhancing the environmental Hg burden. Regular ingestion of TTM leads to chronic exposure of Tibetans to inorganic Hg (IHg) and MeHg, which is 34 to 3000-fold and 0-12-fold higher than from any other known dietary sources, respectively. Application of a human physiology model demonstrated that ingestion of TTM can induce high blood IHg and MeHg levels in the human body. Moreover, 180 days would be required for the MeHg to be cleared out of the human body and return to the initial concentration i.e. prior to the ingestion of 1 TTM pill. Our analysis suggests that high Hg level contained in TTM could be harmful to human health and elevate the environmental Hg burden in Tibet.

Impact of Water-Induced Soil Erosion on the Terrestrial Transport and Atmospheric Emission of Mercury in China

Terrestrial mercury (Hg) transport, induced by water erosion and exacerbated by human activities, constitutes a major disturbance of the natural Hg cycle, but the processes are still not well understood. In this study, we modeled these processes using detailed information on erosion and Hg in soils and found that vast quantities of total Hg (THg) are being removed from land surfaces in China as a result of water erosion, which were estimated at 420 Mg/yr around 2010. This was significantly higher than the 240 Mg/yr mobilized around 1990. The erosion mechanism excavated substantial soil THg, which contributed to enhanced Hg(0) emissions to the atmosphere (4.9 Mg/yr around 2010) and its transport horizontally into streams (310 Mg/yr). Erosion-induced THg transport was driven by the extent of precipitation but was further enhanced or reduced by vegetation cover and land use changes in some regions. Surface air temperature may exacerbate the horizontal THg release into water. Our analyses quantified the processes of erosion-induced THg transport in terrestrial ecosystems, demonstrated its importance, and discussed how this transport is impacted by anthropogenic inputs and legacy THg in soils. We suggest that policy makers should pay more attention to legacy anthropogenic THg sources buried in soil.

Replacing Recycling Rates with Life-Cycle Metrics as Government Materials Management Targets

In Florida, the passing of the Energy, Climate Change, and Economic Security Act of 2008 established a statewide mass-based municipal solid waste recycling rate goal of 75% by 2020. In this study, we describe an alternative approach to tracking performance of materials management systems that incorporates life-cycle thinking. Using both greenhouse gas (GHG) emissions and energy use as life-cycle indicators, we create two different materials management baselines based on a hypothetical 75% recycling rate in Florida in 2008. GHG emission and energy use footprints resulting from various 2020 materials management strategies are compared to these baselines, with the results normalized to the same mass-based 75% recycling rate. For most scenarios, LCI-normalized recycling rates are greater than mass-based recycling rates. Materials management strategies that include recycling of curbside-collected materials such as metal, paper, and plastic result in the largest GHG- and energy-normalized recycling rates. Waste prevention or increase, determined as the net difference in per-person mass discard rate for individual materials, is a major contributor to the life-cycle-normalized recycling rates. The methodology outlined here provides policy makers with one means of transitioning to life-cycle thinking in state and local waste management goal setting and planning.

Increases of Total Mercury and Methylmercury Releases from Municipal Sewage into Environment in China and Implications

As a globally transported pollutant, mercury (Hg) released from human activity and methylmercury (MeHg) in the food web are global concerns due to their increasing presence in the environment. In this study, we found that Hg released from municipal sewage into the environment in China is a substantial anthropogenic source based on mass sampling throughout China. In total, 160 Mg (140-190 Mg, from the 20th percentile to the 80th percentile) of Hg (THg) and 280 kg (240-330 kg) of MeHg were released from municipal sewage in China in 2015. The quantities of released THg and MeHg were the most concentrated in the coastal regions, especially in the East, North and South China regions. However, the per capita release of THg and MeHg was the highest in the Tibetan region, which is recognized as the cleanest region in China. THg released into aquatic environments was mitigated from 2001 to 2015 in China, but the amounts released into other sinks increased. This study provides the first picture of the release of Hg from municipal sewage into various sinks in China, and policy makers should pay more attention to the diversity and complexity of the sources and transport of Hg, which can lead to Hg accumulation in the food web and can threaten human health.

Methods to estimate the transfer of contaminants into recycling products - A case study from Austria

Recycling of waste materials is desirable to reduce the consumption of limited primary resources, but also includes the risk of recycling unwanted, hazardous substances. In Austria, the legal framework demands secondary products must not present a higher risk than comparable products derived from primary resources. However, the act provides no definition on how to assess this risk potential. This paper describes the development of different quantitative and qualitative methods to estimate the transfer of contaminants in recycling processes. The quantitative methods comprise the comparison of concentrations of harmful substances in recycling products to corresponding primary products and to existing limit values. The developed evaluation matrix, which considers further aspects, allows for the assessment of the qualitative risk potential. The results show that, depending on the assessed waste fraction, particular contaminants can be critical. Their concentrations were higher than in comparable primary materials and did not comply with existing limit values. On the other hand, the results show that a long-term, well-established quality control system can assure compliance with the limit values. The results of the qualitative assessment obtained with the evaluation matrix support the results of the quantitative assessment. Therefore, the evaluation matrix can be suitable to quickly screen waste streams used for recycling to estimate their potential environmental and health risks. To prevent the transfer of contaminants into product cycles, improved data of relevant substances in secondary resources are necessary. In addition, regulations for material recycling are required to assure adequate quality control measures, including limit values.